WorldWideScience

Sample records for satellite receiving station

  1. Weather satellite picture receiving stations, APT digital scan converter

    Science.gov (United States)

    Vermillion, C. H.; Kamowski, J. C.

    1975-01-01

    The automatic picture transmission digital scan converter is used at ground stations to convert signals received from scanning radiometers to data compatible with ground equipment designed to receive signals from vidicons aboard operational meteorological satellites. Information necessary to understand the circuit theory, functional operation, general construction and calibration of the converter is provided. Brief and detailed descriptions of each of the individual circuits are included, accompanied by a schematic diagram contained at the end of each circuit description. Listings of integral parts and testing equipment required as well as an overall wiring diagram are included. This unit will enable the user to readily accept and process weather photographs from the operational meteorological satellites.

  2. Optimal link budget to maximize data receiving from remote sensing satellite at different ground stations

    Science.gov (United States)

    Godse, Vinay V.; Rukmini, B.

    2016-10-01

    Earth observation satellite plays a significant role for global situation awareness. The earth observation satellite uses imaging payloads in RF and IR bands, which carry huge amount of data, needs to be transferred during visibility of satellite over the ground station. Location of ground station plays a very important role in communication with LEO satellites, as orbital speed of LEO satellite is much higher than earth rotation speed. It will be accessible for particular equatorial ground station for a very short duration. In this paper we want to maximize data receiving by optimizing link budget and receiving data at higher elevation links. Data receiving at multiple ground stations is preferred to counter less pass duration due to higher elevation links. Our approach is to calculate link budget for remote sensing satellite with a fixed power input and varying different minimum elevation angles to obtain maximum data. The minimum pass duration should be above 3 minutes for effective communication. We are proposing to start process of command handling as soon as satellite is visible to particular ground station with low elevation angle up to 5 degree and start receiving data at higher elevation angles to receive data with higher speed. Cartosat-2B LEO earth observation satellite is taken for the case study. Cartosat-2B will complete around 14 passes over equator in a day, out of which only 4-5 passes will be useful for near equator ground stations. Our aim is to receive data at higher elevation angles at higher speed and increase amount of data download, criteria being minimum pass duration of 3 minutes, which has been set for selecting minimum elevation angle.

  3. Piracy of Satellite Signals by Domestic Receive-Only Earth Stations.

    Science.gov (United States)

    Homan, Steven D.

    Innovations in technology have enabled homeowners to pirate satellite signals intended for cable television operators through the use of home earth-stations. Section 605 of the Communications Act of 1934, which governs reception of signals, is inadequate to regulate this situation because it appears that publication of received programing outside…

  4. Low-cost approach for a software-defined radio based ground station receiver for CCSDS standard compliant S-band satellite communications

    Science.gov (United States)

    Boettcher, M. A.; Butt, B. M.; Klinkner, S.

    2016-10-01

    A major concern of a university satellite mission is to download the payload and the telemetry data from a satellite. While the ground station antennas are in general easy and with limited afford to procure, the receiving unit is most certainly not. The flexible and low-cost software-defined radio (SDR) transceiver "BladeRF" is used to receive the QPSK modulated and CCSDS compliant coded data of a satellite in the HAM radio S-band. The control software is based on the Open Source program GNU Radio, which also is used to perform CCSDS post processing of the binary bit stream. The test results show a good performance of the receiving system.

  5. Design of a Free and Open Source Data Processing, Archiving, and Distribution Subsystem for the Ground Receiving Station of the Philippine Scientific Earth Observation Micro-Satellite

    Science.gov (United States)

    Aranas, R. K. D.; Jiao, B. J. D.; Magallon, B. J. P.; Ramos, M. K. F.; Amado, J. A.; Tamondong, A. M.; Tupas, M. E. A.

    2016-06-01

    The Philippines's PHL-Microsat program aims to launch its first earth observation satellite, DIWATA, on the first quarter of 2016. DIWATA's payload consists of a high-precision telescope (HPT), spaceborne multispectral imager (SMI) with liquid crystal tunable filter (LCTF), and a wide field camera (WFC). Once launched, it will provide information about the Philippines, both for disaster and environmental applications. Depending on the need, different remote sensing products will be generated from the microsatellite sensors. This necessitates data processing capability on the ground control segment. Rather than rely on commercial turnkey solutions, the PHL-Microsat team, specifically Project 3:DPAD, opted to design its own ground receiving station data subsystems. This paper describes the design of the data subsystems of the ground receiving station (GRS) for DIWATA. The data subsystems include: data processing subsystem for automatic calibration and georeferencing of raw images as well as the generation of higher level processed data products; data archiving subsystem for storage and backups of both raw and processed data products; and data distribution subsystem for providing a web-based interface and product download facility for the user community. The design covers the conceptual design of the abovementioned subsystems, the free and open source software (FOSS) packages used to implement them, and the challenges encountered in adapting the existing FOSS packages to DIWATA GRS requirements.

  6. DESIGN OF A FREE AND OPEN SOURCE DATA PROCESSING, ARCHIVING, AND DISTRIBUTION SUBSYSTEM FOR THE GROUND RECEIVING STATION OF THE PHILIPPINE SCIENTIFIC EARTH OBSERVATION MICRO-SATELLITE

    Directory of Open Access Journals (Sweden)

    R. K. D. Aranas

    2016-06-01

    Full Text Available The Philippines’s PHL-Microsat program aims to launch its first earth observation satellite, DIWATA, on the first quarter of 2016. DIWATA’s payload consists of a high-precision telescope (HPT, spaceborne multispectral imager (SMI with liquid crystal tunable filter (LCTF, and a wide field camera (WFC. Once launched, it will provide information about the Philippines, both for disaster and environmental applications. Depending on the need, different remote sensing products will be generated from the microsatellite sensors. This necessitates data processing capability on the ground control segment. Rather than rely on commercial turnkey solutions, the PHL-Microsat team, specifically Project 3:DPAD, opted to design its own ground receiving station data subsystems. This paper describes the design of the data subsystems of the ground receiving station (GRS for DIWATA. The data subsystems include: data processing subsystem for automatic calibration and georeferencing of raw images as well as the generation of higher level processed data products; data archiving subsystem for storage and backups of both raw and processed data products; and data distribution subsystem for providing a web-based interface and product download facility for the user community. The design covers the conceptual design of the abovementioned subsystems, the free and open source software (FOSS packages used to implement them, and the challenges encountered in adapting the existing FOSS packages to DIWATA GRS requirements.

  7. 7 CFR 29.42 - Receiving station.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Regulations Definitions § 29.42 Receiving station. Points at which producer tobacco is offered for marketing (other than sale at auction on a designated market), including tobacco auction warehouses,...

  8. An SDR based AIS receiver for satellites

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Mortensen, Hans Peter; Nielsen, Jens Frederik Dalsgaard

    2011-01-01

    For a few years now, there has been a high interest in monitoring the global ship traffic from space. A few satellite, capable of listening for ship borne AIS transponders have already been launched, and soon the AAUSAT3, carrying two different types of AIS receivers will also be launched. One...... of the AIS receivers onboard AAUSAT3 is an SDR based AIS receiver. This paper serves to describe the background of the AIS system, and how the SDR based receiver has been integrated into the AAUSAT3 satellite. Amongst some of the benefits of using an SDR based receiver is, that due to its versatility, new...

  9. Enhanced AIS receiver design for satellite reception

    Science.gov (United States)

    Clazzer, Federico; Lázaro, Francisco; Plass, Simon

    2016-12-01

    The possibility to detect Automatic Identification System (AIS) messages from low earth orbit (LEO) satellites paves the road for a plurality of new and unexplored services. Besides worldwide tracking of vessels, maritime traffic monitoring, analysis of vessel routes employing big data, and oceans monitoring are just few of the fields, where satellite-aided AIS is beneficial. Designed for ship-to-ship communication and collision avoidance, AIS satellite reception performs poorly in regions with a high density of vessels. This calls for the development of advanced satellite AIS receivers able to improve the decoding capabilities. In this context, our contribution focuses on the introduction of a new enhanced AIS receiver design and its performance evaluation. The enhanced receiver makes use of a coherent receiver for the low signal-to-noise ratio (SNR) region, while for medium to high SNRs, a differential Viterbi receiver is used. Additional novelty of our work is in the exploitation of previously decoded packets from one vessel that is still under the LEO reception range, to improve the vessel detection probability. The assessment of the performance against a common receiver is done making the use of a simple and tight model of the medium access (MAC) layer and the multi-packet reception (MPR) matrix for physical layer (PHY) representation. Performance results show the benefits of such enhanced receiver, especially when it is bundled with successive interference cancellation (SIC).

  10. An SDR based AIS receiver for satellites

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Mortensen, Hans Peter; Nielsen, Jens Frederik Dalsgaard

    2011-01-01

    For a few years now, there has been a high interest in monitoring the global ship traffic from space. A few satellite, capable of listening for ship borne AIS transponders have already been launched, and soon the AAUSAT3, carrying two different types of AIS receivers will also be launched. One...... of the AIS receivers onboard AAUSAT3 is an SDR based AIS receiver. This paper serves to describe the background of the AIS system, and how the SDR based receiver has been integrated into the AAUSAT3 satellite. Amongst some of the benefits of using an SDR based receiver is, that due to its versatility, new...... detection algorithms are easily deployed, and it is easily adapted the new proposed AIS transmission channels....

  11. 47 CFR 25.220 - Non-conforming transmit/receive earth station operations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Non-conforming transmit/receive earth station... CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25.220 Non-conforming transmit/receive... operator acknowledging that the proposed operation of the subject non-conforming earth station with...

  12. Direct broadcast satellite-radio, receiver development

    Science.gov (United States)

    Vaisnys, A.; Bell, D.; Gevargiz, J.; Golshan, Nasser

    1993-01-01

    The status of the ongoing Direct Broadcast Satellite-Radio (DBS-R) Receiver Development Task being performed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) is reported. This work is sponsored by the Voice of America/U.S. Information Agency through an agreement with NASA. The objective of this task is to develop, build, test, and demonstrate a prototype receiver that is compatible with reception of digital audio programs broadcast via satellites. The receiver is being designed to operate under a range of reception conditions, including fixed, portable, and mobile, as well as over a sufficiently wide range of bit rates to accommodate broadcasting systems with different cost/audio quality objectives. While the requirements on the receiver are complex, the eventual goal of the design effort is to make the design compatible with low cost production as a consumer product. One solution may be a basic low cost core design suitable for a majority of reception conditions, with optional enhancements for reception in especially difficult environments. Some of the receiver design parameters were established through analysis, laboratory tests, and a prototype satellite experiment accomplished in late 1991. Many of the necessary design trades will be made during the current simulation effort, while a few of the key design options will be incorporated into the prototype for evaluation during the planned satellite field trials.

  13. Direct broadcast satellite-radio, receiver development

    Science.gov (United States)

    Vaisnys, A.; Bell, D.; Gevargiz, J.; Golshan, Nasser

    The status of the ongoing Direct Broadcast Satellite-Radio (DBS-R) Receiver Development Task being performed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) is reported. This work is sponsored by the Voice of America/U.S. Information Agency through an agreement with NASA. The objective of this task is to develop, build, test, and demonstrate a prototype receiver that is compatible with reception of digital audio programs broadcast via satellites. The receiver is being designed to operate under a range of reception conditions, including fixed, portable, and mobile, as well as over a sufficiently wide range of bit rates to accommodate broadcasting systems with different cost/audio quality objectives. While the requirements on the receiver are complex, the eventual goal of the design effort is to make the design compatible with low cost production as a consumer product. One solution may be a basic low cost core design suitable for a majority of reception conditions, with optional enhancements for reception in especially difficult environments. Some of the receiver design parameters were established through analysis, laboratory tests, and a prototype satellite experiment accomplished in late 1991. Many of the necessary design trades will be made during the current simulation effort, while a few of the key design options will be incorporated into the prototype for evaluation during the planned satellite field trials.

  14. BeiDou Satellites Assistant Determination by Receiving Other GNSS Downlink Signals

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2016-01-01

    Full Text Available GNSS’s orbit determinations always rely on ground station or intersatellite links (ISL. In the emergency of satellite-to-ground links and ISL break-off, BeiDou navigation satellite system (BDS satellites cannot determine their orbits. In this paper, we propose to add a spaceborne annular beam antenna for receiving the global positioning system (GPS and global navigation satellite system (GLONASS signals; therefore, the BDS satellites may be capable of determining their orbits by GPS/GLONASS signals. Firstly, the spectrum selection, the power isolation, the range of Doppler frequency shift, and changing rate are taken into account for the feasibility. Specifically, the L2 band signals are chosen for receiving and processing in order to prevent the overlapping of the receiving and transmitting signals. Secondly, the minimum number of visible satellites (MNVS, carrier-to-noise ratio (C/N0, dilution of precision (GDOP, and geometric distance root-mean-square (gdrms are evaluated for acquiring the effective receiving antennas’ coverage ranges. Finally, the scheme of deploying 3 receiving antennas is proved to be optimal by analysis and simulations over the middle earth orbit (MEO, geostationary earth orbit (GEO, and the inclined geosynchronous satellite orbit (IGSO. The antennas’ structures and patterns are designed to draw a conclusion that installing GPS and GLONASS receivers on BDS satellites for emergent orbits determination is cost-effective.

  15. Blossom Point Satellite Tracking and Command Station

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: The Blossom Point Satellite Command and Tracking Facility (BP) provides engineering and operational support to several complex space systems for the Navy...

  16. On Satellite Multicast to Heterogeneous Receivers

    Science.gov (United States)

    2001-01-01

    combined into one bulk file. Let the multicast source use Reed-Solomon erasure ( RSE ) coding (e.g. [Mac97]) and let the bulk file be encoded into W ≥ 1... RSE -based FEC blocks. Each FEC block consists of h data packets and c parity packets – all of the same length. We assume a multicast tree that has a... RSE -based FEC block, a receiver must receive at least h distinct packets, either data or parity, from the same FEC block. To allow a systematic way

  17. A Collective Detection Based GPS Receiver for Small Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To solve the problem of autonomous navigation on small satellite platforms less than 20 kg, we propose to develop an onboard orbit determination receiver for small...

  18. POSITION ERROR IN STATION-KEEPING SATELLITE

    Science.gov (United States)

    of an error in satellite orientation and the sun being in a plane other than the equatorial plane may result in errors in position determination. The nature of the errors involved is described and their magnitudes estimated.

  19. Bit Error Rate Due to Misalignment of Earth Station Antenna Pointing to Satellite

    Directory of Open Access Journals (Sweden)

    Wahyu Pamungkas

    2010-04-01

    Full Text Available One problem causing reduction of energy in satellite communications system is the misalignment of earth station antenna pointing to satellite. Error in pointing would affect the quality of information signal to energy bit in earth station. In this research, error in pointing angle occurred only at receiver (Rx antenna, while the transmitter (Tx antennas precisely point to satellite. The research was conducted towards two satellites, namely TELKOM-1 and TELKOM-2. At first, measurement was made by directing Tx antenna precisely to satellite, resulting in an antenna pattern shown by spectrum analyzer. The output from spectrum analyzers is drawn with the right scale to describe swift of azimuth and elevation pointing angle towards satellite. Due to drifting from the precise pointing, it influenced the received link budget indicated by pattern antenna. This antenna pattern shows reduction of power level received as a result of pointing misalignment. As a conclusion, the increasing misalignment of pointing to satellite would affect in the reduction of received signal parameters link budget of down-link traffic.

  20. Optimization and Feasibility Analysis of Satellite Earth Station Power System Using Homer

    Directory of Open Access Journals (Sweden)

    Hassen T. Dorrah

    2012-06-01

    Full Text Available Satellite earth stations which located in remote areas are one of many applications powered by the renewable energy sources. Ground system consists of ground station and control centers working together to support the spacecraft and the data user. Earth station consists of major subsystems, transmitter, receiver, antenna, tracking equipment, terrestrial interface equipment and power supply. Power subsystem is an important part that required for supplying the earth station with electrical power to continue communicating with its remote sensing satellite. This paper deals with simulation and optimal sizing of earth station power system using HOMER software. A combination of two energy sources (solar, and wind to provide a continuous electric power production is used to determine the optimum system operation. Three system configurations are compared with respect to the total net present cost (NPC and levelized cost of energy (COE. Also, economical study will be analyzed for energy demand and sensitivity analysis will be performed.

  1. Optimization and Feasibility Analysis of Satellite Earth Station Power System Using Homer

    Directory of Open Access Journals (Sweden)

    Hassen T. Dorrah

    2012-06-01

    Full Text Available Satellite earth stations which located in remote areas are one of many applications powered by the renewable energy sources. Ground system consists of ground station and control centers working together to support the spacecraft and the data user. Earth station consists of major subsystems, transmitter, receiver, antenna, tracking equipment, terrestrial interface equipment and power supply. Power subsystem is an important part that required for supplying the earth station with electrical power to continue communicating with its remote sensing satellite. This paper deals with simulation and optimal sizing of earth station power system using HOMER software. A combination of two energy sources (solar, and wind to provide a continuous electric power production is used to determine the optimum system operation. Three system configurations are compared with respect to the total net present cost (NPC and levelized cost of energy (COE. Also, economical study will be analyzed for energy demand and sensitivity analysis will be performed.

  2. Direct broadcast satellite-radio, space-segment/receiver tradeoffs

    Science.gov (United States)

    Golshan, Nasser

    1993-01-01

    The balance between receiver complexity and the required satellite equivalent isotropically radiated power (EIRP) for Direct Broadcast Satellite-Radio (DBS-R) service is addressed. In general the required receiver complexity and cost can be reduced at the expense of higher space-segment cost by allowing a higher satellite EIRP. The tradeoff outcome is sensitive to the total number of anticipated receivers in a given service area, the number of audio programs, and the required audio quality. An understanding of optimum choice of satellite EIRP for DBS-R under various service requirements is a critical issue at this time when International Radio Consultative Committee (CCIR) is soliciting input in preparation for the International Telecommunications Union (ITU) planning conference for the service.

  3. 47 CFR 80.333 - Stations in the maritime mobile-satellite service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Stations in the maritime mobile-satellite..., Alarm, Urgency and Safety Procedures § 80.333 Stations in the maritime mobile-satellite service. The...-satellite service....

  4. 78 FR 39200 - Federal Earth Stations-Non-Federal Fixed Satellite Service Space Stations; Spectrum for Non...

    Science.gov (United States)

    2013-07-01

    ...-11341; FCC 13-65] Federal Earth Stations--Non-Federal Fixed Satellite Service Space Stations; Spectrum... interference protection for Fixed-Satellite Service (FSS) and Mobile- Satellite Service (MSS) earth stations... and the important role it will play in our nation's economy and technological innovation now and in...

  5. Co-Channel Interference Mitigation Using Satellite Based Receivers

    Science.gov (United States)

    2014-12-01

    While there is some phase noise present in the continuous time-shifted signal, it is important to recognize that this signal is plotted over the [−π...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS CO-CHANNEL INTERFERENCE MITIGATION USING SATELLITE BASED RECEIVERS by John E. Patterson...07-02-2012 to 12-19-2014 4. TITLE AND SUBTITLE CO-CHANNEL INTERFERENCE MITIGATION USING SATELLITE BASED RE- CEIVERS 5. FUNDING NUMBERS 6. AUTHOR(S

  6. 47 CFR 25.140 - Qualifications of fixed-satellite space station licensees.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Qualifications of fixed-satellite space station... CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Space Stations § 25.140 Qualifications of fixed-satellite space station licensees. (a) New fixed-satellites shall comply with...

  7. 47 CFR 80.1185 - Supplemental eligibility for mobile-satellite stations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Supplemental eligibility for mobile-satellite...-Satellite Stations § 80.1185 Supplemental eligibility for mobile-satellite stations. Stations in the maritime mobile-satellite service must meet the eligibility requirements contained in this section. (a)...

  8. Results of the Ongoing Monitoring of the Position of a Geostationary Telecommunication Satellite by the Method of Spatially Separated Basis Receiving of Digital Satellite Television Signals

    Science.gov (United States)

    Bushuev, F.; Kaliuzhnyi, M.; Sybiryakova, Y.; Shulga, O.; Moskalenko, S.; Balagura, O.; Kulishenko, V.

    2016-10-01

    The results of the ongoing monitoring of the position of geostationary telecommunication satellite Eutelsat-13B (13° East) are presented in the article. The results were obtained using a radio engineering complex (RC) of four stations receiving digital satellite television and a data processing centre. The stations are located in Kyiv, Mukachevo, Kharkiv and Mykolaiv. The equipment of each station allows synchronous recording (by the GPS) of fragments of DVB-S signal from the quadrature detector output of the satellite television receiver. Samples of the complex signal are archived and sent to the data processing center through the Internet. Here three linearly independent slant range differences (Δr) for three pairs of the stations are determined as a result of correlation processing of received signals. Every second measured values of Δr are used to calculate Cartesian coordinates (XYZ) of the satellite in the coordinate system WGS84 by multilateration method. The time series of Δr, X, Y and Z obtained during continuous observations from March to May 2015 are presented in the article. Single-measurement errors of Δr, X, Y and Z are equal to 2.6 m, 3540 m, 705 m and 455 m, respectively. The complex is compared with known analogues. Ways of reduction of measurement errors of satellite coordinates are considered. The radio engineering complex could be considered a prototype of a system of independent ongoing monitoring of the position of geostationary telecommunication satellites.

  9. Prototype Environmental Assessment of the impacts of siting and construction of an SPS ground receiving station

    Science.gov (United States)

    Hill, J.

    1980-01-01

    A prototype assessment of the environmental impacts of siting and constructing a Satellite Power System (SPS) Ground Receiving Station (GRS) is reported. The objectives of the study were: (1) to develop an assessment of the nonmicrowave related impacts of the reference system SPS GRS on the natural environment; (2) to assess the impacts of GRS construction and operations in the context of actual baseline data for a site in the California desert; and (3) to identify critical GRS characteristics or parameters that are most significant in terms of the natural environment.

  10. Performance of mismatched Viterbi receiver on satellite channels

    Science.gov (United States)

    Divsalar, D.; Omura, J. K.

    1979-01-01

    This paper presents an analysis of a satellite communication system using a Viterbi receiver. Here we have a bandlimited nonlinear channel where both uplink and downlink are taken into account as well as the effect of Intersymbol Interference, phase and time synchronization errors. In order that ISI can be combatted effectively, we use a Viterbi demodulator which is designed for the satellite channel when there is no uplink noise. The Viterbi demodulator for the channels with large memory is too complex to be implemented. To reduce the complexity, a Viterbi demodulator with memory shorter than the true channel memory is used. The objective of this paper is to analyze the performance degradation of this 'Mismatched Viterbi Receiver' due to the uplink noise and memory truncation, and to understand how the time and phase synchronization errors influence the performance.

  11. 78 FR 14920 - Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-08

    ... forwarding and receiving communications signals via a system of satellites or reselling satellite... specialized telecommunications services, such as satellite tracking, communications telemetry, and radar... of Subjects in 47 CFR Parts 2 and 25 Frequency allocations, Satellites. Federal Communications...

  12. Engineering satellite-based navigation and timing global navigation satellite systems, signals, and receivers

    CERN Document Server

    Betz, J

    2016-01-01

    This book describes the design and performance analysis of satnav systems, signals, and receivers. It also provides succinct descriptions and comparisons of all the world’s satnav systems. Its comprehensive and logical structure addresses all satnav signals and systems in operation and being developed. Engineering Satellite-Based Navigation and Timing: Global Navigation Satellite Systems, Signals, and Receivers provides the technical foundation for designing and analyzing satnav signals, systems, and receivers. Its contents and structure address all satnav systems and signals: legacy, modernized, and new. It combines qualitative information with detailed techniques and analyses, providing a comprehensive set of insights and engineering tools for this complex multidisciplinary field. Part I describes system and signal engineering including orbital mechanics and constellation design, signal design principles and underlying considerations, link budgets, qua tifying receiver performance in interference, and e...

  13. Integrated Cryogenic Satellite Communications Cross-Link Receiver Experiment

    Science.gov (United States)

    Romanofsky, R. R.; Bhasin, K. B.; Downey, A. N.; Jackson, C. J.; Silver, A. H.; Javadi, H. H. S.

    1995-01-01

    An experiment has been devised which will validate, in space, a miniature, high-performance receiver. The receiver blends three complementary technologies; high temperature superconductivity (HTS), pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuits (MMIC), and a miniature pulse tube cryogenic cooler. Specifically, an HTS band pass filter, InP MMIC low noise amplifier, HTS-sapphire resonator stabilized local oscillator (LO), and a miniature pulse tube cooler will be integrated into a complete 20 GHz receiver downconverter. This cooled downconverter will be interfaced with customized signal processing electronics and integrated onto the space shuttle's 'HitchHiker' carrier. A pseudorandom data sequence will be transmitted to the receiver, which is in low Earth orbit (LEO), via the Advanced Communication Technology Satellite (ACTS) on a 20 GHz carrier. The modulation format is QPSK and the data rate is 2.048 Mbps. The bit error rate (BER) will be measured in situ. The receiver is also equipped with a radiometer mode so that experiment success is not totally contingent upon the BER measurement. In this mode, the receiver uses the Earth and deep space as a hot and cold calibration source, respectively. The experiment closely simulates an actual cross-link scenario. Since the receiver performance depends on channel conditions, its true characteristics would be masked in a terrestrial measurement by atmospheric absorption and background radiation. Furthermore, the receiver's performance depends on its physical temperature, which is a sensitive function of platform environment, thermal design, and cryocooler performance. This empirical data is important for building confidence in the technology.

  14. Reduced Precision Redundancy for Satellite Telecommand Receiver Module on FPGA

    Directory of Open Access Journals (Sweden)

    Salman Sadruddin

    2013-01-01

    Full Text Available A novel and highly efficient design of a software defined radiation tolerant baseband module for a LEO satellite telecommand receiver using FPGA is presented. FPGAs in space are subject to single event upsets (SEUs due to high radiation environment. Traditionally, triple modular redundancy (TMR is used for mitigating Single Event Upsets (SEUs. The drawback of using TMR is that it consumes a lot of hardware resources and requires more power. Reduced precision redundancy (RPR can be a viable alternative of TMR in digital systems for arithmetic operations. This paper uses the combination of RPR and TMR for mitigating SEUs. The designed module consumes less resources on FPGA and has bit error rate (BER identical to theoretical results, apart from degradation due to implementation losses. An improved Costas loop and timing recovery algorithm are implemented for achieving carrier recovery and bit synchronization. The hybrid approach mitigates SEUs while consuming 26% less resources than a customary TMR protected receiver.

  15. 78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-08

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 2 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications Commission. ACTION: Proposed rule....

  16. Transportable IOT measurement station for direct-broadcast satellites

    Science.gov (United States)

    Ulbricht, Michael

    A transportable 11.7-12.5-GHz flux-density measurement facility for use in the in-orbit testing (IOT) of the FRG TV-Sat direct-broadcast satellites is described. Major components include a 1.2-m-diameter antenna, the fluxmeter, a radiometer to determine atmospheric attenuation, a weather station, and a control and data-processing computer; all of the components are mounted on a 5.10 x 2.35 x 2.70-m trailer. IOT performance parameters include gain/temperature ratio 15.9 dB/K, measurement range -97 to -117 dBW/sq m, measurement accuracy less than 0.5 dB rms, and measurement rate 250-650 msec. Photographs and a block diagram are provided.

  17. Robustness of a TETRA base station receiver against intentional EMI

    NARCIS (Netherlands)

    Beek, van de Stefan; Leferink, Frank

    2015-01-01

    Terrestrial trunked radio (TETRA) is a digital radio standard that was developed to meet the needs of professional mobile radio systems. TETRA is vulnerable to intentional electromagnetic interference (EMI) because of the wireless link. The EMI can easily be front door coupled to the base station vi

  18. SCaN Network Ground Station Receiver Performance for Future Service Support

    Science.gov (United States)

    Estabrook, Polly; Lee, Dennis; Cheng, Michael; Lau, Chi-Wung

    2012-01-01

    Objectives: Examine the impact of providing the newly standardized CCSDS Low Density Parity Check (LDPC) codes to the SCaN return data service on the SCaN SN and DSN ground stations receivers: SN Current Receiver: Integrated Receiver (IR). DSN Current Receiver: Downlink Telemetry and Tracking (DTT) Receiver. Early Commercial-Off-The-Shelf (COTS) prototype of the SN User Service Subsystem Component Replacement (USS CR) Narrow Band Receiver. Motivate discussion of general issues of ground station hardware design to enable simple and cheap modifications for support of future services.

  19. Teachers guide for building and operating weather satellite ground stations for high school science

    Science.gov (United States)

    Summers, R. J.; Gotwald, T.

    1981-01-01

    A number of colleges and universities are operating APT direct readout stations. However, high school science teachers have often failed to realize the potential of meteorological satellites and their products as unique instructional tools. The ability to receive daily pictures from these satellites offers exciting opportunities for secondary school teachers and students to assemble the electronic hardware and to view real time pictures of Earth from outer space. The station and pictures can be used in the classroom to develop an approach to science teaching that could span many scientific disciplines and offer many opportunities for student research and participation in scientific processes. This can be accomplished with relatively small expenditures of funds for equipment. In most schools some of the equipment may already be available. Others can be constructed by teachers and/or students. Yet another source might be the purchase of used equipment from industry or through the government surplus channels. The information necessary for individuals unfamiliar with these systems to construct a direct readout for receiving real time APT photographs on a daily basis in the classroom is presented.

  20. BeiDou Inter-Satellite-Type Bias Evaluation and Calibration for Mixed Receiver Attitude Determination

    Directory of Open Access Journals (Sweden)

    Noor Raziq

    2013-07-01

    Full Text Available The Chinese BeiDou system (BDS, having different types of satellites, is an important addition to the ever growing system of Global Navigation Satellite Systems (GNSS. It consists of Geostationary Earth Orbit (GEO satellites, Inclined Geosynchronous Satellite Orbit (IGSO satellites and Medium Earth Orbit (MEO satellites. This paper investigates the receiver-dependent bias between these satellite types, for which we coined the name “inter-satellite-type bias” (ISTB, and its impact on mixed receiver attitude determination. Assuming different receiver types may have different delays/biases for different satellite types, we model the differential ISTBs among three BeiDou satellite types and investigate their existence and their impact on mixed receiver attitude determination. Our analyses using the real data sets from Curtin’s GNSS array consisting of different types of BeiDou enabled receivers and series of zero-baseline experiments with BeiDou-enabled receivers reveal the existence of non-zero ISTBs between different BeiDou satellite types. We then analyse the impact of these biases on BeiDou-only attitude determination using the constrained (C-LAMBDA method, which exploits the knowledge of baseline length. Results demonstrate that these biases could seriously affect the integer ambiguity resolution for attitude determination using mixed receiver types and that a priori correction of these biases will dramatically improve the success rate.

  1. 47 CFR 25.215 - Technical requirements for space stations in the Direct Broadcast Satellite Service.

    Science.gov (United States)

    2010-10-01

    ... the Direct Broadcast Satellite Service. 25.215 Section 25.215 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25.215 Technical requirements for space stations in the Direct Broadcast Satellite Service. In addition to §...

  2. Program on application of communications satellites to educational development: Design of a 12 channel FM microwave receiver. [color television from communication satellites

    Science.gov (United States)

    Risch, C. O.; Rosenbaum, F. J.; Gregory, R. O.

    1974-01-01

    The design, fabrication, and performance of elements of a low cost FM microwave satellite ground station receiver is described. It is capable of accepting 12 contiguous color television equivalent bandwidth channels in the 11.72 to 12.2 GHz band. Each channel is 40 MHz wide and incorporates a 4 MHz guard band. The modulation format is wideband FM and the channels are frequency division multiplexed. Twelve independent CATV compatible baseband outputs are provided. The overall system specifications are first discussed, then consideration is given to the receiver subsystems and the signal branching network.

  3. A DTN-ready application for the real-time dissemination of Earth Observation data received by Direct Readout stations

    Science.gov (United States)

    Paronis, Dimitris; Daglis, Ioannis A.; Diamantopoulos, Sotirios; Tsaoussidis, Vassilis; Tsigkanos, Antonis; Ghita, Bogdan; Evans, Michael

    2014-05-01

    The majority of Earth observation satellites operate in low Earth sun-synchronous orbit and transmit data captured by a variety of sensors. The effective dissemination of satellite data in real-time is a crucial parameter for disaster monitoring in particular. Generally, a spacecraft collects data and then stores it on-board until it passes over dedicated ground stations to transmit the data. Additionally, some satellites (e.g. Terra, Aqua, Suomi-NPP, NOAA series satellites) have the so-called Direct Broadcast (DB) capability, which is based on a real-time data transmission sub-system. Compatible Direct Readout (DR) stations in direct line of sight are able to receive these transmissions. To date data exchange between DR stations have not been fully exploited for real-time data dissemination. Stations around the world store data locally, which is then disseminated on demand via Internet gateways based on the standard TCP-IP protocols. On the other hand, Delay Tolerant Networks (DTNs), which deliver data by enabling store-and-forward transmission in order to cope with link failures, service disruptions and network congestion, could prove as an alternative/complementary transmission mechanism for the efficient dissemination of data. The DTN architecture allows for efficient utilization of the network, using in-network storage and taking advantage of the network availability among the interconnected nodes. Although DTNs were originally developed for high-propagation delay, challenged connectivity environments such as deep space, the broader research community has investigated possible architectural enhancements for various emerging applications (e.g., terrestrial infrastructure, ground-to-air communications, content retrieval and dissemination). In this paper, a scheme for the effective dissemination of DB data is conceptualized, designed and implemented based on store-and-forward transmission capabilities provided by DTNs. For demonstration purposes, a set-up has

  4. A Neural Network MLSE Receiver Based on Natural Gradient Descent: Application to Satellite Communications

    Directory of Open Access Journals (Sweden)

    Ibnkahla Mohamed

    2004-01-01

    Full Text Available The paper proposes a maximum likelihood sequence estimator (MLSE receiver for satellite communications. The satellite channel model is composed of a nonlinear traveling wave tube (TWT amplifier followed by a multipath propagation channel. The receiver is composed of a neural network channel estimator (NNCE and a Viterbi detector. The natural gradient (NG descent is used for training. Computer simulations show that the performance of our receiver is close to the ideal MLSE receiver in which the channel is perfectly known.

  5. The Design and Application of Data Storage System in Miyun Satellite Ground Station

    Science.gov (United States)

    Xue, Xiping; Su, Yan; Zhang, Hongbo; Liu, Bin; Yao, Meijuan; Zhao, Shu

    2015-04-01

    China has launched Chang'E-3 satellite in 2013, firstly achieved soft landing on moon for China's lunar probe. Miyun satellite ground station firstly used SAN storage network system based-on Stornext sharing software in Chang'E-3 mission. System performance fully meets the application requirements of Miyun ground station data storage.The Stornext file system is a sharing file system with high performance, supports multiple servers to access the file system using different operating system at the same time, and supports access to data on a variety of topologies, such as SAN and LAN. Stornext focused on data protection and big data management. It is announced that Quantum province has sold more than 70,000 licenses of Stornext file system worldwide, and its customer base is growing, which marks its leading position in the big data management.The responsibilities of Miyun satellite ground station are the reception of Chang'E-3 satellite downlink data and management of local data storage. The station mainly completes exploration mission management, receiving and management of observation data, and provides a comprehensive, centralized monitoring and control functions on data receiving equipment. The ground station applied SAN storage network system based on Stornext shared software for receiving and managing data reliable.The computer system in Miyun ground station is composed by business running servers, application workstations and other storage equipments. So storage systems need a shared file system which supports heterogeneous multi-operating system. In practical applications, 10 nodes simultaneously write data to the file system through 16 channels, and the maximum data transfer rate of each channel is up to 15MB/s. Thus the network throughput of file system is not less than 240MB/s. At the same time, the maximum capacity of each data file is up to 810GB. The storage system planned requires that 10 nodes simultaneously write data to the file system through 16

  6. GPS satellite and receiver instrumental biases estimation using least squares method for accurate ionosphere modelling

    Indian Academy of Sciences (India)

    G Sasibhushana Rao

    2007-10-01

    The positional accuracy of the Global Positioning System (GPS)is limited due to several error sources.The major error is ionosphere.By augmenting the GPS,the Category I (CAT I)Precision Approach (PA)requirements can be achieved.The Space-Based Augmentation System (SBAS)in India is known as GPS Aided Geo Augmented Navigation (GAGAN).One of the prominent errors in GAGAN that limits the positional accuracy is instrumental biases.Calibration of these biases is particularly important in achieving the CAT I PA landings.In this paper,a new algorithm is proposed to estimate the instrumental biases by modelling the TEC using 4th order polynomial.The algorithm uses values corresponding to a single station for one month period and the results confirm the validity of the algorithm.The experimental results indicate that the estimation precision of the satellite-plus-receiver instrumental bias is of the order of ± 0.17 nsec.The observed mean bias error is of the order − 3.638 nsec and − 4.71 nsec for satellite 1 and 31 respectively.It is found that results are consistent over the period.

  7. Fault Detection and Isolation of Satellite Formations using a Ground Station Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development a fault detection and isolation (FDI) algorithm for a formation of satellites but processed at a ground station. The algorithm...

  8. Expected Position Error for an Onboard Satellite GPS Receiver

    Science.gov (United States)

    2015-03-01

    that supports GPS, Galileo, Global’naya Navigatsionnaya Sputnikovaya Sistema (GLONASS), and Quasi-Zenith Satellite System GNSSs. It is designed as a...compared to the main beam half cone angle listed in the GPS Interface Control Document (ICD) [19]. 29 Sidelobes Considered. Power in the sidelobes is...Centered Inertial ENU East-North-Up GDOP Geometric Dilution of Precision GEO Geostationary Orbit GLONASS Global’naya Navigatsionnaya Sputnikovaya Sistema

  9. Economic benefits of the Space Station to commercial communication satellite operators

    Science.gov (United States)

    Price, Kent M.; Dixson, John E.; Weyandt, Charles J.

    1987-01-01

    The economic and financial aspects of newly defined space-based activities, procedures, and operations (APOs) and associated satellite system designs are presented that have the potential to improve economic performance of future geostationary communications satellites. Launch insurance, launch costs, and the economics of APOs are examined. Retrieval missions and various Space Station scenarios are addressed. The potential benefits of the new APOs to the commercial communications satellite system operator are quantified.

  10. East–West GEO Satellite Station-Keeping with Degraded Thruster Response

    OpenAIRE

    Stoian Borissov; Yunhe Wu; Daniele Mortari

    2015-01-01

    The higher harmonic terms of Earth’s gravitational potential slowly modify the nominal longitude of geostationary Earth orbit (GEO) satellites, while the third-body presence (Moon and Sun) mainly affects their latitude. For this reason, GEO satellites periodically need to perform station-keeping maneuvers, namely, east–west and north–south maneuvers to compensate for longitudinal and latitudinal variations, respectively. During the operational lifetime of GEO satellites, the thrusters’ respon...

  11. 78 FR 19172 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit...

    Science.gov (United States)

    2013-03-29

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Parts 2 and 25 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit Space Stations AGENCY: Federal Communications Commission. ACTION: Proposed rule;...

  12. Data communications method for mobile network in fourth generation communications system, involves delivering decoded data to mobile station from relay station, where mobile station receives data from both relay and base stations

    DEFF Research Database (Denmark)

    2008-01-01

    The method involves utilizing a base station (BS) (100) to transmit data to a relay station (RS) (110) and a mobile station (MS) (120), where the data includes two messages. The BS is utilized to transmit the two messages by utilizing a linear combination method, and the data is received in the R...

  13. A 12 GHz satellite video receiver: Low noise, low cost prototype model for TV reception from broadcast satellites

    Science.gov (United States)

    Hreha, M. A.; Baprawski, J. G.; Chamaneria, C. N.; Ferry, S. J.; Keithly, G.; Kuklin, H. S.; Lockyear, W. H.; Schifter, L. H.; Swanberg, N. E.; Swift, G. W.

    1978-01-01

    A 12-channel synchronous phase lock video receiver consisting of an outdoor downconverter unit and an indoor demodulator unit was developed to provide both low noise performance and low cost in production quantities of 1000 units. The prototype receiver can be mass produced at a cost under $1540 without sacrificing system performance. The receiver also has the capability of selecting any of the twelve assigned satellite broadcast channels in the frequency range 11.7 to 12.2 GHz.

  14. The 30 GHz communications satellite low noise receiver

    Science.gov (United States)

    Steffek, L. J.; Smith, D. W.

    1983-10-01

    A Ka-band low noise front end in proof of concept (POC) model form for ultimate spaceborne communications receiver deployment was developed. The low noise receiver consists of a 27.5 to 30.0 GHz image enhanced mixer integrated with a 3.7 to 6.2 GHz FET low noise IF amplifier and driven by a self contained 23.8 GHz phase locked local oscillator source. The measured level of receiver performance over the 27.3 to 30.0 GHz RF/3.7 to 6.2 GHz IF band includes 5.5 to 6.5 dB (typ) SSB noise figure, 20.5 + or - 1.5 dB conversion gain and +23 dBm minimum third order two tone intermodulation output intercept point.

  15. Application of Single-Mode Fiber-Coupled Receivers in Optical Satellite to High-Altitude Platform Communications

    Directory of Open Access Journals (Sweden)

    Oswald Wallner

    2008-05-01

    Full Text Available In a free-space optical communication system employing fiber-optic components, the phasefront distortions induced by atmospheric turbulence limit the efficiency with which the laser beam is coupled into a single-mode fiber. We analyze different link scenarios including a geostationary (GEO satellite, a high-altitude platform (HAP, and an optical ground station (OGS. Single-mode coupled optically preamplified receivers allow for efficient suppression of background noise and highly sensitive detection. While GEO-to-OGS communication suffers from atmospheric turbulence, we demonstrate that GEO-to-HAP communication allows for close to diffraction-limited performance when applying tip-tilt correction.

  16. Application of Single-Mode Fiber-Coupled Receivers in Optical Satellite to High-Altitude Platform Communications

    Directory of Open Access Journals (Sweden)

    Fidler Franz

    2008-01-01

    Full Text Available Abstract In a free-space optical communication system employing fiber-optic components, the phasefront distortions induced by atmospheric turbulence limit the efficiency with which the laser beam is coupled into a single-mode fiber. We analyze different link scenarios including a geostationary (GEO satellite, a high-altitude platform (HAP, and an optical ground station (OGS. Single-mode coupled optically preamplified receivers allow for efficient suppression of background noise and highly sensitive detection. While GEO-to-OGS communication suffers from atmospheric turbulence, we demonstrate that GEO-to-HAP communication allows for close to diffraction-limited performance when applying tip-tilt correction.

  17. An Active K-Band Receive Slot Array for Mobile Satellite Communications

    Science.gov (United States)

    Tulintseff, A. N.; Lee, K. A.; Sukamto, L. M.; Chew, W.

    1994-01-01

    An active receive slot array has been developed for operation in the downlink frequency band, 19.914-20.064 GHz, of NASA's Advanced Communication Technology Satellite (ACTS) for the ACTS Mobile Terminal (AMT) project.

  18. 37 CFR 258.4 - Royalty fee for secondary transmission of digital signals of broadcast stations by satellite...

    Science.gov (United States)

    2010-07-01

    ... transmission of digital signals of broadcast stations by satellite carriers. 258.4 Section 258.4 Patents... AND PROCEDURES ADJUSTMENT OF ROYALTY FEE FOR SECONDARY TRANSMISSIONS BY SATELLITE CARRIERS § 258.4 Royalty fee for secondary transmission of digital signals of broadcast stations by satellite carriers....

  19. 37 CFR 258.3 - Royalty fee for secondary transmission of analog signals of broadcast stations by satellite...

    Science.gov (United States)

    2010-07-01

    ... transmission of analog signals of broadcast stations by satellite carriers. 258.3 Section 258.3 Patents... AND PROCEDURES ADJUSTMENT OF ROYALTY FEE FOR SECONDARY TRANSMISSIONS BY SATELLITE CARRIERS § 258.3 Royalty fee for secondary transmission of analog signals of broadcast stations by satellite carriers....

  20. Neural Network Based Lna Design for Mobile Satellite Receiver

    Directory of Open Access Journals (Sweden)

    Abhijeet Upadhya

    2014-08-01

    Full Text Available Paper presents a Neural Network Modelling approach to microwave LNA design. To acknowledge the specifications of the amplifier, Mobile Satellite Systems are analyzed. Scattering parameters of the LNA in the frequency range 0.5 to 18 GHz are calculated using a Multilayer Perceptron Artificial Neural Network model and corresponding smith charts and polar charts are plotted as output to the model. From these plots, the microwave scattering parameter description of the LNA are obtained. Model is efficiently trained using Agilent ATF 331M4 InGaAs/InP Low Noise pHEMT amplifier datasheet and the neural model’s output seem to follow the various device characteristic curves with high regression. Next, Maximum Allowable Gain and Noise figure of the device are modelled and plotted for the same frequency range. Finally, the optimized model is utilized as an interpolator and the resolution of the amplifying capability with noise characteristics are obtained for the L Band of MSS operation.

  1. Easy-to-Build Satellite Beacon Receiver for Propagation Experimentation at Millimeter Bands

    Directory of Open Access Journals (Sweden)

    F. Machado

    2014-04-01

    Full Text Available This paper describes the design and development of a digital satellite beacon receiver for propagation experimentation. Satellite beacons are frequently available for pointing large antennas, but such signals can be used for measuring rain attenuation and other phenomena as, for example, tropospheric scintillation. A fairly inexpensive beacon receiver has been built using off-the-shelf parts. This instrument is not at all bulky making it suitable for easy transportation. This article analyzes the receiver specifications, describes in detail its structure and presents some operational test results.

  2. Global solar radiation: comparison of satellite-based climatology with station records

    Science.gov (United States)

    Skalak, Petr; Zahradnicek, Pavel; Stepanek, Petr; Farda, Ales

    2016-04-01

    We analyze surface incoming shortwave radiation (SIS) from the SARAH dataset prepared by the EUMETSAT Climate Monitoring Satellite Applications Facility from satellite observations of the visible channels of the MVIRI and SEVIRI instruments onboard the geostationary Meteosat satellites. The satellite SIS data are evaluated within the period 1984-2014 on various time scales: from individual months and years to long-term climate means. The validation is performed using the ground measurements of global solar radiation (GLBR) carried out on 11 meteorological stations of the Czech Hydrometeorological Institute in the Czech Republic with at least 30 years long data series. Our aim is to explore whether the SIS data could potentially serve as an alternative source of information on GLBR outside of a relatively sparse network of meteorological stations recording GLBR. Acknowledgement: Supported by the Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Program I (NPU I), grant number LO1415.

  3. Coherent receiving efficiency in satellite-ground coherent laser communication system based on analysis of polarization

    Science.gov (United States)

    Hao, Shiqi; Zhang, Dai; Zhao, Qingsong; Wang, Lei; Zhao, Qi

    2017-06-01

    Aimed at analyzing the coherent receiving efficiency of a satellite-ground coherent laser communication system, polarization state of the received light is analyzed. We choose the circularly polarized, partially coherent laser as transmitted light source. The analysis process includes 3 parts. Firstly, an theoretical model to analyze received light's polarization state is constructed based on Gaussian-Schell model (GSM) and cross spectral density function matrix. Then, analytic formulas to calculate coherent receiving efficiency are derived in which both initial ellipticity modification and deflection angle between polarization axes of the received light and the intrinsic light are considered. At last, numerical simulations are operated based on our study. The research findings investigate variations of polarization state and obtain analytic formulas to calculate the coherent receiving efficiency. Our study has theoretical guiding significances in construction and optimization of satellite-ground coherent laser communication system.

  4. Spaceborne GPS receiver antenna phase center offset and variation estimation for the Shiyan 3 satellite

    Directory of Open Access Journals (Sweden)

    Gu Defeng

    2016-10-01

    Full Text Available In determining the orbits of low Earth orbit (LEO satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO and phase center variations (PCVs are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centimeters. The antenna PCO and PCV error characteristics and the principles influencing orbit determination are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment (GRACE and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging (KBR and satellite laser ranging (SLR measurements. For GRACE satellites, the average root mean square (RMS of KBR residuals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR residuals improved from 4.95 cm to 4.06 cm.

  5. Spaceborne GPS receiver antenna phase center offset and variation estimation for the Shiyan 3 satellite

    Institute of Scientific and Technical Information of China (English)

    Gu Defeng; Lai Yuwang; Liu Junhong; Ju Bing; Tu Jia

    2016-01-01

    In determining the orbits of low Earth orbit (LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO) and phase center variations (PCVs) are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centime-ters. The antenna PCO and PCV error characteristics and the principles influencing orbit determi-nation are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment (GRACE) and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging (KBR) and satellite laser ranging (SLR) measurements. For GRACE satellites, the average root mean square (RMS) of KBR resid-uals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR resid-uals improved from 4.95 cm to 4.06 cm.

  6. Real-time kinematic positioning of LEO satellites using a single-frequency GPS receiver

    CERN Document Server

    Chen, Pei; Sun, Xiucong

    2016-01-01

    Due to their low cost and low power consumption, single-frequency GPS receivers are considered suitable for low-cost space applications such as small satellite missions. Recently, requirements have emerged for real-time accurate orbit determination at sub-meter level in order to carry out onboard geocoding of high-resolution imagery, open-loop operation of altimeters and radio occultation. This study proposes an improved real-time kinematic positioning method for LEO satellites using single-frequency receivers. The C/A code and L1 phase are combined to eliminate ionospheric effects. The epoch-differenced carrier phase measurements are utilized to acquire receiver position changes which are further used to smooth the absolute positions. A kinematic Kalman filter is developed to implement kinematic orbit determination. Actual flight data from China small satellite SJ-9A are used to test the navigation performance. Results show that the proposed method outperforms traditional kinematic positioning method in term...

  7. Data communications method for mobile network in fourth generation communications system, involves delivering decoded data to mobile station from relay station, where mobile station receives data from both relay and base stations

    DEFF Research Database (Denmark)

    2008-01-01

    The method involves utilizing a base station (BS) (100) to transmit data to a relay station (RS) (110) and a mobile station (MS) (120), where the data includes two messages. The BS is utilized to transmit the two messages by utilizing a linear combination method, and the data is received in the RS...... and decoded. The decoded data is delivered to the MS from the RS, where the RS transmits the decoded data by utilizing another linear combination method. The MS receives data from both the BS and the RS....

  8. Determination of the position of the Station Borowiec No. 7811 by satellite laser observations.

    Science.gov (United States)

    Dobaczewská, W.; Drozyner, A.; Rutkowska, M.; Schillak, S.; Zieliňski, J. B.

    Laser observations were performed in Borowiec in three years 1977 - 79 of the satellites Geos A and Geos C. These data were processed by means of the program ORBITA and station coordinates were calculated by dynamical methods. Another solution was found with the processing by the program GRIPE of SAO. These two dynamical solutions are compared with the translocation solution Wettzel-Borowiec.

  9. 47 CFR 25.210 - Technical requirements for space stations in the Fixed-Satellite Service.

    Science.gov (United States)

    2010-10-01

    ... Service shall have a minimum capability to change transponder saturation flux densities by ground command... spatially independent beams. (g)-(h) (i)(1) Space station antennas in the Fixed-Satellite Service, other than antennas in the 17/24 GHz BSS, must be designed to provide a cross-polarization isolation...

  10. East–West GEO Satellite Station-Keeping with Degraded Thruster Response

    Directory of Open Access Journals (Sweden)

    Stoian Borissov

    2015-09-01

    Full Text Available The higher harmonic terms of Earth’s gravitational potential slowly modify the nominal longitude of geostationary Earth orbit (GEO satellites, while the third-body presence (Moon and Sun mainly affects their latitude. For this reason, GEO satellites periodically need to perform station-keeping maneuvers, namely, east–west and north–south maneuvers to compensate for longitudinal and latitudinal variations, respectively. During the operational lifetime of GEO satellites, the thrusters’ response when commanded to perform these maneuvers slowly departs from the original nominal impulsive behavior. This paper addresses the practical problem of how to perform reliable east–west station-keeping maneuvers when thruster response is degraded. The need for contingency intervention from ground-based satellite operators is reduced by breaking apart the scheduled automatic station-keeping maneuvers into smaller maneuvers. Orbital alignment and attitude are tracked on-board during and in between sub-maneuvers, and any off nominal variations are corrected for with subsequent maneuvers. These corrections are particularly important near the end of the lifetime of GEO satellites, where thruster response is farthest from nominal performance.

  11. Space Station needs, attributes and architectural options. Volume 2, book 1, part 3: Manned Space Station relevance to commercial telecommunications satellites

    Science.gov (United States)

    1983-01-01

    A document containing a forecast of satellite traffic and revelant technology trends to the year 2000 was prepared which includes those space station capabilities and characteristics that should be provided to make the station useful to commercial satellite owners. The document was circulated to key representative organizations within the commercial telecommunications satellite and related communities of interest, including spacecraft manufacturers, commercial satellite owners, communications carriers, networks and risk insurers. The prospectus document is presented as well as the transmittal letter and the mailing list of the people and companies that were asked to review it. Key commercial telecommunications comments are summarized the actual response letters from the industry are included.

  12. Influence of urbanization on the thermal environment of meteorological station:Satellite-observed evidence

    Institute of Scientific and Technical Information of China (English)

    SHI Tao; HUANG Yong; WANG Hong; SHI Chun-E; YANG Yuan-Jian

    2015-01-01

    In this paper, five national meteorological stations in Anhui province are taken as typical examples to explore the effects of local urbanization on their thermal environment by using Landsat data from 1990 to 2010. Satellite-based land use/land cover (LULC), land surface temperature (LST), normalized difference vegetation index (NDVI) are used to investigate the effects. The study shows that LULC around meteorological stations changed significantly due to urban expansion. Fast urbanization is the main factor that affects the spatial-temporal distribution of thermal environment around meteorological stations. Moreover, the normalized LST and NDVI exhibit strong inverse correlations around meteorological stations, so the variability of LST can be monitored through evaluating the variability of NDVI. In addition, station-relocation plays an important role in improving representativeness of thermal environment. Notably, the environment representativeness was improved, but when using the data from the station to study climate change, the relocation-induced inhomogeneous data should be considered and adjusted. Consequently, controlling the scale and layout of the urban buildings and constructions around meteorological stations is an effective method to ameliorate observational thermal environment and to improve regional representativeness of station observation. The present work provides observational evidences that high resolution Landsat images can be used to evaluate the thermal environment of meteorological stations.

  13. Performance analysis of MRC spatial diversity receiver system for satellite-to-ground downlink optical transmissions

    Science.gov (United States)

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Cao, Yubin

    2016-10-01

    The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed turbulence are studied for multiple apertures receiver system. Maximum ratio combining (MRC) technique is considered as a combining scheme to mitigate the atmospheric turbulence under thermal noise limited conditions. Bit-error rate (BER) performances for on-off keying (OOK) modulated direct detection optical communications are analyzed for MRC diversity receptions through an approximation method. To show the net diversity gain of multiple apertures receiver system, BER performances of MRC receiver system are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power) for satellite-to-ground downlink optical communications. All the numerical results are also verified by Monte-Carlo (MC) simulations.

  14. REVISITING THE DOPPLER FILTER OF LEO SATELLITE GNSS RECEIVERS FOR PRECISE VELOCITY ESTIMATION

    Institute of Scientific and Technical Information of China (English)

    Chen Xi; Gao Wenyun; Wan Yunheng

    2013-01-01

    The theoretical aspects of the precise velocity determination of Low Earth Orbit (LEO) satellites' onboard Global Navigation Satellite Systems (GNSS) receivers are derived.It shows that the receiver's Phase Lock Loop (PLL) is required to feature extremely small group delay within its low frequency band,which is in contrast to existing work that proposed wide band linear phase filters.Following this theory,a Finite Impulse Response (FⅠR) filter is proposed.To corroborate,the proposed FIR filter and an Infinite Impulse Response (ⅡR) filter lately proposed in literals are implemented in a LEO satellite onboard GNSS receiver.Tests are conducted using a third party commercial GPS,signal generator.The results show that the GNSS receiver with the proposed FⅠR achieves 11 mm/s R.M.S precision,while the GNSS receiver with the ⅡR filter has a filter-caused velocity error that can not be ignored for space borne GNSS receivers.

  15. Energy-Efficient Network Transmission between Satellite Swarms and Earth Stations Based on Lyapunov Optimization Techniques

    Directory of Open Access Journals (Sweden)

    Weiwei Fang

    2014-01-01

    Full Text Available The recent advent of satellite swarm technologies has enabled space exploration with a massive number of picoclass, low-power, and low-weight spacecraft. However, developing swarm-based satellite systems, from conceptualization to validation, is a complex multidisciplinary activity. One of the primary challenges is how to achieve energy-efficient data transmission between the satellite swarm and terrestrial terminal stations. Employing Lyapunov optimization techniques, we present an online control algorithm to optimally dispatch traffic load among different satellite-ground links for minimizing overall energy consumption over time. Our algorithm is able to independently and simultaneously make control decisions on traffic dispatching over intersatellite-links and up-down-links so as to offer provable energy and delay guarantees, without requiring any statistical information of traffic arrivals and link condition. Rigorous analysis and extensive simulations have demonstrated the performance and robustness of the proposed new algorithm.

  16. Paving the Way for Small Satellite Access to Orbit: Cyclops' Deployment of SpinSat, the Largest Satellite Ever Deployed from the International Space Station

    Science.gov (United States)

    Hershey, Matthew P.; Newswander, Daniel R.; Smith, James P.; Lamb, Craig R.; Ballard, Perry G.

    2015-01-01

    The Space Station Integrated Kinetic Launcher for Orbital Payload Systems (SSIKLOPS), known as "Cyclops" to the International Space Station (ISS) community, successfully deployed the largest satellite ever (SpinSat) from the ISS on November 28, 2014. Cyclops, a collaboration between the NASA ISS Program, NASA Johnson Space Center Engineering, and Department of Defense Space Test Program (DoD STP) communities, is a dedicated 10-100 kg class ISS small satellite deployment system. This paper will showcase the successful deployment of SpinSat from the ISS. It will also outline the concept of operations, interfaces, requirements, and processes for satellites to utilize the Cyclops satellite deployment system.

  17. Multi-antenna synchronized global navigation satellite system receiver and its advantages in high-precision positioning applications

    Science.gov (United States)

    Dong, Danan; Chen, Wen; Cai, Miaomiao; Zhou, Feng; Wang, Minghua; Yu, Chao; Zheng, Zhengqi; Wang, Yuanfei

    2016-12-01

    The multi-antenna synchronized global navigation satellite system receiver is a high precision, low cost, and widely used emerging receiver. Using this type of receiver, the satellite and receiver clock errors can be eliminated simultaneously by forming between antenna single-differences, which is equivalent to the conventional double-difference model. However, current multi-antenna synchronized global navigation satellite system receiver products have not fully realized their potential to achieve better accuracy, efficiency, and broader applications. This paper introduces the conceptual design and derivable products of multi-antenna synchronized global navigation satellite system receivers involving the aspects of attitude determination, multipath effect mitigation, phase center variation correction, and ground-based carrier phase windup calibration. Through case studies, the advantages of multi-antenna synchronized global navigation satellite system receivers in high-precision positioning applications are demonstrated.

  18. The geo-control system for station keeping and colocation of geostationary satellites

    Science.gov (United States)

    Montenbruck, O.; Eckstein, M. C.; Gonner, J.

    1993-01-01

    GeoControl is a compact but powerful and accurate software system for station keeping of single and colocated satellites, which has been developed at the German Space Operations Center. It includes four core modules for orbit determination (including maneuver estimation), maneuver planning, monitoring of proximities between colocated satellites, and interference and event prediction. A simple database containing state vector and maneuver information at selected epochs is maintained as a central interface between the modules. A menu driven shell utilizing form screens for data input serves as the central user interface. The software is written in Ada and FORTRAN and may be used on VAX workstations or mainframes under the VMS operating system.

  19. Determination of the position of the station Borowiec Nr 7811 by satellite laser observations

    Science.gov (United States)

    Dobaczewska, W.; Drozyner, A.; Rutkowska, M.; Schillak, S.; Zielinski, J. B.

    Laser observations during 1977-1979 of the GEOS-1 and GEOS-3 satellites, used to determine the geocentric position of the Astronomical Latitude Observatory in Borowiec (station No. 7811) are examined. The data are processed by means of the ORBITA program and the GRIPE program elaborated at the Smithsonian Astrophysical Observatory. The coordinates of the station are calculated by a dynamical orbital method. Results of the ORBITA and GRIPE solutions are presented in tables. A comparison of these two solutions with the Wettzel-Borowiec translocation solution is considered.

  20. Receiver Function Analysis of Strong-motion Stations in Kaohsiung-Pingtung area, Taiwan

    Science.gov (United States)

    Lin, Che-Min; Wen, Kuo-Liang; Kuo, Chun-Hsiang; Huang, Jyun-Yan

    2016-04-01

    The Kaohsiung City and Pingtung County are located in southern Taiwan and bounded on the west side by several active faults. The shallow velocity structure of thick alluvium basin in this area should be delineated to understand the seismic site effect of strong ground motion. Receiver Function (RF) is a conventional technique for studying the structure of the crust and upper mantle beneath the seismometer. But, the RF analysis of high-frequency acceleration seismograms is also proved to be feasible for estimating shallow structures recently. This study applied the RF technique on the Strong-motion records of almost one-hundred TSMIP stations in Kaohsiung-Pingtung area to estimate the shallow shear-wave velocity structures. The averaged RFs of all stations exhibit the obvious variation because of the different geologies and site conditions. After the forward modeling of RFs based on the Genetic Algorithms (GA) searching, the shallow shear-wave velocity structures beneath all the strong-motion stations in the Kaohsiung-Pingtung area were estimated to delineate the iso-depth contour maps of the main formation interfaces and a preliminary shallow 3D velocity model.

  1. Validation of three satellite-derived databases of surface solar radiation using measurements performed at 42 stations in Brazil

    Science.gov (United States)

    Thomas, Claire; Wey, Etienne; Blanc, Philippe; Wald, Lucien

    2016-06-01

    The SoDa website (www.soda-pro.com) is populated with numerous solar-related Web services. Among them, three satellite-derived irradiation databases can be manually or automatically accessed to retrieve radiation values within the geographical coverage of the Meteosat Second Generation (MSG) satellite: the two most advanced versions of the HelioClim-3 database (versions 4 and 5, respectively HC3v4 and HC3v5), and the CAMS radiation service. So far, these databases have been validated against measurements of several stations in Europe and North Africa only. As the quality of such databases depends on the geographical regions and the climates, this paper extends this validation campaign and proposes an extensive comparison on Brazil and global irradiation received on a horizontal surface. Eleven stations from the Brazilian Institute of Space Research (INPE) network offer 1 min observations, and thirty-one stations from the Instituto Nacional de Meteorologia (INMET) network offer hourly observations. The satellite-derived estimates have been compared to the corresponding observations on hourly, daily and monthly basis. The bias relative to the mean of the measurements for HC3v5 is mostly comprised between 1 and 3 %, and that for HC3v4 between 2 and 5 %. These are very satisfactory results and they demonstrate that HC3v5, and to a lesser extent HC3v4, may be used in studies of long-term changes in SSI in Brazil. The situation is not so good with CAMS radiation service for which the relative bias is mostly comprised between 5 and 10 %. For hourly irradiation, the relative RMSE ranges from 15 to 33 %. The correlation coefficient is very large for all stations and the three databases, with an average of 0.96. The three databases reproduce well the hour from hour changes in SSI. The errors show a tendency to increase with the viewing angle of the MSG satellite. They are greater in tropical areas where the relative humidity in the atmosphere is important. It is concluded

  2. Climate Monitoring Network on Maunakea - Master Station at Summit and Lower Elevation Satellite Stations

    Science.gov (United States)

    McKenzie, M. M.; Klasner, F.; Giambelluca, T. W.; Businger, S.

    2014-12-01

    Maunakea, a dormant shield volcano on the Big Island of Hawai'i, rises 13,796 feet above sea level, making it the highest point in the Pacific Basin. From sea floor to summit, it's the tallest mountain in the world. The high elevation, low air and light pollution, as well as dry weather year round make it the best location in the world for astronomy observations. The summit is home to 13 ground based telescope facilities. Like all alpine regions, it is an extremely fragile and unique ecosystem because of the harsh conditions and short growing seasons located at high altitudes. The summit is home to several federal and/or state protected species. It supports 11 species of arthropods found nowhere else on Earth. Most noted of these is the Wēkiu bug, whose habitat has been altered by the infrastructural development on the mountain. Arthropod habitat model development has highlighted gaps in climate information, for example, lack of climate precipitation data, snow data and reliable temperature data. Furthermore, in tropical regions, precipitation is the most variable climate component due to topography and local winds. The telescopes collect weather data for the purpose of knowing when it is dry and clear for astronomical observation. Although existing weather stations associated with the telescopes meet some weather and climate monitoring needs, it cannot address the full range of issues needed due to technological limitation and site design. Precipitation does not occur often and is likely to be in the form of snow or ice. Snow cover data has not been directly recorded despite astronomical recording of other meteorological data that began in the1960s. Therefore, the need to monitor the weather and climate in a long-term and well-calibrated way is critical for management of the ecosystems on the slopes of Maunakea. Long-term weather and climate monitoring stations are the primary building blocks for research partnerships, which encourage collaboration and ultimately

  3. Study of Ionospheric Perturbations in D-Layer Using VLF Receiver at Tashkent IHY Station

    Science.gov (United States)

    Ahmedov, Bobomurat

    2016-07-01

    Tashkent International Heliophysical Year (IHY) station is a member of Atmospheric Weather Electromagnetic System for Observation, Modeling and Education (AWESOME) network being operated globally to study the ionosphere and the magnetosphere with the help of electromagnetic waves in Very Low Frequency (VLF) band. Regular monitoring of the D- and F-layers of ionosphere over Central Asia territory is being performed on the permanent basis starting year 2008 when one VLF receiver and two SuperSID receivers were provided to Uzbekistan IHY cite by Stanford University. The results obtained at Tashkent IHY station are applied to earthquake electromagnetic precursors, lightning, and Solar flares and to ionospheric disturbances originating from gamma ray flares of Soft Gamma-Ray Repeaters connected with evolution of strongly magnetized neutron stars believed as magnetars. Regular monitoring of the D-layer of ionosphere over Central Asia territory has been performed on the permanent basis. Several Solar events are observed and the analysis has shown that there is simultaneous correlation between the times of change of amplitude of the waves and the Solar flares. Features of the lightning discharge generated by radio atmospherics are studied and its effectiveness in D-region ionosphere diagnostics is examined.

  4. Ionospheric disturbances in D-layer recorded by VLF receiver at Tashkent IHY station

    Science.gov (United States)

    Ahmedov, Bobomurat

    Tashkent International Heliophysical Year (IHY) station is a member of Atmospheric Weather Electromagnetic System for Observation, Modeling and Education (AWESOME) network being operated globally to study the ionosphere and the magnetosphere with the help of electromagnetic waves in Very Low Frequency (VLF) band. Regular monitoring of the D- and F-layers of ionosphere over Central Asia territory is being performed on the permanent basis starting year 2008. Solar flare events are permanently observed and the analysis showed that there is simultaneous correlation between the times of change of amplitude of the waves and the Solar flares. Features of the lightning discharge generated by radio atmospherics are studied and its effectiveness in D-region ionosphere diagnostics is explained. We have studied VLF amplitude anomalies related to the earthquakes (EQs) occurred in the recent years with magnitude more than 5 on the path way from the VLF transmitters to the Tashkent station assuming that propagation of VLF ground-based transmitters signals can be perturbed by EQ preparation can be detectable from the ground-based measurements in the VLF bands. For analyzing narrowband data we have used the Nighttime Fluctuation (NF) method paying attention to the data obtained during the local nighttime (20:00 LT-04:00 LT). The mean nighttime amplitude (or trend) and nighttime fluctuation are found to increase significantly before the EQ occurred on the path way from the transmitters to the receiver. The obtained results have revealed an agreement with VLF amplitude anomalies observed in Tashkent VLF station during the strong EQs occurred on the path way from the transmitters to the receiver. Some results are presented to show the probing potentiality of VLF waves to predict short term EQs with high magnitude.

  5. Comparison of microwave satellite humidity data and radiosonde profiles: a survey of European stations

    Directory of Open Access Journals (Sweden)

    V. O. John

    2005-03-01

    Full Text Available A method to compare upper tropospheric humidity (UTH from satellite and radiosonde data has been applied to the European radiosonde stations. The method uses microwave data as a benchmark for monitoring the performance of the stations. The present study utilizes three years (2002–2003 of data from channel 18 (183.31±1.00 GHz of the Advanced Microwave Sounding Unit-B (AMSU-B aboard the satellites NOAA-15 and NOAA-16. The comparison is done in the radiance space, the radiosonde data were transformed to the channel radiances using a radiative transfer model. The comparison results confirm that there is a dry bias in the UTH measured by the radiosondes. This bias is highly variable among the stations and the years. This variability is attributed mainly to the differences in the radiosonde humidity measurements. The results also hint at a systematic difference between the two satellites, the channel 18 brightness temperature of NOAA-15 is on average 1.0 K higher than that of NOAA-16. The difference of 1 K corresponds to approximately 7% relative error in UTH which is significant for climatological applications.

  6. Preliminary design of a satellite observation system for Space Station Freedom

    Science.gov (United States)

    Cabe, Greg (Editor); Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

    1992-01-01

    Degobah Satellite Systems (DSS), in cooperation with the University Space Research Association (USRA), NASA - Johnson Space Center (JSC), and the University of Texas, has completed the preliminary design of a satellite system to provide inexpensive on-demand video images of all or any portion of Space Station Freedom (SSF). DSS has narrowed the scope of the project to complement the work done by Mr. Dennis Wells at Johnson Space Center. This three month project has resulted in completion of the preliminary design of AERCAM, the Autonomous Extravehicular Robotic Camera, detailed in this design report. This report begins by providing information on the project background, describing the mission objectives, constraints, and assumptions. Preliminary designs for the primary concept and satellite subsystems are then discussed in detail. Included in the technical portion of the report are detailed descriptions of an advanced imaging system and docking and safing systems that ensure compatibility with the SSF. The report concludes by describing management procedures and project costs.

  7. Research on GPS Receiver Autonomous Integrity Monitoring Algorithm In the Occurrence of Two-satellite Faults

    Directory of Open Access Journals (Sweden)

    Wang Er Shen

    2016-01-01

    Full Text Available Reliability is an essential factor for GPS navigation system. Therefore, an integrity monitoring is considered as one of the most important parts for a navigation system. GPS receiver autonomous integrity monitoring (RAIM technique can detect and isolate fault satellite. Based on particle filter, a novel RAIM method was proposed to detect two-satellite faults of the GPS signal by using hierarchical particle filter. It can deal with any system nonlinear and any noise distributions. Because GNSS measurement noise does not follow the Gaussian distribution perfectly, the particle filter can estimate the posterior distribution more accurately. In order to detect fault, the consistency test statistics is established through cumulative log-likelihood ratio (LLR between the main and auxiliary particle filters (PFs.Specifically, an approach combining PF with the hierarchical filter is used in the process of two-satellite faults. Through GPS real measurement, the performance of the proposed GPS two-satellite faults detection algorithm was illustrated. Some simulation results are given to evaluate integrity monitoring performance of the algorithm. Validated by the real measurement data, the results show that the proposed algorithm can successfully detect and isolate the faulty satellite in the case of non-Gaussian measurement noise.

  8. Solar power satellite rectenna design study: Directional receiving elements and parallel-series combining analysis

    Science.gov (United States)

    Gutmann, R. J.; Borrego, J. M.

    1978-01-01

    Rectenna conversion efficiencies (RF to dc) approximating 85 percent were demonstrated on a small scale, clearly indicating the feasibility and potential of efficiency of microwave power to dc. The overall cost estimates of the solar power satellite indicate that the baseline rectenna subsystem will be between 25 to 40 percent of the system cost. The directional receiving elements and element extensions were studied, along with power combining evaluation and evaluation extensions.

  9. Extremely high frequency (EHF) satellite communications (SATCOM) technology-transmitters and receivers

    Science.gov (United States)

    Raue, Jorg E.

    1983-10-01

    During the past three years, interest in satellite communications in the frequency bands above Ku-band has expanded dramatically. As a result, a number of key technology developments, targeted to meet specific next generation spaceborne needs, were undertaken. The state-of-the-art in solid state power transmitters and low noise receivers, including critical passive component technology, is presented. This includes filters as well as a series of rugged high performance ferrite components such as isolators, circulators and latching switches.

  10. A 20 GHz low noise, low cost receiver for digital satellite communication system, ground terminal applications

    Science.gov (United States)

    Allen, Glen

    1988-01-01

    A 45 month effort for the development of a 20 GHz, low-noise, low-cost receiver for digital, satellite communication system, ground terminal applications is discussed. Six proof-of-concept receivers were built in two lots of three each. Performance was generally consistent between the two lots. Except for overall noise figure, parameters were within or very close to specification. While noise figure was specified as 3.5 dB, typical performance was measured at 3.0 to 5.5 dB, over the full temperature range of minus 30 C to plus 75 C.

  11. Study of Ionospheric Perturbations in D-Layer Using Awesome VLF Receiver Data at Tashkent Station

    Science.gov (United States)

    Ahmedov, Bobomurat

    2012-07-01

    One VLF receiver and two SuperSID receivers were provided to Uzbekistan IHY cite by Stanford University and are operating in Tashkent, under the International Heliophysical Year (IHY). The results obtained at Tashkent IHY station are applied to earthquake electromagnetic precursors, lightning, and solar flares and to ionospheric disturbances originating from gamma ray flares of Soft Gamma-Ray Repeaters connected with evolution of strongly magnetized neutron stars believed as magnetars. Regular monitoring of the D-layer of ionosphere over Central Asia territory has been performed on the permanent basis. Few Solar flare events are observed during February in 2010-2011 years and the analysis showed that there is simultaneous correlation between the times of change of amplitude of the waves and the Solar flares. Features of the lightning discharge generated by radio atmospherics are studied and its effectiveness in D-region ionosphere diagnostics is explained. Assuming that earthquakes (EQs) can be preceded by the electromagnetic signals in the VLF bands detectable from ground-based measurements we have studied VLF amplitude anomalies related to the earthquakes occurred in 2009-2010 years with magnitude more than 5 on the path way from the VLF transmitters to the Tashkent station. For analysing narrowband data we have used the Nighttime Fluctuation (NF) method paying attention to the data obtained during the local nighttime (18:00 LT-06:00 LT). The amplitude data are analysed only for the reason that perturbations are identified more clearly in the amplitude data than in phase data. The mean nighttime amplitude (or trend) and normalized trend are found to increase significantly before the EQ with the same tendency as the NF and normalized NF. The obtained results have revealed a fine agreement with VLF amplitude anomalies observed in Tashkent VLF station during the strong earthquakes occurred on the path way from the transmitters to the receiver. Some of the initial

  12. Crustal structure beneath two seismic stations in the Sunda-Banda arc transition zone derived from receiver function analysis

    Energy Technology Data Exchange (ETDEWEB)

    Syuhada, E-mail: hadda9@gmail.com [Graduate Research on Earthquake and Active Tectonics (GREAT), Bandung Institute of Technology, Jalan Ganesha 10, Bandung 40132 (Indonesia); Research Centre for Physics - Indonesian Institute of Sciences (LIPI), Kompleks Puspiptek Serpong, Tangsel 15314, Banten Indonesia (Indonesia); Hananto, Nugroho D.; Handayani, Lina [Research Centre for Geotechnology - Indonesian Institute of Sciences (LIPI), Jl. Sangkuriang (Kompleks LIPI) Bandung 40135 (Indonesia); Puspito, Nanang T; Yudistira, Tedi [Faculty of Mining and Petroleum Engineering ITB, Jalan Ganesha 10, Bandung 40132 (Indonesia); Anggono, Titi [Research Centre for Physics - Indonesian Institute of Sciences (LIPI), Kompleks Puspiptek Serpong, Tangsel 15314, Banten Indonesia (Indonesia)

    2015-04-24

    We analyzed receiver functions to estimate the crustal thickness and velocity structure beneath two stations of Geofon (GE) network in the Sunda-Banda arc transition zone. The stations are located in two different tectonic regimes: Sumbawa Island (station PLAI) and Timor Island (station SOEI) representing the oceanic and continental characters, respectively. We analyzed teleseismic events of 80 earthquakes to calculate the receiver functions using the time-domain iterative deconvolution technique. We employed 2D grid search (H-κ) algorithm based on the Moho interaction phases to estimate crustal thickness and Vp/Vs ratio. We also derived the S-wave velocity variation with depth beneath both stations by inverting the receiver functions. We obtained that beneath station PLAI the crustal thickness is about 27.8 km with Vp/Vs ratio 2.01. As station SOEI is covered by very thick low-velocity sediment causing unstable solution for the inversion, we modified the initial velocity model by adding the sediment thickness estimated using high frequency content of receiver functions in H-κ stacking process. We obtained the crustal thickness is about 37 km with VP/Vs ratio 2.2 beneath station SOEI. We suggest that the high Vp/Vs in station PLAI may indicate the presence of fluid ascending from the subducted plate to the volcanic arc, whereas the high Vp/Vs in station SOEI could be due to the presence of sediment and rich mafic composition in the upper crust and possibly related to the serpentinization process in the lower crust. We also suggest that the difference in velocity models and crustal thicknesses between stations PLAI and SOEI are consistent with their contrasting tectonic environments.

  13. Crustal structure beneath two seismic stations in the Sunda-Banda arc transition zone derived from receiver function analysis

    Science.gov (United States)

    Syuhada, Hananto, Nugroho D.; Puspito, Nanang T.; Anggono, Titi; Handayani, Lina; Yudistira, Tedi

    2015-04-01

    We analyzed receiver functions to estimate the crustal thickness and velocity structure beneath two stations of Geofon (GE) network in the Sunda-Banda arc transition zone. The stations are located in two different tectonic regimes: Sumbawa Island (station PLAI) and Timor Island (station SOEI) representing the oceanic and continental characters, respectively. We analyzed teleseismic events of 80 earthquakes to calculate the receiver functions using the time-domain iterative deconvolution technique. We employed 2D grid search (H-κ) algorithm based on the Moho interaction phases to estimate crustal thickness and Vp/Vs ratio. We also derived the S-wave velocity variation with depth beneath both stations by inverting the receiver functions. We obtained that beneath station PLAI the crustal thickness is about 27.8 km with Vp/Vs ratio 2.01. As station SOEI is covered by very thick low-velocity sediment causing unstable solution for the inversion, we modified the initial velocity model by adding the sediment thickness estimated using high frequency content of receiver functions in H-κ stacking process. We obtained the crustal thickness is about 37 km with VP/Vs ratio 2.2 beneath station SOEI. We suggest that the high Vp/Vs in station PLAI may indicate the presence of fluid ascending from the subducted plate to the volcanic arc, whereas the high Vp/Vs in station SOEI could be due to the presence of sediment and rich mafic composition in the upper crust and possibly related to the serpentinization process in the lower crust. We also suggest that the difference in velocity models and crustal thicknesses between stations PLAI and SOEI are consistent with their contrasting tectonic environments.

  14. A compact and low cost TT&C S-Band Ground Station for low orbit satellites

    Science.gov (United States)

    Pacola, Luiz C.; Ferrari, Carlos A.

    Instituto Nacional de Pesquisas Espaciais (INPE's) S-Band Ground Station for satellite control and monitoring is revised consdiering the current software and hardware technology. A Ground Station concept for low orbit satellites is presented. The front-end uses a small antenna and low cost associated equipment without loss of performance. The baseband equipment is highly standardized and developed on a personal computer IBM compatible using extensively Digital Signal Processing (DSP). A link budget for ranging, telecommand and telemetry is also presented.

  15. Distributed Extended Kalman Filter for Position, Velocity, Time, Estimation in Satellite Navigation Receivers

    Directory of Open Access Journals (Sweden)

    O. Jakubov

    2013-09-01

    Full Text Available Common techniques for position-velocity-time estimation in satellite navigation, iterative least squares and the extended Kalman filter, involve matrix operations. The matrix inversion and inclusion of a matrix library pose requirements on a computational power and operating platform of the navigation processor. In this paper, we introduce a novel distributed algorithm suitable for implementation in simple parallel processing units each for a tracked satellite. Such a unit performs only scalar sum, subtraction, multiplication, and division. The algorithm can be efficiently implemented in hardware logic. Given the fast position-velocity-time estimator, frequent estimates can foster dynamic performance of a vector tracking receiver. The algorithm has been designed from a factor graph representing the extended Kalman filter by splitting vector nodes into scalar ones resulting in a cyclic graph with few iterations needed. Monte Carlo simulations have been conducted to investigate convergence and accuracy. Simulation case studies for a vector tracking architecture and experimental measurements with a real-time software receiver developed at CTU in Prague were conducted. The algorithm offers compromises in stability, accuracy, and complexity depending on the number of iterations. In scenarios with a large number of tracked satellites, it can outperform the traditional methods at low complexity.

  16. An Efficient Two-Fold Marginalized Bayesian Filter for Multipath Estimation in Satellite Navigation Receivers

    Directory of Open Access Journals (Sweden)

    Robertson Patrick

    2010-01-01

    Full Text Available Multipath is today still one of the most critical problems in satellite navigation, in particular in urban environments, where the received navigation signals can be affected by blockage, shadowing, and multipath reception. Latest multipath mitigation algorithms are based on the concept of sequential Bayesian estimation and improve the receiver performance by exploiting the temporal constraints of the channel dynamics. In this paper, we specifically address the problem of estimating and adjusting the number of multipath replicas that is considered by the receiver algorithm. An efficient implementation via a two-fold marginalized Bayesian filter is presented, in which a particle filter, grid-based filters, and Kalman filters are suitably combined in order to mitigate the multipath channel by efficiently estimating its time-variant parameters in a track-before-detect fashion. Results based on an experimentally derived set of channel data corresponding to a typical urban propagation environment are used to confirm the benefit of our novel approach.

  17. Precise Orbit Determination of BeiDou Satellites with Contributions from Chinese National Continuous Operating Reference Stations

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2017-08-01

    Full Text Available The precise orbit determination (POD for BeiDou satellites is usually limited by the insufficient quantity and poor distribution of ground tracking stations. To cope with this problem, this study used the GPS and BeiDou joint POD method based on Chinese national continuous operating reference stations (CNCORS and IGS/MGEX stations. The results show that the 3D RMS of the differences of overlapping arcs is better than 22 cm for geostationary orbit (GEO satellites and better than 10 cm for inclined geosynchronous orbit (IGSO and medium earth orbit (MEO satellites. The radial RMS is better than 2 cm for all three types of BeiDou satellites. The results of satellite laser ranging (SLR residuals show that the RMS of the IGSO and MEO satellites is better than 5 cm, whereas the GEO satellite has a systematic bias. This study investigates the contributions of CNCORS to the POD of BeiDou satellites. The results show that after the incorporation of CNCORS, the precision of overlapping arcs of the GEO, IGSO, and MEO satellites is improved by 15.5%, 57.5%, and 5.3%, respectively. In accordance with the improvement in the precision of overlapping arcs, the accuracy of the IGSO and MEO satellites assessed by the SLR is improved by 30.1% and 4.8%, respectively. The computation results and analysis demonstrate that the inclusion of CNCORS yields the biggest contribution in the improvement of orbit accuracy for IGSO satellites, when compared to GEO satellites, while the orbit improvement for MEO satellites is the lowest due to their global coverage.

  18. Cirrus cloud-temperature interactions over a tropical station, Gadanki from lidar and satellite observations

    Energy Technology Data Exchange (ETDEWEB)

    S, Motty G, E-mail: mottygs@gmail.com; Satyanarayana, M., E-mail: mottygs@gmail.com; Krishnakumar, V., E-mail: mottygs@gmail.com; Dhaman, Reji k., E-mail: mottygs@gmail.com [Department of Optoelectronics, University of Kerala, Kariavattom, Trivandrum-695 581, Kerala (India)

    2014-10-15

    The cirrus clouds play an important role in the radiation budget of the earth's atmospheric system and are important to characterize their vertical structure and optical properties. LIDAR measurements are obtained from the tropical station Gadanki (13.5{sup 0} N, 79.2{sup 0} E), India, and meteorological indicators derived from Radiosonde data. Most of the cirrus clouds are observed near to the tropopause, which substantiates the strength of the tropical convective processes. The height and temperature dependencies of cloud height, optical depth, and depolarization ratio were investigated. Cirrus observations made using CALIPSO satellite are compared with lidar data for systematic statistical study of cirrus climatology.

  19. Minimum-fuel station-change for geostationary satellites using low-thrust considering perturbations

    Science.gov (United States)

    Zhao, ShuGe; Zhang, JingRui

    2016-10-01

    The objective of this paper is to find the minimum-fuel station change for geostationary satellites with low-thrust while considering significant perturbation forces for geostationary Earth orbit (GEO). The effect of Earth's triaxiality, lunisolar perturbations, and solar radiation pressure on the terminal conditions of a long duration GEO transfer is derived and used for establishing the station change model with consideration of significant perturbation forces. A method is presented for analytically evaluating the effect of Earth's triaxiality on the semimajor axis and longitude during a station change. The minimum-fuel problem is solved by the indirect optimization method. The easier and related minimum-energy problem is first addressed and then the energy-to-fuel homotopy is employed to finally obtain the solution of the minimum-fuel problem. Several effective techniques are employed in solving the two-point boundary-value problem with a shooting method to overcome the problem of the small convergence radius and the sensitivity of the initial costate variables. These methods include normalization of the initial costate vector, computation of the analytic Jacobians matrix, and switching detection. The simulation results show that the solution of the minimum-fuel station change with low-thrust considering significant perturbation forces can be obtained by applying these preceding techniques.

  20. BeiDou inter-satellite-type bias evaluation and calibration for mixed receiver attitude determination

    NARCIS (Netherlands)

    Nadarajah, N.; Teunissen, P.J.G.; Raziq, N.

    2013-01-01

    The Chinese BeiDou system (BDS), having different types of satellites, is an important addition to the ever growing system of Global Navigation Satellite Systems (GNSS). It consists of Geostationary Earth Orbit (GEO) satellites, Inclined Geosynchronous Satellite Orbit (IGSO) satellites and Medium

  1. BeiDou inter-satellite-type bias evaluation and calibration for mixed receiver attitude determination

    NARCIS (Netherlands)

    Nadarajah, N.; Teunissen, P.J.G.; Raziq, N.

    2013-01-01

    The Chinese BeiDou system (BDS), having different types of satellites, is an important addition to the ever growing system of Global Navigation Satellite Systems (GNSS). It consists of Geostationary Earth Orbit (GEO) satellites, Inclined Geosynchronous Satellite Orbit (IGSO) satellites and Medium Ea

  2. 基于STK的空间站星载GPS接收机仿真分析%Simulation and Analysis of GPS Receiver Onboard Space Station on STK

    Institute of Scientific and Technical Information of China (English)

    陈志国; 钟红恩

    2011-01-01

    将GPS系统用于航天器的导航、定位和授时是目前的趋势.但是星载接收机的高速轨道运动特点有区别于地面用户.通过建立GPS星座与国际空间站的链路进行仿真分析.仿真结果表明GPS星座可以满足空间站的大于4颗卫星的信号可用性需求.%The GPS system for spacecraft navigation , positioning and timing is the current trend, but the orbital motion feature of high-speed satellite receivers is different from that of the ground user. Link established between the GPS constellation and the international space station is simulated and analyzed, and simulation results show that the GPS constellation can meet the requirements of the space station more than four satellite signals available.

  3. Fatigue life analysis of cracked gas receiver of emergency cut-off system in gas gathering station

    Science.gov (United States)

    Hu, Junzhi; Zhou, Jiyong; Li, Siyuan

    2017-06-01

    Small-scale air compressor and gas receiver are used as the driving gas of the emergency cut-off system in gas gathering station. Operation of block valve is ensured by starting and stopping compressor automatically. The frequent start-stop of compressor and the pressure fluctuation pose a threat to the service life of gas receiver, and then affect normal operation of the emergency cut-off system and security of gas gathering station. In this paper, the fatigue life of a pressure vessel with axial semi-elliptical surface crack in the inner wall is analyzed under the varying pressure by means of the theory of fracture mechanics. The influences of the amplitude of pressure fluctuation and the initial crack size on the residual life of gas receiver are discussed. It provides a basis for setting the working parameters of gas receiver of emergency cut-off system and determining the maintenance cycle.

  4. The Role of Anchor Stations in the Validation of Earth Observation Satellite Data and Products. The Valencia and the Alacant Anchor Stations

    Science.gov (United States)

    Lopez-Baeza, Ernesto; Geraldo Ferreira, A.; Saleh-Contell, Kauzar

    Space technology facilitates humanity and science with a global revolutionary view of the Earth through the acquisition of Earth Observation satellite data. Satellites capture information over different spatial and temporal scales and assist in understanding natural climate processes and in detecting and explaining climate change. Accurate Earth Observation data is needed to describe climate processes by improving the parameterisations of different climate elements. Algorithms to produce geophysical parameters from raw satellite observations should go through selection processes or participate in inter-comparison programmes to ensure performance reliability. Geophysical parameter datasets, obtained from satellite observations, should pass a quality control before they are accepted in global databases for impact, diagnostic or sensitivity studies. Calibration and Validation, or simply "Cal/Val", is the activity that endeavours to ensure that remote sensing products are highly consistent and reproducible. This is an evolving scientific activity that is becoming increasingly important as more long-term studies on global change are undertaken, and new satellite missions are launched. Calibration is the process of quantitatively defining the system responses to known, controlled signal inputs. Validation refers to the process of assessing, by independent means, the quality of the data products derived from the system outputs. These definitions are generally accepted and most often used in the remote sensing context to refer specifically and respectively to sensor radiometric calibration and geophysical parameter validation. Anchor Stations are carefully selected locations at which instruments measure quantities that are needed to run, calibrate or validate models and algorithms. These are needed to quanti-tatively evaluate satellite data and convert it into geophysical information. The instruments collect measurements of basic quantities over a long timescale

  5. Relativistic electrons high doses at International Space Station and Foton M2/M3 satellites

    Science.gov (United States)

    Dachev, T. P.; Tomov, B.; Matviichuk, Yu.; Dimitrov, Pl.; Bankov, N.

    2009-12-01

    The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the period February 20 - April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°-60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 μGy h -1 behind 1.75 g cm -2 shielding at Foton M2, 2314 μGy h -1 behind 0.71 g cm -2 shielding at Foton M3 and 19,195 μGy h -1 (Flux is 8363 cm -2 s -1) behind les than 0.4 g cm -2 shielding at ISS.

  6. A software radio approach to global navigation satellite system receiver design

    Science.gov (United States)

    Akos, Dennis Matthew

    1997-12-01

    The software radio has been described as the most significant evolution in receiver design since the development of the superheterodyne concept in 1918. The software radio design philosophy is to position an analog-to-digital converter (ADC) as close to the antenna as possible and then process the samples using a combination of software and a programmable microprocessor. There are a number of important advantages to be gained through full exploitation of the software radio concept. The most notable include: (1) The removal of analog signal processing components and their associated nonlinear, temperature-based, and age-based performance characteristics. (2) A single antenna/front-end configuration can be used to receive and demodulate a variety of radio frequency (RF) transmissions. (3) The software radio provides the ultimate simulation/testing environment. Global Navigation Satellite Systems (GNSSs) are the latest and most complex radionavigation systems in widespread use. The United States' Global Positioning System (GPS) and, to a lesser extent, the Russian Global Orbiting Navigation Satellite System (GLONASS) are being targeted for use as next generation aviation navigation systems. As a result, it is critical that a GNSS achieve the reliability and integrity necessary for use within the aerospace system. The receiver design is a key element in achieving the high standards required. This work presents the complete development of a GNSS software radio. A GNSS receiver front end has been constructed, based on the software radio design goals, and has been evaluated against the traditional design. Trade-offs associated with each implementation are presented along with experimental results. Novel bandpass sampling front end designs have been proposed, implemented and tested for the processing of multiple GNSS transmissions. Finally, every aspect of GNSS signal processing has been implemented in software from the necessary spread spectrum acquisition algorithms to

  7. An anti-image interference quadrature IF architecture for satellite receivers

    Directory of Open Access Journals (Sweden)

    He Weidong

    2014-08-01

    Full Text Available Since Global Navigation Satellite System (GNSS signals span a wide range of frequency, wireless signals coming from other communication systems may be aliased and appear as image interference. In quadrature intermediate frequency (IF receivers, image aliasing due to in-phase and quadrature (I/Q channel mismatches is always a big problem. I/Q mismatches occur because of gain and phase imbalances between quadrature mixers and capacitor mismatches in analog-to-digital converters (ADC. As a result, the dynamic range and performance of a receiver are severely degraded. In this paper, several popular receiver architectures are summarized and the image aliasing problem is investigated in detail. Based on this analysis, a low-IF architecture is proposed for a single-chip solution and a novel and feasible anti-image algorithm is investigated. With this anti-image digital processing, the image reject ratio (IRR can reach approximately above 50 dB, which relaxes image rejection specific in front-end circuit designs and allows cheap and highly flexible analog front-end solutions. Simulation and experimental data show that the anti-image algorithm can work effectively, robustly, and steadily.

  8. An anti-image interference quadrature IF architecture for satellite receivers

    Institute of Scientific and Technical Information of China (English)

    He Weidong; Lu Xiaochun; He Chengyan; James Torley

    2014-01-01

    Since Global Navigation Satellite System (GNSS) signals span a wide range of frequency, wireless signals coming from other communication systems may be aliased and appear as image interference. In quadrature intermediate frequency (IF) receivers, image aliasing due to in-phase and quadrature (I/Q) channel mismatches is always a big problem. I/Q mismatches occur because of gain and phase imbalances between quadrature mixers and capacitor mismatches in ana-log-to-digital converters (ADC). As a result, the dynamic range and performance of a receiver are severely degraded. In this paper, several popular receiver architectures are summarized and the image aliasing problem is investigated in detail. Based on this analysis, a low-IF architecture is pro-posed for a single-chip solution and a novel and feasible anti-image algorithm is investigated. With this anti-image digital processing, the image reject ratio (IRR) can reach approximately above 50 dB, which relaxes image rejection specific in front-end circuit designs and allows cheap and highly flexible analog front-end solutions. Simulation and experimental data show that the anti-image algorithm can work effectively, robustly, and steadily.

  9. Multi-user satellite communications system using an innovative compressive receiver

    Science.gov (United States)

    Staples, Edward J.

    1992-01-01

    There is a need for an onboard simultaneous multi-channel demodulation system for a satellite communications system. Studies indicate that Convolve Multiply Convolve (CMC) filtering with surface acoustic wave (SAW) dispersive delay lines will eliminate the necessity of onboard satellite channelized filters of complex fourier transform processors. The reason for choosing the CMC technique is its ability to perform Fourier transformations in a shorter time with less space and power consumption than digital Fourier transform processors. Each ground terminal in this multi-users communications system is remotely located and operates independently; hence, a method of synchronizing the transmission of these users is presented which utilizes the existing Global Positioning System (GPS) system. Each ground user is equipped with a low cost ground terminal that has a synchronization subsystem attached to it. The system design of an onboard Multi-channel Receiver and Demodulator utilizes Quadrature Phase Shift Keying (QPSK) as the modulation technique. This technique provides the best figure of merit, i.e., the lowest transmitter power requirement per communication channel.

  10. Simultaneous Laser Ranging and Communication from an Earth-Based Satellite Laser Ranging Station to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Neumann, Gregory A.; McIntire, Leva; Zellar, Ronald S.; Davidson, Frederic M.; Fong, Wai H.; Krainak, Michael A.; Zuber, Maria T.; Smith, David E.

    2013-01-01

    We report a free space laser communication experiment from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit through the on board one-way Laser Ranging (LR) receiver. Pseudo random data and sample image files were transmitted to LRO using a 4096-ary pulse position modulation (PPM) signal format. Reed-Solomon forward error correction codes were used to achieve error free data transmission at a moderate coding overhead rate. The signal fading due to the atmosphere effect was measured and the coding gain could be estimated.

  11. Information management system: A summary discussion. [for use in the space shuttle sortie, modular space station and TDR satellite

    Science.gov (United States)

    Sayers, R. S.

    1972-01-01

    An information management system is proposed for use in the space shuttle sortie, the modular space station, the tracking data relay satellite and associated ground support systems. Several different information management functions, including data acquisition, transfer, storage, processing, control and display are integrated in the system.

  12. Satellite diversity and its implications on the RAKE receiver architecture for CDMA-based S-PCN's

    Science.gov (United States)

    Taaghol, P.; Sammut, A.; Tafazolli, R.; Evans, B. G.

    1995-01-01

    In this paper we examine the applicability of RAKE receivers in a mobile LEO satellite channel and identify the potential problem areas. We then proceed to investigate the possibility of a coherent combining architecture (downlink) in the presence of satellite diversity. We closely examine the path delay difference statistics of a diversity channel and propose a delay compensation scheme for the downlink in order to reduce the complexity of the user terminal. Finally, the required modifications to the conventional RAKE receiver are proposed and discussed.

  13. Determination of SLR station coordinates on the basis of tracking 45 GNSS satellites: benefits for future ITRF realizations

    Science.gov (United States)

    Sośnica, Krzysztof; Bury, Grzegorz; Zajdel, Radosław; Kaźmierski, Kamil; Drożdżewski, Mateusz

    2017-04-01

    The SLR station coordinates and SLR-derived Earth Rotation Parameters (ERPs) are typically derived on the basis of SLR tracking of four spherical geodetic satellites: two LAGEOS and two Etalons. Between 2014 and 2016, the International Laser Ranging Service (ILRS) initiated four intensive SLR tracking campaigns for Galileo and three campaigns devoted to tracking all GNSS spacecraft. As a result, the number of SLR observations and the number of tracked GNSS satellites have dramatically increased allowing for determining SLR station coordinates and ERPs solely on the basis of SLR tracking of GNSS satellites. This paper shows, for the first time, the solution in which the SLR station coordinates, geocenter motion, and ERPs are determined using the SLR observations to 26 GLONASS, 14 Galileo, 2 BeiDou IGSO, 2 BeiDou MEO, and 1 QZSS satellite. We compare the SLR station coordinate stability derived from GNSS-based results to the LAGEOS-only solution and from a combined 'SLR to GNSS+LAGEOS' solution. We address the issues related to the GNSS orbit determination using sparse SLR data and the issues related to handling range biases in the GNSS solutions. We found that the coordinate stability of those SLR stations which provide a large number of GNSS observations can remarkably be improved. The Length-of-day parameter can be derived from SLR-GNSS solutions with a much better accuracy than from the LAGEOS-only solutions. Finally, we show that the SLR tracking of GNSS satellites improves the consistency between SLR and GNSS solutions, and thus, can be beneficial for the future ITRF realizations.

  14. A new method for determination of satellite orbits by transfer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency Transfer (TWSTFT). The original method is called "determination of satellite orbit by transfer". The method is not only for determination of satellite orbit but also for the time transfer with high accuracy and precision. The advantage is that the accuracy and the precision for determination of satellite orbit are very high and the new method is favorable for various applications. The combination of various signals disseminated and received forms various modes of satellite orbit determinations. If receivers at stations receive the own station-disseminated signals via a satellite transponder, it forms an orbit determination mode called "receiving the own station-disseminated signals mode". If receivers at all stations receive the signals disseminated from the master station via satellite transponders, it forms an orbit determination mode called "receiving the master station-disseminated signals mode". If all of receivers at stations receive all stations-disseminated signals via satellite transponders, it forms an orbit determination mode called "receiving all stations-disseminated signals mode". Also there are other combinations of signals for satellite orbit determination. For dif- ferent orbit determination modes with different signal combinations, their rigorous formulae of proc- essing are hereby presented in this paper. The accurate and the precise satellite orbit determination for both of the modes, "receiving the own station-disseminated signals mode" and "receiving the master station-disseminated signals mode" is attempted. It shows that the accuracy and precision for both of modes are nearly the same, the ranging accuracy is better than 1 cm, and the observation residuals of satellite orbit determination are better than 9 cm in the observation duration of 1 day.

  15. A new method for determination of satellite orbits by transfer

    Institute of Scientific and Technical Information of China (English)

    LI ZhiGang; YANG XuHai; AI GuoXiang; SI HuLi; QIAO RongChuan; FENG ChuGang

    2009-01-01

    The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency Transfer (TWSTFT).The original method is called "determination of satellite orbit by transfer".The method is not only for determination of satellite orbit but also for the time transfer with high accuracy and precision.The advantage is that the accuracy and the precision for determination of satellite orbit are very high and the new method is favorable for various applications.The combination of various signals disseminated and received forms various modes of satellite orbit determinations.If receivers at stations receive the own station-disseminated signals via a satellite transponder,it forms an orbit determination mode called "receiving the own station-disseminated signals mode".If receivers at all stations receive the signals disseminated from the master station via satellite transponders,it forms an orbit determination mode called "receiving the master station-disseminated signals mode".If all of receivers at stations receive all stations-disseminated signals via satellite transponders,it forms an orbit determination mode called "receiving all stations-disseminated signals mode".Also there are other combinations of signals for satellite orbit determination.For different orbit determination modes with different signal combinations,their rigorous formulae of processing are hereby presented in this paper.The accurate and the precise satellite orbit determination for both of the modes,"receiving the own station-disseminated signals mode" and "receiving the master station-disseminated signals mode" is attempted.It shows that the accuracy and precision for both of modes are nearly the same,the ranging accuracy is better than 1 cm,and the observation residuals of satellite orbit determination are better than 9 cm in the observation duration of 1 day.

  16. Merged dust climatology in Phoenix, Arizona based on satellite and station data

    Science.gov (United States)

    Lei, Hang; Wang, Julian X. L.; Tong, Daniel Q.; Lee, Pius

    2016-11-01

    In order to construct climate quality long-term dust storm dataset, merged dust storm climatology in Phoenix is developed based on three data sources: regular meteorological records, in situ air quality measurements, and satellite remote sensing observations. The result presented in this paper takes into account the advantages of each dataset and integrates individual analyses demonstrated and presented in previous studies that laid foundation to reconstruct a consistent and continuous time series of dust frequency. A key for the merging procedure is to determine analysis criteria suitable for each individual data source. A practical application to historic records of dust storm activities over the Phoenix area is presented to illustrate detailed steps, advantages, and limitations of the newly developed process. Three datasets are meteorological records from the Sky Harbor station, satellite observed aerosol optical depth data from moderate resolution imaging spectroradiometer, and the U.S. Environmental Protection Agency Air Quality System particulate matter data of eight sites surrounding Phoenix. Our purpose is to construct dust climatology over the Phoenix region for the period 1948-2012. Data qualities of the reconstructed dust climatology are assessed based on the availability and quality of the input data. The period during 2000-2012 has the best quality since all datasets are well archived. The reconstructed climatology shows that dust storm activities over the Phoenix region have large interannual variability. However, seasonal variations show a skewed distribution with higher frequency of dust storm activities in July and August and relatively quiet during the rest of months. Combining advantages of all the available datasets, this study presents a merged product that provides a consistent and continuous time series of dust storm activities suitable for climate studies.

  17. Real-time precise orbit determination of LEO satellites using a single-frequency GPS receiver: Preliminary results of Chinese SJ-9A satellite

    Science.gov (United States)

    Sun, Xiucong; Han, Chao; Chen, Pei

    2017-10-01

    Spaceborne Global Positioning System (GPS) receivers are widely used for orbit determination of low-Earth-orbiting (LEO) satellites. With the improvement of measurement accuracy, single-frequency receivers are recently considered for low-cost small satellite missions. In this paper, a Schmidt-Kalman filter which processes single-frequency GPS measurements and broadcast ephemerides is proposed for real-time precise orbit determination of LEO satellites. The C/A code and L1 phase are linearly combined to eliminate the first-order ionospheric effects. Systematic errors due to ionospheric delay residual, group delay variation, phase center variation, and broadcast ephemeris errors, are lumped together into a noise term, which is modeled as a first-order Gauss-Markov process. In order to reduce computational complexity, the colored noise is considered rather than estimated in the orbit determination process. This ensures that the covariance matrix accurately represents the distribution of estimation errors without increasing the dimension of the state vector. The orbit determination algorithm is tested with actual flight data from the single-frequency GPS receiver onboard China's small satellite Shi Jian-9A (SJ-9A). Preliminary results using a 7-h data arc on October 25, 2012 show that the Schmidt-Kalman filter performs better than the standard Kalman filter in terms of accuracy.

  18. Research on Rake Receiving Performance Based on Multi-satellite Diversity%基于多星分集的Rake接收性能研究

    Institute of Scientific and Technical Information of China (English)

    于开勇

    2014-01-01

    In LEO satellite mobile communication system of CDMA,there are at least two satellites over the gateway station simul-taneously.According to this feature,Rake receiver is studied by considering the channel characteristics of LEO satellite communication systems.In order to track in real time the change of the channel,a multipath combining scheme based on fast convergence LMS algorithm (FC-LMS) is proposed.The simulation results show that the multi-satellite transmits diversity and Rake receiver can be used to reduce the BER and improve the performance of system.%在低轨卫星CDMA移动通信系统中,信关站的上空会同时存在至少2颗卫星。针对这一特点,综合考虑低轨卫星通信信道的特性,研究分析了在信关站端采用的多星分集和Rake接收技术,提出了一种基于快速收敛LMS算法( FC-LMS)的多径合并方案,实现对信道变化的实时跟踪。仿真结果表明,在信关站端采用多星发送分集方案与Rake接收技术,可以有效降低系统误码率,改善系统性能。

  19. wavelet de-noising technique applied to the PLL of a GPS receiver embedded in an observation satellite

    Directory of Open Access Journals (Sweden)

    Dib Djamel Eddine

    2012-02-01

    Full Text Available In this paper, we study the Doppler effect on a GPS(Global Positioning System on board of an observation satellite that receives information on a carrier wave L1 frequency 1575.42 MHz .We simulated GPS signal acquisition. This allowed us to see the behavior of this type of receiver in AWGN channel (AWGN and we define a method to reduce the Doppler Effect in the tracking loop which is wavelet de-noising technique.

  20. Single-frequency receivers as master permanent stations in GNSS networks: precision and accuracy of the positioning in mixed networks

    Science.gov (United States)

    Dabove, Paolo; Manzino, Ambrogio Maria

    2015-04-01

    The use of GPS/GNSS instruments is a common practice in the world at both a commercial and academic research level. Since last ten years, Continuous Operating Reference Stations (CORSs) networks were born in order to achieve the possibility to extend a precise positioning more than 15 km far from the master station. In this context, the Geomatics Research Group of DIATI at the Politecnico di Torino has carried out several experiments in order to evaluate the achievable precision obtainable with different GNSS receivers (geodetic and mass-market) and antennas if a CORSs network is considered. This work starts from the research above described, in particular focusing the attention on the usefulness of single frequency permanent stations in order to thicken the existing CORSs, especially for monitoring purposes. Two different types of CORSs network are available today in Italy: the first one is the so called "regional network" and the second one is the "national network", where the mean inter-station distances are about 25/30 and 50/70 km respectively. These distances are useful for many applications (e.g. mobile mapping) if geodetic instruments are considered but become less useful if mass-market instruments are used or if the inter-station distance between master and rover increases. In this context, some innovative GNSS networks were developed and tested, analyzing the performance of rover's positioning in terms of quality, accuracy and reliability both in real-time and post-processing approach. The use of single frequency GNSS receivers leads to have some limits, especially due to a limited baseline length, the possibility to obtain a correct fixing of the phase ambiguity for the network and to fix the phase ambiguity correctly also for the rover. These factors play a crucial role in order to reach a positioning with a good level of accuracy (as centimetric o better) in a short time and with an high reliability. The goal of this work is to investigate about the

  1. Micro satellite swarm reduces vulnerability: adaptive electronics modify receiver/transmitters to match conditions

    NARCIS (Netherlands)

    Van Kasteren, J.

    2004-01-01

    Bacteria, polyps, ants, and bees are the living proof that, given inhospitable conditions, colonies stand a better chance of survival than individuals.At TU Delft, this biological principle is now being used on spacecraft. A colony of micro satellites will be less vulnerable than a normal satellite,

  2. Correlation Between the "seeing FWHM" of Satellite Optical Observations and Meteorological Data at the OWL-Net Station, Mongolia

    Science.gov (United States)

    Bae, Young-Ho; Jo, Jung Hyun; Yim, Hong-Suh; Park, Young-Sik; Park, Sun-Youp; Moon, Hong Kyu; Choi, Young-Jun; Jang, Hyun-Jung; Roh, Dong-Goo; Choi, Jin; Park, Maru; Cho, Sungki; Kim, Myung-Jin; Choi, Eun-Jung; Park, Jang-Hyun

    2016-06-01

    The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and the seeing of satellite optical observation data was analyzed. Meteorological data and satellite optical observation data from June 2014 to November 2015 were analyzed. The analyzed meteorological data were the outdoor air temperature, relative humidity, wind speed, and cloud index data, and the analyzed satellite optical observation data were the seeing full-width at half-maximum (FWHM) data. The annual meteorological pattern for Mongolia was analyzed by collecting meteorological data over four seasons, with data collection beginning after the installation and initial set-up of the OWL-Net Station No. 1 in Mongolia. A comparison of the meteorological data and the seeing of the satellite optical observation data showed that the seeing degrades as the wind strength increases and as the cloud cover decreases. This finding is explained by the bias effect, which is caused by the fact that the number of images taken on the less cloudy days was relatively small. The seeing FWHM showed no clear correlation with either temperature or relative humidity.

  3. A Single Chip VLSI Implementation of a QPSK/SQPSK Demodulator for a VSAT Receiver Station

    Science.gov (United States)

    Kwatra, S. C.; King, Brent

    1995-01-01

    This thesis presents a VLSI implementation of a QPSK/SQPSK demodulator. It is designed to be employed in a VSAT earth station that utilizes the FDMA/TDM link. A single chip architecture is used to enable this chip to be easily employed in the VSAT system. This demodulator contains lowpass filters, integrate and dump units, unique word detectors, a timing recovery unit, a phase recovery unit and a down conversion unit. The design stages start with a functional representation of the system by using the C programming language. Then it progresses into a register based representation using the VHDL language. The layout components are designed based on these VHDL models and simulated. Component generators are developed for the adder, multiplier, read-only memory and serial access memory in order to shorten the design time. These sub-components are then block routed to form the main components of the system. The main components are block routed to form the final demodulator.

  4. Changes in satellite-derived impervious surface area at US historical climatology network stations

    Science.gov (United States)

    Gallo, Kevin; Xian, George

    2016-10-01

    The difference between 30 m gridded impervious surface area (ISA) between 2001 and 2011 was evaluated within 100 and 1000 m radii of the locations of climate stations that comprise the US Historical Climatology Network. The amount of area associated with observed increases in ISA above specific thresholds was documented for the climate stations. Over 32% of the USHCN stations exhibited an increase in ISA of ⩾20% between 2001 and 2011 for at least 1% of the grid cells within a 100 m radius of the station. However, as the required area associated with ISA change was increased from ⩾1% to ⩾10%, the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 113 (9% of stations). When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius. However, as the required area associated with ISA change was increased to ⩾10% the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 35 (less than 3% of the stations). The gridded ISA data provides an opportunity to characterize the environment around climate stations with a consistently measured indicator of a surface feature. Periodic evaluations of changes in the ISA near the USHCN and other networks of stations are recommended to assure the local environment around the stations has not significantly changed such that observations at the stations may be impacted.

  5. The Use of Chaff in Space as a Jamming Device between Ground Stations and Satellites

    Science.gov (United States)

    1988-12-01

    of Fi•Yu es Figure Page 1. Rasic Orbital Parameters . . . . . . . .... 2. Satellite Orientation for Cases I, II, III, and IV...Moti r on Spin Direction PCe of sot on c.SSO..!Path of notion Case.X AngLe of Tk~t Case-III Cast IV Figure 2. SatelLite Orientation for Cases I, II

  6. Satellite range scheduling with the priority constraint: An improved genetic algorithm using a station ID encoding method

    Directory of Open Access Journals (Sweden)

    Li Yuqing

    2015-06-01

    Full Text Available Satellite range scheduling with the priority constraint is one of the most important problems in the field of satellite operation. This paper proposes a station coding based genetic algorithm to solve this problem, which adopts a new chromosome encoding method that arranges tasks according to the ground station ID. The new encoding method contributes to reducing the complexity in conflict checking and resolving, and helps to improve the ability to find optimal resolutions. Three different selection operators are designed to match the new encoding strategy, namely random selection, greedy selection, and roulette selection. To demonstrate the benefits of the improved genetic algorithm, a basic genetic algorithm is designed in which two cross operators are presented, a single-point crossover and a multi-point crossover. For the purpose of algorithm test and analysis, a problem-generating program is designed, which can simulate problems by modeling features encountered in real-world problems. Based on the problem generator, computational results and analysis are made and illustrated for the scheduling of multiple ground stations.

  7. Project Hermes 'Use of Smartphones for Receiving Telemetry and Commanding a Satellite'

    Science.gov (United States)

    Maharaja, Rishabh (Principal Investigator)

    2016-01-01

    TCPIP protocols can be applied for satellite command, control, and data transfer. Project Hermes was an experiment set-up to test the use of the TCPIP protocol for communicating with a space bound payload. The idea was successfully demonstrated on high altitude balloon flights and on a sub-orbital sounding rocket launched from NASAs Wallops Flight Facility. TCPIP protocols can be applied for satellite command, control, and data transfer. Project Hermes was an experiment set-up to test the use of the TCPIP protocol for communicating with a space bound payload. The idea was successfully demonstrated on high altitude balloon flights and on a sub-orbital sounding rocket launched from NASAs Wallops Flight Facility.

  8. The SPectral Ocean Color (SPOC) Small Satellite Mission: From Payload to Ground Station Development and Everything in Between

    Science.gov (United States)

    Bernardes, S.; Cotten, D. L.

    2016-12-01

    This work introduces the mission concept, technologies, and development status for the measuring SPectral Ocean Color (SPOC) small satellite mission, which will use a hyperspectral imager to map sensitive coastal regions and off coast water quality near the state of Georgia and beyond. SPOC is being developed by The University of Georgia's Small Satellite Research Laboratory (SSRL) with funds from NASA's Undergraduate Student Instrument Project (USIP). The project is led by undergraduates from a wide range of backgrounds and supervised by a multidisciplinary team of Principal Investigators. Using optical components, electronics boards, a grating spectrometer, and a CMOS array the students will assemble and integrate the payload components and ensure their compatibility with the other subsystems. In-house development and assembly includes building the hyperspectral imager, as well integrating it into the satellite, and testing of the different subsystems of the satellite. The mission will collect spectral data along a 300 km swath using the grating spectrometer to diffract the incoming radiation into the 440-865 nm spectral range. The resulting images will be 75 km x 300 km in size, have a 120 m spatial resolution, and a spectral resolution of 2 nm, covering 100 spectral bands. The resulting dataset will allow for spectral analysis comparisons with some of NASA's legacy satellites. The work describes the timeline and current progress of the SPOC mission. Focus will be equally distributed to all the different systems of the satellite including their development, testing, and integration. Particular emphasis is given to Attitude Determination and Control System (ADCS), command and data handling (CDH), payload, power generation, S-Band/X-Band transceivers, and the development of ground station capabilities (S-Band/X-Band).

  9. Industry leading satellite based GNSS (Global Navigation Satellite System) positioning and monitoring solutions with real-time CORS (Continuously Operating Reference Station) networks

    Science.gov (United States)

    Janousek, Martin

    2010-05-01

    Real-Time CORS (Continuously Operating Reference Station Networks) today are typically GNSS networks for positioning and monitoring purposes. Real-Time networks can consist of a few stations for a local network up to nation- or continental wide networks with several hundred CORS stations. Such networks use wide area modeling of GNSS error sources including ionospheric, tropospheric and satellite orbit correction parameters to produce highest precision and efficiency method of positioning using GNSS. In 1998 Trimble Navigation Ltd. introduced a method of surveying with a non-physical or computed base station, called VRS (Virtual Reference Station). It is the most widely supported method of producing a network solution for precise carrier phase positioning in the industry. Surveying historically required one base as the fixed point of reference, and one or multiple rovers using that point of reference to compute their location by processing a vector result, either in real-time or in a postprocessed sense. Real-time survey is often referred to as RTK, short for real-time kinematic, and as the name suggests the results are in real time and you can move. The power of VRS is in the ability to compute a real-time wide-area solution to the factors that cause single base methods to degrade with distance. Namely, ionospheric and tropospheric modeling, and satellite orbit corrections. This is achieved by the reference network of CORS. A wide scattering of CORS across a state, typically 50-70km in mid-latitudes, creates a ground based sampling which significantly reduces the distance dependent errors that accumulate in the single base-rover relationship described early. Furthermore, GNSS networks can be used for real-time monitoring purposes at various distance range. Trimble Integrity Manager software provides a suite of motion engines designed to detect and quantify any movement in a range of scales from slow, creeping movement like subsidence, through sudden events such as

  10. Synchronized Position and Hold Reorient Experimental Satellites - International Space Station (SPHERES-ISS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Payload Systems Inc. (PSI) and the MIT Space Systems Laboratory (MIT-SSL) propose an innovative research program entitled SPHERES-ISS that uses their satellite...

  11. Two-day period fluctuation of PMC occurrence over Syowa Station, Antarctica observed by a ground-based lidar and AIM satellite.

    Science.gov (United States)

    Nakamura, T.; Suzuki, H.; Tsutsumi, M.; Ejiri, M. K.; Tomikawa, Y.; Abo, M.; Kawahara, T.; Tsuda, T. T.; Nishiyama, T.

    2014-12-01

    A Rayleigh/Raman lidar system has been operated by the Japanese Antarctic Research Expedition (JARE) since February, 2011 (JARE 52nd) in Syowa Station Antarctica (69.0S, 39.5E). The lidar system consists of a pulsed Nd:YAG laser (355nm) as a transmitter and two telescopes with four photo multiplier tubes which are to detect Rayleigh scattered light from low and high atmosphere at 355 nm and N2 Raman emission at 387nm. Polar Mesospheric Cloud (PMC) was detected by the lidar at 22:30UT (+3hr for LT) on Feb 4th, 2011, the first day of a routine operation. This event was the first time to detect PMC over Syowa Station by a lidar [Suzuki et al., Ann. Geophys., 2013]. However, signal to noise ratio (SNR) of the PMC event was not so good due to large shot noises from daytime background signals. Moreover, a receiver system was designed mainly for nighttime observations. In this way, observation of PMC during the midnight sun, which also corresponds to most frequent PMC season, was difficult. Thus, to improve SNR of the PMC observation with the lidar during daytime, a narrow band-pass Fabry-Perot etalon unit has been developed and installed in the receiver system on Dec 2013 by JARE 55th. By using this new system, clear PMC signals were successfully detected under daylight condition during the period of summer operation of JARE55th. During this period of 53 days (from 17 Dec. 2013 to 7 Feb. 2014), only 11 days were with a clear sky and suitable for PMC observation. Thus, it was difficult to study temporal variations on a PMC activity only by using the lidar data. Fortunately, NASA's AIM satellite had passed near Syowa Station and provided with complimentary PMC data during observation gap of the lidar. By combining our lidar data with the AIM/CIPS data, nearly continuous monitoring of PMC variability over Syowa Station was achieved for period between 13th and 18th in January 2014. PMC occurrence with an interval of two days over Syowa Station during the period was clearly

  12. Receiver DCB estimation and GPS vTEC study at a low latitude station in the South Pacific

    Science.gov (United States)

    Prasad, Ramendra; Kumar, Sushil; Jayachandran, P. T.

    2016-11-01

    The statistical estimation of receiver differential code bias (DCB) of the GSV4004B receiver at a low latitude station, Suva (lat. 18.15°S, long. 178.45°E, Geomag. Lat. 21.07°S), Fiji, and the subsequent behaviour of vTEC, are presented. By means of least squares linear regression fitting technique, the receiver DCB was determined using the GPS vTEC data recorded during the year 2010, CODE TEC and IRI-2012 model for 2010. To substantiate the results, minimization of the standard deviation (SD) method was also used for GPS vTEC data. The overall monthly DCB was estimated to be in the range of 62.6 TECU. The vTEC after removing the resultant monthly DCB was consistent with other low latitude observations. The GPS vTEC 2010 data after eliminating the resultant DCB were lower in comparison to Faraday rotation vTEC measurements at Suva during 1984 primarily due to higher solar activity during 1984 as compared to 2010. Seasonally, vTEC was maximum during summer and minimum during winter. The winter showed least vTEC variability whereas equinox showed the largest daytime variability. The geomagnetic disturbances effect showed that both vTEC and its variability were higher on magnetically disturbed days as compared to quiet days with maximum variability in the daytime. Two geomagnetic storms of moderate strengths with main phases in the local daytime showed long duration (∼52 h) increase in vTEC by 33-67% which can be accounted by changes in E×B drifts due to prompt penetration of storm-time auroral electric field in the daytime and disturbance dynamo electric field in the nighttime to low latitudes.

  13. Earth rotation, station coordinates and orbit determination from satellite laser ranging

    Science.gov (United States)

    Murata, Masaaki

    The Project MERIT, a special program of international colaboration to Monitor Earth Rotation and Intercompare the Techniques of observation and analysis, has come to an end with great success. Its major objective was to evaluate the ultimate potential of space techniques such as VLBI and satellite laser ranging, in contrast with the other conventional techniques, in the determination of rotational dynamics of the earth. The National Aerospace Laboratory (NAL) has officially participated in the project as an associate analysis center for satellite laser technique for the period of the MERIT Main Campaign (September 1983-October 1984). In this paper, the NAL analysis center results are presented.

  14. Installing the earth station of Ka-band satellite frequency in Malaysia: conceptual framework for site decision

    Science.gov (United States)

    Mahmud, M. R.; Reba, M. N. M.; Jaw, S. W.; Arsyad, A.; Ibrahim, M. A. M.

    2017-05-01

    This paper developed a conceptual framework in determining the suitable location in installing the earth station for Ka-band satellite communication in Malaysia. This current evolution of high throughput satellites experienced major challenge due to Malaysian climate. Because Ka-band frequency is highly attenuated by the rainfall; it is an enormous challenge to define the most appropriate site for the static communication. Site diversity, a measure to anticipate this conflict by choosing less attenuated region and geographically change the transmission strategy on season basis require accurate spatio-temporal information on the geographical, environmental and hydro-climatology at local scale. Prior to that request, this study developed a conceptual framework to cater the needs. By using the digital spatial data, acquired from site measurement and remote sensing, the proposed framework applied a multiple criteria analysis to perform the tasks of site selection. With the advancement of high resolution remotely sensed data, site determination can be conducted as in Malaysia; accommodating a new, fast, and effective satellite communication. The output of this study is one of the pioneer contributions to create a high tech-society.

  15. Design of 1.5 bit quantization correlator in satellite navigation software receiver

    Institute of Scientific and Technical Information of China (English)

    Hongwei Zhou; Tian Jin; Fangyao L

    2016-01-01

    Currently, 1 bit or 2 bit signal quantization is widely used in satelite navigation software receivers. The bit-wise paralel algorithm has been proposed for 1 bit and 2 bit signal quantization, which performs correlation with high efficiency. In order to improve the performance of the correlator, this paper proposes a new 1.5 bit quantization method. Theoreti-cal analyses are made from the aspects of complexity and quantization loss, and performance comparison between 1.5 bit quantization correlator and traditional correlators is dis-cussed. The results show that the 1.5 bit quantization algo-rithm can save about 30 percent complexity under similar quantization loss, reduce more than 0.5 dB signal noise ratio (SNR) loss under similar complexity. It shows great perform-ance improvement for correlators of satelite navigation soft-ware receivers.

  16. Phase Residual Estimations for PCVs of Spaceborne GPS Receiver Antenna and Their Impacts on Precise Orbit Determination of GRACE Satellites

    Institute of Scientific and Technical Information of China (English)

    TU Jia; GU Defeng; WU Yi; YI Dongyun

    2012-01-01

    In-flight phase center systematic errors of global positioning system (GPS) receiver antenna are the main restriction for improving the precision of precise orbit determination using dual-frequency GPS.Residual approach is one of the valid methods for in-flight calibration of GPS receiver antenna phase center variations (PCVs) from ground calibration.In this paper,followed by the correction model of spaceborne GPS receiver antenna phase center,ionosphere-free PCVs can be directly estimated by ionosphere-free carrier phase post-fit residuals of reduced dynamic orbit determination.By the data processing of gravity recovery and climate experiment (GRACE) satellites,the following conclusions are drawn.Firstly,the distributions of ionosphere-free carrier phase post-fit residuals from different periods have the similar systematic characteristics.Secondly,simulations show that the influence of phase residual estimations for ionosphere-free PCVs on orbit determination can reach the centimeter level.Finally,it is shown by in-flight data processing that phase residual estimations of current period could not only be used for the calibration for GPS receiver antenna phase center of foretime and current period,but also be used for the forecast of ionosphere-free PCVs in future period,and the accuracy of orbit determination can be well improved.

  17. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    Directory of Open Access Journals (Sweden)

    S. Coco

    2008-01-01

    Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.

  18. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    OpenAIRE

    Coco, S; Di Maggio, F.; A. Laudani; I. Pomona

    2008-01-01

    This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB) for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase nois...

  19. Narrow multibeam satellite ground station antenna employing a linear array with a geosynchronous arc coverage of 60 deg. I - Theory

    Science.gov (United States)

    Amitay, N.; Gans, M. J.

    1982-11-01

    The feasibility of using an appropriately squinted linear scan in narrow multibeam satellite ground station antennas employing phased arrays is demonstrated. This linear scan has the potential of reducing the complexity of a narrow-beam planar array to that of a linear array. Calculations for such antennas placed at cities throughout the U.S. show that the peak beam pointing error in covering the 70 deg W to 130 deg W geosynchronous equatorial arc (GEA) is under 5/1000th of a degree. Communication at a 300 MBd rate in the 12/14 GHz band can be made feasible, for a grating lobe-free scan and 0.5 deg beamwidth antenna, by using a relatively simple time equalization.

  20. Role of Indian remote sensing imaging satellites for the Antarctic monitoring and mapping: a case study around Indian Antarctic research stations

    Science.gov (United States)

    Jayaprasad, P.; Mehra, Raghav; Chawla, Saket; Rajak, D. Ram; Oza, Sandip R.

    2016-05-01

    Antarctic research station's existence largely depend on the supply of fuel, food and other commodities through Antarctic Scientific Expedition using ship voyage. Safer Ship Navigation demands high resolution satellite monitoring of the ice conditions which varies from 30 km to 200 km from the Antarctic coast of Research stations. During the last couple of years Indian Satellites play a major role in safer ship navigation in sea ice regions of the Arctic and the Antarctic. Specifically Indian Scientific Expedition to the Antarctica (ISEA) through National Centre for Antarctic and Oceanic Research (NCAOR) is one of the beneficiaries for safer ship navigation using information derived from Indian Satellite data. Space Applications Centre, Indian Space Research Organisation (SAC-ISRO) is providing Sea Ice Advisories for the safer optimum entry and exit for the expedition ship at two of the Research stations Bharati and Maitri. Two of the Indian Satellites namely Radar Imaging Satellite-1 (RISAT-1) and ResourceSAT-2 (RS-2) are the two major workhorses of ISRO for monitoring and mapping of the Antarctic terrain. The present study demonstrate the utilisation potential of these satellite images for various Polar Science Applications. Mosaic of the Antarctic Terrain was generated from RISAT-1 CRS data. The preliminary results of the mosaic from CRS- circular polarisation data is presented. Demonstration of the study is extended for other applications such as change detection studies, safer ship navigation and extreme events of Antarctica. The use of multi resolution multi sensor data is also shown in the study.

  1. UAS Satellite Earth Station Emission Limits for Terrestrial System Interference Protection

    Science.gov (United States)

    Kerczewski, Robert J.; Bishop, William D.

    2017-01-01

    Unmanned aircraft systems (UAS) will have a major impact on future aviation. Medium and large UA operating at altitudes above 3000 feet will require access to non-segregated, that is, controlled airspace. In order for unmanned aircraft to be integrated into the airspace and operate with other commercial aircraft, a very reliable command and control (C2, a. k. a. control and non-payload communications, (CNPC)) link is required. For operations covering large distances or over remote locations, a beyond-line-of-sight (BLOS) CNPC link would need to be implemented through satellite. Significant progress has taken place on several fronts to advance the integration of UAS into controlled airspace, including the recent completion of Minimum Operational Performance Standards (MOPS) for terrestrial line-of-sight (LOS) UAS command and control (C2) links. The development of MOPS for beyond line-of-sight C2 satellite communication links is underway. Meanwhile the allocation of spectrum for UAS C2 by the International Telecommunications Union Radiocommunication Sector (ITU-R) has also progressed. Spectrum for LOS C2 was allocated at the 2012 World Radiocommunication Conference (WRC-12), and for BLOS C2 an allocation was made at WRC-15, under WRC-15 Resolution 155. Resolution 155, however, does not come into effect until several other actions have been completed. One of these required actions is the identification of a power flux density (pfd) limit on the emissions of UAS Ku-Band satellite communications transmitters reaching the ground. The pfd limit is intended to protect terrestrial systems from harmful interference. WRC-19 is expected to finalize the pfd limit. In preparation for WRC-19, analyses of the required pfd limit are on-going, and supporting activities such as propagation modeling are also planned. This paper provides the status of these activities.

  2. Spatial and temporal variation of CO over Alberta using measurements from satellite, aircrafts, and ground stations

    Science.gov (United States)

    Marey, H. S.; Hashisho, Z.; Fu, L.; Gille, J.

    2014-12-01

    Alberta is Canada's largest oil producer and its oil sand deposits comprise 30% of the world's oil reserves. The process of bitumen extraction and upgrading releases trace gases and aerosols to the atmosphere. In this study we present satellite-based analysis to explore, for the first time, various contributing factors that affect tropospheric carbon monoxide (CO) levels over Alberta. The multispectral product that uses both near-infrared (NIR) and the thermal-infrared (TIR) radiances for CO retrieval from the Measurements of Pollution in the Troposphere (MOPITT) are examined for the 12 year period from 2002-2013. Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomaly product from 2001 to 2013 is employed to investigate the seasonal and temporal variations of forest fires. Additionally, in situ CO measurements at industrial and urban sites are compared to satellite data. Furthermore, the available MOZAIC/IAGOS (Measurement of Ozone, Water Vapor, Carbon Monoxide, Nitrogen Oxide by Airbus In-Service Aircraft/In service Aircraft for Global Observing System) aircraft CO profiles (April 2009-December 2011) are used to validate MOPITT CO data. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons, summer and spring. Distinct seasonal patterns of CO at the urban site s (Edmonton and Calgary cities) point to the strong influence of traffic. Meteorological parameters play an important role on the CO spatial distribution at various pressure levels. Northern Alberta shows stronger upward lifting motion which leads to larger CO total column values while the poor dispersion in central and south Alberta exacerbates the surface CO pollution. Inter-annual variations of satellite data depict a slightly decreasing trend for both regions while the decline trend is more evident from ground observations, especially at the urban sites. MOPITT CO vertical

  3. Spatial and temporal variation in CO over Alberta using measurements from satellites, aircraft, and ground stations

    Science.gov (United States)

    Marey, H. S.; Hashisho, Z.; Fu, L.; Gille, J.

    2015-04-01

    Alberta is Canada's largest oil producer, and its oil sands deposits comprise 30% of the world's oil reserves. The process of bitumen extraction and upgrading releases trace gases and aerosols to the atmosphere. In this study we present satellite-based analysis to explore, for the first time, various contributing factors that affect tropospheric carbon monoxide (CO) levels over Alberta. The multispectral product that uses both near-infrared (NIR) and the thermal-infrared (TIR) radiances for CO retrieval from the Measurements of Pollution in the Troposphere (MOPITT) is examined for the 12-year period from 2002 to 2013. The Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomaly product from 2001 to 2013 is employed to investigate the seasonal and temporal variations in forest fires. Additionally, in situ CO measurements at industrial and urban sites are compared to satellite data. Furthermore, the available MOZAIC/IAGOS (Measurement of Ozone, Water Vapor, Carbon Monoxide, Nitrogen Oxide by Airbus In-Service Aircraft/In service Aircraft for Global Observing System) aircraft CO profiles (April 2009-December 2011) are used to validate MOPITT CO data. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons: summer and spring. Distinct seasonal patterns of CO at the urban sites (Edmonton and Calgary) point to the strong influence of traffic. Meteorological parameters play an important role in the CO spatial distribution at various pressure levels. Northern Alberta shows a stronger upward lifting motion which leads to larger CO total column values, while the poor dispersion in central and southern Alberta exacerbates the surface CO pollution. Interannual variations in satellite data depict a slightly decreasing trend for both regions, while the decline trend is more evident from ground observations, especially at the urban sites. MOPITT CO vertical

  4. Spatial and temporal variation of CO over Alberta using measurements from satellite, aircrafts, and ground stations

    Directory of Open Access Journals (Sweden)

    H. S. Marey

    2014-12-01

    Full Text Available Alberta is Canada's largest oil producer and its oil sand deposits comprise 30% of the world's oil reserves. The process of bitumen extraction and upgrading releases trace gases and aerosols to the atmosphere. In this study we present satellite-based analysis to explore, for the first time, various contributing factors that affect tropospheric carbon monoxide (CO levels over Alberta. The multispectral product that uses both near-infrared (NIR and the thermal-infrared (TIR radiances for CO retrieval from the Measurements of Pollution in the Troposphere (MOPITT are examined for the 12 year period from 2002–2013. Moderate Resolution Imaging Spectroradiometer (MODIS thermal anomaly product from 2001 to 2013 is employed to investigate the seasonal and temporal variations of forest fires. Additionally, in situ CO measurements at industrial and urban sites are compared to satellite data. Furthermore, the available MOZAIC/IAGOS (Measurement of Ozone, Water Vapor, Carbon Monoxide, Nitrogen Oxide by Airbus In-Service Aircraft/In service Aircraft for Global Observing System aircraft CO profiles (April 2009–December 2011 are used to validate MOPITT CO data. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons, summer and spring. Distinct seasonal patterns of CO at the urban site s (Edmonton and Calgary cities point to the strong influence of traffic. Meteorological parameters play an important role on the CO spatial distribution at various pressure levels. Northern Alberta shows stronger upward lifting motion which leads to larger CO total column values while the poor dispersion in central and south Alberta exacerbates the surface CO pollution. Inter-annual variations of satellite data depict a slightly decreasing trend for both regions while the decline trend is more evident from ground observations, especially at the urban sites. MOPITT CO

  5. Response of Global Navigation Satellite System receivers to known shaking between 0.2 and 20 Hertz

    Science.gov (United States)

    Langbein, John; Evans, John R.; Blume, Fredrick; Johanson, Ingrid

    2014-01-01

    Over the past decade, several technological advances have allowed Global Navigation Satellite Systems (GNSS) receivers to have the capability to record displacements at high frequencies, with sampling rates approaching 100 samples per second (sps). In addition, communication and computer hardware and software have allowed various institutions, including the U.S. Geological Survey (USGS), to retrieve, process, and display position changes recorded by a network of GNSS sites with small, less than 1-s delays between the time that the GNSS receiver records signals from a constellation of satellites and the time that the position is estimated (a method known as “real-time”). These improvements in hardware and software have allowed the USGS to process GNSS (or a subset of the GNSS, the Global Positioning System, GPS) data in real-time at 1 sps with the goal of determining displacements from earthquakes and volcanoes in real-time. However, the current set of GNSS equipment can record at rates of 100 sps, which allows the possibility of using this equipment to record earthquake displacements over the full range of frequencies that typically are recorded by acceleration and velocity transducers. The advantage of using GNSS to record earthquakes is that the displacement, rather than acceleration or velocity, is recorded, and for large earthquakes, the GNSS sensor stays on scale and will not distort the observations due to clipping of the signal at its highest amplitude. The direct observation of displacement is advantageous in estimating the size and spatial extent of the earthquake rupture. Otherwise, when using velocity or acceleration sensors, the displacements are determined by numerical integration of the observations, which can introduce significant uncertainty in the estimated displacements. However, GNSS technology can, at best, resolve displacements of a few millimeters, and for most earthquakes, their displacements are less than 1 mm. Consequently, to be useful

  6. Whistler-triggered VLF noise bursts observed on the DE-1 satellite and simultaneously at Antarctic ground stations

    Science.gov (United States)

    Smith, A. J.; Carpenter, D. L.; Inan, U. S.

    1985-01-01

    Simultaneous observations of whistler-triggered very low-frequency noise bursts on the ground at Anarctic stations, Halley and Siple, and on the high-altitude satellite DE-1 are reported. Results of a case study from June 25, 1982 in which the satellite data were recorded near 25 deg south magnetic latitude and the L = 4.7 magnetic shell, are presented. Analysis indicates that the chorus bursts that are triggered in whistler ducts travel downwards in the ducts to low altitudes in the ionosphere, and that propagation to DE-1 is by upward reflection into a nonducted mode. A means of estimating the propagation characteristics of the wave bursts is provided by comparisons of nonducted signals from the Siple transmitter and discrete periodic emissions. The ducted-nonducted mode conversion process is a mechanism for the large-scale spreading into the magnetosphere of coherent whistler-mode wave energy which is generated, amplified, or triggered in small localized ducts. The DE-1 data show that a strong interaction exists between whistler-triggered noise bursts and prevailing hiss levels.

  7. Telecom and scintillation first data analysis for DOMINO: laser communication between SOTA, onboard SOCRATES satellite, and MEO optical ground station

    Science.gov (United States)

    Phung, D.-H.; Samain, E.; Maurice, N.; Albanesse, D.; Mariey, H.; Aimar, M.; M. Lagarde, G.; Artaud, G.; Issler, J.-L.; Vedrenne, N.; Velluet, M.-T.; Toyoshima, M.; Akioka, M.; Kolev, D.; Munemasa, Y.; Takenaka, H.; Iwakiri, N.

    2016-03-01

    In collaboration between CNES, NICT, Geoazur, the first successful lasercom link between the micro-satellite SOCRATES and an OGS in Europe has been established. This paper presents some results of telecom and scintillation first data analysis for 4 successful links in June & July 2015 between SOTA terminal and MEO optical ground station (OGS) at Caussols France. The telecom and scintillation data have been continuously recorded during the passes by using a detector developed at the laboratory. An irradiance of 190 nW/m2 and 430 nW/m2 has been detected for 1549 nm and 976 nm downlinks at 35° elevation. Spectrums of power fluctuation measured at OGS are analyzed at different elevation angles and at different diameters of telescope aperture to determine fluctuations caused by pointing error (due to satellite & OGS telescope vibrations) and caused by atmospheric turbulence. Downlink & Uplink budgets are analyzed, the theoretical estimation matches well to measured power levels. Telecom signal forms and bit error rates (BER) of 1549 nm and 976 nm downlink are also shown at different diameters of telescope aperture. BER is 'Error Free' with full-aperture 1.5m telescope, and almost in `good channel' with 0.4 m sub-aperture of telescope. We also show the comparison between the expected and measured BER distributions.

  8. 我国液化天然气接收站防爆设计%China's liquefied natural gas receiving station explosion proof design

    Institute of Scientific and Technical Information of China (English)

    朱向东

    2015-01-01

    天然气所具有易燃、易爆特点,使得液化天然气(LNG)接收站工程设计中要始终把防爆安全问题放在首要位置来考虑.文章依据LNG接收站爆炸事故特征,通过对于接收站中不同程度危险区域的划分,研究了液化天然气接收站防爆设计.%Natural gas is flammable, explosive has characteristics, which makes the liquefied natural gas (LNG) receiving station project design should always put the explosion-proof safety problems in the first place to consider. According to the characteristics of explosion accident of LNG receiving station, through the division of the different degree for hazardous area in a receiving station, studies the liquefied natural gas receiving station explosion proof design.

  9. GLORI (GLObal navigation satellite system Reflectometry Instrument): A New Airborne GNSS-R receiver for land surface applications

    Science.gov (United States)

    Motte, Erwan; Zribi, Mehrez; Fanise, Pascal

    2015-04-01

    GLORI (GLObal navigation satellite system Reflectometry Instrument) is a new receiver dedicated to the airborne measurement of surface parameters such as soil moisture and biomass above ground and sea state (wave height and direction) above oceans. The instrument is based on the PARIS concept [Martin-Neira, 1993] using both the direct and surface-reflected L-band signals from the GPS constellation as a multistatic radar source. The receiver is based on one up-looking and one down-looking dual polarization hemispherical active antennas feeding a low-cost 4-channel SDR direct down-conversion receiver tuned to the GPS L1 frequency. The raw measurements are sampled at 16.368MHz and stored as 2-bit, IQ binary files. In post-processing, GPS acquisition and tracking are performed on the direct up-looking signal while the down-looking signal is processed blindly using tracking parameters from the direct signal. The obtained direct and reflected code-correlation waveforms are the basic observables for geophysical parameters inversion. The instrument was designed to be installed aboard the ATR42 experimental aircraft from the French SAFIRE fleet as a permanent payload. The long term goal of the project is to provide real-time continuous surface information for every flight performed. The aircraft records attitude information through its Inertial Measurement Unit and a commercial GPS receiver records additional information such as estimated doppler and code phase, receiver location, satellites azimuth and elevation. A series of test flights were performed over both the Toulouse and Gulf of Lion (Mediterranean Sea) regions during the period 17-21 Nov 2014 together with the KuROS radar [Hauser et al., 2014]. Using processing methods from the literature [Egido et al., 2014], preliminary results demonstrate the instrument sensitivity to both ground and ocean surface parameters estimation. A dedicated scientific flight campaign is planned at the end of second quarter 2015 with

  10. Global manifestations of a substorm onset observed by a multi-satellite and ground station network

    Directory of Open Access Journals (Sweden)

    H. Wang

    2006-12-01

    Full Text Available With a favorable constellation of spacecraft and ground stations, a study is made on the global manifestations of a substorm onset. The onset occurred simultaneously and conjugately in both hemispheres, confirmed by observations of the auroral breakup from IMAGE FUV-WIC and a sudden intensification of a westward electrojet from ground-based magnetometers. Concurrently with the onset, field-aligned and Hall currents in the auroral ionosphere are observed by CHAMP, which are consistent with the signature of a Harang discontinuity. Immediately after the onset a magnetic field dipolarization is clearly observed by Double Star TC-1, located near the central magnetotail and subsequently, by the Cluster quartet. The observations can be explained by a dawnward propagation of the substorm current wedge at a speed of about 300 km/s.

  11. Time-transfer experiments between satellite laser ranging ground stations via one-way laser ranging to the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Mao, D.; Sun, X.; Skillman, D. R.; Mcgarry, J.; Hoffman, E.; Neumann, G. A.; Torrence, M. H.; Smith, D. E.; Zuber, M. T.

    2014-12-01

    Satellite laser ranging (SLR) has long been used to measure the distance from a ground station to an Earth-orbiting satellite in order to determine the spacecraft position in orbit, and to conduct other geodetic measurements such as plate motions. This technique can also be used to transfer time between the station and satellite, and between remote SLR sites, as recently demonstrated by the Time Transfer by Laser Link (T2L2) project by the Centre National d'Etudes Spatiaes (CNES) and Observatorire de la Cote d'Azur (OCA) as well as the Laser Time Transfer (LTT) project by the Shanghai Astronomical Observatory, where two-way and one-way measurements were obtained at the same time. Here we report a new technique to transfer time between distant SLR stations via simultaneous one-way laser ranging (LR) to the Lunar Reconnaissance Orbiter (LRO) spacecraft at lunar distance. The major objectives are to establish accurate ground station times and to improve LRO orbit determination via these measurements. The results of these simultaneous LR measurements are used to compare the SLR station times or transfer time from one to the other using times-of-flight estimated from conventional radio frequency tracking of LRO. The accuracy of the time transfer depends only on the difference of the times-of-flight from each ground station to the spacecraft, and is expected to be at sub-nano second level. The technique has been validated by both a ground-based experiment and an experiment that utilized LRO. Here we present the results to show that sub-nanosecond precision and accuracy are achievable. Both experiments were carried out between the primary LRO-LR station, The Next Generation Satellite Laser Ranging (NGSLR) station, and its nearby station, Mobile Laser System (MOBLAS-7), both at Greenbelt, Maryland. The laser transmit time from both stations were recorded by the same event timer referenced to a Hydrogen maser. The results have been compared to data from a common All

  12. Geostatistical improvements of evapotranspiration spatial information using satellite land surface and weather stations data

    Science.gov (United States)

    de Carvalho Alves, Marcelo; de Carvalho, Luiz Gonsaga; Vianello, Rubens Leite; Sediyama, Gilberto C.; de Oliveira, Marcelo Silva; de Sá Junior, Arionaldo

    2013-07-01

    The objective of the present study was to use the simple cokriging methodology to characterize the spatial variability of Penman-Monteith reference evapotranspiration and Thornthwaite potential evapotranspiration methods based on Moderate Resolution Imaging Spetroradiometer (MODIS) global evapotranspiration products and high-resolution surfaces of WordClim temperature and precipitation data. The climatic element data referred to 39 National Institute of Meteorology climatic stations located in Minas Gerais state, Brazil and surrounding states. The use of geostatistics and simple cokriging technique enabled the characterization of the spatial variability of the evapotranspiration providing uncertainty information on the spatial prediction pattern. Evapotranspiration and precipitation surfaces were implemented for the climatic classification in Minas Gerais. Multivariate geostatistical determined improvements of evapotranspiration spatial information. The regions in the south of Minas Gerais derived from the moisture index estimated with the MODIS evapotranspiration (2000-2010), presented divergence of humid conditions when compared to the moisture index derived from the simple kriged and cokriged evapotranspiration (1961-1990), indicating climate change in this region. There was stronger pattern of crossed covariance between evapotranspiration and precipitation rather than temperature, indicating that trends in precipitation could be one of the main external drivers of the evapotranspiration in Minas Gerais state, Brazil.

  13. Galileo satellite antenna modeling

    Science.gov (United States)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  14. Uplink Power Control For Earth/Satellite/Earth Communication

    Science.gov (United States)

    Chakraborty, Dayamoy

    1994-01-01

    Proposed control subsystem adjusts power radiated by uplink transmitter in Earth station/satellite relay station/ Earth station communication system. Adjustments made to compensate for anticipated changes in attenuation by rain. Raw input is a received downlink beacon singal, amplitude of which affected not only by rain fade but also by scintillation, attenuation in atmospheric gases, and diurnal effects.

  15. Tropospheric ozone variability during the East Asian summer monsoon as observed by satellite (IASI), aircraft (MOZAIC) and ground stations

    Science.gov (United States)

    Safieddine, Sarah; Boynard, Anne; Hao, Nan; Huang, Fuxiang; Wang, Lili; Ji, Dongsheng; Barret, Brice; Ghude, Sachin D.; Coheur, Pierre-François; Hurtmans, Daniel; Clerbaux, Cathy

    2016-08-01

    Satellite measurements from the thermal Infrared Atmospheric Sounding Interferometer (IASI), aircraft data from the MOZAIC/IAGOS project, as well as observations from ground-based stations, are used to assess the tropospheric ozone (O3) variability during the East Asian Summer Monsoon (EASM). Six years 2008-2013 of IASI data analysis reveals the ability of the instrument to detect the onset and the progression of the monsoon seen by a decrease in the tropospheric 0-6 km O3 column due to the EASM, and to reproduce this decrease from one year to the other. The year-to-year variability is found to be mainly dependent on meteorology. Focusing on the period of May-August 2011, taken as an example year, IASI data show clear inverse relationship between tropospheric 0-6 km O3 on one hand and meteorological parameters such as cloud cover, relative humidity and wind speed, on the other hand. Aircraft data from the MOZAIC/IAGOS project for the EASM of 2008-2013 are used to validate the IASI data and to assess the effect of the monsoon on the vertical distribution of the tropospheric O3 at different locations. Results show good agreement with a correlation coefficient of 0.73 (12 %) between the 0-6 km O3 column derived from IASI and aircraft data. IASI captures very well the inter-annual variation of tropospheric O3 observed by the aircraft data over the studied domain. Analysis of vertical profiles of the aircraft data shows a decrease in the tropospheric O3 that is more important in the free troposphere than in the boundary layer and at 10-20° N than elsewhere. Ground station data at different locations in India and China show a spatiotemporal dependence on meteorology during the monsoon, with a decrease up to 22 ppbv in Hyderabad, and up to 5 ppbv in the North China Plain.

  16. Detection of Transionospheric SuperDARN HF Waves by the Radio Receiver Instrument on the enhanced Polar Outflow Probe Satellite

    Science.gov (United States)

    Gillies, R. G.; Yau, A. W.; James, H. G.; Hussey, G. C.; McWilliams, K. A.

    2014-12-01

    The enhanced Polar Outflow Probe (ePOP) Canadian small-satellite was launched in September 2013. Included in this suite of eight scientific instruments is the Radio Receiver Instrument (RRI). The RRI has been used to measure VLF and HF radio waves from various ground and spontaneous ionospheric sources. The first dedicated ground transmission that was detected by RRI was from the Saskatoon Super Dual Auroral Radar Network (SuperDARN) radar on Nov. 7, 2013 at 14 MHz. Several other passes over the Saskatoon SuperDARN radar have been recorded since then. Ground transmissions have also been observed from other radars, such as the SPEAR, HAARP, and SURA ionospheric heaters. However, the focus of this study will be on the results obtained from the SuperDARN passes. An analysis of the signal recorded by the RRI provides estimates of signal power, Doppler shift, polarization, absolute time delay, differential mode delay, and angle of arrival. By comparing these parameters to similar parameters derived from ray tracing simulations, ionospheric electron density structures may be detected and measured. Further analysis of the results from the other ground transmitters and future SuperDARN passes will be used to refine these results.

  17. The effective and dust free receiving station and handling for the low calorific value solid fuels; Tehokas ja poelytoen seospolttoaineiden vastaanottoasema sekae kaesittely- ja kuljetinjaerjestelmae

    Energy Technology Data Exchange (ETDEWEB)

    Nojonen, O. [Finntech Oy, Espoo (Finland); Jaervinen, T. [VTT Energy, Jyvaeskylae (Finland). Energy Use

    1995-12-31

    The aim of the project was to get higher automatization level and improve dust preventing in solid fuel receiving stations. There are two general types of receiving stations in the Finnish power plants: large unloading stations for the side tipping devices of trucks and small ones for the rear tipping devices of trucks. In the first ones the trucks empty their load (approx. 100 m{sup 3} loose bulk density) divided by hauling unit and trailer within few (5-10) minutes into a rectangular box, which depth is approx. 3 m. The discharging causes a strong counter current air and dust flow (20-40 m{sup 3}/s) upwards and the dust will easily spread out all over the station. In the second ones the discharging takes place from the rear of truck and trailer using loadspace conveyor of the vehicle within 20 minutes. The material falls on a (belt) conveyor, which is on the floor level. The problems in side tipping system are connected with dust and surplus time, which is needed for the preparation and completion of unloading and sampling. For the fine dust control has also been tested water spray (fog) nozzles and tried to utilise a settling chamber for the dust stream. Also the using the settling chamber equipped with air suction connections and cyclone separation may be effective. In the rear tipping system are also applied bag filters because of smaller air quantities. The rapid truck positioning and control in the receiving station is one of the presupposition for the fast and accurate unloading. This can be done using ultrasonic sensing methods. Also the ensuring of accurate discharging can be based on the modern technology. One of the basic things is the enlarging of video control (CCD -cameras)

  18. Concept for a Lunar Transfer Vehicle for Small Satellite Delivery to the Moon from the International Space Station

    Science.gov (United States)

    Elliott, John; Alkalai, Leon

    2010-01-01

    The International Space Station (ISS) has developed as a very capable center for scientific research in Lower Earth Orbit. An additional potential of the ISS that has not thus far been exploited, is the use of this orbiting plat-form for the assembly and launching of vehicles that could be sent to more distant destinations. This paper reports the results of a recent study that looked at an architecture and conceptual flight system design for a lunar transfer vehicle (LTV) that could be delivered to the ISS in segments, assembled, loaded with payload and launched from the ISS with the objective of delivering multiple small and micro satellites to lunar orbit. The design of the LTV was optimized for low cost and high payload capability, as well as ease of assembly. The resulting design would use solar electric propulsion (SEP) to carry a total payload mass of 250 kg from the ISS to a 100 km lunar orbit. A preliminary concept of operations was developed considering currently available delivery options and ISS capabili-ties that should prove flexible enough to accommodate a variety of payloads and missions. This paper will present an overview of the study, including key trades, mission and flight system design, and notional operational concept.

  19. Studies of Geomagnetic Pulsations Using Magnetometer Data from the CHAMP Low-Earth-Orbit Satellite and Ground-Based Stations: a Review

    Directory of Open Access Journals (Sweden)

    P R Sutcliffe

    2011-06-01

    Full Text Available We review research on geomagnetic pulsations carried out using magnetic field measurements from the CHAMP low-Earth-orbit (LEO satellite and ground-based stations in South Africa and Hungary. The high quality magnetic field measurements from CHAMP made it possible to extract and clearly resolve Pi2 and Pc3 pulsations in LEO satellite data. Our analyses for nighttime Pi2 pulsations are indicative of a cavity mode resonance. However, observations of daytime Pi2 pulsation events identified in ground station data show no convincing evidence of their occurrence in CHAMP data. We also studied low-latitude Pc3 pulsations and found that different types of field line resonant structure occur, namely discrete frequencies driven by a narrow band source and L-dependent frequencies driven by a broad band source.

  20. Estimation of differential code biases for Beidou navigation system using multi-GNSS observations: How stable are the differential satellite and receiver code biases?

    Science.gov (United States)

    Xue, Junchen; Song, Shuli; Zhu, Wenyao

    2016-04-01

    Differential code biases (DCBs) are important parameters that must be estimated accurately and reliably for high-precision GNSS applications. For optimal operational service performance of the Beidou navigation system (BDS), continuous monitoring and constant quality assessment of the BDS satellite DCBs are crucial. In this study, a global ionospheric model was constructed based on a dual system BDS/GPS combination. Daily BDS DCBs were estimated together with the total electron content from 23 months' multi-GNSS observations. The stability of the resulting BDS DCB estimates was analyzed in detail. It was found that over a long period, the standard deviations (STDs) for all satellite B1-B2 DCBs were within 0.3 ns (average: 0.19 ns) and for all satellite B1-B3 DCBs, the STDs were within 0.36 ns (average: 0.22 ns). For BDS receivers, the STDs were greater than for the satellites, with most values BDS satellite DCBs between two consecutive days was BDS DCBs, they only require occasional estimation or calibration. Furthermore, the 30-day averaged satellite DCBs can be used reliably for the most demanding BDS applications.

  1. Deployment Forecast of Bistatic Receive Station Based on Threat Evaluation%基于威胁评估的双基地R站配置预测

    Institute of Scientific and Technical Information of China (English)

    孙云辉; 陈永光; 汪亚夫; 吕栋雷

    2011-01-01

    Because the position of receive station is unknown, the jamming efficiency that the traditional jamming measures against bistatic radar is dissatisfactory. If the position of receive station is forecasted and estimated, the threat degree of bistatic radar will be reduced when the penetrating route of attacker is ascertained. So a deployment forecast method of receive station of bistatic radar based on threat evaluation is put forward. The method bases on a precondition that where the higher threat degree of receive station is, where the more possible the receiver is. The threat evaluation model is studied in the condition of decided penetrating route. The simulation method of deployment forecast region is given. The simulation results can work for electronic jamming decision.%双基地R站未知,传统的干扰手段很难对其取得理想的干扰效果.如果进攻方能够基于自身突防航线对R站配置位置作出大致预测和估计,进而实施针对性干扰,将可大大降低来自双基地系统的探测、定位与跟踪威胁.基于上述考虑,提出了一种基于威胁评估的双基地R站配置预测方法.该方法基于“R站对突防航段的威胁越大,则雷达方在该处作实际配置部署的可能性就越大”.这一前提和假设,研究了已知航线条件下的R站威胁评估模型,给出了配置预测区域的仿真绘制方法,仿真结果可为电子干扰决策提供依据.

  2. Design of Discrete Time Radio Receiver for the Demodulation of Power-Separated Co-Channel Satellite Communication Signals

    Science.gov (United States)

    2013-09-01

    video broadcasting [7]. ViaSat-1 (pictured in Figure 1), a high capacity Ka - band communications satellite went into service on 16 January 2012 as the...Video Broadcasting- satellite , Second Generation 8PSK 8- Phase Shift Keying GTED Gardner Timing Error Detector HP High Power signal, in layered...Spectral Density QPSK Quadrature Phase Shift Keying SCADA Supervisory Control and Data Acquisition SNR Signal to Noise Ratio SRRC Squared Raised

  3. 卫星便携站天线自动对星系统的设计与实现%Design and implement of satellite auto-aiming system on antenna of satellite portable station

    Institute of Scientific and Technical Information of China (English)

    胡明; 王星全; 郑振华; 杨华

    2012-01-01

    In the porcess of narrow-beam portable station antenna aiming the satellite, there are three problems: finding the satellite difficulty, aiming the satellite long-time and low-precision. In this article, an auto-aim instrument on equipment is designed and implemented. This instrument based on PIC singlechip can implement rapid, automatic and precise aiming the satellite by collecting and porcessing the data from GPS and sensors and signal strength module, controling stepping motors to adjust the azimuth and elevation of portable station antenna. Using this system, we can reduce the time, improve the precision in aiming the satellite and prove the efficiency of communication markedly.%针对卫星便携站窄波束天线找星难度大、对星耗时多、对星精度差的问题,设计并实现了一个附加在实装设备上的自动对星工具,以PIC单片机为核心,通过采集和处理GPS数据、方位俯仰传感器数据和卫星信号强度数据,控制高精度步进电机自动调整便携站天线方位角和俯仰角,从而实现快速、自动、精确对星.通过使用高精度步进电机代替传统手工操作,能够明显缩短对星时间、提高对星精度,且体积较小、安装拆卸容易、携带方便,显著提高了通信效能.

  4. A System for Receiving and Analyzing Meteorological Satellite Data at Small Meteorological/Oceanographic Centres or Aboard Ship,

    Science.gov (United States)

    1983-10-01

    variability. Used wih SACLANTCEN’s growing archive of satellite data and its SONDA data base of environmental data <A.2> it assists in pre-cruise planning . It...SATDI General image display program (menu driven) $ TAREA Temperature/Albedo/Pixel level histogram over an an defined irregular area (trackball driven...can be determined. This allows flexibility in further pro- cessing by other routines (GRUTM, GRD, TCURV, TAREA ). A.2.2 The GRUTM routine (’GR’) In

  5. 浅谈我校卫星电视接收系统%Satellite TV Receiving System in Shanghai Ocean University

    Institute of Scientific and Technical Information of China (English)

    乔文增

    2012-01-01

    The Satellite TV Receiving System in our school is in front of digital TV, and its information source comes from 6 sets of programs of SINOSAT-1. It combines with the cable TV transmission system to output cable TV, and combines with the campus television system to achieve the collection, compilation, review, broadcast, deposit business management of satellite program content.%我校的卫星接收系统处于数字电视的前端,采集鑫诺一号卫星的6套节目作为信源,并与有线电视传输系统结合输出有线电视,和校园电视台系统结合实现卫星节目内容的采、编、审、播、存业务管理.

  6. Shipboard Satellite TV and Remote Sensing Receiving System%船载卫星电视/遥感接收系统

    Institute of Scientific and Technical Information of China (English)

    刘晓明; 艾文光

    2013-01-01

    A shipboard satellite TV and remote sensing receiving system (SSTV/RSRS) is developed to acquire global remote sensing data for scientific study and weather forecast to increase the ocean voyage safety, and to enrich the entertainment of ship’s crew. The system adopts stability scheme of two-axis stability platform and two-axis servo. The two-axis stability platform overcomes the impacts of ship swing. Two-axis antenna system implements the accurate tracking of the antenna to polar orbit satellites or geostationary satellites, and the receiving of remote sensing data or satellite TV programs. Using dual GPS attitude measurement system and auxiliary precision gyrocompass provided the course information. The ship orientation is compensated by antenna control unit. The influence of ship orientation change on orbit tracking is solved. Use tracking scheme of orbit prediction-based step-track. The system has been used for 3 years on a ship. The results show that the system can receive and process the remote sensing data of polar orbit satellites such as US NOAA, ORBVIEW and Chinese FENGYUN, etc. When a polar orbit pass is over, it receives TV signals from geostationary satellite automatically.%  为了获取全球卫星遥感数据进行科学研究,并利用遥感数据进行气象预报,提高远洋船的航行安全;同时,为了丰富船员的业余文化生活,研制了船载卫星电视/遥感接收系统(shipboard satellite TV and remote sensing receiving system,SSTV-RSRS)。系统采用二轴稳定平台加二轴伺服的稳定方案。二轴稳定平台克服船的摇摆对跟踪的影响;二轴天线系统精确跟踪极轨卫星和同步卫星,完成船载条件下的遥感数据接收和卫星电视接收。双GPS姿态测量系统及辅助的精密电罗经提供航向信息,由天线控制单元提供补偿,解决舰船的航向变化对轨道跟踪的影响。采用轨道预报程序跟踪加步进跟踪方案

  7. LNG接收站工艺管道试压、吹扫%LNG receiving station process piping pressure test and purging

    Institute of Scientific and Technical Information of China (English)

    张华伟; 仇德朋; 鹿晓斌; 曲顺利

    2014-01-01

    LNG receiving station process piping pressure test and purging is the final inspection of construction quality before project put into operation, to ensure that project smoothly has the vital significance. In view of the LNG clean and low temperature properties, pressure test after the pipe cleaner and dry degree is particularly important, the terminal piping pressure test use hydraulic or pneumatic according to the difference of the pressure or medium..This paper introduces the pipeline pressure test, purging process and matters needing attention, to the future of LNG receiving station test, purging process has a certain reference significance.%LNG接收站工艺管道试压、吹扫是工程投运前对施工质量的最终检验,对确保工程顺利投产具有重要的意义。鉴于LNG清洁及低温特性,试压后管道内的清洁度及干燥度显得尤为重要,目前接收站压力试验根据管道压力、介质的不同通常采用水压或气压。本文介绍了LNG工艺管道试压吹扫的方法、流程和注意事项等,对今后的LNG接收站试压、吹扫具有一定的借鉴意义。

  8. Application of Genetic Control with Adaptive Scaling Scheme to Signal Acquisition in Global Navigation Satellite System Receiver

    Directory of Open Access Journals (Sweden)

    Ho-Nien Shou

    2012-02-01

    Full Text Available This paper presents a genetic-based control scheme that not only utilizes evolutionary characteristics to find the signal acquisition parameters, but also employs an adaptive scheme to control the search space and avoid the genetic control converging to local optimal value so as to acquire the desired signal precisely and rapidly. Simulations and experiment results show that the proposed method can improve the precision of signal parameters and take less signal acquisition time than traditional serial search methods for global navigation satellite system (GNSS signals.

  9. 一发多收 MIMO 雷达的目标关联特性%Association Characteristics of MIMO Radar with Single Transmitting Station and Multiple Receiving Stations

    Institute of Scientific and Technical Information of China (English)

    朱丽芳; 任翠霞; 李军; 谢菊兰; 刘静秋

    2016-01-01

    MIMO radar with single transmitting station and multiple receiving stations combines the features and the performance advantages of centralized and distributed MIMO radars.By transmitting orthogonal signals, the angle information of transmitting station can be measured from receiving arrays independently.Thus infor-mation redundancy appears and high localization precision can be obtained with weighted least square fusion algorithm.The improvement of localization accuracy is bound to have positive effects on target correlation. The target association performance of the MIMO radar of T/R-R model is analysed.The probability model is established to calculate the correct association probability and error probability.Then the results of numerical computation and the Monte Carlo simulation show the validity of the model.At last,the association perform-ance advantages of MIMO radar are verified by comparing with the conventional phased array radar.%一发多收 MIMO 雷达结合了集中式和分布式 MIMO 雷达的工作特点,兼有两种模式的性能优势。接收站可以独立测得发射站角度信息,存在信息冗余,通过加权最小二乘融合可得到高精度的定位结果,这将会使目标关联的结果更加精确。基于 T/R-R 模式一发双收 MIMO 雷达,分析了 MIMO 雷达目标关联的性能,建立了概率模型,推算了正确关联概率和错误关联概率,数值计算和蒙特卡洛仿真结果显示了模型的正确性。最后通过与普通相控阵雷达比较,验证了一发多收 MIMO 雷达目标关联的性能优势。

  10. Effects of solar and geomagnetic activities on the sub-ionospheric very low frequency transmitter signals received by the DEMETER micro-satellite

    Directory of Open Access Journals (Sweden)

    Günter Stangl

    2012-04-01

    Full Text Available

    In the framework of seismic precursor electromagnetic investigations, we analyzed the very low frequency (VLF amplitude signals recorded by the Instrument Champ Electrique (ICE experiment on board the DEMETER micro-satellite. The sun-synchronous orbits of the micro-satellite allowed us to cover an invariant latitude of between –65° and +65° in a time interval of about 40 min. We considered four transmitter signals emitted by stations in Europe (France, FTU, 18.3 kHz; Germany, DFY, 16.58 kHz, Asia (Japan, JP, 17.8 kHz and Australia (Australia, NWC, 19.8 kHz. We studied the variations of these VLF signals, taking into consideration: the signal-to-noise ratio, sunspots, and the geomagnetic activity. We show that the degree of correlation in periods of high geomagnetic and solar activities is, on average, about 40%. Such effects can be fully neglected in the period of weak activity. We also find that the solar activity can have a more important effect on the VLF transmitter signal than the geomagnetic activity. Our data are combined with models where the coupling between the lithosphere, atmosphere and ionosphere is essential to explain how ionospheric disturbances scatter the VLF transmitter signal.


  11. An all-digital receiver for satellite audio broadcasting signals using trellis coded quasi-orthogonal code-division multiplexing

    Science.gov (United States)

    Braun, Walter; Eglin, Peter; Abello, Ricard

    1993-02-01

    Spread Spectrum Code Division Multiplex is an attractive scheme for the transmission of multiple signals over a satellite transponder. By using orthogonal or quasi-orthogonal spreading codes the interference between the users can be virtually eliminated. However, the acquisition and tracking of the spreading code phase can not take advantage of the code orthogonality since sequential acquisition and Delay-Locked loop tracking depend on correlation with code phases other than the optimal despreading phase. Hence, synchronization is a critical issue in such a system. A demonstration hardware for the verification of the orthogonal CDM synchronization and data transmission concept is being designed and implemented. The system concept, the synchronization scheme, and the implementation are described. The performance of the system is discussed based on computer simulations.

  12. 基于BGAN的大型海洋浮标岸站接收系统设计%Design of large marine buoy shore station data receiving system based on the BGAN

    Institute of Scientific and Technical Information of China (English)

    王朋朋; 赵士伟; 孙庆国; 刘咏; 杨健; 陈文广

    2014-01-01

    设计基于BGAN的大型海洋浮标岸站接收系统,主要实现与浮标系统的通讯、采集数据的实时显示、存储、转发和部分数据的分析功能,以及对系统通讯参数、运行参数进行远程控制功能。该系统主要基于客户端/服务器模式,采用Visual C++语言,通过CSocket网络编程方法和多线程技术,利用高速海事卫星实现基于TCP/IP协议的高速网络通信,解决大型浮标快速传输大容量数据的问题。该系统已经完成编写和测试,最终能够接收声阵列数据、声指纹数据和浮标状态数据,并预留开发了气象、水文要素数据接口,能够根据用户需求自行调整,达到项目设计要求。%A large marine buoy shore station data receiving system were founded based on the BGAN to realize the communication to the buoy system, data real-time display, storage, transmission and data analysis function, and the system communication parameters, operation parameters for remote control function. Using VC++ language and TCP/IP protocol, based on a client/server model, through network programming method of CSocket and multi -threading technology, and high-speed maritime satellite, the system achieved large-capacity data network transmission between the buoy system and the shore station. The system has been tested,and was able to receive the acoustic array data, the acoustic fingerprint data and the buoy state data. Moreover,the system reserved the data interface of the meteorological and the hydrological,which could adjust by the user demand automatically,and finally it has met the design requirements of the project.

  13. Preliminary Results of the Ground/Orbiter Lasercomm Demonstration Experiment between Table Mountain and teh ETS-V1 Satellite

    Science.gov (United States)

    Wilson, K. E.; Lesh, J. R.; Araki, K.; Arimoto, Y.

    1996-01-01

    The Ground/Orbiter Lasercomm Demonstration (GOLD) is an optical communications demonstration between the Japanese Engineering Test Satellite (ETS-V1) and an optical ground transmitting and receiving station at the Table Mountain FAcility in Wrightwood California. Laser transmissions to the satellite are performed approximately four hours every third night when the satellite is at apogee above Table Mountain.

  14. Preliminary Results of the Ground/Orbiter Lasercomm Demonstration Experiment between Table Mountain and teh ETS-V1 Satellite

    Science.gov (United States)

    Wilson, K. E.; Lesh, J. R.; Araki, K.; Arimoto, Y.

    1996-01-01

    The Ground/Orbiter Lasercomm Demonstration (GOLD) is an optical communications demonstration between the Japanese Engineering Test Satellite (ETS-V1) and an optical ground transmitting and receiving station at the Table Mountain FAcility in Wrightwood California. Laser transmissions to the satellite are performed approximately four hours every third night when the satellite is at apogee above Table Mountain.

  15. Comparison of satellite-derived land surface temperature and air temperature from meteorological stations on the Pan-Arctic scale

    NARCIS (Netherlands)

    Urban, M.; Eberle, J.; Hüttich, C.; Schmullius, C.; Herold, M.

    2013-01-01

    Satellite-based temperature measurements are an important indicator for global climate change studies over large areas. Records from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR) and (Advanced) Along Track Scanning Radiometer ((A)ATSR) are pr

  16. High altitude clouds impacts on the design of optical feeder link and optical ground station network for future broadband satellite services

    Science.gov (United States)

    Poulenard, S.; Ruellan, M.; Roy, B.; Riédi, J.; Parol, F.; Rissons, A.

    2014-03-01

    Optical links at 1.55μm are envisaged to cope with the increasing capacity demand from geostationary telecom satellite operators without the need of Radio Frequency (RF) coordination. Due to clouds blockages, site diversity techniques based on a network of Optical Ground Stations (OGS) are necessary to reach the commonly required link availability (e.g. 99.9% over the year). Evaluation of the N Optical Ground Station Network (N-OGSN) availability is based on Clouds Masks (CMs) and depends on the clouds attenuation taken in the optical communication budget link. In particular, low attenuation of high semitransparent clouds (i.e. cirrus) could be incorporated into the budget link at the price of larger or more powerful optical terminals. In this paper, we present a method for the calibration of the attenuation at 1.55 μm of high semitransparent clouds. We perform OGS localization optimization in Europe and we find that the incorporation of thin cirrus attenuation in the budget link reduces by 20% the number of handover (i.e. switches OGS) and the handover rate. It is also shown that the minimum number of station required in Europe to reach 99.9% link availability is 10 to 11. When the zone of research is enlarged the Africa, this number is reduced to 3 to 4.

  17. Atmosphere Impact and Ground Station Selection for Satellite-to-Ground Laser Communication%星地链路激光通信地面站址选择及大气影响研究

    Institute of Scientific and Technical Information of China (English)

    娄岩; 赵义武; 陈纯毅

    2014-01-01

    综合考虑我国方量的地理分布和气候特点,提出了一项星地激光通信的地面多址布站方案,仿真分析了大气散射引起的衰减及大气湍流对星地链路的影响.利用卫星工具包(STK)软件分析了地球静止轨道(GEO)卫星与5个地面站的链路特性.结果表明,西藏的阿里站同时具有最理想的经度和纬度,地平角为52°,最有利于开展星地激光通信.在一定天气条件下,随着波长的增加,对应的散射引起的功率衰减减小;随着能见度的降低,大气散射引起的光功率平均衰减增加;随着地平角的升高,大气引起的功率平均衰减减小;波长越长,闪烁指数越小;随着接收孔径直径的增大,闪烁指数快速减小;随着海拔高度的增加,闪烁方差减小.该研究为星地激光通信外场实验提供了一定的理论依据.%A multiple ground stations scheme satellite-to-ground laser communication is proposed with the geographical distribution of cloud cover and climatic features considered.The effect of attenuation caused by atmospheric scattering and atmospheric turbulence is analyzed for different paths from geosynchronous earth orbit (GEO) satellites to five ground stations.Link characteristics between the GEO satellite and the five ground stations are simulated using the satellite tool kit (STK) software.The results show that Ali region in Tibet has the best longitude and latitude conditions with a horizontal angle of 52 °,which is most beneficial to laser satelliteto-ground communications.The power attenuation shows a decreasing trend as the wavelength increases due to scattering under the same weather conditions.The optical power attenuation is intensified as visibility falls.The average power attenuation caused by atmosphere decreases along with the rise of horizontal angle.The longer the wavelength λ,the smaller the scintillation index; the scintillation index decreases rapidly when the diameter of receiving aperture

  18. A technique for measurement of earth station antenna G/T by radio stars and Applications Technology Satellites.

    Science.gov (United States)

    Kochevar, H. J.

    1972-01-01

    A new technique has been developed to accurately measure the G/T of a small aperture antenna using geostationary satellites and the well established radio star method. A large aperture antenna having the capability of accurately measuring its G/T by using a radio star of known power density is used to obtain an accurate G/T to use as a reference. The CNR of both the large and small aperture antennas are then measured using an Applications Technology Satellite (ATS). After normalizing the two C/N ratios to the large antenna system noise temperature the G/T or the gain G of the small aperture antenna can then be determined.

  19. A multievent study of broadband electrons observed by the DMSP satellites and their relation to red aurora observed at midlatitude stations

    Science.gov (United States)

    Shiokawa, K.; Meng, C.-I.; Reeves, G. D.; Rich, F. J.; Yumoto, K.

    1997-07-01

    Broadband electrons during magnetic storms are characterized by an unusually intense flux of precipitating electrons in the broadband energy range from 30 eV to 30 keV near the equatorward edge of the auroral oval (47°-66° magnetic latitude). Broadband electrons were first reported by Shiokawa et al. [1996]. In this paper, we report a multievent study of broadband electrons, using particle data obtained by the Defense Meteorological Satellite Program (DMSP) satellites during 23 magnetic storms from January 1989 through May 1992. Twelve broadband electron events are identified. Most of them are observed in the night sector, but some are observed in the morning sector. Particle data for successive polar passes of the DMSP multisatellites are used to show that broadband electrons generally last for less than 30 min and that for some events, they precipitate over a wide range of local times simultaneously. On the basis of a quantitative calculation of optical emissions from electrons in the neutral atmosphere, we conclude that broadband electrons are a possible cause of red auroras observed at midlatitude ground stations. We suggest that broadband electrons are associated with certain substorms during the main phase of magnetic storms. This conjecture comes from observations of H component positive bays and Pi 2 pulsations observed at low-latitude magnetic stations and from magnetic field variations observed at geosynchronous satellites. We conclude that the magnetospheric source of broadband electrons lies within the inner part of the plasma sheet. This conclusion is based on the facts that broadband electrons appear in latitudes where plasma sheet particles were observed before the event and that broadband electrons are observed poleward of the subauroral ion drifts, a position that corresponds to the inner edge of the injected particle layer during storms. High-energy particle data obtained at geosynchronous satellites show that both strong magnetopause

  20. 新型皮卫星星载接收机设计%A New Receiver Structure of TT&C Transponder for Pico-Satellite

    Institute of Scientific and Technical Information of China (English)

    周阳; 王春晖; 金小军; 金仲和

    2011-01-01

    The traditional receiver requires large volume, complex structure design and high power consumption. These characteristics don't fit the requirement of the Pico-satellite's application. Meanwhile, a low-power receiver structure has already been proposed by our team. But this low-power receiver has low sensitivity and thus can't be used widely. To resolve these problems, a new receiver structure is Proposed. This new structure mixes digital frequency synthesizer with traditional PLL. The lock-time, noise behavior and sensitivity of this new structure are analyzed and tested. The result shows that the simulation and the experiment are perfectly matched, and the performance meets the requirement well. This new structure can not only preserve the excellence of traditional receiver, but also can make the loop design much easier with less volume and lower power consumption, which are all critical to Pico-satellite.%传统星载接收机体积大、结构复杂、功耗高,无法满足皮卫星的应用要求;而项目组已研制成功的星载接收机虽然克服了这一缺点,但灵敏度不高,这就严重限制了它的使用范围.在分析两者结构特点的基础上提出了一种基于数字式频率合成器和模拟锁相环混合结构的新型皮卫星星载接收机结构,并对该结构的锁定时间、噪声和灵敏度进行了分析、仿真实验和样机实测,实验证明仿真结果与实际相互吻合,实验结果满足要求.新型结构与传统星载接收机相比大大减小了体积,降低了功耗,简化了结构,而性能与传统星载接收机相当,可以较好的满足皮卫星的应用要求.

  1. Real-time monitoring of seismic data using satellite telemetry

    Directory of Open Access Journals (Sweden)

    L. Merucci

    1997-06-01

    Full Text Available This article describes the ARGO Satellite Seismic Network (ARGO SSN as a reliable system for monitoring, collection, visualisation and analysis of seismic and geophysical low-frequency data, The satellite digital telemetry system is composed of peripheral geophysical stations, a centraI communications node (master sta- tion located in CentraI Italy, and a data collection and processing centre located at ING (Istituto Nazionale di Geofisica, Rome. The task of the peripheral stations is to digitalise and send via satellite the geophysical data collected by the various sensors to the master station. The master station receives the data and forwards them via satellite to the ING in Rome; it also performs alI the monitoring functions of satellite communications. At the data collection and processing centre of ING, the data are received and analysed in real time, the seismic events are identified and recorded, the low-frequency geophysical data are stored. In addition, the generaI sta- tus of the satellite network and of each peripheral station connected, is monitored. The procedure for analysjs of acquired seismic signals allows the automatic calculation of local magnitude and duration magnitude The communication and data exchange between the seismic networks of Greece, Spain and Italy is the fruit of a recent development in the field of technology of satellite transmission of ARGO SSN (project of European Community "Southern Europe Network for Analysis of Seismic Data"

  2. Comparison of radiometric scaling laws and detailed wave-optics simulations for designing ground-based laser satellite-illumination and receiver systems

    Science.gov (United States)

    Bush, Keith A.

    2002-12-01

    Ground-based optical transmitter and receiver systems designed for active imaging, active tracking and laser ranging of satellites in Earth orbit are very sensitive to physical conditions limiting the radiometric returns for achieving these measurements. The initial design of these systems is often based on simple radiometric scaling laws that provide estimates of average radiometric returns and are derived from experimental data or from more complex theoretical calculations. While these laws are quite useful, it is often easy to lose sight of the initial assumptions made in their formulation, and hence, the limits of their accuracy for designing certain systems. The objective of this paper is to review some of the commonly used radiometric scaling laws for active systems and to establish guidelines for their use based on comparisons of their predictions with results from detailed wave-optics simulations for different system design requirements and physical conditions. The combined effects of laser and transmitter beam parameters, wave-front aberrations, atmospheric turbulence, and satellite optical cross-section are considered.

  3. Comparison of Satellite-Derived Land Surface Temperature and Air Temperature from Meteorological Stations on the Pan-Arctic Scale

    Directory of Open Access Journals (Sweden)

    Christiane Schmullius

    2013-05-01

    Full Text Available Satellite-based temperature measurements are an important indicator for global climate change studies over large areas. Records from Moderate Resolution Imaging Spectroradiometer (MODIS, Advanced Very High Resolution Radiometer (AVHRR and (Advanced Along Track Scanning Radiometer ((AATSR are providing long-term time series information. Assessing the quality of remote sensing-based temperature measurements provides feedback to the climate modeling community and other users by identifying agreements and discrepancies when compared to temperature records from meteorological stations. This paper presents a comparison of state-of-the-art remote sensing-based land surface temperature data with air temperature measurements from meteorological stations on a pan-arctic scale (north of 60° latitude. Within this study, we compared land surface temperature products from (AATSR, MODIS and AVHRR with an in situ air temperature (Tair database provided by the National Climate Data Center (NCDC. Despite analyzing the whole acquisition time period of each land surface temperature product, we focused on the inter-annual variability comparing land surface temperature (LST and air temperature for the overlapping time period of the remote sensing data (2000–2005. In addition, land cover information was included in the evaluation approach by using GLC2000. MODIS has been identified as having the highest agreement in comparison to air temperature records. The time series of (AATSR is highly variable, whereas inconsistencies in land surface temperature data from AVHRR have been found.

  4. Retrieval and satellite intercomparison of O3 measurements from ground-based FTIR Spectrometer at Equatorial Station: Addis Ababa, Ethiopia

    Directory of Open Access Journals (Sweden)

    T. von Clarmann

    2013-02-01

    Full Text Available Since May 2009, high-resolution Fourier Transform Infrared (FTIR solar absorption spectra have been recorded at Addis Ababa (9.01° N latitude, 38.76° E longitude, 2443 m altitude above sea level, Ethiopia. The vertical profiles and total column amounts of ozone (O3 are deduced from the spectra by using the retrieval code PROFFIT (V9.5 and regularly determined instrumental line shape (ILS. A detailed error analysis of the O3 retrieval is performed. Averaging kernels of the target gas shows that the major contribution to the retrieved information comes from the measurement. The degrees of freedom for signals is found to be 2.1 on average for the retrieval of O3 from the observed FTIR spectra. The ozone Volume Mixing Ratio (VMR profiles and column amounts retrieved from FTIR spectra are compared with the coincident satellite observations of Microwave Limb Sounding (MLS, Michelson Interferometer for Passive Atmospheric Sounding (MIPAS, Tropospheric Emission Spectrometer (TES, Ozone Monitoring Instrument (OMI, Atmospheric Infrared Sounding (AIRS and Global Ozone Monitoring Experiment (GOME-2 instruments. The mean relative differences in ozone profiles of FTIR from MLS and MIPAS are generally lower than 15% within the altitude range of 27 to 36 km, whereas difference from TES is lower than 1%. Comparisons of measurements of column amounts from the satellite and the ground-based FTIR show very good agreement as exhibited by relative differences within +0.2% to +2.8% for FTIR versus MLS and GOME-2; and −0.9 to −9.0% for FTIR versus OMI, TES and AIRS. The corresponding standard deviations are within 2.0 to 2.8% for FTIR versus MLS and GOME-2 comparisons whereas that of FTIR versus OMI, TES and AIRS are within 3.5 to 7.3%. Thus, the retrieved O3 VMR and column amounts from a tropical site, Addis Ababa, is found to exhibit very good agreement with all coincident satellite observations over an approximate 3-yr period.

  5. Retrieval and satellite intercomparison of O3 measurements from ground-based FTIR Spectrometer at Equatorial Station: Addis Ababa, Ethiopia

    Science.gov (United States)

    Takele Kenea, S.; Mengistu Tsidu, G.; Blumenstock, T.; Hase, F.; von Clarmann, T.; Stiller, G. P.

    2013-02-01

    Since May 2009, high-resolution Fourier Transform Infrared (FTIR) solar absorption spectra have been recorded at Addis Ababa (9.01° N latitude, 38.76° E longitude, 2443 m altitude above sea level), Ethiopia. The vertical profiles and total column amounts of ozone (O3) are deduced from the spectra by using the retrieval code PROFFIT (V9.5) and regularly determined instrumental line shape (ILS). A detailed error analysis of the O3 retrieval is performed. Averaging kernels of the target gas shows that the major contribution to the retrieved information comes from the measurement. The degrees of freedom for signals is found to be 2.1 on average for the retrieval of O3 from the observed FTIR spectra. The ozone Volume Mixing Ratio (VMR) profiles and column amounts retrieved from FTIR spectra are compared with the coincident satellite observations of Microwave Limb Sounding (MLS), Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), Tropospheric Emission Spectrometer (TES), Ozone Monitoring Instrument (OMI), Atmospheric Infrared Sounding (AIRS) and Global Ozone Monitoring Experiment (GOME-2) instruments. The mean relative differences in ozone profiles of FTIR from MLS and MIPAS are generally lower than 15% within the altitude range of 27 to 36 km, whereas difference from TES is lower than 1%. Comparisons of measurements of column amounts from the satellite and the ground-based FTIR show very good agreement as exhibited by relative differences within +0.2% to +2.8% for FTIR versus MLS and GOME-2; and -0.9 to -9.0% for FTIR versus OMI, TES and AIRS. The corresponding standard deviations are within 2.0 to 2.8% for FTIR versus MLS and GOME-2 comparisons whereas that of FTIR versus OMI, TES and AIRS are within 3.5 to 7.3%. Thus, the retrieved O3 VMR and column amounts from a tropical site, Addis Ababa, is found to exhibit very good agreement with all coincident satellite observations over an approximate 3-yr period.

  6. Assessment of Modeled Received Sound Pressure Levels and Movements of Satellite-Tagged Odontocetes Exposed to Mid-Frequency Active Sonar at the Pacific Missile Range Facility: February 2011 Through February 2013

    Science.gov (United States)

    2014-05-30

    Brandon L. Southall3 1Cascadia Research Collective, 218 ½ W. 4th Avenue, Olympia, WA 98501 2Marine Mammal Scientific and Veterinary Support...location data from satellite tags and available acoustic recordings and selected a subset of data for which there was sufficient overlap. The MFAS...location data from satellite- tagged individuals and modeling to estimate received levels from acoustic recordings from the PMRF hydrophones is a viable and

  7. Handbook on satellite communications and broadcasting

    Science.gov (United States)

    Askinazi, G. B.; Bykov, V. L.; Vodopianov, G. V.; D'Iachkova, M. N.; Kantor, L. Ia.; Model, A. M.; Pokras, A. M.; Timofeev, V. V.; Tsirlin, V. M.; Tsirlin, I. S.

    Principles underlying the design and operation of satellite communications systems (SCSs) are reviewed with emphasis on multiple-access techniques. Particular consideration is given to the quality characteristics of CSCs, the frequency ranges assigned to SCSs, an energy analysis of satellite lines, EMC aspects, and the effective utilization of the geostationary orbit. Also examined are the design of earth-station equipment, waveguides and multiplexing equipment, satellite antennas, reliability issues, the Ekran receiving installation, and Gradient-N and Gruppa multiple-access equipment.

  8. Formulation of geopotential difference determination using optical-atomic clocks onboard satellites and on ground based on Doppler cancellation system

    Science.gov (United States)

    Shen, Ziyu; Shen, Wen-Bin; Zhang, Shuangxi

    2016-08-01

    In this study, we propose an approach for determining the geopotential difference using high-frequency-stability microwave links between satellite and ground station based on Doppler cancellation system. Suppose a satellite and a ground station are equipped with precise optical-atomic clocks (OACs) and oscillators. The ground oscillator emits a signal with frequency fa towards the satellite and the satellite receiver (connected with the satellite oscillator) receives this signal with frequency fb which contains the gravitational frequency shift effect and other signals and noises. After receiving this signal, the satellite oscillator transmits and emits, respectively, two signals with frequencies fb and fc towards the ground station. Via Doppler cancellation technique, the geopotential difference between the satellite and the ground station can be determined based on gravitational frequency shift equation by a combination of these three frequencies. For arbitrary two stations on ground, based on similar procedures as described above, we may determine the geopotential difference between these two stations via a satellite. Our analysis shows that the accuracy can reach 1 m2 s- 2 based on the clocks' inaccuracy of about 10-17 (s s-1) level. Since OACs with instability around 10-18 in several hours and inaccuracy around 10-18 level have been generated in laboratory, the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimetre level accuracy in the near future.

  9. A Deep Space Network Portable Radio Science Receiver

    Science.gov (United States)

    Jongeling, Andre P.; Sigman, Elliott H.; Chandra, Kumar; Trinh, Joseph T.; Navarro, Robert; Rogstad, Stephen P.; Goodhart, Charles E.; Proctor, Robert C.; Finley, Susan G.; White, Leslie A.

    2009-01-01

    The Radio Science Receiver (RSR) is an open-loop receiver installed in NASA s Deep Space Network (DSN), which digitally filters and records intermediate-frequency (IF) analog signals. The RSR is an important tool for the Cassini Project, which uses it to measure perturbations of the radio-frequency wave as it travels between the spacecraft and the ground stations, allowing highly detailed study of the composition of the rings, atmosphere, and surface of Saturn and its satellites.

  10. Seasonal variation of near surface black carbon and satellite derived vertical distribution of aerosols over a semi-arid station in India

    Science.gov (United States)

    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah; Kotalo, Rama Gopal; Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy; Shaik, Nazeer Hussain; Maraka, Vasudeva Reddy; Rajuru, Ramakrishna Reddy; Surendran Nair, Suresh Babu

    2017-02-01

    Extensive measurements of aerosol black carbon mass concentration (BC) and vertical profiles of atmospheric aerosols have been carried out using Aethalometer and CALIPSO level - 2 satellite data from December 2012 to November 2014 over a semi-arid station, Anantapur. We found a bimodal distribution in the mass concentrations of BC aerosols on a diurnal scale. A sharp peak was observed during morning rush hours (7:00 to 8:00 LT) almost an hour after the local sunrise. After which, a broad nocturnal peak was found during 21:00 to 22:00 LT. The seasonal mean BC concentrations (Mixed layer height (ML)) were found to be 3.45 ± 1.44 μg/m3 (676 ± 117 m), 2.55 ± 0.85 μg/m3 (1215 ± 190 m), 1.22 ± 0.31 μg/m3 (1134 ± 194 m) and 1.75 ± 0.70 μg/m3 (612 ± 135 m), during the winter, summer, monsoon and post-monsoon respectively. The vertical profiles of aerosol extinction coefficient and back scattering ratio profiles were derived from Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) showed a strong seasonal variation with aerosols mostly confined below 2 km during the post-monsoon and winter seasons whereas in the other two seasons, the aerosol layer expands beyond 6 km. Depolarization ratios (> 0.2) are higher during summer and monsoon at higher altitude regions demonstrate the presence of dust particles, which contribute to the large aerosol extinction at higher levels. These results are further supported by the backward trajectory cluster analysis.

  11. Point-surface fusion of station measurements and satellite observations for mapping PM2.5 distribution in China: methods and assessment

    CERN Document Server

    Li, Tongwen; Zeng, Chao; Yuan, Qiangqiang; Zhang, Liangpei

    2016-01-01

    Fine particulate matter (PM2.5) is associated with adverse human health effects, and China is currently suffering from serious PM2.5 pollution. To obtain spatially continuous ground-level PM2.5 concentrations, several models established by point-surface fusion of ground station and satellite observations have been developed. However, how well do these models perform at national scale in China? Is there space to improve the estimation accuracy of PM2.5 concentration? The contribution of this study is threefold. Firstly, taking advantage of the newly established national monitoring network, we develop a national-scale generalized regression neural network (GRNN) model to estimate PM2.5 concentrations. Secondly, different assessment experiments are undertaken in time and space, to comprehensively evaluate and compare the performance of the widely used models. Finally, to map the yearly and seasonal mean distribution of PM2.5 concentrations in China, a pixel-based merging strategy is proposed. The results indicat...

  12. Trends in communications satellites

    CERN Document Server

    Curtin, Denis J

    1979-01-01

    Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

  13. Study on the Transformation Measures of Chengdu North Railway Station Based on the Capacity of Receiving and Dispatching Trains%基于列车接发能力的成都北站改造措施研究

    Institute of Scientific and Technical Information of China (English)

    李薇

    2012-01-01

    In recent years, the scale of China's passenger terminal is becoming larger and larger, which brings burden to the increasingly scarce urban land. Chengdu North Railway Station and tile ground yard of Tokyo Station occupy the same scale of land, therefore, the comprehensive overview of the two stations and their timetables are analyzed, obtaining that there is a huge gap on the capacity of receiving and dispatching trains between the two stations. The reasons for this gap are as follows: the differences of the yards' layout and station tracks' distribution, the occupancy situation of receiving and dispatching tracks, China's train management system and the current situation of China. In view of Chengdu North Railway Station on the occasion of the positive transformation, the capacity of receiving and dispatching trains under the premise that doesn't blindly expand the scale of the station needs improving, and then some suggestions on the transformation of Chengdu North Railway Station are put forward.%近年来,我国客运站的建设规模越来越大,给日益紧张的城市用地带来了负担。成都北站与东京火车站的地上站场具有同等的占地规模,将两站的综合概况和列车时刻表进行分析,得出两站的列车接发能力存在巨大差距。造成这种差距的原因是站场布局、站线分布和到发线占用情况不同,以及管理体制和国情现状不同。成都北站正值改造之际,力求在不盲目扩大车站规模的前提下提高列车接发能力,对成都北站的改造提出建议。

  14. The Omninet mobile satellite system

    Science.gov (United States)

    Salmasi, A.; Curry, W.

    Mobile Satellite System (MSS) design offering relatively low cost voice, data, and position location services to nonmetropolitan areas of North America is proposed. The system provides spectrally efficient multiple access and modulation techniques, and flexible user interconnection to public and private switched networks. Separate UHF and L-band satellites employing two 9.1 m unfurlable antennas each, achieve a 6048 channel capacity and utilize spot beams. Mobile terminals have modular design and employ 5 dBi omnidirectional antennas. Gateway stations (with two 5 m Ku-band antennas) and base stations (with a single 1.8 m Ku-band antenna) transmit terrestrial traffic to the satellite, where traffic is then transponded via an L-band or UHF downlink to mobile users. The Network Management Center uses two 5-m antennas and incorporates the Integrated-Adaptive Mobile Access Protocol to assure demand assignment of satellite capacity. Preliminary implementation of this low-risk system involves a mobile alphanumeric data service employing receive-only terminals at Ku-band projected for 1987, and plans for the launching of L-band receive-only packages as early as 1988.

  15. A figure of merit for competing communications satellite designs

    Science.gov (United States)

    Lovell, R. R.; Fordyce, S. W.

    1983-01-01

    Trends in launch schedules, weights, power, and space segment costs per transponder year for Intelsats and North American domsats (domestic communications satellites) are discussed. The Intelsat system currently services 25,000 point to point telephone links at any one moment, and a $3 billion order has been placed for Intelsat VIs, which feature 36,000 telephone circuits each. The Intelsat VI spacecraft will weigh 1670 kg in orbit, a continuance of the trend to heavier satellites, while the domsats will stay at 650 kg due to launch vehicle limitations. Direct television broadcast satellites are being designed for receive only (R/O) earth stations, with each satellite capable of servicing 50,000 individual ground stations. Competition is growing for C and Ku band satellite transponders for DBS, with costs $350,000 each. No standardized design has yet emerged.

  16. 新型船载气象卫星接收系统%A new type of shipboard meteorological satellite receiving - processing system

    Institute of Scientific and Technical Information of China (English)

    曾志刚; 蒋富清; 翟世奎; 秦蕴珊; 侯增谦

    2000-01-01

    strong magnetic disturbance. It has two sets of recaiving imagery proceasang systems for polar orbit low - resolution and quasi - stationary high - resolution satellites. The key creation points of this system are as follows: (1) The active gyro- control stabilization platform and a mixed mounting system of three rotating α - βand X - Y axes ave used. It solved the tracing difiiculties both in the low elevation angle and very high elevation angle of polar - orbit satellite, even in the status of ship moving with continuously changing its position, direction and ship roll and pitch. (2) Imagery processing subsystem. The newest BORLAND- DELPHI language programming and PASCAL language software are used under Windows 95 environment. It has a dynamic positoning nested - grid system and electric mapping grid data system. It can show the latitude - longitude of any point on the map, and marks any object such as ship, station or island, and draws the route. It can monitor cloud and temperature, forest fire, anomalous change of ocean and land. It can output satellite cloud maps of 24 bit with very high clarity. This system is very advanced in technique for the whole structure with the features of small volume, light weight and very low cost. It suits to very bad climate and ocean environment. Its imagery processing system has complete functions with high resolution and beiing very easy to operate. It is not only suit to land use, but also specially to all kinds of ship ovdr the sea.It can be extended to domestic and international use.

  17. Two-way time transfers between NRC/NBS and NRC/USNO via the Hermes (CTS) satellite

    Science.gov (United States)

    Costain, C. C.; Daams, H.; Boulanger, J. S.; Hanson, D. W.; Klepczynski, W. J.

    1978-01-01

    At each station the differences were measured between the local UTC seconds pulse and the remote UTC pulse received by satellite. The difference between the readings, if station delays are assumed to be symmetrical, is two times the difference between the clocks at the two ground station sites. Over a 20-minute period, the precision over the satellite is better than 1 ns. The time transfer from NRC to the CRC satellite terminal near Ottawa and from NBS to the Denver HEW terminal was examined.

  18. Design of servo monitoring software for remote sensing satellite receiving system%遥感卫星接收系统伺服监控软件设计

    Institute of Scientific and Technical Information of China (English)

    李宏科; 王万玉; 冯旭祥; 王永华

    2016-01-01

    伺服系统是遥感卫星地面接收系统的重要组成部分,可靠性和安全性要求高。采用单进程、多线程、并行多模块的结构,设计伺服系统监控软件,实现了天线控制、设备监视、信息显示、数据处理、通信及伺服性能指标自动化测试等功能,具有实时性强,自动化程度高,容错性、可靠性及扩展性好等特点。该设计已用于实际工程项目中,实际使用结果表明该设计是合理可行的。%The sever system is an important component in the ground receiving system of the remote sensing satellite,and has high reliability and security. The structures of single process,multi⁃thread,and parallel multi⁃module are adopted to design the monitoring software for servo system. The functions of antenna control,equipment monitoring,information display,data pro⁃cessing,communications and automatic test of servo performance index were implemented. The software has the characteristics of good real⁃time performance,high automation level,good fault tolerance,excellent reliability and extensibility. This design was applied to the practical engineering projects. The practical use result shows that the design is reasonable and feasible.

  19. Point-surface fusion of station measurements and satellite observations for mapping PM2.5 distribution in China: Methods and assessment

    Science.gov (United States)

    Li, Tongwen; Shen, Huanfeng; Zeng, Chao; Yuan, Qiangqiang; Zhang, Liangpei

    2017-03-01

    Fine particulate matter (PM2.5, particulate matters with aerodynamic diameters less than 2.5 μm) is associated with adverse human health effects, and China is currently suffering from serious PM2.5 pollution. To obtain spatially continuous ground-level PM2.5 concentrations, several models established by the point-surface fusion of station measurements and satellite observations have been developed. However, how well do these models perform at national scale in China? Is there space to improve the estimation accuracy of PM2.5 concentration? The contribution of this study is threefold. Firstly, taking advantage of the newly established national monitoring network, we develop a national-scale generalized regression neural network (GRNN) model to estimate PM2.5 concentrations. Secondly, different assessment experiments are undertaken in time and space, to comprehensively evaluate and compare the performance of the widely used models. Finally, to map the yearly and seasonal mean distribution of PM2.5 concentrations in China, a pixel-based merging strategy is proposed. The results indicate that the conventional models (linear regression, multiple linear regression, and semi-empirical model) do not obtain the expected results at national scale, with cross-validation R values of 0.49-0.55 and RMSEs of 30.80-31.51 μg /m3 , respectively. In contrast, the more advanced models (geographically weighted regression, back-propagation neural network, and GRNN) have great advantages in PM2.5 estimation, with R values ranging from 0.61 to 0.82 and RMSEs from 20.93 to 28.68 μg /m3 , respectively. In particular, the proposed GRNN model obtains the best performance. Furthermore, the mapped PM2.5 distribution retrieved from 3-km MODIS aerosol optical depth (AOD) products agrees quite well with the station measurements. The results also show that the approach used in this study has the capacity to provide reasonable information for the global monitoring of PM2.5 pollution in China.

  20. Research on Application Performance of Vehicle-mounted Station of Satellite Mobile Communication%卫星移动通信车载站应用性能研究

    Institute of Scientific and Technical Information of China (English)

    汪洋

    2012-01-01

    在对各类卫星移动通信系统性能分析比较的基础上,从系统造价和可实现程度的角度考虑,同步静止轨道(GEO)系统更适合于区域覆盖卫星移动通信系统,卫星移动通信车载站(简称动中通)是实现地面卫星移动通信系统的关键设备。给出了动中通系统设计中卫星转发器带宽占用率和功率占用率的计算,对动中通站型能力和天线口径的选取进行了分析和讨论,并结合相关计算给出了动中通站型和天线选取的建议。%Based on the system performance comparison among some kinds of satellite mobile communication systems and the consideration of the cost and the extent of realization,the GEO system is more propitious to regional satellite mobile communication system. Vehicle-mounted station of satellite mobile communication is the key device to realize land mobile satellite communication system. The calculation methods of occupancy rates of bandwidth and power of satellite transponder in mobile communication system design are described in this paper. How to choose the size of antenna and the type of the station is analyzed and discussed. Some suggestions are given for choosing antenna and type of the station.

  1. Space station, 1959 to . .

    Science.gov (United States)

    Butler, G. V.

    1981-04-01

    Early space station designs are considered, taking into account Herman Oberth's first space station, the London Daily Mail Study, the first major space station design developed during the moon mission, and the Manned Orbiting Laboratory Program of DOD. Attention is given to Skylab, new space station studies, the Shuttle and Spacelab, communication satellites, solar power satellites, a 30 meter diameter radiometer for geological measurements and agricultural assessments, the mining of the moons, and questions of international cooperation. It is thought to be very probable that there will be very large space stations at some time in the future. However, for the more immediate future a step-by-step development that will start with Spacelab stations of 3-4 men is envisaged.

  2. Low-tech Highly Efficient Radiotechnical Solutions for Meteors and Satellite Observations

    Directory of Open Access Journals (Sweden)

    Vovk, V.S.

    2017-01-01

    Full Text Available Single-station technique of meteors’ observation using inexpensive receivers is developed. The receivers are also suitable for observing active artificial Earth’s satellites on solar-synchronous orbits when measuring the Doppler shift frequency at which they emit.

  3. 双圆极化遥感卫星数据接收系统极化鉴别率需求分析%Analysis on XPD requirement of dual-polarized remote satellite data receiving system

    Institute of Scientific and Technical Information of China (English)

    王万玉; 王永华; 王强

    2014-01-01

    The impact of rain attenuation and depolarization on the performance of LEO satellite X-band data transmission link with dual-circular polarization are analyzed. Base on a bit error rate threshold requirement, the cross-polarization interference caused by depolarization may be regarded as AGWN. The XPD requirements of the X-band remote sensing satellite data receive system are proposed. The results have been used in the design of the data receiving system for the double-circular polarized re-mote sensing satellite. The data from ZY-3 satellite (dual circular polarization frequency reuse remote sensing satellite, whose data rate is 450Mbps×2) was successfully received.%针对双圆极化频率复用中的交叉极化干扰问题,分析了雨衰及雨致去极化对LEO卫星X频段双圆极化频率复用的影响,然后将交叉极化干扰按高斯白噪声处理,并依据数据接收链路误码率门限要求,提出了X频段双圆极化频率复用遥感卫星数据接收系统极化鉴别率的技术需求。研究结果已用于双圆极化遥感卫星数据接收系统的设计,并已成功接收了国内首颗双圆极化频率复用遥感卫星(资源三号卫星,数据速率为450 Mb/s×2)的数据。

  4. In Orbit Validation of the AAUSAT3 SDR based AIS receiver

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Mortensen, Hans Peter

    2013-01-01

    During the past years, there has been a high interest in monitoring the global ship traffic from space. The recently launched AAUSAT3 satellite carries an SDR based AIS receiver, which during the past months have been transmitting space based AIS data down to the Aalborg University Ground Station...

  5. In Orbit Validation of the AAUSAT3 SDR based AIS receiver

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Mortensen, Hans Peter

    2013-01-01

    During the past years, there has been a high interest in monitoring the global ship traffic from space. The recently launched AAUSAT3 satellite carries an SDR based AIS receiver, which during the past months have been transmitting space based AIS data down to the Aalborg University Ground Station...

  6. Regional vertical total electron content (VTEC) modeling together with satellite and receiver differential code biases (DCBs) using semi-parametric multivariate adaptive regression B-splines (SP-BMARS)

    Science.gov (United States)

    Durmaz, Murat; Karslioglu, Mahmut Onur

    2015-04-01

    There are various global and regional methods that have been proposed for the modeling of ionospheric vertical total electron content (VTEC). Global distribution of VTEC is usually modeled by spherical harmonic expansions, while tensor products of compactly supported univariate B-splines can be used for regional modeling. In these empirical parametric models, the coefficients of the basis functions as well as differential code biases (DCBs) of satellites and receivers can be treated as unknown parameters which can be estimated from geometry-free linear combinations of global positioning system observables. In this work we propose a new semi-parametric multivariate adaptive regression B-splines (SP-BMARS) method for the regional modeling of VTEC together with satellite and receiver DCBs, where the parametric part of the model is related to the DCBs as fixed parameters and the non-parametric part adaptively models the spatio-temporal distribution of VTEC. The latter is based on multivariate adaptive regression B-splines which is a non-parametric modeling technique making use of compactly supported B-spline basis functions that are generated from the observations automatically. This algorithm takes advantage of an adaptive scale-by-scale model building strategy that searches for best-fitting B-splines to the data at each scale. The VTEC maps generated from the proposed method are compared numerically and visually with the global ionosphere maps (GIMs) which are provided by the Center for Orbit Determination in Europe (CODE). The VTEC values from SP-BMARS and CODE GIMs are also compared with VTEC values obtained through calibration using local ionospheric model. The estimated satellite and receiver DCBs from the SP-BMARS model are compared with the CODE distributed DCBs. The results show that the SP-BMARS algorithm can be used to estimate satellite and receiver DCBs while adaptively and flexibly modeling the daily regional VTEC.

  7. Principle and Maintenance of DVR-1000 PIB Digital Satellite Receiver Switching Power Supply%PIB DVR-1000数字卫星接收机开关电源原理与检修

    Institute of Scientific and Technical Information of China (English)

    周凤岐; 南长德; 金雷

    2015-01-01

    文章主要介绍了PIB DVR-1000数字卫星接收机开关电源原理与检修,并根据实物绘出原理图从理论和实践上做了详细的分析。%This paper mainly introduces the principle and maintenance of DVR-1000 PIB digital satellite receiver switching power supply, and analyzes the theory and practice of the theory and practice.

  8. 河北电台大型数字卫星直播车的系统设计%System Design of Large Direct Broadcasting Satellite Car for Hebei Radio Station

    Institute of Scientific and Technical Information of China (English)

    牛晓静

    2013-01-01

      本文较系统地介绍了河北电台大型数字卫星直播车技术系统的设计思路、建设方案以及设计过程中的几项技术创新,为卫星直播车的设计、建设和使用提供了有益的借鉴。%Design ideas, construction programs and some technique innovation of large digital satellite direct broadcasting car for Hebei Radio Station were systematically introduced, which provided beneficial reference for the design, construction and use of satellite direct broadcasting car.

  9. 移动通信基站对C波段卫星信号接收的影响%Mobile Communication base Station of C-band Satellite Reception

    Institute of Scientific and Technical Information of China (English)

    李世杰

    2014-01-01

    卫星信号的传输,不可避免地会受到各种电磁波干扰,通过对宁波电视台C波段卫星信号被干扰情况的分析、查找,针对移动通信基站对C波段卫星电视信号的干扰进行分析,并提出解决办法。%Satellite signal transmission is affected inevitably by various kinds of electromagnetic interference . This article proposes a resolution for interference to C-band satellite signal at Ningbo TV station ,which is based on detail analysis on interference by mobile communication base stations .

  10. Tactical Satellite 3

    Science.gov (United States)

    Davis, T. M.; Straight, S. D.; Lockwook, R. B.

    2008-08-01

    Tactical Satellite 3 is an Air Force Research Laboratory Science and Technology (S&T) initiative that explores the capability and technological maturity of small, low-cost satellites. It features a low cost "plug and play" modular bus and low cost militarily significant payloads - a Raytheon developed Hyperspectral imager and secondary payload data exfiltration provided by the Office of Naval Research. In addition to providing for ongoing innovation and demonstration in this important technology area, these S&T efforts also help mitigate technology risk and establish a potential concept of operations for future acquisitions. The key objectives are rapid launch and on-orbit checkout, theater commanding, and near-real time theater data integration. It will also feature a rapid development of the space vehicle and integrated payload and spacecraft bus by using components and processes developed by the satellite modular bus initiative. Planned for a late summer 2008 launch, the TacSat-3 spacecraft will collect and process images and then downlink processed data using a Common Data Link. An in-theater tactical ground station will have the capability to uplink tasking to spacecraft and will receive full data image. An international program, the United Kingdom Defence Science and Technology Laboratory (DSTL) and Australian Defence Science and Technology Organisation (DSTO) plan to participate in TacSat-3 experiments.

  11. An operational satellite remote sensing system for ocean fishery

    Institute of Scientific and Technical Information of China (English)

    MAOZhihua; ZHUQiankun; PANDelu

    2004-01-01

    Ocean environmental information is very important to supporting the fishermen in fishing and satellite remote sensing technology can provide it in large scale and in near real-time. Ocean fishery locations are always far away beyond the coverage of the satellite data received by a land-based satellite receiving station. A nice idea is to install the satellite ground station on a fishing boat. When the boat moves to a fishery location, the station can receive the satellite data to cover the fishery areas. One satellite remote sensing system was once installed in a fishing boat and served fishing in the North Pacific fishery areas when the boat stayed there. The system can provide some oceanic environmental charts such as sea surface temperature (SST) and relevant derived products which are in most popular use in fishery industry. The accuracy of SST is the most important and affects the performance of the operational system, which is found to be dissatisfactory. Many factors affect the accuracy of SST and it is difficult to increase the accuracy by SST retrieval algorithms and clouds detection technology. A new technology of temperature error control is developed to detect the abnormity of satellite-measured SST. The performance of the technology is evaluated to change the temperature bias from-3.04 to 0.05 ℃ and the root mean square (RMS) from 5.71 to 1.75 ℃. It is suitable for employing in an operational satellite-measured SST system and improves the performance of the system in fishery applications. The system has been running for 3 a and proved to be very useful in fishing. It can help to locate the candidates of the fishery areas and monitor the typhoon which is very dangerous to the safety of fishing boats.

  12. Modeling and dynamic simulation of receiver in a solar tower power station%塔式太阳能电站接收器的建模及动态仿真

    Institute of Scientific and Technical Information of China (English)

    盛玲霞; 李佳燕; 赵豫红

    2016-01-01

    太阳能接收器是塔式太阳能电站的重要组成部分,是光热转换的重要部件,因此接收器的建模和仿真对实现电站的平稳运行具有重要意义。根据能量守恒、质量守恒定律,对以美国Solar Two电站接收器为原型的高温熔盐接收器吸热管进行空间离散化,建立了接收器分段集总参数模型。模型稳态仿真结果与Solar Two电站接收器测试结果的对比验证了模型的正确性。通过接收器动态仿真,分析了输入变化和接收器接收能量不均匀时的传热特性,可为定日镜场聚焦策略以及电站安全运行的研究提供依据。%The receiver is an important part for photothermal conversion in the solar tower power station. Thus, modeling and simulation of the receiver is extremely significant for the safety and steady-operation of the plant. The sectional lumped parameter model of the molten salt receiver, whose prototype is Solar Two located in USA, is established by the space discretization of the heat tubes according to the law of conservation of energy and mass. The validity of the model is verified through the comparisons between the test results of the receiver in Solar Two plant and the simulation results. The heat transfer characteristics of the receiver in the cases where the inputs change and the received energy distribution isn’t uniform are analyzed by the transient simulation, which can provide the foundation for the investigation of the aiming points strategy and safe operation of the station.

  13. GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling.

    Science.gov (United States)

    Wang, Fuhong; Chen, Xinghan; Guo, Fei

    2015-06-30

    Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1-7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%-40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the

  14. 卫星导航专利分析报告之三──接收机四臂螺旋天线%The Third Report for Satellite Navigation Patent Analysis--quadrifilar helix antenna for receiver

    Institute of Scientific and Technical Information of China (English)

    程小亮; 丰学民; 王海波

    2015-01-01

    As the critical part for satellite navigation receiver receiving satellite signal, antenna affects directly the navigation and positioning effects with its performance. As the second part of series reports for receiver antenna patent analysis and on the basis of mass exact data statistics, this paper studies the characteristics of principal applicants and origin countries deeply, selects the important patents from Sarantel Inc. which is an important company in industry, and shows comprehensively the technique status and development trends in future in the art by means of technical efifciency analysis.%天线作为卫星导航接收机接收卫星信号的关键部分,其性能直接影响到卫星导航接收机的导航和定位效果。本文作为接收机天线专利分析报告系列的第三部分,以大量精确的数据统计为基础,深入研究了四臂螺旋天线的主要申请人及来源国特点,对行业重点企业萨恩特尔公司的重要专利进行筛选,并借助技术功效分析将该领域的技术现状和未来发展趋势给予全面展现。

  15. 液化天然气(LNG)卫星站设备选型分析%Analysis on Type Selection of Equipments for Satellite Stations of Liquefied Natural Gas

    Institute of Scientific and Technical Information of China (English)

    苏圣钧

    2015-01-01

    The main role of LNG satellite station is storage, gasification and liquefaction of natural gas, and transports natural gas to downstream users. In this paper, the composition and working principle of the main system in LNG satellite station were introduced; type selection of LNG tanker, LNG storage tanks, air temperature vaporizer and the water bath heater was analyzed. At last, the rationality of type selection was verified by an example.%LNG 卫星站主要作用为储存、气化液化天然气,并将气化后的气态天然气输送给下游用户。简单介绍了 LNG 卫星站主要系统组成及其工作原理,对卫星站主要设备 LNG 槽车、LNG 储罐、空温气化器和水浴加热器进行了选型分析,最后通过实例进行验证选型。

  16. Ka频段遥感卫星数据接收系统跟踪性能测试新方法%A New Tracking Performance Test Method for Ka-band Remote Sensing Satellite Data Receiving System

    Institute of Scientific and Technical Information of China (English)

    朱维祥; 穆伟; 王万玉; 冯旭祥; 王永华

    2015-01-01

    To solve the problems in the tracking performance test of Ka-band Low Earth Orbit( LEO) re-mote sensing satellite data receiving system,a new method is proposed. Simulation data is generated by u-sing Ka-band LEO satellite,and dynamic target tracking is simulated with the method of tracking Ka-band beacon on the calibration tower by rotating the third axis of antenna. A verification test on tracking per-formance of receiving system is carried out in the developed prototype system. The proposed method pro-vides a reference for acceptance test for Ka-band LEO satellite data receiving system.%针对Ka频段低轨遥感卫星数据接收系统跟踪性能测试中的问题,提出了一种新的测试方法。利用设计的Ka频段低轨卫星动态目标模拟数据,采用转动第三轴跟踪标校塔Ka频段信标的方式模拟动态目标的跟踪,在研制的原型系统中开展了接收系统跟踪性能的测试验证。该测试方法可为Ka频段低轨卫星数据接收系统跟踪性能的测试验收提供参考。

  17. Experimental study of mountain lee—waves by means of satellite photographs and aircraft measurements

    OpenAIRE

    Cruette, Denise

    2011-01-01

    This paper is a summary of a Ph.D. Thesis1 which was a systematic study of the influence of various meteorological factors on the occurrence and characteristics of mountain waves, more specifically of lee-waves of great horizontal extent. The data used are, beside classical meteorological informations, that given by satellite pictures completed by quasi-simultaneous measurements from planes or gliders. The analysis of many satellite pictures received at the french station of Lannion (Brittany...

  18. An Accurate Method for the BDS Receiver DCB Estimation in a Regional Network

    Directory of Open Access Journals (Sweden)

    LI Xin

    2016-08-01

    Full Text Available An accurate approach for receiver differential code biases (DCB estimation is proposed with the BDS data obtained from a regional tracking network. In contrast to the conventional methods for BDS receiver DCB estimation, the proposed method does not require a complicated ionosphere model, as long as one reference station receiver DCB is known. The main idea for this method is that the ionosphere delay is highly dependent on the geometric ranges between the BDS satellite and the receiver normally. Therefore, the non-reference station receivers DCBs in this regional area can be estimated using single difference (SD with reference stations. The numerical results show that the RMS of these estimated BDS receivers DCBs errors over 30 days are about 0.3 ns. Additionally, after deduction of these estimated receivers DCBs and knowing satellites DCBs, the extractive diurnal VTEC showed a good agreement with the diurnal VTEC gained from the GIM interpolation, indicating the reliability of the estimated receivers DCBs.

  19. A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP for a Single Frequency Global Position System (GPS + BeiDou Navigation Satellite System (BDS Receiver

    Directory of Open Access Journals (Sweden)

    Chuang Qian

    2016-12-01

    Full Text Available As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS + BeiDou Navigation Satellite System (BDS is proposed. The method uses a Time-differenced Carrier Phase (TDCP model, which eliminates the Inner-System Bias (ISB between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

  20. A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP) for a Single Frequency Global Position System (GPS) + BeiDou Navigation Satellite System (BDS) Receiver.

    Science.gov (United States)

    Qian, Chuang; Liu, Hui; Zhang, Ming; Shu, Bao; Xu, Longwei; Zhang, Rufei

    2016-12-05

    As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS) + BeiDou Navigation Satellite System (BDS) is proposed. The method uses a Time-differenced Carrier Phase (TDCP) model, which eliminates the Inner-System Bias (ISB) between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM) to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

  1. Intercomparison of stratospheric nitrogen dioxide columns retrieved from ground-based DOAS and FTIR and satellite DOAS instruments over the subtropical Izana station

    OpenAIRE

    Robles-Gonzalez, Cristina; Navarro-Comas, Mónica; Puentedura, Olga; Schneider, Matthias; Hase, Frank; Garcia, Omaira; Blumenstock, Thomas; Gil-Ojeda, Manuel

    2016-01-01

    A 13-year analysis (2000–2012) of the NO2 vertical column densities derived from ground-based (GB) instruments and satellites has been carried out over the Izaña NDACC (Network for the Detection of the Atmospheric Composition Change) subtropical site. Ground-based DOAS (differential optical absorption spectroscopy) and FTIR (Fourier transform infrared spectroscopy) instruments are intercompared to test mutual consistency and then used for validation of stratospheric NO2 fro...

  2. Efficiency Evaluation of ECM Against Bistatic Radar Based on Uncertain Receiver Station%基于R站不确定的双基地雷达ECM效能评估

    Institute of Scientific and Technical Information of China (English)

    孙云辉; 陈永光; 吕栋雷; 徐晓东

    2011-01-01

    An efficiency evaluation method of electronic countermeasure (ECM) against bistatic radar based on uncertain receiver station is proposed, so as to overcome the disadvantage of traditional evaluation method. Based on a precondition that the bistatic radar will be interfered only if each menace receiver is jammed effectively, an efficiency index called efficient jamming ratio is given, which can calculate probability of efficient jamming against unknown receiver. Then, some correlative models are given. Finally, evaluation example validates the method and draws some useful conclusion.%针对传统评价方法在双基地雷达电子干扰效能研究中的弊端,提出了基于R站不确定的双基地雷达电子干扰效能评估方法.该方法基于“对双基地有效干扰需对双基地可行配置区域内所有具有威胁价值的R站布站点均能保持有效作用”这一假设,选取“有效干扰比”作为指标,估算对未知R站的干扰可能性,并给出了计算所需的相关模型;评估实例验证了方法的可行性和合理性,得出了一些有意义的结论.

  3. Seamless Handovers in Cobra Teardrop Satellite Arrays

    Science.gov (United States)

    Draim, John E.; Cefola, Paul J.; Ernandes, Kenneth J.

    2007-06-01

    Satellite systems provide the most efficient and possibly the only means of achieving two-way global communications with mobile systems (ships, aircraft, and vehicular traffic). To date, such systems have used only circular orbits, either GEO or LEO. Medium altitude elliptical constellations, on the other hand, can provide an efficient and affordable alternative to these architectures. Users also benefit from their very high average and minimum elevation angles, resulting in minimum signal attenuation. Cobra Teardrop is unique in that it employs time synchronized 8-h left- and right-leaning elliptical orbits giving mid-latitude observers the illusion of viewing a single satellite continuously orbiting almost directly overhead! In reality, observers see six different satellites per day, for 4 h each (while in their active duty cycles). By design, Teardrop satellites are physically in very close proximity at the handover points. This favorable geometry can be utilized to achieve a seamless handover from one satellite to the other (not requiring any electronic buffering). Handover is accomplished at the precise instant that the total path lengths from the transmitting station through both satellites to the receiving station are exactly equal. In these improved Cobra Teardrop arrays, an order of magnitude increase in global communications capacity (equivalent GEO slots) can be realized over earlier Basic Cobra systems. For decades into the future, these new orbital systems could satisfy a widely expanding range of commercial, government, and military high data rate communication requirements. These would include, but not be limited to, satellite cellular, air traffic control, meteorological, and combat net radio systems. With these arrays, a much larger number of system operators could be supported, without mutual electronic interference, than would ever be possible with circular orbits.

  4. Business earth stations for telecommunications

    Science.gov (United States)

    Morgan, Walter L.; Rouffet, Denis

    The current status of technology for small commercial satellite-communication earth stations is reviewed on the basis of an application study undertaken in the U.S. and Europe. Chapters are devoted to an overview of satellite communication networks, microterminal design and hardware implementation, microterminal applications, the advantages of microterminals, typical users, services provided, the U.S. market for small earth stations, network operators, and the economics of satellite and terrestrial communication services. Consideration is given to the operation of a microterminal network, standards and regulations, technological factors, space-segment requirements, and insurance aspects. Diagrams, graphs, tables of numerical data, and a glossary of terms are provided.

  5. An adaptive linearizer for 16-QAM transmission over non-linear satellite channels

    Science.gov (United States)

    Shanmugan, K. Sam; Ruggles, M. J.

    An adaptive nonlinear equalization scheme that consists of a predistorter located at the transmitting earth station and a linear equalizer at the receiving earth station is described. Algorithms for automatically adjusting the predistorter and the linear equalizer are presented. The effectiveness of the scheme is evaluated using simulations. It is shown that the scheme improves the performance of a 16-queued access memory system operating over a typical satellite channel by minimizing degradations in the signal as it is transmitted over a band-limited satellite channel.

  6. Satellite triangulation in Europe from WEST and ISAGEX data. [computer programs

    Science.gov (United States)

    Leick, A.; Arur, M.

    1975-01-01

    Observational data that was acquired during the West European Satellite Triangulation (WEST) program and the International Satellite Geodesy Experiment (ISAGEX) campaign was obtained for the purpose of performing a geometric solution to improve the present values of coordinates of the European stations in the OSU WN14 solutions, adding some new stations and assessing the quality of the WN14 solution with the help of the additional data available. The status of the data as received, the preprocessing required and the preliminary tests carried out for the initial screening of the data are described. The adjustment computations carried out and the results of the adjustments are discussed.

  7. Zero-power receiver

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert W.

    2016-10-04

    An unpowered signal receiver and a method for signal reception detects and responds to very weak signals using pyroelectric devices as impedance transformers and/or demodulators. In some embodiments, surface acoustic wave devices (SAW) are also used. Illustrative embodiments include satellite and long distance terrestrial communications applications.

  8. 基于LEON3开源软核的卫星导航接收机设计%Design of a Satellite Navigation Receiver Based on LEON3 Open Source Soft Core

    Institute of Scientific and Technical Information of China (English)

    魏东明; 王峰; 刘浩成; 王家燃; 曹鼎

    2016-01-01

    In order to improve the performance and realize miniaturization of satellite navigation receiver, this paper introduces the design of a satellite navigation receiver with independent intellectual property and based on the LEON3 open source soft core on the DE2-115 Field Programmable Gate Array( FPGA) plat-form. The baseband System on a Chip( SoC) design of satellite navigation receiver mainly includes the ar-chitecture of LEON3 open source soft core and the homegrown IP core of acquisition modules designs based on the combination of Partial Matched Filter( PMF) and Fast Fourier Transform( FFT) and tracking mod-ules designs based on delay-locked code loop and Costas carrier loop. Finally,the performance of the re-ceiver system is verified and tested after the software design of the receiver system is completed. The experi-mental result show that the performance of the designed receiver can meet the demands. The result of acqui-sition and tracking is correct and the positioning result with an accuracy of three meters circular error prob-ability( CEP) is correct. The designed receiver with complete hardware and software source code and excel-lent performance has important implications for the development of domestic navigation.%为了提高卫星导航接收机的工作性能以及小型化设计,在现场可编程门阵列( FPGA)平台上开发一款基于LEON3开源软核的拥有自主知识产权的卫星导航接收机。通过LEON3开源软核架构和自主设计的分段匹配滤波器( PMF)与快速傅里叶变换( FFT)相结合的捕获模块、基于延迟锁定环的码跟踪环路和基于科斯塔斯环的载波跟踪环路相结合的跟踪模块IP核实现卫星导航接收机的基带系统级芯片( SoC)设计,最后完成接收机系统的软件设计并在DE2-115 FPGA平台上对接收机系统进行验证测试。实验结果表明所设计的接收机性能优良,能够正常捕获并且跟踪到卫星信号,定位

  9. Communication Systems through Artificial Earth Satellites (Selected Pages)

    Science.gov (United States)

    1987-02-05

    POX Fs (8.2.11) is 0(F) dF If on input of weighing circuit fluctuation noise with uniform spectrum acts, spectral power density in numerator and...Possibly also realization MV with asynchronous operation of terrestrial stations, that we will designate through MVA . In the case MVA each terrestrial...according to the frequcrncy. With MVA through receiving-transmitting equipment of satellite into some tiMe intervals simultaneous possible passage of signals

  10. BeiDou satellite's differential code biases estimation based on uncombined precise point positioning with triple-frequency observable

    Science.gov (United States)

    Fan, Lei; Li, Min; Wang, Cheng; Shi, Chuang

    2017-02-01

    The differential code bias (DCB) of BeiDou satellite is an important topic to make better use of BeiDou system (BDS) for many practical applications. This paper proposes a new method to estimate the BDS satellite DCBs based on triple-frequency uncombined precise point positioning (UPPP). A general model of both triple-frequency UPPP and Geometry-Free linear combination of Phase-Smoothed Range (GFPSR) is presented, in which, the ionospheric observable and the combination of triple-frequency satellite and receiver DCBs (TF-SRDCBs) are derived. Then the satellite and receiver DCBs (SRDCBs) are estimated together with the ionospheric delay that is modeled at each individual station in a weighted least-squares estimator, and the satellite DCBs are determined by introducing the zero-mean condition of all available BDS satellites. To validate the new method, 90 day's real tracking GNSS data (from January to March in 2014) collected from 9 Multi-GNSS Experiment (MGEX) stations (equipped with Trimble NETR9 receiver) is used, and the BDS satellite DCB products from German Aerospace Center (DLR) are taken as reference values for comparison. Results show that the proposed method is able to precisely estimate BDS satellite DCBs: (1) the mean value of the day-to-day scattering for all available BDS satellites is about 0.24 ns, which is reduced in average by 23% when compared with the results derived by only GFPSR. Moreover, the mean value of the day-to-day scattering of IGSO satellites is lower than that of GEO and MEO satellites; (2) the mean value of RMS of the difference with respect to DLR DCB products is about 0.39 ns, which is improved by an average of 11% when compared with the results derived by only GFPSR. Besides, the RMS of IGSO and MEO satellites is at the same level which is better than that of GEO satellites.

  11. Dependent surveillance through an experimental satellite data link system

    Science.gov (United States)

    Cobley, G. A.

    The development and testing of an experimental dependent aircraft-surveillance system using a satellite data link is reported. In this system, the aircraft position is determined onboard using GPS or inertial navigation, enclosed in a message block using a data-link system, and transmitted to an Inmarsat GEO communication satellites; the ground station receives and analyzes the data to keep constant track of the aircraft position. The hardware implementation and the results of demonstrations performed on flights from Iowa to Wisconsin and the North Atlantic are discussed, and diagrams and maps are provided.

  12. 622 Mbps High-speed satellite communication system for WINDS

    Science.gov (United States)

    Ogawa, Yasuo; Hashimoto, Yukio; Yoshimura, Naoko; Suzuki, Ryutaro; Gedney, Richard T.; Dollard, Mike

    2006-07-01

    WINDS is the experimental communications satellite currently under joint development by Japanese Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The high-speed satellite communication system is very effective for quick deployment of high-speed networks economically. The WINDS will realize ultra high-speed networking and demonstrate operability of satellite communication systems in high-speed internet. NICT is now developing high-speed satellite communication system for WINDS. High-speed TDMA burst modem with high performance TPC error correction is underdevelopment. Up to the DAC on the transmitter and from the ADC on the receiver, all modem functions are performed in the digital processing technology. Burst modem has been designed for a user data rate up to 1244 Mbps. NICT is developing the digital terminal as a user interface and a network controller for this earth station. High compatibility with the Internet will be provided.

  13. Research on Receiving Technology Based on Blind Signal Separation for Satellite MIMO Communication System%基于盲分离的卫星MIMO系统接收技术研究

    Institute of Scientific and Technical Information of China (English)

    辛吉荣; 万坚; 陈绍贺; 程建

    2013-01-01

    针对卫星MIMO(Multi-Input Multi-Output)通信系统,提出采用盲分离的思路对各卫星信号进行接收.考虑到盲分离性能易受噪声、混合矩阵病态性的影响,分析了噪声对接收性能影响最小时信道传输矩阵(即盲分离中的混合矩阵)应满足的条件,并给出了满足此条件的等距线阵的构建方式.通过计算机仿真分析了在此方式下,等距线阵的方位角、间距以及信号频率对盲分离接收的影响,最后得出对天线阵列建设具有一定指导意义的结论,为进一步进行实验奠定基础.%Methods of using blind signal processing was proposed to receive the communication signal in Satellite MIMO (Multi-Input Multi-Output) system. Since the receiving performance was affected by noise and illness of mixing matrix, the channel transfer matrix (also called mixing matrix in blind signal processing) that minimized the noise affection was analyzed. The relationship between the transfer matrix and the uniform linear array's parameter such as azimuth angle, distance between two adjacent antennas and the frequency was also analyzed by simulation. Final, some conclusions useful in designing an antenna array in satellite communication system were given out.

  14. A method of time transfer between remote stations via LRO

    Science.gov (United States)

    Hoffman, Evan; Sun, Xiaoli; Skillman, David R.; McGarry, Jan F.; Mao, Dandan

    2014-05-01

    Satellite Laser Ranging (SLR) is a standard geodetic technique that uses the round trip time of light from a ground station to a satellite to determine distance. When combined with a spacecraft detector and timing system, this technique can also be used to transfer time between ground stations, demonstrated by the Time Transfer by Laser Link (T2L2) project by the Centre National d'Etudes Spatiaes (CNES) and Observatorire de la Cote d'Azur (OCA) as well as the Laser Time Transfer (LTT) project by the Shanghai Astronomical Observatory. We describe an additional method of time transfer using simultaneous one-way laser ranging (LR) by two or more ground stations to the Lunar Reconnaissance Orbiter (LRO). A one way ranging is necessary, as two way ranging via retroreflectors for time transfer becomes impractical at lunar distances. The method will utilize the one-way LR currently being performed as a part of the LRO mission, allowing time transfer to be a by-product of the conventional usage of the data. Each ground station is referenced to a Master Clock using a multifrequency all-view GPS receiver at both the ground station and Master Clock locations.The Master Clock is located close enough to the ground station to make ionospheric differences in signal path negligible. Two or more stations range to LRO at the same time and their times of arrival are compared. Results from a ground-based experiment are shown, with sub-nanosecond precision shown to be achievable. Ultimately this measurement will provide a more precise and accurate relation of timing standards between stations, leading to a marked improvement in orbit determination.

  15. Tracking on non-active collaborative objects from San Fernando Laser station

    Science.gov (United States)

    Catalán, Manuel; Quijano, Manuel; Cortina, Luis M.; Pazos, Antonio A.; Martín-Davila, José

    2016-04-01

    The Royal Observatory of the Spanish Navy (ROA) works on satellite geodesy from the early days of the space age, when the first artificial satellite tracking telescope was installed in 1958: the Baker-Nunn camera. In 1975 a French satellite Laser ranging (SLR) station was installed and operated at ROA . Since 1980, ROA has been operating this instrument which was upgraded to a third generation and it is still keep into a continuous update to reach the highest level of operability. Since then ROA has participated in different space geodesy campaigns through the International Laser Service Stations (ILRS) or its European regional organization (EUROLAS), tracking a number of artificial satellites types : ERS, ENVISAT, LAGEOS, TOPEX- POSEIDON to name but a few. Recently we opened a new field of research: space debris tracking, which is receiving increasing importance and attention from international space agencies. The main problem is the relatively low accuracy of common used methods. It is clear that improving the predicted orbit accuracy is necessary to fulfill our aims (avoiding unnecessary anti-collision maneuvers,..). Following results obtained by other colleagues (Austria, China, USA,...) we proposed to share our time-schedule using our satellite ranging station to obtain data which will make orbital elements predictions far more accurate (sub-meter accuracy), while we still keep our tracking routines over active satellites. In this communication we report the actions fulfill until nowadays.

  16. The BDS iGMAS RIOS station at Observatório Nacional, Rio de Janeiro

    Science.gov (United States)

    Humberto Andrei, Alexandre; Song, Shuli; Junqueira, Selma; Beauvalet, Laurene

    2016-07-01

    GNSS navigation satellites are currently being developed by all major players in the science and technology scene, to compete with the GPS system. Because their applications span many different areas, from traffic and cargo control, to geodesy and seismic monitoring, it is required to assess the coherence between the different constellations. BDS is the GNSS system currently developed in China. Its first generation of satellites consisted of 3 geostationnary satellites allowing geolocalisation in China only. In addition to these satellites, other satellites have been launched in geostationnary and geosynchronous orbits, as well as satellites orbiting with a classical GNSS semi-major axis. With these additions, the BDS system possesses 19 operating satellites, and though the system is mostly efficient for geolocalisation in Asia, the satellites are also visible in other parts of the globe. In parallel to the development of the BDS constellation, China has launched the iGMAS (International GNSS Monitoring and Assessment Service) project to develop a global tracking network of multi-GNSS geodetic receivers. One of the goals of this project is to evaluate the efficiency of the BDS constellation as well as the efficiency of the receivers developed by the Chinese laboratories. As part of the Brazilian program COSBAN leaded by the Foreign Affairs Ministry to foster up the science and technology partnership with China, materialized by the collaboration between the Shanghai Astronomical Observatory/CAS and the Observatório Nacional/MCTI, in Rio de Janeiro. Through it the RIOS-iGMAS station was installed at Observatório Nacional, where the RJEP GNSS station already operates as part of the Brazilian reference system. Thus at the Observatório Nacional can be observed satellites from any constellation with both systems of reception, leading to a direct, efficient way to compare the results obtained for each network. In this communication we focus on the determination of the

  17. Radiofrequency testing of satellite segment of simulated 30/20 GHz satellite communications system

    Science.gov (United States)

    Leonard, R. F.; Kerczewski, R.

    1985-01-01

    A laboratory communications system has been developed that can serve as a test bed for the evaluation of advanced microwave (30/20 GHz) components produced under NASA technology programs. The system will ultimately permit the transmission of a stream of high-rate (220 Mbps) digital data from the originating user, through a ground terminal, through a hardware-simulated satellite, to a receiving ground station, to the receiving user. This report contains the results of radiofrequency testing of the satellite portion of that system. Data presented include output spurious responses, attainable signal-to-noise ratios, a baseline power budget, usable frequency bands, phase and amplitude response data for each of the frequency bands, and the effects of power level variation.

  18. Simulating Global AeroMACS Airport Ground Station Antenna Power Transmission Limits to Avoid Interference With Mobile Satellite Service Feeder Uplinks

    Science.gov (United States)

    Wilson, Jeffrey D.

    2013-01-01

    The Aeronautical Mobile Airport Communications System (AeroMACS), which is based upon the IEEE 802.16e mobile wireless standard, is expected to be implemented in the 5091 to 5150 MHz frequency band. As this band is also occupied by Mobile Satellite Service feeder uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference are under analysis in order to enable the definition of standards that assure that such interference will be avoided. In this study, the cumulative interference power distribution at low Earth orbit from transmitters at global airports was simulated with the Visualyse Professional software. The dependence of the interference power on antenna distribution, gain patterns, duty cycle, and antenna tilt was simulated. As a function of these parameters, the simulation results are presented in terms of the limitations on transmitter power from global airports required to maintain the cumulative interference power under the established threshold.

  19. 47 CFR 25.259 - Time sharing between NOAA meteorological satellite systems and non-voice, non-geostationary...

    Science.gov (United States)

    2010-10-01

    ... Atmospheric Administration (“NOAA”) satellite systems. When calculating the protection areas for a NOAA... contact person and telephone number so that claims of harmful interference into NOAA earth station users... Administration (“NTIA”) notifies the Commission that NOAA is receiving unacceptable interference from a...

  20. Design of multi-layer circularly polarized microstrip antenna in satellite navigation receiver system%卫星导航接收机系统中的多层圆极化微带天线设计

    Institute of Scientific and Technical Information of China (English)

    王喜龙; 魏昆

    2015-01-01

    Several circularly polarized receiving antennas with different frequency in small space are placed on satellite naviga⁃tion receiver system. The double⁃deck circularly polarized antenna,which receives signals from the GPS with L1 frequency point and L2 frequency point is studied and designed to save space. The double⁃deck antenna consists of two separate single feed point antenna,which is working at L1 frequency range and L2 frequency range independently,right⁃hand circular polarization and left⁃hand circular polarization of the antenna is working as receiving antenna and sending antenna. It′s easy to debug and in⁃stall since the antenna is processed with 4 mm thickness composite material. The simulation analysis and optimization proved that the designed antenna with high gain,excellent polarization and qualifies bandwidth requirement,and it is suitable for satel⁃lite navigation receiver system application.%卫星导航接收机系统有时需要在较小的区域中放置多个不同频率的圆极化接收天线。通过研究并设计出一种GPS的L1和L2双频点双层叠放圆极化天线,可以在很大程度上节约空间。该天线上下层是两个独立的单馈点天线,可以分别在L1和L2频段独立工作,分别为右旋圆极化和左旋圆极化,可作接收天线和发射天线。天线由厚度为4 mm的复合材料加工而成,调试和组装均比较方便。经过仿真分析优化,设计的天线增益较高,极化特性优良,带宽满足要求,完全适合于卫星导航接收机系统的应用。

  1. 三星 GPS 接收机全地形 RTK 测量精度测试与应用的探索%Exploratory Testing and Application of all Terrain Measurement Accuracy of Tri-Satellite RTK Receiver

    Institute of Scientific and Technical Information of China (English)

    杨春全; 齐中华; 徐丽丽

    2015-01-01

    The GPS, GLONASS, Beidou ( COMPASS) GPS receiver functions of three global positioning system in one receiver (hereinafter referred to as:Tri GPS receiver), the receiver can receive the satellite positioning information increased to more than 18, the observation conditions relatively poor, in navigation and positioning, RTK measurements showed great advantage.This test Zhong-haida company production of H32, RTK precision test in observation in different conditions, and the accuracy of the results and the observation of terrain analysis, concluded:Ring view, by the building block within 50%, but completely normal operation, block 50-70%, can get the fixed solution, but the PDOP value will increase obviously, reliability reduce.In the city, the field control survey operation will reduce the position requirements, control survey to reduce the aerial survey as the workload of great significance.%将GPS,GLONASS、北斗( COMPASS)3种全球定位系统的接收功能集于一身的GPS接收机(以下简称:三星GPS接收机),能接收18颗以上卫星的定位信息,观测条件相对差时,在导航定位、RTK测量方面表现出巨大优势。本次测试中海达公司生产的H32,在各种观测条件下进行RTK精度测试,并对成果精度和观测地形进行对比分析。可以看出,环视图上,被建筑物遮挡50%以内,可完全正常作业;遮挡50~70%,能够得出固定解,但PDOP值会明显增大,可靠性降低。在城市、野外控制作业将降低对点位的要求,对减轻航测外业像控测量的工作量意义重大。

  2. 星地光通信的天气可用性与地面站选址研究%Satellite-to-ground optical communication's usability with different weathers and ground station location

    Institute of Scientific and Technical Information of China (English)

    姜晓峰; 赵尚弘; 李勇军; 王翔; 李瑞欣

    2012-01-01

    The attenuation of satellite-to-ground optical link in fog, rain, snow and cloud is calculated with empirical formulas. The result of simulation shows the longer the length of the light wave, the smaller the attenuation of the laser in the fog; the attenuation in the snow is 10 -100 times higher than that in the rain; when the optical depth of cloud is 4. 7, the laser attenuation is higher than 20 dB. Considering the geographic distribution, meteorological features and cloud cover statistics, it is suggested that the Tarim basin, the desert of western Inner Mongolia and the northwestern part of Loess Plateau in northwest of China should be favorable for satellite-to-ground optical communication ground station location.%利用经验公式计算了星地光链路在雾、雨、雪、云天气中的衰减,仿真结果表明:波长越长,雾对激光的衰减越小;雪对激光的衰减量高于雨对激光衰减量1~2个数量级;当光学厚度达到4.7时,云层对激光的衰减已达到20 dB以上.综合考虑我国的地理分布和气候特点以及云层覆盖情况,建议我国星地光通信地面站选址可以考虑西北地区的塔里木盆地-内蒙古西部戈壁沙漠-黄土高原西北部一带.

  3. Analysis of BOC Modulation and Receiver Technique for Satellite Navigation System%卫星导航系统中的BOC调制和接收技术分析

    Institute of Scientific and Technical Information of China (English)

    袁润平; 翟建勇; 王伟

    2013-01-01

    BOC调制是一种新的调制方式,能够实现频谱分离并能够充分利用整个频带,比传统的BPSK调制拥有更好的自相关特性,以至于能够改善定位精度。由于BOC调制信号在载波频率点处有较低的功率谱密度,因而,在未来的卫星导航系统中使用 BOC 调制信号将能够减少信号间的干扰。本文详细地分析了BOC调制信号的特点,通过对功率谱密度函数、自相关函数、Gabor带宽和码跟踪精度等参数的分析和仿真,验证了BOC调制信号在相关特性、抗干扰能力和码跟踪精度方面的优越性。并针对 BOC 调制信号自相关峰的多峰带来的跟踪不确定性会使捕获复杂度增加和带来跟踪误差的问题,本文介绍了几种BOC调制信号的接收技术,可为我国自主研发的导航系统的信号体制设计和系统优化提供技术支撑。%BOC modulation is a type of new modulation method, which realizes the split of spectrum to make full use of the available frequency bands, and possesses better autocorrelation property than the classic BPSK modulation, so can improve the precision of the positioning. Thus, the use of the Binary Offset Carrier (BOC) modulated signal in incoming satellite navigation systems can reduce the interference as it has low PSD at carrier frequency. the signal characteristic of BOC is analyzed in detail. BOC modulation signal has the advantages of correlate characteristics, code tracking accuracy and anti-jamming ability which are validated by the analysis and simulation of the power spectral density function, correlation function, Gabor bandwidth, and code tracking accuracy. According to the problems which can be brought by the tracking uncertainty of BOC modulation signal, several receiver techniques for BOC modulation signal are introduced in order to design the satellite signal and optimize the satellite system.

  4. Intercomparison of stratospheric nitrogen dioxide columns retrieved from ground-based DOAS and FTIR and satellite DOAS instruments over the subtropical Izana station

    Science.gov (United States)

    Robles-Gonzalez, Cristina; Navarro-Comas, Mónica; Puentedura, Olga; Schneider, Matthias; Hase, Frank; Garcia, Omaira; Blumenstock, Thomas; Gil-Ojeda, Manuel

    2016-09-01

    A 13-year analysis (2000-2012) of the NO2 vertical column densities derived from ground-based (GB) instruments and satellites has been carried out over the Izaña NDACC (Network for the Detection of the Atmospheric Composition Change) subtropical site. Ground-based DOAS (differential optical absorption spectroscopy) and FTIR (Fourier transform infrared spectroscopy) instruments are intercompared to test mutual consistency and then used for validation of stratospheric NO2 from OMI (Ozone Monitoring Instrument) and SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY). The intercomparison has been carried out taking into account the various differences existing in instruments, namely temporal coincidence, collocation, sensitivity, field of view, etc. The paper highlights the importance of considering an "effective solar zenith angle" instead of the actual one when comparing direct-sun instruments with zenith sky ones for a proper photochemical correction. Results show that NO2 vertical column densities mean relative difference between FTIR and DOAS instruments is 2.8 ± 10.7 % for a.m. data. Both instruments properly reproduce the NO2 seasonal and the interannual variation. Mean relative difference of the stratospheric NO2 derived from OMI and DOAS is -0.2 ± 8.7 % and from OMI and FTIR is -1.6 ± 6.7 %. SCIAMACHY mean relative difference is of 3.7 ± 11.7 and -5.7 ± 11.0 % for DOAS and FTIR, respectively. Note that the days used for the intercomparison are not the same for all the pairs of instruments since it depends on the availability of data. The discrepancies are found to be seasonally dependent with largest differences in winter and excellent agreement in the spring months (AMJ). A preliminary analysis of NO2 trends has been carried out with the available data series. Results show increases in stratospheric NO2 columns in all instruments but larger values in those that are GB than that expected by nitrous oxide oxidation. The

  5. Spatial Cloud Detection and Retrieval System for Satellite Images

    Directory of Open Access Journals (Sweden)

    Ayman Nasr

    2013-01-01

    Full Text Available In last the decade we witnessed a large increase in data generated by earth observing satellites. Hence, intelligent processing of the huge amount of data received by hundreds of earth receiving stations, with specific satellite image oriented approaches, presents itself as a pressing need. One of the most important steps in earlier stages of satellite image processing is cloud detection. Satellite images having a large percentage of cloud cannot be used in further analysis. While there are many approaches that deal with different semantic meaning, there are rarely approaches that deal specifically with cloud detection and retrieval. In this paper we introduce a novel approach that spatially detect and retrieve clouds in satellite images using their unique properties .Our approach is developed as spatial cloud detection and retrieval system (SCDRS that introduce a complete framework for specific semantic retrieval system. It uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tile sizes using spatial and textural properties of cloud regions. Second, we retrieve our tiles using a parametric statistical approach within a multilevel refinement process. Our approach has been experimentally validated against the conventional ones yielding enhanced precision and recall rates in the same time it gives more precise detection of cloud coverage regions.

  6. The First Chinese Ocean Color Satellite HY-1A

    Institute of Scientific and Technical Information of China (English)

    PAN Delu; HE Xianqiang

    2004-01-01

    HY-1A is China's first ocean color satellite, and was launched on 15 May 2002as a piggyback satellite on the FY-1D satellite using the Long March rocket.There are two sensors on the satellite: China's Ocean Color and Temperature Scanner (COCTS), and the CCD Coastal Zone Imager (CZI). In the report,first, the properties and characteristics of HY-1A are briefly introduced; Second, the quality and availability of the data are evaluated by the mean of the Complex Signal Noise Ratio (CSNR) which is simulated theoretically; Third,the received HY-1A data are compared with SeaSTAR data to understand the accuracy of radiance measurement by the HY-1A; Finally, the remote sensing products of ocean color and temperature are mapped by HY-1A to study its application potentiality. The results show that the HY-1A has a latent capability for the application of marine environment detection, the management and protection of marine resources, and the furthering of national rights and interests.Meanwhile, some modifications are proposed for the next ocean satellite, suchas adding the case of tilt scanning, modification of the CCD element uniformity,and adding more ocean satellite receiving stations.

  7. Monte Carlo simulations of precise timekeeping in the Milstar communication satellite system

    Science.gov (United States)

    Camparo, James C.; Frueholz, R. P.

    1995-01-01

    The Milstar communications satellite system will provide secure antijam communication capabilities for DOD operations into the next century. In order to accomplish this task, the Milstar system will employ precise timekeeping on its satellites and at its ground control stations. The constellation will consist of four satellites in geosynchronous orbit, each carrying a set of four rubidium (Rb) atomic clocks. Several times a day, during normal operation, the Mission Control Element (MCE) will collect timing information from the constellation, and after several days use this information to update the time and frequency of the satellite clocks. The MCE will maintain precise time with a cesium (Cs) atomic clock, synchronized to UTC(USNO) via a GPS receiver. We have developed a Monte Carlo simulation of Milstar's space segment timekeeping. The simulation includes the effects of: uplink/downlink time transfer noise; satellite crosslink time transfer noise; satellite diurnal temperature variations; satellite and ground station atomic clock noise; and also quantization limits regarding satellite time and frequency corrections. The Monte Carlo simulation capability has proven to be an invaluable tool in assessing the performance characteristics of various timekeeping algorithms proposed for Milstar, and also in highlighting the timekeeping capabilities of the system. Here, we provide a brief overview of the basic Milstar timekeeping architecture as it is presently envisioned. We then describe the Monte Carlo simulation of space segment timekeeping, and provide examples of the simulation's efficacy in resolving timekeeping issues.

  8. Waste Transfer Stations

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund

    2011-01-01

    tion and transport is usually the most costly part of any waste management system; and when waste is transported over a considerable distance or for a long time, transferring the waste from the collection vehicles to more efficient transportation may be economically beneficial. This involves...... a transfer station where the transfer takes place. These stations may also be accessible by private people, offering flexibility to the waste system, including facilities for bulky waste, household hazardous waste and recyclables. Waste transfer may also take place on the collection route from small...... satellite collection vehicles to large compacting vehicles that cannot effectively travel small streets and alleys within the inner city or in residential communities with narrow roads. However, mobile transfer is not dealt with in this chapter, which focuses on stationary transfer stations. This chapter...

  9. Report of study group 3.3 ''LNG and LPG peak shaving and satellite plants''; Rapport du groupe d'etude 3.3 ''usines d'ecretement de pointes et stations satellites GNL et GPL''

    Energy Technology Data Exchange (ETDEWEB)

    Klein Nagelvoort, R.

    2000-07-01

    This report presents a world-wide overview of LNG and LPG Peak Shaving and Satellite Plants, compiled by the study group 3.3 of the International Gas Union. The scope of the work of the study group includes: - LPG peak shavers (LPG + air, N{sub 2}) in gas distribution networks; - LPG peak shavers for start-up and back-up fuel for LNG terminals and power stations; - LNG peak shavers for gas distribution networks; - Small-scale liquefaction plants for distribution to satellites and dedicated consumers (e.g. power generators, chemical plants, trucking companies etc.); - LNG peak shavers as back-up for large consumers; - Alternative liquefaction technologies for LNG and LPG (e.g. refrigeration cycles, supersonic expansion, thermo-acoustic designs); - Alternative storage tank designs for LNG and LPG. The report presents an overview of current installations world-wide and considers the prospects of technological developments with respect to equipment, remote operations and safety constraints. It also includes where possible a review of capital and operating costs, regulations, and an identification of opportunities and trends. The report collates the information available to the study group at the time of the writing, which may explain some heterogeneity in the document. (author)

  10. 高灵敏度微小卫星可变带宽接收机设计%Design of variable loop bandwidth high sensitivity micro-satellite receiver

    Institute of Scientific and Technical Information of China (English)

    张朝杰; 金小军; 杨伟君; 金仲和

    2011-01-01

    针对微小卫星发射功率低、天线增益小的特点对星载测控应答机提出的高接收灵敏度及高动态范围要求,研究卫星接收机的实现方法.提出一种基于正交欠采样技术及全数字载波恢复环的可变带宽卫星接收机结构.在全数字载波恢复环的实现中,通过相干自动增益控制(AGC)来控制环路带宽,使得在高信噪比下的环路带宽增大,从而获得更佳的跟踪性能;在低信噪比下,降低环路带宽使得接收机有更高的接收灵敏度.经实验测试可知,在250Hz环路带宽下,接收灵敏度为-144 dBm,动态范围达到80 dB以上.%The characteristic of low transmit power and antenna gain in micro-satellite requires high receiver sensitivity and high dynamic range for board transponders. A variable loop bandwidth receiver architecture based on all digital carrier recovery loop was presented using I/Q sub-sampling technique. A coherent automatic gain control (AGC) was used in order to control the loop bandwidth. The loop bandwidth was expanded to achieve better tracking performance at high signal to noise ratio; the loop bandwidth was decreased to realize high receiver sensitivity at low signal to noise ratio. -144 dBm receiver sensitivity was achieved and the dynamic range was better than 80 dB under the condition of 250 Hz loop bandwidth.

  11. Discussion on Time Reduction to Open Vehicular Base Station through Satellite Circuit%关于缩短通过卫星电路开通车载基站时间问题的浅谈

    Institute of Scientific and Technical Information of China (English)

    陈炳

    2015-01-01

    In CDMA emergency safeguard, the delay of vehicular CDMA network base station (BS) opening due to switch-off circuit of temporary scheduling happens more often than not. It degrades enterprise’s image and user’s perception. Based on operational lfow of opening vehicular CDMA network BS through satellite circuit, the main reasons to inlfuence emergency BS opening were discussed to investigate the approach to shortening time to open vehicular BS from aspects of lfow optimization and system construction.%在C网应急保障中,因临时调度的电路不通而延误车载C网基站开通的事情时有发生,给企业形象和用户感知造成一定的不良影响。通过分析经由卫星电路开通车载C网基站的操作全流程,查找到影响应急基站开通的主要原因,现尝试从操作流程优化和制度建设上探索如何缩短开通车载基站时间的办法。

  12. JERS-1 Workshop on the Ground Station for ASEAN

    Science.gov (United States)

    Peanvijarnpong, Chanchai

    1990-11-01

    Presented in viewgraph format, the present status of the ground station and future plan for utilizing earth observation satellites in Thailand is outlined. Topics addressed include: data acquisition system; operation status of LANDSAT, SPOT, and MOS-1 (Marine Observation Satellite-1); remote sensors of satellites; data output form; data correction level; data system in Thailand; ground station for MOS-1 satellite in Thailand; and future plan.

  13. HECO annually conducts and reports results of a biological monitoring program for waters receiving effluent from the Kahe Generating Station, O'ahu, Hawai'i from 1977 to 1996 (NODC Accession 9900012)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The volume of sand and silt entrained and circulated by operation of the Kahe Generating Station is an environmental parameter of considerable geological and...

  14. Station Capacity

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    Stations are often limiting the capacity of railway networks. This is due to extra need of tracks when trains stand still, trains turning around, and conflicting train routes. Although stations are often the capacity bottlenecks, most capacity analysis methods focus on open line capacity. Therefore......, this paper presents methods to analyze station capacity. Four methods to analyze station capacity are developed. The first method is an adapted UIC 406 capacity method that can be used to analyze switch zones and platform tracks at stations that are not too complex. The second method examines the need...... the probability of conflicts and the minimum headway times into account. The last method analyzes how optimal platform tracks are used by examining the arrival and departure pattern of the trains. The developed methods can either be used separately to analyze specific characteristics of the capacity of a station...

  15. Space Station

    Science.gov (United States)

    Anderton, D. A.

    1985-01-01

    The official start of a bold new space program, essential to maintain the United States' leadership in space was signaled by a Presidential directive to move aggressively again into space by proceeding with the development of a space station. Development concepts for a permanently manned space station are discussed. Reasons for establishing an inhabited space station are given. Cost estimates and timetables are also cited.

  16. Man-made Satellites

    Institute of Scientific and Technical Information of China (English)

    郝昌明

    2005-01-01

    If you watch the sky about an hour after the sun goes down, you may see some “moving stars”. But they're not real stars. They're manmade satellites (卫星). And the biggest of all is the International Space Station (ISS国际空间站).

  17. Position surveillance using one active ranging satellite and time-of-arrival of a signal from an independent satellite

    Science.gov (United States)

    Anderson, R. E.; Frey, R. L.; Lewis, J. R.

    1980-01-01

    Position surveillance using one active ranging/communication satellite and the time-of-arrival of signals from an independent satellite was shown to be feasible and practical. A towboat on the Mississippi River was equipped with a tone-code ranging transponder and a receiver tuned to the timing signals of the GOES satellite. A similar transponder was located at the office of the towing company. Tone-code ranging interrogations were transmitted from the General Electric Earth Station Laboratory through ATS-6 to the towboat and to the ground truth transponder office. Their automatic responses included digital transmissions of time-of-arrival measurements derived from the GOES signals. The Earth Station Laboratory determined ranges from the satellites to the towboat and computed position fixes. The ATS-6 lines-of-position were more precise than 0.1 NMi, 1 sigma, and the GOES lines-of-position were more precise than 1.6 NMi, 1 sigma. High quality voice communications were accomplished with the transponders using a nondirectional antenna on the towboat. The simple and effective surveillance technique merits further evaluation using operational maritime satellites.

  18. The Space Station

    Science.gov (United States)

    Sharples, R.; Hieatt, J.

    1984-11-01

    The configuration of the Space Station under design studies by NASA is limited only by the capabilities of the Shuttle and the purposes to which it is applied. Once the standard interlocks, launch vibration modes, and pallet designs are fixed, all other assembly of modular components, testing, and trim will be performed in space. The Station will serve for long-term experiments, as a base for planetary missions asembly, launch, and retrieval, and for loading and launching multiple satellites on an orbital transfer vehicle. Materials processing research will be carried out in the Station, as will various scientific and commercial remote sensing activities. The first operational version (1990) will require four Shuttle launches to reach an assembled mass of 70,000 kg drawing 30 kWe from solar panels and housing a crew of five. By the year 2000 the station will support 10-12 crew members in five habitat modules, will be 31 m long, will have cost $18-20 billion, and will be returning $2 billion per year. The station will be periodically reboosted to higher orbits that decay suficiently for orbiter rendezvous for supplies and assignments.

  19. Measurements of Integration Gain for the Cospas-Sarsat System from Geosynchronous Satellites

    Science.gov (United States)

    Klein-Lebbink, Elizabeth; Christo, James; Peters, Robert; Nguyen, Xuan

    2015-01-01

    The GOES-R satellite is the first satellite to use a standard straight bent pipe transponder with no on-board re-modulation to support Search and Rescue (SAR) operations. Here, we report on the link measurements with a high fidelity satellite transponder simulator made up of satellite EDU (Engineering Design Units) components using an uplink from a beacon simulator and received by a GEOLUT (GEOsynchronous satellite Local User Terminal). We also report on the first ever measurements showing the performance gain obtained by the signal integration performed by the GEOLUT. In addition, a simulator made of commercially available off-the-shelf components assembled to develop the test plan was found to perform very close to the high fidelity simulator. In this paper, we describe what message integration is, how it is implemented in the particular satellite receiving station model used for this tests, and show the measured improvement in message decoding due to this integration process. These are the first tests to quantify the integration gain and are the first tests on the new SARSAT standard for the bent pipe (no onboard re-modulation) repeater used in GOES-R. An inexpensive satellite simulator to run test scripts built from off the shelf components was also found to have the same performance as a high fidelity simulator using actual satellite EDUs.

  20. Satellite delivered cable television - A Warner-Amex experience

    Science.gov (United States)

    Stasi, D.; Setos, A.

    1984-03-01

    Operational aspects of the ground reception of C-band satellite transmissions by CATV operators are discussed. The current C-band network with 20 transmitters and 6000 receivers is shown to have been made possible by the relaxation of the earth-station licensing requirements, while economic factors have been responsible for the introduction of sophisticated and less sophisticated techniques to obtain 'adequate' picture quality with smaller antennas located in more difficult reception sites. The adoption of a quality standard of -18 dB C/I on the basis of empirical tests of viewer perception is considered reasonable, but further lowering of the standard (beyond -15 dB) is questioned. It is pointed out that antenna systems providing only minimal reception with 4-deg satellite spacing may be rendered useless by satellite video-traffic interference when 2-deg spacing is introduced over the next two years.

  1. Satellite Communication.

    Science.gov (United States)

    Technology Teacher, 1985

    1985-01-01

    Presents a discussion of communication satellites: explains the principles of satellite communication, describes examples of how governments and industries are currently applying communication satellites, analyzes issues confronting satellite communication, links mathematics and science to the study of satellite communication, and applies…

  2. A New Approach for Enhanced Communication to LEO Satellites

    NARCIS (Netherlands)

    Gill, E.K.A.; Verhoeven, C.; Gill, K.; De Milliano, M.

    2010-01-01

    Operations of satellites in Low-Earth Orbit (LEO) have been based on exploiting the maximum time of visibility of satellites over their ground stations. In this paper, it is shown that a key parameter for communication between a satellite and a ground station is not the time of visibility but the am

  3. Station Capacity

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    Stations are often limiting the capacity of railway networks. This is due to extra need of tracks when trains stand still, trains turning around, and conflicting train routes. Although stations are often the capacity bottlenecks, most capacity analysis methods focus on open line capacity. Therefore......, this paper presents methods to analyze station capacity. Four methods to analyze station capacity are developed. The first method is an adapted UIC 406 capacity method that can be used to analyze switch zones and platform tracks at stations that are not too complex. The second method examines the need...... for platform tracks and the probability that arriving trains will not get a platform track immediately at arrival. The third method is a scalable method that analyzes the conflicts in the switch zone(s). In its simplest stage, the method just analyzes the track layout while the more advanced stages also take...

  4. Structural System Design of Mobile Satellite Communication System Vehicular Station Based on SUV Platform%某SUV平台动中通结构总体设计探讨

    Institute of Scientific and Technical Information of China (English)

    白旭东

    2011-01-01

    介绍了某运动型多功能车(Sport Utility Vehicle,SUV)平台动中通的结构总体设计。针对SUV平台的特点,结合系统使用要求,选择了中轮廓动中通天线和取力发电的供电方式,通过对设备分类布局来提高空间利用率的方法解决了载车空间小、上装设备多的问题。从人机工程的角度探讨了在行驶状态下操作的舒适性,并给出了设备机架的限制高度。阐述了上装设备采取的抗振设计考虑。对系统的整车载荷及行驶稳定性进行了分析计算。在满足系统使用要求的同时保持了原车的优越性能,使载车完整性、安全性、可靠性和舒适性最大化,实现了人机环境的和谐。%This paper introduces the structural system design of a mobile satellite communication system vehicular station based on SUV platform.According to the characteristics of SUV platform and the using requirements of system,medium contour antenna and engine driven generator system are selected.The problem of"many facilities in small space" is well solved through classifying facilities to improve space using efficiency.From the viewpoint of ergonomics,operating comfortableness under running condition is discussed and the height limit of rack is presented.Furthermore,the anti-vibration design of facilities are described,the traveling stability and the load of vehicular station are analyzed and calculated.The design retains the superior performance of SUV while satisfying the system requirements,thus maximizing the integrity,safety,reliability,comfortableness of the vehicle,realizing a harmonious human-machine environment.

  5. 卫星小站远程监控系统通信协议设计与实现%Communication Protocol Design and Realization for the Very Small Aperture Terminal Satellite Station Remote Monitoring System

    Institute of Scientific and Technical Information of China (English)

    贾本凯; 庄卉; 王国平; 郭随平; 陈志禄

    2012-01-01

    For the larger internet delay and higher data packet loss rate of telephone lines, we researched and designed communication protocol for the VSAT satellite station remote monitoring system. We designed 5 categories data frames 46 strips by referencing connection o-riented service serial interface communication protocol system structure and adopting classification first and definition after method. Referencing 802.3 protocol, we designed error retransmission to guarantee the reliability for data frame transmission, by using the data buffer and o-vertime setting. According to the VSAT station parameters actual reading and writing operation, we designed the data frames workflow, make sure the ultimate realization of the system communication protocol design. The test results show that the system communication protocol we designed can ensure system data safe, reliable and correct transmission.%针对电话线路网络延时较大和数据丢包率较高的情况,对VSAT卫星小站远程监控系统通信协议进行了设计研究;借鉴面向连接服务串口通信协议体系结构,采用先分类后定义的方法,设计了5类共46条数据帧;参照802.3协议,利用数据缓冲和超时设置对数据帧可靠性传输进行了出错重传设计;根据VSAT小站参数实际读写操作方式,对数据帧的工作流程进行设计,确保系统通信协议设计的最终实现;测试结果表明:设计的通信协议能够保障系统数据安全可靠正确地传输.

  6. Gaussian Entanglement Distribution via Satellite

    CERN Document Server

    Hosseinidehaj, Nedasadat

    2014-01-01

    In this work we analyse three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the trade-off between space-based engineering complexity and the rate of ground-station entanglement generation...

  7. Gravity Station Data for Portugal

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 3064 records. This data base was received in April 1997. Principal gravity parameters include Free-air Anomalies which have been...

  8. Interior Alaska Gravity Station Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 9416 records. This data base was received in March 1997. Principal gravity parameters include Free-air Anomalies which have been...

  9. Gravity Station Data for Spain

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data total 28493 records. This data base was received in April 1997. Principal gravity parameters include Free-air Anomalies which have been...

  10. Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

    Science.gov (United States)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

  11. GNSS信号接收机的构件初识──GNSS导航信号的收发问题之十%The Current Status and Development on Reifning GNSS Ephemeris by Means of Satellite Laser Ranging--Transmitting/receiving Issue(10) of GNSS Navigation Signals

    Institute of Scientific and Technical Information of China (English)

    刘基余

    2015-01-01

    The GNSS signal receiver is GNSS user equipment for satellite navigation and the terminal equipment for realizing GNSS satellite navigation/positioning. It is the radio receiving equipment that is able to receive, process, track and measure the GNSS navigation signals. It has not only the common performance of the radio receiving equipments, but also the characteristic performance for acquiring, tracking and surveying the weak satellite signals of 3.5E-16W~2.5E-17W. For this reason the structural components of GNSS signal receivers must meet the needs to capture, track, and measure the GNSS signals.%GNSS信号接收机是GNSS导航卫星的用户设备,是实现GNSS卫星导航定位的终端仪器。它是一种能够接收、跟踪、变换和测量GNSS卫星导航定位信号的无线电接收设备,既具有常用无线电接收设备的共性,又具有捕获、跟踪和处理弱达3.5E-16W~2.5E-17W卫星微弱信号的特性。为此,GNSS信号接收机的构件必须满足这种捕获、跟踪和测量GNSS信号的需求。

  12. Mobile satellite news gathering (SNG) system; Soko SNG (Satellite News Gathering) shasaikyoku

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Commercialization was made for broadcasting stations on a mobile station system capable of capturing a satellite automatically while the system is moving. Its feature is the enhanced tracking accuracy as a result of using the Company's original null-sensor (see Note), and detecting and controlling intersecting polarized waves of reference signals from the satellite. The material for transmission is digitally transmitted by MPEG2, making it possible to transmit more data than by conventional systems. The system is being used for live broadcasting of marathon races and emergency news broadcasting. It is expected that the system may be applied to applications other than broadcasting stations, such as automobiles and ships. (Note: A null-sensor is a unit used for adjusting antenna directions for an SNG transmitter. It uses IF receiving signals of H/V polarized waves of parabolic antenna as an input, and outputs the main polarized wave level and the intersecting polarized wave level.) (translated by NEDO)

  13. Advanced receiver autonomous integrity monitoring using triple frequency data with a focus on treatment of biases

    Science.gov (United States)

    El-Mowafy, Ahmed

    2017-04-01

    Most current Advanced Receiver Autonomous Integrity Monitoring (ARAIM) methods are designed to use dual-frequency ionosphere-free observations. These methods assume that receiver bias is absorbed in the common receiver clock offset and bound satellite biases by nominal values. However, most multi-constellation Global Navigation Satellite Systems (GNSS) can offer triple frequency data that can be used for civilian applications in the future, which can improve observation redundancy, solution precision and detection of faults. In this contribution, we explore the use of this type of observations from GPS, Galileo and BeiDou in ARAIM. Nevertheless, the use of triple frequency data introduces receiver differential biases that have to be taken into consideration. To demonstrate the significance of these additional biases we first present a method to quantify them at stations of known coordinates and using available products from the International GNSS service (IGS). To deal with the additional receiver biases, we use a between-satellite single difference (BSSD) observation model that eliminates their effect. A pilot test was performed to evaluate ARAIM availability for Localizer Performance with Vertical guidance down to 200 feet (LPV-200) when using the triple-frequency observations. Real data were collected for one month at stations of known coordinates located in regions of different satellite coverage characteristics. The BSSD triple-frequency model was evaluated to give early indication about its feasibility, where the implementation phase still requires further comprehensive studies. The vertical position error was always found to be bounded by the protection level proven initial validity of the proposed integrity model.

  14. 生命在最后奉献中延续--复旦大学遗体捐献接收站巡礼%Life Goes on after the Last Dedication--Pilgrimage to Dody Donation Receiving Station of Fudan University

    Institute of Scientific and Technical Information of China (English)

    周建莹

    2014-01-01

    Dody Donation Receiving Station of Fudan University (formerly Dody Donation Receiving Station of Shanghai Medical University, Receiving station for short) is part of Red Cross Society of Fudan University. Receiving station had existed before it was officially established in 1982, where the total enrollment rate and the donation rate have been the level in Shanghai leading position, even in the whole country. About 70%of voluntary donation bodies are used for medical teaching, which is an important support for medical education; and about 30% are for medical research, focusing on training pathology professionals. In addition to the receiving station, there are about 5,000 specimens in the pathological specimen museum and the human body Science museum, donated altruistically by the countless unknown deceased. Although the specimens are stationary, their lives are not over, always making dedications to health undertaking. It is the donors who made choice at the end of their lives to dedicate bodies for medical research or medical students’ anatomy practice, and who are hornored as “General Anatomy Teachers”. For 32 years, the hardware facilities and software services of receiving station continue to improve, and the station has been awarded“Shanghai Red Cross advanced collective”, “Shanghai Red Cross advanced individual”, and “China Red Cross advanced collective”; the station has been reported by media for many times.%复旦大学遗体接收站(原上海医科大学遗体接收站,简称接收站)隶属于复旦大学红十字会。接收站在1982年正式成立前已存在,遗体的总登记率和实现率一直处于上海市乃至全国领先水平。志愿捐献的遗体约70%用于医学教学,是医学教学的重要支撑,约30%用于医学科研,着重于病理专业人才的培养。除了遗体接收站,在病理标本博物馆和人体科学馆,约5000件标本是无数不知名的逝者无偿捐献,虽然标本是

  15. Data Collection Satellite Application in Precision Agriculture

    Science.gov (United States)

    Durào, O.

    2002-01-01

    Agricultural Instrumentation Research Center, Brazilian Agricultural Research Corporation; Space Programs Brazil launched in 1993 its first satellite partially built and entirely designed, integrated, tested and operated in the country. It was the SCD-1 satellite, a small (115 kg. and an octagonal prism with 80 cm. height and an external diameter of 100 cm.) with a payload transponder that receives data from ground platforms spread all over the country (including its sea shore). These data are then retransmitted to a receiving station at every satellite pass. Data collected and received are processed at Data Collection Mission Center for distribution via internet at most 30 min after the satellite pass. The ground platforms are called PCD's and differ in the parameters measured according to its purpose and location. Thus, they are able to measure temperature, rain level, wind direction, solar radiation, carbon monoxide as well as many others, beyond its own location. SCD- 1 had a nominal designed life of one year, but is still functioning. It is a LEO satellite with inclination of 25°. In 1998, the country launched SCD-2, with the same purpose, but in phase with SCD-1 . Other differences were a higher index of Brazilian made components and an active attitude control subsystem for the spin rate provided by the magnetic torque coils (these in accordance with a development strategy previously planned). In 1999 the country launched in cooperation with China a remote sensing satellite (mass of 1.4 ton.) called CBERS-1. This satellite is sun synchronous (98° inclination) and also carries a transponder for data collection/transmission as a secondary payload. Thus, the country has now three satellites with data collection/transmission capabilities, two in low inclination phased orbits and one in polar orbit, providing a nice coverage both geographical and temporal not only to its territory but also to other regions of the world.. At first there were not too many PCD

  16. Submicrosecond comparisons of time standards via the Navigation Technology Satellites (NTS)

    Science.gov (United States)

    Buisson, J. A.; Mccaskill, T.; Oaks, J.; Lynch, D.; Wardrip, S. C.; Whitworth, G.

    1978-01-01

    An interim demonstration was performed of the time transfer capability of the NAVSTAR GPS system using a single NTS satellite. Measurements of time difference (pseudo-range) are made from the NTS tracking network and at the participating observatories. The NTS network measurements are used to compute the NTS orbit trajectory. The central NTS tracking station has a time link to the Naval Observatory UTC (USNO,MC1) master clock. Measurements are used with the NTS receiver at the remote observatory, the time transfer value UTC (USNO,MC1)-UTC (REMOTE, VIA NTS) is calculated. Intercomparisons were computed using predicted values of satellite clock offset and ephemeus.

  17. Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance

    Science.gov (United States)

    2015-11-01

    UNCLASSIFIED Satellite Laser Ranging Photon-Budget Calculations for a Single Satellite Cornercube Retroreflector: Attitude Control Tolerance Philip C...the SLR station, and the direction of the satellite from the SLR station. The required attitude control tolerance is to within 17◦ of the optimal... attitude control strategy determined in the present work. A pre-launch measurement of the re- flectance (diffraction) pattern of each retroreflector is

  18. A Synthetic Aperture System Based on Backscattering Signals of Compass Navigation Satellite: Concept and Feasibility

    Directory of Open Access Journals (Sweden)

    Wang Hai-yang

    2012-06-01

    Full Text Available A concept of a bi-static geosynchronous synthetic aperture system, which is formed by reusing backscattered signals of Compass Navigation Satellite System (CNSS, is proposed. The geometric relations of a geostationary satellite of CNSS, located on a geosynchronous satellite receiver, which is illuminated by the backscattered energy of a satellite of CNSS, and a ground station is built up, and following the relations as well as principle of synthetic aperture radar, we expatiate the feasibility of the system by considering parameters such as imaging resolution, ratio of signal to noise and link budget, etc.. Besides, the potential remote sensing applications for measurement of terrain humidity, characteristics of space-time dynamics of changing of terrain surface and atmospheric characteristic, etc..

  19. Hydrogen vehicle fueling station

    Energy Technology Data Exchange (ETDEWEB)

    Daney, D.E.; Edeskuty, F.J.; Daugherty, M.A. [Los Alamos National Lab., NM (United States)] [and others

    1995-09-01

    Hydrogen fueling stations are an essential element in the practical application of hydrogen as a vehicle fuel, and a number of issues such as safety, efficiency, design, and operating procedures can only be accurately addressed by a practical demonstration. Regardless of whether the vehicle is powered by an internal combustion engine or fuel cell, or whether the vehicle has a liquid or gaseous fuel tank, the fueling station is a critical technology which is the link between the local storage facility and the vehicle. Because most merchant hydrogen delivered in the US today (and in the near future) is in liquid form due to the overall economics of production and delivery, we believe a practical refueling station should be designed to receive liquid. Systems studies confirm this assumption for stations fueling up to about 300 vehicles. Our fueling station, aimed at refueling fleet vehicles, will receive hydrogen as a liquid and dispense it as either liquid, high pressure gas, or low pressure gas. Thus, it can refuel any of the three types of tanks proposed for hydrogen-powered vehicles -- liquid, gaseous, or hydride. The paper discusses the fueling station design. Results of a numerical model of liquid hydrogen vehicle tank filling, with emphasis on no vent filling, are presented to illustrate the usefulness of the model as a design tool. Results of our vehicle performance model illustrate our thesis that it is too early to judge what the preferred method of on-board vehicle fuel storage will be in practice -- thus our decision to accommodate all three methods.

  20. Simultaneous ground- and satellite-based observation of MF/HF auroral radio emissions

    Science.gov (United States)

    Sato, Yuka; Kumamoto, Atsushi; Katoh, Yuto; Shinbori, Atsuki; Kadokura, Akira; Ogawa, Yasunobu

    2016-05-01

    We report on the first simultaneous measurements of medium-high frequency (MF/HF) auroral radio emissions (above 1 MHz) by ground- and satellite-based instruments. Observational data were obtained by the ground-based passive receivers in Iceland and Svalbard, and by the Plasma Waves and Sounder experiment (PWS) mounted on the Akebono satellite. We observed two simultaneous appearance events, during which the frequencies of the auroral roar and MF bursts detected at ground level were different from those of the terrestrial hectometric radiation (THR) observed by the Akebono satellite passing over the ground-based stations. This frequency difference confirms that auroral roar and THR are generated at different altitudes across the F peak. We did not observe any simultaneous observations that indicated an identical generation region of auroral roar and THR. In most cases, MF/HF auroral radio emissions were observed only by the ground-based detector, or by the satellite-based detector, even when the satellite was passing directly over the ground-based stations. A higher detection rate was observed from space than from ground level. This can primarily be explained in terms of the idea that the Akebono satellite can detect THR emissions coming from a wider region, and because a considerable portion of auroral radio emissions generated in the bottomside F region are masked by ionospheric absorption and screening in the D/E regions associated with ionization which results from auroral electrons and solar UV radiation.

  1. Observation Station

    Science.gov (United States)

    Rutherford, Heather

    2011-01-01

    This article describes how a teacher integrates science observations into the writing center. At the observation station, students explore new items with a science theme and use their notes and questions for class writings every day. Students are exposed to a variety of different topics and motivated to write in different styles all while…

  2. Performance of static positioning for medium distances based on data from a virtual reference station and ASG-PL Network

    Science.gov (United States)

    Bakula, M.

    The use of a network of reference stations instead of a single reference station allows the modelling of some systematic errors in a region and allows a user to increase the distance between the rover receiver and reference stations. In some countries, GPS reference stations exist and GPS observations are available for users in real-time mode and in post-processing. Observations from several GPS reference stations in a regional network enable modelling spatially-correlated errors and their modelling on an epoch-by-epoch and satellite-by-satellite basis. As a result, observations of a virtual reference station can be created at a rover's approximate position and its observations can be used in the precise baseline positioning of the rover. This paper presents the performance of the static positioning of a rover station, its quality and reliability for two different baselines. Single-baseline and network static solutions are presented and compared. Network solutions are based on data from a virtual reference station (VRS) obtained by the Wasoft/Virtuall software. In both cases, the same strategy of ambiguity resolution was used. These approaches have been tested with the use of 24-hour GPS data from the Polish Active Geodetic Network (ASG-PL). The data from three reference stations with medium-range separation were used in the process of generating VRS data. GPS data of the rover station were divided into 20, 10 and 5-min. sessions with a sampling interval of 5 sec. Practical calculations and analyses of horizontal and vertical accuracy of coordinates clearly show the improvement of static positioning in terms of time observation span and ambiguity reliability.

  3. women Contrlbute to Satellite Technology

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    IN the early morning of August 14, 1992, at the Xichang satellite launching center, China Central Television Station was about to do a live, worldwide broadcast on the launching of an Australian communications satellite made by the United States. With the order of the commander, "Ignition," people could watch the white rocket rise, pierce the blue sky and race toward the space with a long flaming tail trailing behind it.

  4. Geostationary satellites collocation

    CERN Document Server

    Li, Hengnian

    2014-01-01

    Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

  5. Passive correlation ranging of a geostationary satellite using DVB-S payload signals.

    Science.gov (United States)

    Shakun, Leonid; Shulga, Alexandr; Sybiryakova, Yevgeniya; Bushuev, Felix; Kaliuzhnyi, Mykola; Bezrukovs, Vladislavs; Moskalenko, Sergiy; Kulishenko, Vladislav; Balagura, Oleg

    2016-07-01

    Passive correlation ranging (PaCoRa) for geostationary satellites is now considered as an alternate to tone-ranging (https://artes.esa.int/search/node/PaCoRa). The PaCoRa method has been employed in the Research Institute "Nikolaev astronomical observatory" since the first experiment in August 2011 with two stations spatially separated on 150 km. The PaCoRa has been considered as an independent method for tracking the future Ukrainian geostationary satellite "Lybid'. Now a radio engineering complex (RC) for passive ranging consists of five spatially separated stations of receiving digital satellite television and a data processing center located in Mykolaiv. The stations are located in Kyiv, Kharkiv, Mukacheve, Mykolaiv (Ukraine) and in Ventspils (Latvia). Each station has identical equipment. The equipment allows making synchronous recording of fragments of the DVB-S signal from the quadrature detector output of a satellite television receiver. The fragments are recorded every second. Synchronization of the stations is performed using GPS receivers. Samples of the complex signal obtained in this way are archived and are sent to the data processing center over the Internet. Here the time differences of arrival (TDOA) for pairs of the stations are determined as a result of correlation processing of received signals. The values of the TDOA that measured every second are used for orbit determination (OD) of the satellite. The results of orbit determination of the geostationary telecommunication satellite "Eutelsat-13B" (13º East) obtained during about four months of observations in 2015 are presented in the report. The TDOA and OD accuracies are also given. Single-measurement error (1 sigma) of the TDOA is equal about 8.7 ns for all pairs of the stations. Standard deviations and average values of the residuals between the observed TDOA and the TDOA computed using the orbit elements obtained from optical measurements are estimated for the pairs Kharkiv-Mykolaiv and

  6. UMTS Network Stations

    Science.gov (United States)

    Hernandez, C.

    2010-09-01

    The weakness of small island electrical grids implies a handicap for the electrical generation with renewable energy sources. With the intention of maximizing the installation of photovoltaic generators in the Canary Islands, arises the need to develop a solar forecasting system that allows knowing in advance the amount of PV generated electricity that will be going into the grid, from the installed PV power plants installed in the island. The forecasting tools need to get feedback from real weather data in "real time" from remote weather stations. Nevertheless, the transference of this data to the calculation computer servers is very complicated with the old point to point telecommunication systems that, neither allow the transfer of data from several remote weather stations simultaneously nor high frequency of sampling of weather parameters due to slowness of the connection. This one project has developed a telecommunications infrastructure that allows sensorizadas remote stations, to send data of its sensors, once every minute and simultaneously, to the calculation server running the solar forecasting numerical models. For it, the Canary Islands Institute of Technology has added a sophisticated communications network to its 30 weather stations measuring irradiation at strategic sites, areas with high penetration of photovoltaic generation or that have potential to host in the future photovoltaic power plants connected to the grid. In each one of the stations, irradiance and temperature measurement instruments have been installed, over inclined silicon cell, global radiation on horizontal surface and room temperature. Mobile telephone devices have been installed and programmed in each one of the weather stations, which allow the transfer of their data taking advantage of the UMTS service offered by the local telephone operator. Every minute the computer server running the numerical weather forecasting models receives data inputs from 120 instruments distributed

  7. The Advanced Communication Technology Satellite and ISDN

    Science.gov (United States)

    Lowry, Peter A.

    1996-01-01

    This paper depicts the Advanced Communication Technology Satellite (ACTS) system as a global central office switch. The ground portion of the system is the collection of earth stations or T1-VSAT's (T1 very small aperture terminals). The control software for the T1-VSAT's resides in a single CPU. The software consists of two modules, the modem manager and the call manager. The modem manager (MM) controls the RF modem portion of the T1-VSAT. It processes the orderwires from the satellite or from signaling generated by the call manager (CM). The CM controls the Recom Laboratories MSPs by receiving signaling messages from the stacked MSP shelves ro units and sending appropriate setup commands to them. There are two methods used to setup and process calls in the CM; first by dialing up a circuit using a standard telephone handset or, secondly by using an external processor connected to the CPU's second COM port, by sending and receiving signaling orderwires. It is the use of the external processor which permits the ISDN (Integrated Services Digital Network) Signaling Processor to implement ISDN calls. In August 1993, the initial testing of the ISDN Signaling Processor was carried out at ACTS System Test at Lockheed Marietta, Princeton, NJ using the spacecraft in its test configuration on the ground.

  8. Beginnings of Satellite Navigation

    Directory of Open Access Journals (Sweden)

    Miljenko Solarić

    2008-05-01

    Full Text Available The first satellite navigation system called the Navy Navigation Satellite System (NNSS or TRANSIT was planned in the USA in 1958. It consisted of 5-6 artificial Earth satellites, was set in motion for the USA military in 1964, and in 1967 for civilian purposes. The frequency shift of received radio waves emitted from the satellite and caused by the Doppler effect was measured. The TRANSIT satellite speed of approaching or moving away was derived from that; the TRANSIT satellites emmited also their own coordinates. Then the ship's position was determined by an intersection of three hyperboloids, which were determined from differences of distances in three time intervals. Maintenance of this navigation system was stopped in 1996, but it is still being used in the USA Navy for exploring the ionosphere. Furthermore, results of Doppler measurements in international projects at the Hvar Observatory from 1982 and 1983. This was the first time in Croatia and the former country that the coordinates of the Hvar Observatory were determined in the unique world coordinate system WGS'72. The paper ends with a brief representation of the Tsiklon Doppler navigation system produced in the former Soviet Union, and there is a list of some of numerous produced and designed satellite navigation systems.Ključne riječi

  9. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world. This paper introduces how to establish the system, a positioning system based on communication satellites called Chinese Area Positioning System (CAPS). Instead of the typical navigation satellites, the communication satellites are configured firstly to transfer navigation signals from ground stations, and can be used to obtain service of the positioning, velocity and time, and to achieve the function of navigation and positioning. Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites, the measur- ing and calculation of transfer time of the signals, the carrier frequency drift in communication satellite signal transfer, how to improve the geometrical configuration of the constellation in the system, and the integration of navigation & communication. Several innovative methods are developed to make the new system have full functions of navigation and communication. Based on the development of crucial techniques and methods, the CAPS demonstration system has been designed and developed. Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E, 110.5°E, 134°E, 142°E and barometric altimetry are used in the CAPS system. The GEO satellites located at 134°E and 142°E are decommissioned GEO (DGEO) satellites. C-band is used as the navigation band. Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted. The ground segment consists of five ground stations; the master station is in Lintong, Xi’an. The ground stations take a lot of responsibilities, including monitor and management of the operation of all system components, determination of the satellite position and prediction of the satellite orbit, accomplishment of the virtual atomic clock

  10. Evaluating Pseudorange Multipath at CGPS Stations Spanning Mexico

    Science.gov (United States)

    Vazquez, G.; Bennett, R. A.; Spinler, J. C.

    2013-12-01

    the pseudo-range observable, the accuracy with which a roaming user may locate their assets with respect to the ITRF may be limited by site-specific multipath. The issue is particularly critical for users depending on pseudorange measurements for 'real-time' (or 'near-real-time') kinematic GPS positioning, where ambiguity resolution is a critical step. Therefore, to identify the most and the least affected GPS stations we analyzed the averaged daily root mean square pseudorange multipath variations (MP1-RMS and MP2-RMS) for all feasible satellites tracked by the CGPS networks. We investigated the sources of multipath, including changes associated with hardware replacement (i.e., receiver and antenna type) and receiver firmware upgrades.

  11. Satellite-Based Sunshine Duration for Europe

    Directory of Open Access Journals (Sweden)

    Bodo Ahrens

    2013-06-01

    Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

  12. Optimization of Passive Coherent Receiver System Placement

    Science.gov (United States)

    2013-09-01

    from satellites can be considered to cover the entirety of the area of interest. In an effort to increase the range of their signals, many cell...broadcasting jazz and pop music tend to have more clearly defined peaks than those stations broadcasting rock or news radio [9]. These ambiguities can

  13. Discussion of the design of satellite-laser measurement stations in the eastern Mediterranean under the geological aspect. Contribution to the earthquake prediction research by the Wegener Group and to NASA's Crustal Dynamics Project

    Science.gov (United States)

    Paluska, A.; Pavoni, N.

    1983-01-01

    Research conducted for determining the location of stations for measuring crustal dynamics and predicting earthquakes is discussed. Procedural aspects, the extraregional kinematic tendencies, and regional tectonic deformation mechanisms are described.

  14. Satellite Upper Air Network (SUAN)

    Science.gov (United States)

    Reale, Tony L.; Thorne, Peter

    2004-10-01

    During the past 20 years of NOAA operational polar satellites, it has become evident that a growing problem concerning their utilization in Climate and also Numerical Weather Prediction (NWP) applications are the systematic errors and uncertainties inherent in the satellite measurements. Similar arguments can be made for global radiosonde observations. These uncertainties are often larger than the sensitive signals and processes, that satellite and radiosonde measurements are designed to reveal, particularly in the realm of climate. Possible strategies to quantify and compensate for these problems include the analysis of satellite overlap data and/or available collocations of satellite and ground truth (radiosonde) observations. However, overlap observations are typically not available except in extreme polar regions and current sampling strategies for compiling collocated radiosonde and satellite observations are insufficient, further compounding the inherent uncertainties in the ground-truth radiosonde data. A Satellite Upper Air Network is proposed to provide reference radiosonde launches coincident with operational polar satellite(s) overpass. The SUAN consist of 36 global radiosonde stations sub-sampled from the Global Upper Air Network (GUAN), and is designed to provide a robust, global sample of collocated radiosonde and satellite observations conducive to the monitoring and validation of satellite and radiosonde observations. The routine operation of such a network in conjunction with operational polar satellites would provide a long-term of performance for critical observations of particular importance for climate. The following report presents a candidate network of 36 upper-air sites that could comprise a SUAN. Their selection along with the mutual benefit across the satellite, radiosonde, climate, numerical weather prediction (NWP) and radiative transfer (RT) model areas are discussed.

  15. Induction studies with satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils

    1999-01-01

    analysis of the geomagnetic field is performed, and the Q-response, which is the transfer function between the internal (induced) and the external (inducing) expansion coefficients is determined for a specific frequency. In the second approach, known as the geomagnetic depth sounding method, the C....... This paper reviews and discusses the possibilities for induction studies using high-precision magnetic measurements from low-altitude satellites. The different methods and various transfer functions are presented, with special emphasis on the differences in analysing data from ground stations and from...... satellites. The results of several induction studies with scalar satellite data (from the POGO satellites) and with vector data (from the Magsat mission) demonstrate the ability to probe the Earth's conductivity from space. However, compared to the results obtained with ground data the satellite results...

  16. Combining METEOSAT-10 satellite image data with GPS tropospheric path delays to estimate regional Integrated Water Vapor (IWV) distribution

    OpenAIRE

    2016-01-01

    Using GPS satellites signals, we can study different processes and coupling mechanisms that can help us understand the physical conditions in the upper atmosphere, which might lead or act as proxies for severe weather events such as extreme storms and flooding. GPS signals received by ground stations are multi-purpose and can also provide estimates of tropospheric zenith delays, which can be converted into mm-accuracy Precipitable Water Vapor (PWV) using collocated pressure and temperature me...

  17. Satellite RNAs and Satellite Viruses.

    Science.gov (United States)

    Palukaitis, Peter

    2016-03-01

    Satellite RNAs and satellite viruses are extraviral components that can affect either the pathogenicity, the accumulation, or both of their associated viruses while themselves being dependent on the associated viruses as helper viruses for their infection. Most of these satellite RNAs are noncoding RNAs, and in many cases, have been shown to alter the interaction of their helper viruses with their hosts. In only a few cases have the functions of these satellite RNAs in such interactions been studied in detail. In particular, work on the satellite RNAs of Cucumber mosaic virus and Turnip crinkle virus have provided novel insights into RNAs functioning as noncoding RNAs. These effects are described and potential roles for satellite RNAs in the processes involved in symptom intensification or attenuation are discussed. In most cases, models describing these roles involve some aspect of RNA silencing or its suppression, either directly or indirectly involving the particular satellite RNA.

  18. Performance Analysis of Integrated Wireless Sensor and Multibeam Satellite Networks Under Terrestrial Interference

    Directory of Open Access Journals (Sweden)

    Hongjun Li

    2016-10-01

    Full Text Available This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs, satellite sinks (SSs, multibeam satellite and remote monitoring hosts (RMHs. The multibeam satellite covers multiple beams and multiple SSs in each beam. The SSs can be directly used as SNs to transmit sensing data to RMHs via the satellite, and they can also be used to collect the sensing data from other SNs to transmit to the RMHs. We propose the hybrid one-dimensional (1D and 2D beam models including the equivalent intra-beam interference factor β from terrestrial communication networks (TCNs and the equivalent inter-beam interference factor α from adjacent beams. The terrestrial interference is possibly due to the signals from the TCNs or the signals of sinks being transmitted to other satellite networks. The closed-form approximations of capacity per beam are derived for the return link of IWSMSNs under terrestrial interference by using the Haar approximations where the IWSMSNs experience the Rician fading channel. The optimal joint decoding capacity can be considered as the upper bound where all of the SSs’ signals can be jointly decoded by a super-receiver on board the multibeam satellite or a gateway station that knows all of the code books. While the linear minimum mean square error (MMSE capacity is where all of the signals of SSs are decoded singularly by a multibeam satellite or a gateway station. The simulations show that the optimal capacities are obviously higher than the MMSE capacities under the same conditions, while the capacities are lowered by Rician fading and converge as the Rician factor increases. α and β jointly affect the performance of hybrid 1D and 2D beam models, and the number of SSs also contributes different effects on the optimal capacity and MMSE capacity of the IWSMSNs.

  19. Performance Analysis of Integrated Wireless Sensor and Multibeam Satellite Networks Under Terrestrial Interference.

    Science.gov (United States)

    Li, Hongjun; Yin, Hao; Gong, Xiangwu; Dong, Feihong; Ren, Baoquan; He, Yuanzhi; Wang, Jingchao

    2016-10-14

    This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs) under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs), satellite sinks (SSs), multibeam satellite and remote monitoring hosts (RMHs). The multibeam satellite covers multiple beams and multiple SSs in each beam. The SSs can be directly used as SNs to transmit sensing data to RMHs via the satellite, and they can also be used to collect the sensing data from other SNs to transmit to the RMHs. We propose the hybrid one-dimensional (1D) and 2D beam models including the equivalent intra-beam interference factor β from terrestrial communication networks (TCNs) and the equivalent inter-beam interference factor α from adjacent beams. The terrestrial interference is possibly due to the signals from the TCNs or the signals of sinks being transmitted to other satellite networks. The closed-form approximations of capacity per beam are derived for the return link of IWSMSNs under terrestrial interference by using the Haar approximations where the IWSMSNs experience the Rician fading channel. The optimal joint decoding capacity can be considered as the upper bound where all of the SSs' signals can be jointly decoded by a super-receiver on board the multibeam satellite or a gateway station that knows all of the code books. While the linear minimum mean square error (MMSE) capacity is where all of the signals of SSs are decoded singularly by a multibeam satellite or a gateway station. The simulations show that the optimal capacities are obviously higher than the MMSE capacities under the same conditions, while the capacities are lowered by Rician fading and converge as the Rician factor increases. α and β jointly affect the performance of hybrid 1D and 2D beam models, and the number of SSs also contributes different effects on the optimal capacity and MMSE capacity of the IWSMSNs.

  20. Analysis on BDS Satellite Internal Multipath and Its Impact on Wide-lane FCB Estimation

    Directory of Open Access Journals (Sweden)

    RUAN Rengui

    2017-08-01

    Full Text Available To the issue of the satellite internal multipath (SIMP of BeiDou satellites, it proposed and emphasized that the SIMP model should be established as a function of the nadir angle with respect to the observed satellite rather than the elevation of the measurement, so that it can be used for receivers at various altitude. BDS data from global distributed stations operated by the International Monitoring and Assessment System (iGMAS and the Multi-GNSS Experiment (MGEX of the International GNSS Service (IGS are collected and a new SIMP model as a piece-wise linear function of the nadir angle is released for the IGSO-and MEO-satellite groups and for B1, B2 and B3 frequency band individually. The SIMP of GEO,IGSO and MEO satellites is further analyzed with B1/B2 dual-frequency data onboard the FengYun-3 C(FY3C satellite at an altitude of~830 km, and it showed that, for nadir angles smaller than 7°, the SIMP values for GEO is quite close to the IGSO's, especially for B2, which may suggest that the SIMP model for IGSO satellites possibly also works for GEO satellites. It also demonstrated that, when the nadir angle is smaller than 12°for the MEO and 7°for the IGSO, the estimated SIMP model with data from FY3C is considerable consistent with that estimated with data collected at ground stations. Experiments are carried out to investigate the impacts of the SIMP on wide-lane fractional cycle bias (FCB estimation for BDS satellites. The result indicates that, with the correction of the estimated SIMP, the repeatability of the FCB series is significantly improved by more than 60% for all satellites. Specifically, for the MEO and IGSO satellites, the repeatability is smaller than 0.05 cycle; the repeatability of 0.023 and 0.068 cycles achieved for GEO satellites C01 and C02 respectively with the estimated SIMP model for IGSO satellites.

  1. Advanced Extremely High Frequency Satellite (AEHF)

    Science.gov (United States)

    2015-12-01

    High Frequency Satellite (AEHF) is a joint service satellite communications system that provides global , survivable, secure, protected, and jam...three satellites fully integrated into the Milstar constellation. October 2014: On October 16, 2014, the program received PEO certification for the...Combined Orbital Operation, Logistics Sustainment ( COOLS ) contract, it will be completed and coordinated in CY 2016. The AEHF system being sustained

  2. The principle of the positioning system based on communication satellites

    Institute of Scientific and Technical Information of China (English)

    AI GuoXiang; SHI HuLi; WU HaiTao; LI ZhiGang; GUO Ji

    2009-01-01

    It is a long dream to realize the communication and navigation functionality in a satellite system in the world.This paper introduces how to establish the system,a positioning system based on communication satellites called Chinese Area Positioning System (CAPS).Instead of the typical navigation satelIites,the communication satellites are configured firstly to transfer navigation signals from ground stations,and can be used to obtain service of the positioning,velocity and time,and to achieve the function of navigation and positioning.Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites,the measuring and calculation of transfer time of the signals,the carrier frequency drift in communication satellite ignal transfer,how to improve the geometrical configuration of the constellation in the system,and the integration of navigation & communication.Several innovative methods are developed to make the new system have full functions of navigation and communication.Based on the development of crucial techniques and methods,the CAPS demonstration system has been designed and developed.Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E,110.5°E,134°E,142°E and barometric altimetry are used in the CAPS system.The GEO satellites located at 134°E and 142°E re decommissioned GEO (DGEO) satellites.C-band is used as the navigation band.Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted.The ground segment consists of five ground stations; the master station is in Lintong,Xi'an.The ground stations take a lot of responsibilities,including monitor and management of the operation of all system components,determination of the satellite position and prediction of the satellite orbit,accomplishment of the virtual atomic clock measurement,transmission and receiving

  3. Evaluation of RTKLIB's Positioning Accuracy Using low-cost GNSS Receiver and ASG-EUPOS

    Directory of Open Access Journals (Sweden)

    Bartosz Wisniewski

    2013-03-01

    Full Text Available The paper focuses on a comparison of different positioning methods provided by free and open source software (FOSS package called RTKLIB. The RTKLIB supports real-time and post-processed positioning. The most important modes of operation tested by the authors are Kinematic, Static, Fixed and Precise Point Positioning (PPP. The data for evaluation were obtained from low-cost Global Navigation Satellite System (GNSS receiver. The tested receiver was based on the u-blox's LEA-6T GNSS module. This receiver provides different types of information including raw carrier phase measurements. It gives the possibility for centimeter-level precision of positioning. As the supporting source of data ASG-EUPOS system was used. ASG-EUPOS is a Polish network of GNSS reference stations providing the real-time corrections and post processing services for the entire territory of Poland.

  4. Direct Broadcast Satellite: Radio Program

    Science.gov (United States)

    Hollansworth, James E.

    1992-01-01

    NASA is committed to providing technology development that leads to the introduction of new commercial applications for communications satellites. The Direct Broadcast Satellite-Radio (DBS-R) Program is a joint effort between The National Aeronautics and Space Administration (NASA) and The United States Information Agency/Voice of America (USIA/VOA) directed at this objective. The purpose of this program is to define the service and develop the technology for a direct-to-listener satellite sound broadcasting system. The DBS-R Program, as structured by NASA and VOA, is now a three-phase program designed to help the U.S. commercial communications satellite and receiver industry bring about this new communications service. Major efforts are being directed towards frequency planning hardware and service development, service demonstration, and experimentation with new satellite and receiver technology.

  5. Centriolar satellites

    DEFF Research Database (Denmark)

    Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

    2015-01-01

    Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

  6. Satellite theory

    Science.gov (United States)

    Kozai, Y.

    1981-04-01

    The dynamical characteristics of the natural satellite of Mars, Jupiter, Saturn, Uranus and Neptune are analyzed on the basis of the solar tidal perturbation factor and the oblateness factor of the primary planet for each satellite. For the inner satellites, for which the value of the solar tidal factor is much smaller than the planetary oblateness factor, it is shown that the eccentricity and inclination of satellite orbits are generally very small and almost constant; several pairs of inner satellites are also found to exhibit commensurable mean motions, or secular accelerations in mean longitude. In the case of the outer satellites, for which solar perturbations are dominant, secular perturbations and long-period perturbations may be derived by the solution of equations of motion reduced to one degree of freedom. The existence of a few satellites, termed intermediary satellites, for which the solar tidal perturbation is on the order of the planetary oblateness factor, is also observed, and the pole of the orbital plane of the satellite is noted to execute a complex motion around the pole of the planet or the orbital plane of the planet.

  7. An access alternative for mobile satellite networks

    Science.gov (United States)

    Wu, W. W.

    1988-05-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  8. Broadcast satellite service: The international dimension

    Science.gov (United States)

    Samara, Noah

    1991-09-01

    The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

  9. Multi-mission Satellite Management

    Science.gov (United States)

    Jamilkowski, M. L.; Teter, M. A.; Grant, K. D.; Dougherty, B.; Cochran, S.

    2015-12-01

    NOAA's next-generation environmental satellite, the Joint Polar Satellite System (JPSS) replaces the current Polar-orbiting Operational Environmental Satellites (POES). JPSS satellites carry sensors which collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The first JPSS satellite was launched in 2011 and is currently NOAA's primary operational polar satellite. The JPSS ground system is the Common Ground System (CGS), and provides command, control, and communications (C3) and data processing (DP). A multi-mission system, CGS provides combinations of C3/DP for numerous NASA, NOAA, DoD, and international missions. In preparation for the next JPSS satellite, CGS improved its multi-mission capabilities to enhance mission operations for larger constellations of earth observing satellites with the added benefit of streamlining mission operations for other NOAA missions. CGS's multi-mission capabilities allows management all of assets as a single enterprise, more efficiently using ground resources and personnel and consolidating multiple ground systems into one. Sophisticated scheduling algorithms compare mission priorities and constraints across all ground stations, creating an enterprise schedule optimized to mission needs, which CGS executes to acquire the satellite link, uplink commands, downlink and route data to the operations and data processing facilities, and generate the final products for delivery to downstream users. This paper will illustrate the CGS's ability to manage multiple, enterprise-wide polar orbiting missions by demonstrating resource modeling and tasking, production of enterprise contact schedules for NOAA's Fairbanks ground station (using both standing and ad hoc requests), deconflicting resources due to ground outages, and updating resource allocations through dynamic priority definitions.

  10. Beyond Factionalism? Cultural and Children's Programs on Palestinian Satellite TV

    NARCIS (Netherlands)

    M.O. AlMoghayer (Mohammed)

    2016-01-01

    markdownabstractThis study examines the production of Palestinian satellite television in the contemporary era. The focus is on cultural and children’s programs of two key stations, the Hamas-based Al Aqsa Satellite Channel (ASC) and the Fatah-based Palestine Satellite Channel (PSC). The study inter

  11. Geosynchronous Earth Orbit/Low Earth Orbit Space Object Inspection and Debris Disposal: A Preliminary Analysis Using a Carrier Satellite With Deployable Small Satellites

    OpenAIRE

    Crockett, Derick A.

    2013-01-01

    Detailed observations of geosynchronous satellites from earth are very limited. To better inspect these high altitude satellites, the use of small, refuelable satellites is proposed. The small satellites are stationed on a carrier platform in an orbit near the population of geosynchronous satellites. A carrier platform equipped with deployable, refuelable SmallSats is a viable option to inspect geosynchronous satellites. The propellant requirement to transfer to a targeted geosynchronous sate...

  12. Use of Very Stable Clocks in Satellite Geodesy

    Science.gov (United States)

    Hugentobler, Urs; Romanyuk, Tetyana

    2016-07-01

    Time and frequency play an essential role in satellite geodesy and navigation. Global Navigation Satellite Systems (GNSS) rely on precise measurements of signal travel times. The satellite and receiver clocks involved in measuring this time interval need to be synchronized at the picosecond level. The concept of GNSS allows for an epoch-wise synchronization of space and ground clocks, a feature which is consequently used in satellite geodesy by estimating epoch-wise clock corrections for all clocks in the system, either explicitly or implicitly by forming double differences. Ultra-stable clocks allow to estimate only few parameters for each clock, e.g., offset and drift. The much reduced number of parameters should stabilize GNSS solutions, e.g., tracking network station coordinates. On the other hand systematic errors, e.g., from troposphere or orbit modeling deficiencies or temperature induced hardware delay variations may systematically affect the solutions. The presentation shows trade-offs of modelling higly stable clocks and negative impact of error sources based on simulations.

  13. Polarization-Basis Tracking Scheme in Satellite Quantum Key Distribution

    Directory of Open Access Journals (Sweden)

    Morio Toyoshima

    2011-01-01

    Full Text Available Satellite quantum key distribution is a promising technique that overcomes the limited transmission distance in optical-fiber-based systems. The polarization tracking technique is one of the key techniques in the satellite quantum key distribution. With free-space quantum key distribution between an optical ground station and a satellite, the photon polarization state will be changed according to the satellite movement. To enable polarization based quantum key distribution between mobile terminals, we developed a polarization-basis tracking scheme allowing a common frame of reference to be shared. It is possible to orient two platforms along a common axis by detecting the reference optical signal only on the receiver side with no prior information about the transmitter's orientation. We developed a prototype system for free-space quantum key distribution with the polarization-basis tracking scheme. Polarization tracking performance was 0.092° by conducting quantum key distribution experiments over a 1 km free space between two buildings in a Tokyo suburb.

  14. 47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

    Science.gov (United States)

    2010-10-01

    ...-satellite service and 2 GHz mobile-satellite service. 25.143 Section 25.143 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Space Stations § 25.143 Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2...

  15. 采用伴随星接收LEO到GEO上行信号的一种方案%A Method Receiving Uplink Signal from LEO to GEO by Companion Satellites

    Institute of Scientific and Technical Information of China (English)

    万艳飞; 张军

    2005-01-01

    伴随卫星上部署动态跟踪天线,难以进行卫星姿态控制,为此提出了一种采用两颗伴随卫星部署非跟踪天线的接收方案,用于接收低轨圆轨道星(LEO)到地球同步静止卫星(GEO)的上行信号.理论分析及STK(Satellite Tool Kit)软件仿真结果表明,伴随星姿态只需在惯性空间内稳定,就可实现动态信号接收,大大降低了系统的实现难度.

  16. Radio-location of mobile stations in third generation networks

    Directory of Open Access Journals (Sweden)

    Milan Manojle Šunjevarić

    2013-06-01

    direction, if specified by a direction on an object, (b circle, if determined by measuring the distance of an object, or (c a hyperbola, if the difference is determined by measuring the distance between two objects. In cellular networks, the location of mobile stations can be estimated roughly by proximity sensing methods and methods based on an evaluation of the characteristics of base stations (fingerprinting. Basic characteristics of the UMTS standard The radio network controller (RNC has three different roles and is therefore known as: Controlling RNC (CRNC, Serving RNC (SRNC and Drifting RNC (DRNC. The Local Measurement Unit (LMU performs radio measurements (measuring the delay of signals from base stations to the LMU and forwards the data to the CRNC. The main location functions are performed within the Serving RNC which can operate in two modes: RNC central and central SAS (Standalone SMLC. The RNC in the RNC central mode controls the flow of requirements for the localization, chooses the method of localization, provides information as necessary and, finally, estimates the location of the user. The SAS mode performs the procedures based on the requirements of the service radio network controller (SRNC. The SAS executes the global location (Global Navigation Satellite System and location on the uplink, based on measuring the time difference U-TDoA (Uplink - Time Difference of Arrival. Methods of locating the MS in a UMTS network In the UMTS network, depending on the used network infrastructure,  both the station and network-based method can be used, i.e. determining the MS location can be performed on the MS or on the network side. In UMTS networks, the following methods can be used: methods based on measurements in the time domain (time-based, methods based on measurements of a received power level (Received Signal Strength - RSS, methods based on measuring the angle under which the signal arrives to the receiving antenna and methods based on the global location

  17. Effect of parallactic refraction correction on station height determination

    Science.gov (United States)

    Lerch, F. J.; Huston, H. A.

    1973-01-01

    The effect of omitting the parallactic refraction correction for satellite optical observations in the determination of station coordinates is analyzed for a large satellite data distribution. A significant error effect is seen in station heights. A geodetic satellite data distribution of 23 close earth satellites, containing 30,000 optical observations obtained by 13 principal Baker-Nunn camera sites, is employed. This distribution was used in a preliminary Goddard Earth Model (GEM 1) for the determination of the gravity field of the earth and geocentric tracking station locations. The parallactic refraction correction is modeled as an error on the above satellite data and a least squares adjustment for station locations is obtained for each of the 13 Baker-Nunn sites. Results show an average station height shift of +8 meters with a dispersion of plus or minus 0.7 meters for individual sites. Station latitude and longitude shifts amounted to less than a meter. Similar results are obtained from a theoretical method employing a probability distribution for the satellite optical observations.

  18. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  19. Experimental Satellite Quantum Communications.

    Science.gov (United States)

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers.

  20. Integration of mobile satellite and cellular systems

    Science.gov (United States)

    Drucker, Elliott H.; Estabrook, Polly; Pinck, Deborah; Ekroot, Laura

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established. Users equipped for both cellular and satellite service can take advantage of a number of features made possible by such integration, including seamless handoff and universal roaming. To provide maximum benefit at lowest posible cost, the means by which these systems are integrated must be carefully considered. Mobile satellite hub stations must be configured to efficiently interface with cellular Mobile Telephone Switching Offices (MTSO's), and cost effective mobile units that provide both cellular and satellite capability must be developed.

  1. Reference Station Network Based RTK Systems-Concepts and Progress

    Institute of Scientific and Technical Information of China (English)

    C. Rizos; S. Han

    2003-01-01

    The limitation of single base "real-time kinematic"(RTK) techniques is the distance between base receiver and the rover receiver due to distance-dependent biases, namely orbit bias,ionosphere bias and troposphere bias. Techniques have been developed to overcome this distance dependence using a network of GPS reference stations spread over a wide geographic area. Because the measurement biases will be modelled and corrected for, the positioning accuracy will be almost independent of the inter-receiver distance.Since the mid-1990s investigators have been investigating the optimal means of processing reference receiver data, and then providing generally referred to as Network-RTK. In 1993 the International Association of Geodesy (IAG) established a Special Study Group on"Wide Area Modelling for Precise Satellite Positioning" . This paperfocusses on the progress made during the last few years in designing Network-RTK architectures and the associated data processing algorithms and issues. Although many university investigators have been researching the fundamental challenges in functional and stochastic modelling, currently there is only one commercially available Network-RTK product, the Trimble VRS. However, with the use of the Internet as the primary data communication link, it is predicted that various sites around the world, over the next few years.

  2. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites........ The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...

  3. Technology for a quasi-GSO satellite communications system

    OpenAIRE

    Katagi, T.; Yonezawa, R.; Chiba, I.; Urasaki, S.

    1999-01-01

    In this paper, a satellite communications system using a Quasi Geostationary Satellite Orbit (Quasi-GSO) is proposed. A 24-hour period Quasi-GSO system could give high quality communication to high latitude regions with its satellites observed from earth stations having high elevation angles. In this paper, a system concept and a deployable flat antenna with light weight antenna elements are described proposing it to be a good candidate for mobile communications satellite use.

  4. 7 CFR 993.149 - Receiving of prunes by handlers.

    Science.gov (United States)

    2010-01-01

    ... information: (i) The place where samples were drawn and the date and place of inspection; (ii) the name and... the following information: (i) The date and place of the delivery; (ii) the name and address of the... at any receiving station so designated by the Committee. Receiving station shall mean any plant of a...

  5. Satellite (Natural)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    In its most general sense, any celestial object in orbit around a similar larger object. Thus, for example, the Magellanic Clouds are satellite galaxies of our own Milky Way galaxy. Without qualification, the term is used to mean a body in orbit around a planet; an alternative term is moon. The term natural satellite distinguishes these bodies from artificial satellites—spacecraft placed in orbi...

  6. Soil Moisture Remote Sensing with GNSS-R at the Valencia Anchor Station. The SOMOSTA (Soil Moisture Station) Experiment

    Science.gov (United States)

    Lopez-Baeza, Ernesto

    2016-07-01

    In this paper, the SOMOSTA (Soil Moisture Monitoring Station) experiment on soil moisture monitoring byGlobal Navigation Satellite System Reflected signals(GNSS-R) at the Valencia Anchor Station is introduced. L-band microwaves have very good advantages in soil moisture remote sensing, for being unaffected by clouds and the atmosphere, and for the ability to penetrate vegetation. During this experimental campaign, the ESA GNSS-R Oceanpal antenna was installed on the same tower as the ESA ELBARA-II passive microwave radiometer, both measuring instruments having similar field of view. This experiment is fruitfully framed within the ESA - China Programme of Collaboration on GNSS-R. The GNSS-R instrument has an up-looking antenna for receiving direct signals from satellites, and two down-looking antennas for receiving LHCP (left-hand circular polarisation) and RHCP (right-hand circular polarisation) reflected signals from the soil surface. We could collect data from the three different antennas through the two channels of Oceanpal and, in addition, calibration could be performed to reduce the impact from the differing channels. Reflectivity was thus measured and soil moisture could be retrieved by the L- MEB (L-band Microwave Emission of the Biosphere) model considering the effect of vegetation optical thickness and soil roughness. By contrasting GNSS-R and ELBARA-II radiometer data, a negative correlation existed between reflectivity measured by GNSS-R and brightness temperature measured by the radiometer. The two parameters represent reflection and absorption of the soil. Soil moisture retrieved by both L-band remote sensing methods shows good agreement. In addition, correspondence with in-situ measurements and rainfall is also good.

  7. Commercial satellite broadcasting for Europe

    Science.gov (United States)

    Forrest, J. R.

    1988-12-01

    A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future.

  8. Workload characterization for the space station data communications system

    Science.gov (United States)

    Sevcik, K. C.

    1986-01-01

    NASA plans to launch a permanent manned space station in the early 1990's. The station will be used to support a wide variety of activities involving Earth and space observation, satellite maintenance, scientific experimentation, and commercial manufacturing. The control and monitoring of many of these activities will require extensive computer and communications system support. In order to identify an appropriate computer and communication system for supporting the space station, an attempt to characterize the space station's data communications subsystem workload is currently underway. Some of the special aspects of the workload characterization problem are discussed in connection with the space station, and some possible approaches are presented.

  9. Discussion on the Upgrading of L-band in Traditional Satellite Earth Station(1)%浅析传统卫星通信地球站的L频段升级(一)

    Institute of Scientific and Technical Information of China (English)

    石玉龙

    2014-01-01

    On account of the existing features of network in China United Network Communication Corp Beijing Branch, this paper analyzes the main indicators of satellite communication system, identified the key technical parameters of transmission; carefully studies and compares the performance of major equipments, complies with communication technology trends; considers many factors such as transmission, routing deployment, centralized network, online monitoring; makes plans of upgrading L-band of satellite communication system based on the general principles of cutting the cost, efifciency and energy conservation. Moreover, this paper has already carried out some practical researches. It will pave the way for the future development of satellite services.%本文针对北京联通卫星局现有卫星通信网络特点,分析了与承载业务相关的卫星通信系统主要指标,确定了保障业务正常传送的关键技术参数;细致研究、比较各类主流设备性能,顺应通信技术发展趋势;综合考虑业务传送、路由调配、集中网管、在线监测等各方面因素;立足于降本增效、节能减排的总体原则确定了卫星通信系统L频段升级的实施方案;并对其中相关方面进行了细致研究,为今后卫星业务发展铺平了道路。

  10. 浅析传统卫星通信地球站的L频段升级(二)%Discussion on the Upgrading of L-band in Traditional Satellite Earth Station(2)

    Institute of Scientific and Technical Information of China (English)

    石玉龙

    2014-01-01

    On account of the existing features of network in China United Network Communication Corp Beijing Branch, this paper analyzes the main indicators of satellite communication system, identified the key technical parameters of transmission; carefully studies and compares the performance of major equipments, complies with communication technology trends; considers many factors such as transmission, routing deployment, centralized network, online monitoring; makes plans of upgrading L-band of satellite communication system based on the general principles of cutting the cost, efifciency and energy conservation. Moreover, this paper has already carried out some practical researches. It will pave the way for the future development of satellite services.%本文针对北京联通卫星局现有卫星通信网络特点,分析了与承载业务相关的卫星通信系统主要指标,确定了保障业务正常传送的关键技术参数;细致研究、比较各类主流设备性能,顺应通信技术发展趋势;综合考虑业务传送、路由调配、集中网管、在线监测等各方面因素;立足于降本增效、节能减排的总体原则确定了卫星通信系统L频段升级的实施方案;并对其中相关方面进行了细致研究,为今后卫星业务发展铺平了道路。

  11. Electronic warfare receivers and receiving systems

    CERN Document Server

    Poisel, Richard A

    2014-01-01

    Receivers systems are considered the core of electronic warfare (EW) intercept systems. Without them, the fundamental purpose of such systems is null and void. This book considers the major elements that make up receiver systems and the receivers that go in them.This resource provides system design engineers with techniques for design and development of EW receivers for modern modulations (spread spectrum) in addition to receivers for older, common modulation formats. Each major module in these receivers is considered in detail. Design information is included as well as performance tradeoffs o

  12. Radio interferometry and satellite tracking

    CERN Document Server

    Kawase, Seiichiro

    2012-01-01

    Worldwide growth of space communications has caused a rapid increase in the number of satellites operating in geostationary orbits, causing overcrowded orbits. This practical resource is designed to help professionals overcome this problem. This timely book provides a solid understanding of the use of radio interferometers for tracking and monitoring satellites in overcrowded environments. Practitioners learn the fundamentals of radio interferometer hardware, including antennas, receiving equipment, signal processing and phase detection, and measurement accuracies. This in-depth volume describ

  13. Some Signals of Seismic Origin Received at Pacific Sofar Stations.

    Science.gov (United States)

    1953-03-03

    none have ever approached this one in duration. dough compi~tation.indicate that the sound energy in the 20—500 cpa frequency bane released to the water...the sour cesof theni are still undcterr~iined since it has not been possible to correlate them ~4th any reported seismic or explosive disturbances. It

  14. On Chinese National Continuous Operating Reference Station System of GNSS

    Directory of Open Access Journals (Sweden)

    CHEN Junyong

    2007-11-01

    Full Text Available Objective: Global navigation satellite system (GNSS Continuous Operating Reference Station (CORS System can maintain a accurate, 3D, geocentric and dynamic reference coordinate frame in the corresponding area, can provide positioning and navigation service. It can also serve for the meteorology, geodynamics, earthquake monitoring and Location Based services (LBS etc in the same area. Until now, our country can’t provide a facing National CORS System serving for every profession and trade, and the national sharing platform of CORS System resources has not been established. So this paper discusses some valuable insight how to construct the National CORS System in China. Method: Constructing goal、Service object、CORS distribution、CORS geographic、geology and communication environment and other factors, are major considerations for the Constructing the National CORS System. Moreover, constructing GNSS CORS is more specific, mainly from four aspects, namely site-selection、civil construction、security measures and equipment-selection for consideration. Outcome: The project of the Constructing Global navigation satellite system (GNSS Continuous Operating Reference Station (CORS System in china is put forward, and is discussed from goal、principle、project and other for construction. Some meaning thought how to construct the National CORS System is submitted Conclusion: The Global navigation satellite system (GNSS Continuous Operating Reference Station (CORS System in china is the lack of a unified planning and design in the national level. So far, the national CORS system serving all walks of life has not been provided, and the national sharing platform of CORS System resources has not been established The primary mission of the Global navigation satellite system (GNSS Continuous Operating Reference Station (CORS System in china is as follows: using data set of GNSS and receiving, transport, process, integration, transmit information and

  15. Automatic Weather Station (AWS) Lidar

    Science.gov (United States)

    Rall, Jonathan A.R.; Abshire, James B.; Spinhirne, James D.; Smith, David E. (Technical Monitor)

    2000-01-01

    An autonomous, low-power atmospheric lidar instrument is being developed at NASA Goddard Space Flight Center. This compact, portable lidar will operate continuously in a temperature controlled enclosure, charge its own batteries through a combination of a small rugged wind generator and solar panels, and transmit its data from remote locations to ground stations via satellite. A network of these instruments will be established by co-locating them at remote Automatic Weather Station (AWS) sites in Antarctica under the auspices of the National Science Foundation (NSF). The NSF Office of Polar Programs provides support to place the weather stations in remote areas of Antarctica in support of meteorological research and operations. The AWS meteorological data will directly benefit the analysis of the lidar data while a network of ground based atmospheric lidar will provide knowledge regarding the temporal evolution and spatial extent of Type la polar stratospheric clouds (PSC). These clouds play a crucial role in the annual austral springtime destruction of stratospheric ozone over Antarctica, i.e. the ozone hole. In addition, the lidar will monitor and record the general atmospheric conditions (transmission and backscatter) of the overlying atmosphere which will benefit the Geoscience Laser Altimeter System (GLAS). Prototype lidar instruments have been deployed to the Amundsen-Scott South Pole Station (1995-96, 2000) and to an Automated Geophysical Observatory site (AGO 1) in January 1999. We report on data acquired with these instruments, instrument performance, and anticipated performance of the AWS Lidar.

  16. Simultaneous single epoch satellite clock modelling in Global Navigation Satellite Systems

    Science.gov (United States)

    Thongtan, Thayathip

    In order to obtain high quality positions from navigation satellites, range errors have to be identified and either modelled or estimated. This thesis focuses on satellite clock errors, which are needed to be known because satellite clocks are not perfectly synchronised with navigation system time. A new approach, invented at UCL, for the simultaneous estimation, in a single epoch, of all satellite clock offsets within a Global Navigation Satellite System (GNSS) from range data collected at a large number of globally distributed ground stations is presented. The method was originally tested using only data from a limited number of GPS satellites and ground stations. In this work a total of 50 globally distributed stations and the whole GPS constellation are used in order to investigate more fully the capabilities of the method, in terms of both accuracy and reliability. A number of different estimation models have been tested. These include those with different weighting schemes, those with and without tropospheric bias parameters and those that include assumptions regarding prior knowledge of satellite orbits. In all cases conclusions have been drawn based on formal error propagation theory. Accuracy has been assessed largely through the sizes of the predicted satellite clock standard deviations and, in the case of simultaneously estimating satellite positions, their error ellipsoids. Both internal and external reliability have been assessed as these are important contributors to integrity, something that is essential for many practical applications. It has been found that the accuracy and reliability of satellite clock offsets are functions of the number of known ground station clocks and distance from them, quality of orbits and quality of range measurement. Also the introduction of tropospheric zenith delay parameters into the model reduces both accuracy and reliability by amounts depending on satellite elevation angles. (Abstract shortened by UMI.)

  17. 47 CFR 1.4000 - Restrictions impairing reception of television broadcast signals, direct broadcast satellite...

    Science.gov (United States)

    2010-10-01

    ... broadcast signals, direct broadcast satellite services or multichannel multipoint distribution services. 1... Broadcast Satellite Services, or Multichannel Multipoint Distribution Services or the Ability To Receive or... broadcast signals, direct broadcast satellite services or multichannel multipoint distribution services....

  18. GLONASS fractional-cycle bias estimation across inhomogeneous receivers for PPP ambiguity resolution

    Science.gov (United States)

    Geng, Jianghui; Bock, Yehuda

    2016-04-01

    The key issue to enable precise point positioning with ambiguity resolution (PPP-AR) is to estimate fractional-cycle biases (FCBs), which mainly relate to receiver and satellite hardware biases, over a network of reference stations. While this has been well achieved for GPS, FCB estimation for GLONASS is difficult because (1) satellites do not share the same frequencies as a result of Frequency Division Multiple Access (FDMA) signals; (2) and even worse, pseudorange hardware biases of receivers vary in an irregular manner with manufacturers, antennas, domes, firmware, etc., which especially complicates GLONASS PPP-AR over inhomogeneous receivers. We propose a general approach where external ionosphere products are introduced into GLONASS PPP to estimate precise FCBs that are less impaired by pseudorange hardware biases of diverse receivers to enable PPP-AR. One month of GLONASS data at about 550 European stations were processed. From an exemplary network of 51 inhomogeneous receivers, including four receiver types with various antennas and spanning about 800 km in both longitudinal and latitudinal directions, we found that 92.4 % of all fractional parts of GLONASS wide-lane ambiguities agree well within ± 0.15 cycles with a standard deviation of 0.09 cycles if global ionosphere maps (GIMs) are introduced, compared to only 51.7 % within ± 0.15 cycles and a larger standard deviation of 0.22 cycles otherwise. Hourly static GLONASS PPP-AR at 40 test stations can reach position estimates of about 1 and 2 cm in RMS from ground truth for the horizontal and vertical components, respectively, which is comparable to hourly GPS PPP-AR. Integrated GLONASS and GPS PPP-AR can further achieve an RMS of about 0.5 cm in horizontal and 1-2 cm in vertical components. We stress that the performance of GLONASS PPP-AR across inhomogeneous receivers depends on the accuracy of ionosphere products. GIMs have a modest accuracy of only 2-8 TECU (Total Electron Content Unit) in vertical

  19. LOD First Estimates In 7406 SLR San Juan Argentina Station

    Science.gov (United States)

    Pacheco, A.; Podestá, R.; Yin, Z.; Adarvez, S.; Liu, W.; Zhao, L.; Alvis Rojas, H.; Actis, E.; Quinteros, J.; Alacoria, J.

    2015-10-01

    In this paper we show results derived from satellite observations at the San Juan SLR station of Felix Aguilar Astronomical Observatory (OAFA). The Satellite Laser Ranging (SLR) telescope was installed in early 2006, in accordance with an international cooperation agreement between the San Juan National University (UNSJ) and the Chinese Academy of Sciences (CAS). The SLR has been in successful operation since 2011 using NAOC SLR software for the data processing. This program was designed to calculate satellite orbits and station coordinates, however it was used in this work for the determination of LOD (Length Of Day) time series and Earth Rotation speed.

  20. Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

    Science.gov (United States)

    Paul, K. S.; Paul, A.

    2017-05-01

    The ionosphere around the northern crest of the equatorial ionization anomaly (EIA) and beyond exhibits rapid temporal as well as spatial development of ionization density irregularities during postsunset hours. A GPS campaign was conducted during September 2012 and April 2013 from the Institute of Radio Physics and Electronics, Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N), and North Bengal University (NBU), Siliguri (26.72°N, 88.39°E geographic, magnetic dip: 39.49°N) in India in order to assess and quantify differences, if any, in the nature of carrier to noise ratio (C/N0) fluctuations observed on the same satellite link around the same time interval from these stations. Significant decorrelation of the received signals was found when tracking the same satellite vehicle (SV) link from these stations during periods of scintillations. Low values of correlation coefficient of C/N0 at L1 frequency recorded on the same SV link at these two stations were found to correspond with high irregularity characteristic velocities. North-south spatial displacement rates of the impact of ionospheric irregularities were calculated based on coordinated GPS observations which followed an increasing trend with irregularity characteristic velocities measured at VHF. Values of characteristic velocities in excess of 36 m/s were also found to result in large receiver position deviations 3.5-4.0 m during periods of scintillations. Information related to time lag associated with occurrence of scintillations on the same SV link observed from two stations could be useful for improving performance of transionospheric satellite-based position determination techniques.

  1. Heart Monitoring By Satellite

    Science.gov (United States)

    1978-01-01

    The ambulance antenna shown is a specially designed system that allows satellite-relayed two-way communications between a moving emergency vehicle and a hospital emergency room. It is a key component of a demonstration program aimed at showing how emergency medical service can be provided to people in remote rural areas. Satellite communication permits immediate, hospital- guided treatment of heart attacks or other emergencies by ambulance personnel, saving vital time when the scene of the emergency is remote from the hospital. If widely adopted, the system could save tens of thousands of lives annually in the U.S. alone, medical experts say. The problem in conventional communication with rural areas is the fact that radio signals travel in line of sight. They may be blocked by tall buildings, hills and mountains, or even by the curvature of the Earth, so signal range is sharply limited. Microwave relay towers could solve the problem, but a complete network of repeater towers would be extremely expensive. The satellite provides an obstruction-free relay station in space.

  2. An introduction to optimal satellite range scheduling

    CERN Document Server

    Vázquez Álvarez, Antonio José

    2015-01-01

    The satellite range scheduling (SRS) problem, an important operations research problem in the aerospace industry consisting of allocating tasks among satellites and Earth-bound objects, is examined in this book. SRS principles and solutions are applicable to many areas, including: Satellite communications, where tasks are communication intervals between sets of satellites and ground stations Earth observation, where tasks are observations of spots on the Earth by satellites Sensor scheduling, where tasks are observations of satellites by sensors on the Earth. This self-contained monograph begins with a structured compendium of the problem and moves on to explain the optimal approach to the solution, which includes aspects from graph theory, set theory, game theory and belief networks. This book is accessible to students, professionals and researchers in a variety of fields, including: operations research, optimization, scheduling theory, dynamic programming and game theory. Taking account of the distributed, ...

  3. Meteosat Second Generation station: processing software and computing arquitecture; Estacion de Recepcion de Imagenes del Satelite Meteosat Segunda generacion: Arquitectura Informatica y Software de Proceso

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L.; Cony, M.; Navarro, A. A.; Zarzalejo, L. F.; Polo, J.

    2010-05-01

    The Renewable Energy Division of CIEMAT houses a specific station for receiving the Meteosat Second Generation images, which is of interest in the works being carried out concerning the solar radiation derived from satellite images. The complexity, the huge amount of information being received and the particular characteristics of the MSG images encouraged the design and development of a specific computer structure and the associated software as well, for a better and more suitable use of the images. This document describes the mentioned structure and software. (Author) 8 refs.

  4. Advanced technology for a satellite multichannel demultiplexer/demodulator

    Science.gov (United States)

    Abramovitz, Irwin J.; Flechsig, Drew E.; Matteis, Richard M., Jr.

    1994-01-01

    Satellite on-board processing is needed to efficiently service multiple users while at the same time minimizing earth station complexity. The processing satellite receives a wideband uplink at 30 GHz and down-converts it to a suitable intermediate frequency. A multichannel demultiplexer then separates the composite signal into discrete channels. Each channel is then demodulated by bulk demodulators, with the baseband signals routed to the downlink processor for retransmission to the receiving earth stations. This type of processing circumvents many of the difficulties associated with traditional bent-pipe repeater satellites. Uplink signal distortion and interference are not retransmitted on the downlink. Downlink power can be allocated in accordance with user needs, independent of uplink transmissions. This allows the uplink users to employ different data rates as well as different modulation and coding schemes. In addition, all downlink users have a common frequency standard and symbol clock on the satellite, which is useful for network synchronization in time division multiple access schemes. The purpose of this program is to demonstrate the concept of an optically implemented multichannel demultiplexer (MCD). A proof-of-concept (POC) model has been developed which has the ability to receive a 40 MHz wide composite signal consisting of up to 1000 40 kHz QPSK modulated channels and perform the demultiplexing process. In addition a set of special test equipment (STE) has been configured to evaluate the performance of the POC model. The optical MCD is realized as an acousto-optic spectrum analyzer utilizing the capability of Bragg cells to perform the required channelization. These Bragg cells receive an optical input from a laser source and an RF input (the signal). The Bragg interaction causes optical output diffractions at angles proportional to the RF input frequency. These discrete diffractions are optically detected and output to individual demodulators for

  5. 基于成本控制角度卫星移动通信终端的零中频接收机设计%Design of Zero-IF Receiver of Satellite Mobile Communication Terminal Based on Cost Control Point

    Institute of Scientific and Technical Information of China (English)

    许敏; 陈伟

    2014-01-01

    以往卫星移动终端的接收机其功耗大,价格高,使得公司设备预算居高不下,尤其对于中小型的通信公司而言,更是急于降低这项成本。零中频(Zero-IF)接收机又称为直接变频(Direct Conversion)接收机,其结构简单,具有很高集成度,对镜像信号抑制的要求也不高,且功耗较小也使得成本较低。因此采用零中频结构来实现无线接收机是未来的一个趋势,正成为射频接收机中极具竞争力的一种构案。%Receiver of satellite mobile terminals in past is of great power consumption,high price,which make company's’equipment budget high,especially for small and medium-sized communications company.Zero intermediate frequency(Zero-IF) receiver is also known as(Direct Conversion receiver which has simple structure and high integration.Meanwhile,the requirement of image signal suppression is not high.Less power consumption make it cost less.So it is a trend to use Zero-IF structure to realize the wireless receiver in the future.Zero-IF structure is becoming a highly competitive in RF receiver.

  6. Performance of low-cost GNSS receiver for landslides monitoring: test and results

    Directory of Open Access Journals (Sweden)

    Alberto Cina

    2015-07-01

    Full Text Available Italy is deeply afflicted by geo-hydrological risk, where a predominant part of its area is under risk.Recently, advanced research and sensors have played an important role in realizing automatic systems for landslide monitoring and to alerting. The cost of these systems, considering all parts, limits their use and the cost of each sensor influences the investment. Geodetic global navigation satellite system (GNSS receivers, which are commonly used to realize these activities, are an appropriate example; however, their costs are quite high.The aim of this research was to test the actual performance of a mass-market GNSS receiver, with the purpose of verifying if such type of sensors can be used for landslide monitoring. In particular, the benefits due to the coupling between mass-market receivers and products offered by a network of GNSS permanent stations (e.g. Virtual RINEX have been investigated.To verify the capability of these sensors to detect a deformation, under the minimum deformation detectable point of view, a special slide was built, in order to conduct a dedicated test. The support was moved both in horizontal and vertical directions with high precision, with purpose to detect correctly a three-dimensional movement.Tests were carried out considering the dependence of some factors: the most important are the acquisition time and the distance from the GNSS reference station. Interesting is the use of virtual reference station based on GNSS network, as a reference station: the performance achieved using Virtual RINEX for the control of movements and deformations are analysed. The accuracy and precision of movement determination were evaluated and compared, for each test, considering the different factors. The tests and results are described in this contribution.

  7. Master station control and capacity assignment for Italsat network

    Science.gov (United States)

    Morris, Adrian; Sampson, Nicholas; Lopes, Antonino; di Martino, Roberto; Saitto, Antonio

    1990-11-01

    The design approach to developing a network-controller and capacity-assignment software package for the Italsat satellite switched/time division multiple-access (SS/TDMA) network is covered. The network consists of TDMA traffic stations (TS) allowing a full mesh connectivity between all sites; one of the TSs is designated as a control station (CS). The major processing elements of the network, the functions of the master station, and database configurations are discussed, along with TDMA-station control and traffic reconfiguration, the assignment of satellite capacity on demand, and interactions among these network elements. Emphasis is placed on the traffic reconfiguration process, and it is pointed out that the satellite network control processor and the CS overhead burst processor work together to provide the system with the necessary support to operate the network.

  8. Scientific Satellites

    Science.gov (United States)

    1967-01-01

    followed Hale’s into orbit. In 1879, Jules Verne wrote about launching small satellites with a gun possessing a muzzle velocity of 10 000 m/sec (ref. 3...was activated in 1950.11 It was located only a few tens of miles from the spot where Jules Verne had his Baltimore Gun Club fire a manned projectile to...principle, satellites can be launched by a single impulse applied at the Earth’s surface-say, with a large cannon, & la Jules Verne (sec. 8-3). In

  9. Future large broadband switched satellite communications networks

    Science.gov (United States)

    Staelin, D. H.; Harvey, R. R.

    1979-01-01

    Critical technical, market, and policy issues relevant to future large broadband switched satellite networks are summarized. Our market projections for the period 1980 to 2000 are compared. Clusters of switched satellites, in lieu of large platforms, etc., are shown to have significant advantages. Analysis of an optimum terrestrial network architecture suggests the proper densities of ground stations and that link reliabilities 99.99% may entail less than a 10% cost premium for diversity protection at 20/30 GHz. These analyses suggest that system costs increase as the 0.6 power of traffic. Cost estimates for nominal 20/30 GHz satellite and ground facilities suggest optimum system configurations might employ satellites with 285 beams, multiple TDMA bands each carrying 256 Mbps, and 16 ft ground station antennas. A nominal development program is outlined.

  10. A preliminary study on dead geostationary satellite removal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The collision between satellites IRIDIUM 33 and COSMOS 2251 indicated that the clash of two on-orbit satellites was becoming an inevitable reality. Our calculation with the two-line orbit element by NORAD showed that some two geostationary satellites had approached very close in July 2009. Therefore, more attention should be given to avoid such collisions. This paper analyzes the orbital long-term variation of a dead satellite drifting in the geostationary orbit. Also, the negative effects posed by dead satellites upon the on-orbit operational geostationary satellites are studied. Then the paper proposes a novel idea to launch a satellite sweeper whose purpose is to collect the on-orbit dead satellites and help them de-orbit to a "graveyard". The satellite sweeper consists of a parent satellite and a child satellite. The child satellite collects a dead satellite and transfers it to a higher orbit. The parent satellite stationed in the geostationary orbit is in charge of refueling the child satellite. The strategy of maneuver and rendezvous is presented and a series of formulas are derived. The analysis results show that our method to clean the geostationary orbital zone is practical and fuel-saving. With the help of just a few satellite sweepers, we can gain a clean environment of geostationary orbit environment again.

  11. Real-time monitoring for fast deformations using GNSS low-cost receivers

    Directory of Open Access Journals (Sweden)

    T. Bellone

    2016-03-01

    Full Text Available Landslides are one of the major geo-hazards which have constantly affected Italy especially over the last few years. In fact 82% of the Italian territory is affected by this phenomenon which destroys the environment and often causes deaths: therefore it is necessary to monitor these effects in order to detect and prevent these risks. Nowadays, most of this type of monitoring is carried out by using traditional topographic instruments (e.g. total stations or satellite techniques such as global navigation satellite system (GNSS receivers. The level of accuracy obtainable with these instruments is sub-centimetrical in post-processing and centimetrical in real-time; however, the costs are very high (many thousands of euros. The rapid diffusion of GNSS networks has led to an increase of using mass-market receivers for real-time positioning. In this paper, the performances of GNSS mass-market receiver are reported with the aim of verifying if this type of sensor can be used for real-time landslide monitoring: for this purpose a special slide was used for simulating a landslide, since it enabled us to give manual displacements thanks to a micrometre screw. These experiments were also carried out by considering a specific statistical test (a modified Chow test which enabled us to understand if there were any displacements from a statistical point of view in real time. The tests, the algorithm and results are reported in this paper.

  12. Improved gravity field and station-coordinate estimates from laser tracking data

    Science.gov (United States)

    Gaposchkin, E. M.

    1976-01-01

    Knowledge of the long-wavelength features of the geopotential and the geocentric coordinates of satellite-tracking stations is significantly improved by the use of precision satellite tracking with lasers. Tracking data on nine satellites are combined with terrestrial gravimetry to obtain a spherical-harmonics representation of the geopotential complete through degree and order 24. Laser tracking data are used to determine the coordinates of tracking stations. This coordinate system is referred to an inertial reference frame by use of camera observations and observations of deep-space probes. Resulting geodetic parameters provide better satellite ephemerides and a reference for analyzing satellite-to-sea-surface altimetry.

  13. Temperature influences in receiver clock modelling

    Science.gov (United States)

    Wang, Kan; Meindl, Michael; Rothacher, Markus; Schoenemann, Erik; Enderle, Werner

    2016-04-01

    In Precise Point Positioning (PPP), hardware delays at the receiver site (receiver, cables, antenna, …) are always difficult to be separated from the estimated receiver clock parameters. As a result, they are partially or fully contained in the estimated "apparent" clocks and will influence the deterministic and stochastic modelling of the receiver clock behaviour. In this contribution, using three years of data, the receiver clock corrections of a set of high-precision Hydrogen Masers (H-Masers) connected to stations of the ESA/ESOC network and the International GNSS Service (IGS) are firstly characterized concerning clock offsets, drifts, modified Allan deviations and stochastic parameters. In a second step, the apparent behaviour of the clocks is modelled with the help of a low-order polynomial and a known temperature coefficient (Weinbach, 2013). The correlations between the temperature and the hardware delays generated by different types of antennae are then analysed looking at daily, 3-day and weekly time intervals. The outcome of these analyses is crucial, if we intend to model the receiver clocks in the ground station network to improve the estimation of station-related parameters like coordinates, troposphere zenith delays and ambiguities. References: Weinbach, U. (2013) Feasibility and impact of receiver clock modeling in precise GPS data analysis. Dissertation, Leibniz Universität Hannover, Germany.

  14. Satellite and lunar laser ranging in infrared

    Science.gov (United States)

    Courde, Clement; Torre, Jean-Marie; Samain, Etienne; Martinot-Lagarde, Gregoire; Aimar, Mourad; Albanese, Dominique; Maurice, Nicolas; Mariey, Hervé; Viot, Hervé; Exertier, Pierre; Fienga, Agnes; Viswanathan, Vishnu

    2017-05-01

    We report on the implementation of a new infrared detection at the Grasse lunar laser ranging station and describe how infrared telemetry improves the situation. We present our first results on the lunar reflectors and show that infrared detection permits us to densify the observations and allows measurements during the new and the full moon periods. We also present the benefit obtained on the ranging of Global Navigation Satellite System (GNSS) satellites and on RadioAstron which have a very elliptic orbit.

  15. Astrometry and Geostationary Satellites in Venezuela

    Science.gov (United States)

    Lacruz, E.; Abad, C.

    2015-10-01

    We present the current status and the first results of the astrometric project CIDA - ABAE for tracking geo-stationary satellites. This project aims to determine a preliminary orbit for the Venezuelan satellite VENESAT-1, using astrometric positions obtained from an optical telescope. The results presented here are based on observations from the Luepa space tracking ground station in Venezuela, which were processed using astrometric procedures.

  16. Response of the equatorial ionosphere to the total solar eclipse of 22 July 2009 and annular eclipse of 15 January 2010 as observed from a network of stations situated in the Indian longitude sector

    Directory of Open Access Journals (Sweden)

    A. Paul

    2011-10-01

    Full Text Available Dual-frequency GPS TEC monitors have been used to study the response of the ionosphere to the solar eclipses of 22 July 2009 and 15 January 2010. The receivers were located at three stations, Calcutta, Kharagpur and Baharampore which are situated outside the umbra zone in the Indian longitude sector with each baseline being ~200 km. Effects of obscuration of the solar disc were noted in the ambient TEC recorded at the three stations. A series of depletions in TEC along the track of a GPS satellite and associated wave-like structures were identified on some GPS links during both the eclipses.

  17. Coded throughput performance simulations for the time-varying satellite channel. M.S. Thesis

    Science.gov (United States)

    Han, LI

    1995-01-01

    The design of a reliable satellite communication link involving the data transfer from a small, low-orbit satellite to a ground station, but through a geostationary satellite, was examined. In such a scenario, the received signal power to noise density ratio increases as the transmitting low-orbit satellite comes into view, and then decreases as it then departs, resulting in a short-duration, time-varying communication link. The optimal values of the small satellite antenna beamwidth, signaling rate, modulation scheme and the theoretical link throughput (in bits per day) have been determined. The goal of this thesis is to choose a practical coding scheme which maximizes the daily link throughput while satisfying a prescribed probability of error requirement. We examine the throughput of both fixed rate and variable rate concatenated forward error correction (FEC) coding schemes for the additive white Gaussian noise (AWGN) channel, and then examine the effect of radio frequency interference (RFI) on the best coding scheme among them. Interleaving is used to mitigate degradation due to RFI. It was found that the variable rate concatenated coding scheme could achieve 74 percent of the theoretical throughput, equivalent to 1.11 Gbits/day based on the cutoff rate R(sub 0). For comparison, 87 percent is achievable for AWGN-only case.

  18. Benefits Derived From Laser Ranging Measurements for Orbit Determination of the GPS Satellite Orbit

    Science.gov (United States)

    Welch, Bryan W.

    2007-01-01

    While navigation systems for the determination of the orbit of the Global Position System (GPS) have proven to be very effective, the current research is examining methods to lower the error in the GPS satellite ephemerides below their current level. Two GPS satellites that are currently in orbit carry retro-reflectors onboard. One notion to reduce the error in the satellite ephemerides is to utilize the retro-reflectors via laser ranging measurements taken from multiple Earth ground stations. Analysis has been performed to determine the level of reduction in the semi-major axis covariance of the GPS satellites, when laser ranging measurements are supplemented to the radiometric station keeping, which the satellites undergo. Six ground tracking systems are studied to estimate the performance of the satellite. The first system is the baseline current system approach which provides pseudo-range and integrated Doppler measurements from six ground stations. The remaining five ground tracking systems utilize all measurements from the current system and laser ranging measurements from the additional ground stations utilized within those systems. Station locations for the additional ground sites were taken from a listing of laser ranging ground stations from the International Laser Ranging Service. Results show reductions in state covariance estimates when utilizing laser ranging measurements to solve for the satellite s position component of the state vector. Results also show dependency on the number of ground stations providing laser ranging measurements, orientation of the satellite to the ground stations, and the initial covariance of the satellite's state vector.

  19. Receptores GPS de três precisões e estação total na caracterização de cotas básicas para projetos rurais Receiving GPS of three precision and total station in the characterization of basic cota for rural projects

    Directory of Open Access Journals (Sweden)

    Vilmar A. Rodrigues

    2006-04-01

    Full Text Available O objetivo deste estudo foi comparar cotas de vértices de uma poligonal, considerando dados coletados por três diferentes receptores GPS, usando como testemunha uma estação total. Os dados foram obtidos em uma poligonal fechada, sendo posteriormente tratados pelo software Topograph. As cotas obtidas pelos três receptores foram confrontadas com aquelas calculadas a partir do levantamento com a estação total, mediante a aplicação do teste "t", constatando-se que as mesmas foram satisfatórias para o equipamento GPS Trimble® 4600 LS. Para o equipamento GPS Trimble® modelo PRO XR, as cotas não foram totalmente satisfatórias, mas possíveis de serem consideradas em anteprojetos. Para o equipamento GPS Garmin® de navegação 12 XS, as cotas mostraram-se inaceitáveis para a finalidade estudada.The objective of this work was to compare cotas of polygonal vertices, through three different receiving GPS, using as reference a total station. The data were obtained in a closed polygonal, being treated later by the software Topograph. The cotas obtained by the three receivers were confronted with those calculated by means of the application of the test, being verified that the cotas were satisfactory for the equipment GPS Geodesic Trimble® 4600 LS. For the equipment GPS Trimble® topographical model PRO XR, the cotas weren't totally satisfactory, but possible of being considered in preliminary projects. For the navigation equipment GPS Garmin® 12 XS the cotas were shown unacceptable for the studied purpose.

  20. Spacecraft design project: High latitude communications satellite

    Science.gov (United States)

    Josefson, Carl; Myers, Jack; Cloutier, Mike; Paluszek, Steve; Michael, Gerry; Hunter, Dan; Sakoda, Dan; Walters, Wes; Johnson, Dennis; Bauer, Terry

    1989-01-01

    The spacecraft design project was part of AE-4871, Advanced Spacecraft Design. The project was intended to provide experience in the design of all major components of a satellite. Each member of the class was given primary responsibility for a subsystem or design support function. Support was requested from the Naval Research Laboratory to augment the Naval Postgraduate School faculty. Analysis and design of each subsystem was done to the extent possible within the constraints of an eleven week quarter and the design facilities (hardware and software) available. The project team chose to evaluate the design of a high latitude communications satellite as representative of the design issues and tradeoffs necessary for a wide range of satellites. The High-Latitude Communications Satellite (HILACS) will provide a continuous UHF communications link between stations located north of the region covered by geosynchronous communications satellites, i.e., the area above approximately 60 N latitude. HILACS will also provide a communications link to stations below 60 N via a relay Net Control Station (NCS), which is located with access to both the HILACS and geosynchronous communications satellites. The communications payload will operate only for that portion of the orbit necessary to provide specified coverage.

  1. Environmental assessment for the satellite power system concept development and evaluation program: nonmicrowave health and ecological effects

    Energy Technology Data Exchange (ETDEWEB)

    White, M R

    1980-11-01

    A Concept Development and Evaluation Program is being carried out for a proposed Satellite Power System (SPS). For purposes of this evaluation, a preliminary reference system has been developed. SPS, as described in the reference system, would collect solar energy on satellites in geosychronous orbit in space. The energy would be converted to microwaves and beamed to an earth-receiving antenna (rectenna). One task in the environmental part of the program is the assessment of the nonmicrowave effects on health and the environment. These effects would result from all phases of SPS development and operation. This report covers the current knowledge regarding these effects, and is based on the reference system. The assessment is summarized as to scope, methodology, impacts of terrestrial development, launch and recovery of spacecraft, space activities (including health effects of the space environment, ionizing radiation, electromagnetic exposure, spacecraft charging and environmental interactions, occupational hazards, etc.) and construction and operation of rectenna (ground receiving station).

  2. Scintillation-Hardened GPS Receiver

    Science.gov (United States)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  3. Temporal change of EIA asymmetry revealed by a beacon receiver network in Southeast Asia

    Science.gov (United States)

    Watthanasangmechai, Kornyanat; Yamamoto, Mamoru; Saito, Akinori; Maruyama, Takashi; Yokoyama, Tatsuhiro; Nishioka, Michi; Ishii, Mamoru

    2015-05-01

    To reveal the temporal change of the equatorial ionization anomaly (EIA) asymmetry, a multipoint satellite-ground beacon experiment was conducted along the meridional plane of the Thailand-Indonesia sector. The observation includes one station near the magnetic equator and four stations at off-equator latitudes. This is the first EIA asymmetry study with high spatial resolution using GNU Radio Beacon Receiver (GRBR) observations in Southeast Asia. GRBR-total electron contents (TECs) from 97 polar-orbit satellite passes in March 2012 were analyzed in this study. Successive passes captured rapid evolution of EIA asymmetry, especially during geomagnetic disturbances. The penetrating electric fields that occur during geomagnetic disturbed days are not the cause of the asymmetry. Instead, high background TEC associated with an intense electric field empowers the neutral wind to produce severe asymmetry of the EIA. Such rapid evolution of EIA asymmetry was not seen during nighttime, when meridional wind mainly controlled the asymmetric structures. Additional data are necessary to identify the source of the variations, i.e., atmospheric waves. Precisely capturing the locations of the crests and the evolution of the asymmetry enhances understanding of the temporal change of EIA asymmetry at the local scale and leads to a future local modeling for TEC prediction in Southeast Asia.

  4. Monitoring of the orbital position of a geostationary satellite by the spatially separated reception of signals of digital satellite television

    Science.gov (United States)

    Kaliuzny, M. P.; Bushuev, F. I.; Sibiriakova, Ye. S.; Shulga, O. V.; Shakun, L. S.; Bezrukovs, V.; Kulishenko, V. F.; Moskalenko, S. S.; Malynovsky, Ye. V.; Balagura, O. A.

    2017-02-01

    The results of the determination of the geostationary satellite "Eutelsat-13B" orbital position obtained during 2015-2016 years using European stations' network for reception of DVB-S signals from the satellite are presented. The network consists of five stations located in Ukraine and Latvia. The stations are equipped with a radio engineering complex developed by the RI "MAO". The measured parameter is a time difference of arrival (TDOA) of the DVB-S signals to the stations of the network. The errors of TDOA determination and satellite coordinates, obtained using a numerical model of satellite motion, are equal ±2.6 m and ±35 m respectively. Software implementation of the numerical model is taken from the free space dynamics library OREKIT.

  5. Satellite single-axis attitude determination based on Automatic Dependent Surveillance - Broadcast signals

    Science.gov (United States)

    Zhou, Kaixing; Sun, Xiucong; Huang, Hai; Wang, Xinsheng; Ren, Guangwei

    2017-10-01

    The space-based Automatic Dependent Surveillance - Broadcast (ADS-B) is a new technology for air traffic management. The satellite equipped with spaceborne ADS-B system receives the broadcast signals from aircraft and transfers the message to ground stations, so as to extend the coverage area of terrestrial-based ADS-B. In this work, a novel satellite single-axis attitude determination solution based on the ADS-B receiving system is proposed. This solution utilizes the signal-to-noise ratio (SNR) measurement of the broadcast signals from aircraft to determine the boresight orientation of the ADS-B receiving antenna fixed on the satellite. The basic principle of this solution is described. The feasibility study of this new attitude determination solution is implemented, including the link budget and the access analysis. On this basis, the nonlinear least squares estimation based on the Levenberg-Marquardt method is applied to estimate the single-axis orientation. A full digital simulation has been carried out to verify the effectiveness and performance of this solution. Finally, the corresponding results are processed and presented minutely.

  6. Characterization of an In-Situ Ground Terminal via a Geostationary Satellite

    Science.gov (United States)

    Piasecki, Marie; Welch, Bryan; Mueller, Carl

    2015-01-01

    In 2015, the Space Communications and Navigation (SCaN) Testbed project completed an S-Band ground station located at the NASA Glenn Research Center in Cleveland, Ohio. This S-Band ground station was developed to create a fully characterized and controllable dynamic link environment when testing novel communication techniques for Software Defined Radios and Cognitive Communication Systems. In order to provide a useful environment for potential experimenters, it was necessary to characterize various RF devices at both the component level in the laboratory and at the system level after integration. This paper will discuss some of the laboratory testing of the ground station components, with a particular focus emphasis on the near-field measurements of the antenna. It will then describe the methodology for characterizing the installed ground station at the system level via a Tracking and Data Relay Satellite (TDRS), with specific focus given to the characterization of the ground station antenna pattern, where the max TDRS transmit power limited the validity of the non-noise floor received power data to the antenna main lobe region. Finally, the paper compares the results of each test as well as provides lessons learned from this type of testing methodology.

  7. GPS Receiver On-Orbit Performance for the GOES-R Spacecraft

    Science.gov (United States)

    Winkler, Stephen; Ramsey, Graeme; Frey, Charles; Chapel, Jim; Chu, Donald; Freesland, Douglas; Krimchansky, Alexander; Concha, Marco

    2017-01-01

    This paper evaluates the on-orbit performance of the first civilian operational use of a Global Positioning System Receiver (GPSR) at a geostationary orbit (GEO). The GPSR is on-board the newly launched Geostationary Operational Environmental Satellite (GOES-R). GOES-R is the first of four next generation GEO weather satellites for NOAA, now in orbit GOES-R is formally identified as GOES-16. Among the pioneering technologies required to support its improved spatial, spectral and temporal resolution is a GPSR. The GOES-16 GPSR system is a new design that was mission critical and therefore received appropriate scrutiny. As ground testing of a GPSR for GEO can only be done by simulations with numerous assumptions and approximations regarding the current GPS constellation, this paper reveals what performance can be achieved in using on orbit data. Extremely accurate orbital position is achieved using GPS navigation at GEO. Performance results are shown demonstrating compliance with the1007575 meter and 6 cms radial/in-track/cross-track orbital position and velocity accuracy requirements of GOES-16. The aforementioned compliance includes station-keeping and momentum management maneuvers, contributing to no observational outages. This performance is achieved by a completely new system design consisting of a unique L1 GEOantenna, low-noise amplifier (LNA) assembly and a 12 channel GPSR capable of tracking the edge of the main beam and the side lobes of the GPS L1 signals. This paper presents the definitive answer that the GOES-16 GPSR solution exceeds all performance requirements tracking up to 12 satellites and achieving excellent carrier-to-noise density (C/N0). Additionally, these performance results show the practicality of this approach. This paper makes it clear that all future GEO Satellites should consider the addition of a GPSR in their spacecraft design, otherwise they may be sacrificing spacecraft capabilities and accuracy along with incurring increased and

  8. Experimental millimeter-wave satellite communications system

    Science.gov (United States)

    Suzuki, Yoshiaki; Shimada, Masaaki; Arimoto, Yoshinori; Shiomi, Tadashi; Kitazume, Susumu

    This paper describes an experimental system of millimeter-wave satellite communications via Japan's Engineering Test Satellite-VI (ETS-VI) and a plan of experiments. Two experimental missions are planned using ETS-VI millimeter-wave (43/38 GHz bands) transponder, considering the millimeter-wave characteristics such as large transmission capacity and possibility to construct a small earth station with a high gain antenna. They are a personal communication system and an inter-satellite communication system. Experimental system including the configuration and the fundamental functions of the onboard transponder and the outline of the experiments are presented.

  9. Advanced tracking and data relay satellite system

    Science.gov (United States)

    Stern, Daniel

    1992-01-01

    The purpose of this communication satellite system are as follows: to provide NASA needs for satellite tracking and communications through the year 2012; to maintain and augment the current TDRS system when available satellite resources are expended in the latter part of the decade; to provide the necessary ground upgrade to support the augmented services; and to introduce new technology to reduce the system life cycle cost. It is concluded that no ATDRS spacecraft requirement for new modulation techniques, that data rate of 650 MBps is required, and that Space Station Freedom requirement is for 650 MBps data some time after the year 2000.

  10. Identifying potential solar power generation sites using satellite apt images

    Science.gov (United States)

    Fawz-Ul-Haq, K. R.; Siddiqui, Z. R.

    1994-01-01

    In this paper, satellite APT images have been used to study cloud-cover over Pakistan, so as to determine those areas which have the least frequency of cloudiness. Such areas are likely to receive maximum insolation, and have been shown on a contour map of Pakistan. It is observed that more than half of Pakistan is highly sunny, and has many promising areas for establishing large scale solar electric power generation stations. It is further observed that, some of the productive mineral-rich areas in remote parts, such as Chagai, are highly cloud-free, therefore, it may be possible to meet their mining needs through solar energy. Thus Pakistan, on the threshold of industrialization, has high prospects of obtaining `clean' energy, free of greenhouse gases.

  11. NRAO Scientists on Team Receiving International Astronautics Award

    Science.gov (United States)

    2005-10-01

    The International Academy of Astronautics (IAA) is presenting an award to a pioneering team of scientists and engineers who combined an orbiting radio-astronomy satellite with ground-based radio telescopes around the world to produce a "virtual telescope" nearly three times the size of the Earth. The team, which includes two scientists from the National Radio Astronomy Observatory (NRAO), will receive the award in a ceremony Sunday, October 16, in Fukuoka, Japan. VSOP Satellite and Ground Telescopes Artist's conception of HALCA satellite and ground observatories together making "virtual telescope" (blue) about three times the size of Earth. CREDIT: ISAS, JAXA (Click on image for larger version) The IAA chose the VLBI Space Observatory Program (VSOP), an international collaboration, to receive its 2005 Laurels for Team Achievement Award, which recognizes "extraordinary performance and achievement by a team of scientists, engineers and managers in the field of Astronautics to foster its peaceful and international use." VSOP team members named in the IAA award include NRAO astronomers Edward Fomalont, of Charlottesville, Virginia, and Jonathan Romney, of Socorro, New Mexico. "This is a well-deserved award for an international team whose hard work produced a scientific milestone that yielded impressive results and provides a foundation for more advances in the future," said Dr. Fred K.Y Lo, NRAO Director. The VSOP program used a Japanese satellite, HALCA (Highly Advanced Laboratory for Communications and Astronomy), that included an 8-meter (26-foot) radio telescope. HALCA was launched in 1997 and made astronomical observations in conjunction with ground-based radio telescopes from 14 countries. Five tracking stations, including one at NRAO's Green Bank, West Virginia, facility, received data from HALCA which later was combined with data from the ground-based telescopes to produce images more detailed than those that could have been made by ground-based systems alone

  12. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering

    Science.gov (United States)

    Hanley, G. M.

    1980-09-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  13. Satellite Power Systems (SPS) concept definition study. Volume 2, part 2: System engineering. [cost and programmatics

    Science.gov (United States)

    Hanley, G. M.

    1980-01-01

    The latest technical and programmatic developments are considered as well as expansions of the Rockwell SPS cost model covering each phase of the program through the year 2030. Comparative cost/economic analyses cover elements of the satellite, construction system, space transportation vehicles and operations, and the ground receiving station. System plans to define time phased costs and planning requirements that support major milestones through the year 2000. A special analysis is included on natural resources required to build the SPS reference configuration. An appendix contains the SPS Work Breakdown Structure and dictionary along with detail cost data sheet on each system and main element of the program. Over 200 line items address DDT&E, theoretical first unit, investment cost per satellite, and operations charges for replacement capital and normal operations and maintenance costs.

  14. The SPOT satellite

    Science.gov (United States)

    Fouquet, J.-P.

    1981-03-01

    The background, objectives and data products of the French SPOT remote sensing satellite system are presented. The system, which was developed starting in 1978 with the subsequent participation of Sweden and Belgium, is based on a standard multimission platform with associated ground control station and a mission-specific payload, which includes two High-Resolution Visible range instruments allowing the acquisition of stereoscopic views from different orbits. Mission objectives include the definition of future remote sensing systems, the compilation of a cartographic and resources data base, the study of species discrimination and production forecasting based on frequent access and off-nadir viewing, the compilation of a stereoscopic data base, and platform and instrument qualification, for possible applications in cartography, geology and agriculture. Standard data products will be available at three levels of preprocessing: radiometric correction only, precision processing for vertical viewing, and cartographic quality processing.

  15. Analysis of L5 phase variations in GPS IIF satellites by the raw observation PPP approach

    Science.gov (United States)

    Liu, Sha; Becker, Matthias

    2015-04-01

    GPS modernization along with Glonass modernization and the emerging Galileo and Compass system has been highly anticipated by every GNSS user since several years. The third civilian L5 signal transmitted by the modernized GPS satellites brings us to the GNSS multi-frequency era. The first GPS IIF satellite was launched in May 2010, until now there are eight block IIF satellites in service and the remaining four IIF satellites are planned to be launched by 2016. The introduction of the third frequency to GPS and the usage of advanced atomic clocks not only provide the users more possibilities but also enable higher positioning accuracy. Nevertheless phase variations are found on the new L5 observation of GPS SVN62. Further investigations suggest that the variations of this satellite are strongly dependent on the satellite inner temperature variation caused by sun illumination. Besides achieving precise positioning accuracy, PPP is also frequently used as a tool to analyze and evaluate various GNSS errors, for instance, tropospheric delays and receiver clock errors. Other than with differential GNSS, it is possible to separate different errors and to identify the error sources with PPP. Conventional PPP is based on the ionosphere-free linear combination, in order to eliminate the first-order ionospheric delays. However only dual frequencies can be used to build ionosphere-free linear combination, which leads to the waste of the information on the third frequency. Furthermore, the frequency dependent errors can not be separated and traced. A new PPP approach that avoids using any linear combination is proposed recently, which is called the raw observation PPP. One advantage of the raw observation PPP approach is that data of all frequencies and all GNSS systems can be jointly used. In addition, the frequency dependent errors are possible to be separated, identified and analyzed. In this paper the raw observation PPP is utilized to analyze the phase variations on L5

  16. A new PPP algorithm for deformation monitoring with single-frequency receiver

    Indian Academy of Sciences (India)

    Yanli Zheng; Rui Zhang; Shengfeng Gu

    2014-12-01

    Considering the applications of deformation monitoring, PPP (precise point positioning) with singlefrequency (SF) receivers has the advantages of stand-alone, absolute positioning and cost efficiency. However, the existing SF PPP methods can be hardly implemented for deformation monitoring directly due to their limited precision of submeter level. For this purpose, an innovative approach is presented in this paper with several improvements to the existing approaches: firstly, the SEID (Satellite-specific Epoch-differenced Ionospheric Delay) model is adopted in SF kinematic PPP to handle the ionospheric delays for SF receivers embedded in networks of dual-frequency (DF) receivers; secondly, according to the dynamic characteristic of the monitor station, a combination of kinematic PPP and sliding window based static PPP algorithm is adopted. To confirm the availability of the algorithm for deformation monitoring with SF receiver, a seismic experiment is carried out on an earthquake simulation platform. Comparable positioning precision with 1.5 cm for horizontal and 2.2 cm for vertical is achieved by SF PPP with respect to RTK (real-time kinematic) solution. The new deformation monitoring algorithm with SF receiver can be treated as an effective and low cost way to realize some types of geological hazard monitoring in a wide range.

  17. Impact of GPS tracking data of LEO satellites on global GPS solutions

    Science.gov (United States)

    Rothacher, M.; Svehla, D.

    Already at present quite a few Low Earth Orbiting (LEO) satellites (SAC-C, CHAMP, JASON-1, GRACE-1 and GRACE-2) are equipped with one or more GPS receivers for precise orbit determination or other applications (atmospheric sounding, gravity field recovery, . . . ). This trend will continue in the near future (e.g., with the GOCE and COSMIC missions) and we will soon have an entire "constellation" of LEO satellites tracked by GPS at our disposal. In this contribution we want to study the impact of LEO GPS measurements (from a single LEO satellite or from a LEO constellation) on global GPS solutions, where GPS satellite orbits and clocks, Earth rotation parameters (ERPs), station coordinates and troposphere zenith delays are determined simultaneously using the data of the global network of the International GPS Service (IGS). In order to assess the impact of the LEO GPS data on global IGS results, we have to perform a combined analysis of the space-borne and the ground-based GPS data. Such a combination may benefit on one hand from the differences between a ground station and a LEO, e.g., (1) the different tracking geometry (coverage of isolated geographical areas by LEOs, rapidly changing geometry, . . . ), (2) that LEOs connect all ground stations within 1-2 hours, (3) that baselines between LEO and ground stations may be longer than station-station baselines, (4) that no tropospheric delays have to be estimated for LEOs, and (5) that LEOs orbit the Earth within the ionosphere and may therefore contribute to global ionosphere models. On the other hand we have to deal with difficult aspects of precise orbit determination for the LEOs: only if we succeed to obtain very accurate dynamic or reduced-dynamic orbits for the LEOs, we will have a chance at all to improve the global GPS results. We present first results concerning the influence of LEO data on GPS orbits, ERPs, site coordinates, and troposphere zenith delays using both, variance-covariance analyses based on

  18. Radio broadcasting via satellite

    Science.gov (United States)

    Helm, Neil R.; Pritchard, Wilbur L.

    1990-10-01

    Market areas offering potential for future narrowband broadcast satellites are examined, including international public diplomacy, government- and advertising-supported, and business-application usages. Technical issues such as frequency allocation, spacecraft types, transmission parameters, and radio receiver characteristics are outlined. Service and system requirements, advertising revenue, and business communications services are among the economic issues discussed. The institutional framework required to provide an operational radio broadcast service is studied, and new initiatives in direct broadcast audio radio systems, encompassing studies, tests, in-orbit demonstrations of, and proposals for national and international commercial broadcast services are considered.

  19. Cold Start Strategy of the CubeSat GPS Receiver

    Directory of Open Access Journals (Sweden)

    KOVAR, P.

    2014-05-01

    Full Text Available The cold start of the LEO satellite GPS receiver is complicated due to a large Doppler frequency shift, Doppler frequency rate of the navigation signals and a rapid change of the satellite visibility. The cold start time can be shortened by a proper strategy of a selection of the satellites to be searched for. The cold start simulator was developed and used for optimization of the sequence of the satellites search, for development and testing of an advanced satellite selection algorithm that utilizes information on the satellites already detected and for optimization of a frequency search range. The best performance was achieved by using an advanced selection strategy. The strategy is based on the selection of the satellites nearest to the detected satellite, using the average angle between the Earth center (apex and the satellites. Furthermore, the simulation shows that it is not practical to investigate all frequencies within the range of the maximum possible Doppler frequency shift of the carrier wave of the navigation signal, but investigate approximately +/- 35 kHz range and, if not successful, switch to the next satellite. The simulations proved that a simple GPS receiver with the sequential search algorithms can operate in the LEO orbit.

  20. Fire Stations - 2007

    Data.gov (United States)

    Kansas Data Access and Support Center — Fire Station Locations in Kansas Any location where fire fighters are stationed at or based out of, or where equipment that such personnel use in carrying out their...

  1. Big Game Reporting Stations

    Data.gov (United States)

    Vermont Center for Geographic Information — Point locations of big game reporting stations. Big game reporting stations are places where hunters can legally report harvested deer, bear, or turkey. These are...

  2. Water Level Station History

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Images contain station history information for 175 stations in the National Water Level Observation Network (NWLON). The NWLON is a network of long-term,...

  3. Streamflow Gaging Stations

    Data.gov (United States)

    Department of Homeland Security — This map layer shows selected streamflow gaging stations of the United States, Puerto Rico, and the U.S. Virgin Islands, in 2013. Gaging stations, or gages, measure...

  4. Hammond Bay Biological Station

    Data.gov (United States)

    Federal Laboratory Consortium — Hammond Bay Biological Station (HBBS), located near Millersburg, Michigan, is a field station of the USGS Great Lakes Science Center (GLSC). HBBS was established by...

  5. Fire Stations - 2009

    Data.gov (United States)

    Kansas Data Access and Support Center — Fire Stations in Kansas Any location where fire fighters are stationed or based out of, or where equipment that such personnel use in carrying out their jobs is...

  6. Capacity at Railway Stations

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    Stations do have other challenges regarding capacity than open lines as it is here the traffic is dispatched. The UIC 406 capacity method that can be used to analyse the capacity consumption can be exposed in different ways at stations which may lead to different results. Therefore, stations need...... special focus when conducting UIC 406 capacity analyses.This paper describes how the UIC 406 capacity method can be expounded for stations. Commonly for the analyses of the stations it is recommended to include the entire station including the switch zone(s) and all station tracks. By including the switch...... is changed, this paper recommends that the railway lines are not always be divided. In case trains turn around on open (single track) line, the capacity consumption may be too low if a railway line is divided. The same can be the case if only few trains are overtaken at an overtaking station. For dead end...

  7. Weather Radar Stations

    Data.gov (United States)

    Department of Homeland Security — These data represent Next-Generation Radar (NEXRAD) and Terminal Doppler Weather Radar (TDWR) weather radar stations within the US. The NEXRAD radar stations are...

  8. Reference Climatological Stations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Reference Climatological Stations (RCS) network represents the first effort by NOAA to create and maintain a nationwide network of stations located only in areas...

  9. Newport Research Station

    Data.gov (United States)

    Federal Laboratory Consortium — The Newport Research Station is the Center's only ocean-port research facility. This station is located at Oregon State University's Hatfield Marine Science Center,...

  10. Satellite communications for the next generation telecommunication services and networks

    Science.gov (United States)

    Chitre, D. M.

    1991-01-01

    Satellite communications can play an important role in provisioning the next-generation telecommunication services and networks, provided the protocols specifying these services and networks are satellite-compatible and the satellite subnetworks, consisting of earth stations interconnected by the processor and the switch on board the satellite, interwork effectively with the terrestrial networks. The specific parameters and procedures of frame relay and broadband integrated services digital network (B-ISDN) protocols which are impacted by a satellite delay. Congestion and resource management functions for frame relay and B-ISDN are discussed in detail, describing the division of these functions between earth stations and on board the satellite. Specific onboard and ground functions are identified as potential candidates for their implementation via neural network technology.

  11. Data capture and processing. [for Space Station

    Science.gov (United States)

    Lyon, John; Smith, Gene; Carper, Richard

    1987-01-01

    A systems concept developed in response to the specific requirements imposed by the Space Station and affiliated instrumentation is described. Particular attention is given to those subsystems associated with initial data capture, handling, routing, and distribution control for return link data via the Tracking and Data Relay Satellite System. The conceived approach, designated the Customer Data and Operations System, includes a data interface facility and a data handling center whose functions are data capture, demultiplexing and routing, early preprocessing, and ancillary data handling.

  12. Station Climatic Summaries, Asia

    Science.gov (United States)

    1989-07-01

    OCDS) ................................................... 077 BIRJAND 408090 8612 (OCDS) ............................................. ( 381 BUSHEHR...ALL HOURS # 2 1 0 1 0 # 0 # 1 # 1 1 CACECR-IB 080 OPERATIONAL CLIMATIC DATA SUMM ARY STATION: BIRJAND , IRAN STATION #: 408090 ICAO ID...082. L@ OPERATIONAL CLIMATIC DATA SIJ44ARY STATION: BIRJAND , IRAN STATION #: 408090 ICAO ID: OIMB LOCATION: 32054’N, 59016’E ELEVATION (FEET): 4823 LST

  13. Autonomous Acoustic Receiver System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Collects underwater acoustic data and oceanographic data. Data are recorded onboard an ocean buoy and can be telemetered to a remote ship or shore station...

  14. Latitudinal GRBR-TEC estimation in Southeast Asia region based on the two-station method

    Science.gov (United States)

    Watthanasangmechai, Kornyanat; Yamamoto, Mamoru; Saito, Akinori; Tsugawa, Takuya; Yokoyama, Tatsuhiro; Supnithi, Pornchai; Yatini, Clara Yono

    2014-10-01

    Total electron content (TEC) is an important parameter for revealing latitudinal ionospheric structures, such as the equatorial ionization anomaly (EIA) in Southeast Asia. Understanding the EIA is beneficial for studying equatorial spread F. To reveal the structures, the absolute TEC as a function of latitude must be accurately determined. In early 2012, we expanded a GNU Radio Beacon Receiver (GRBR) network to provide latitudinal coverage in the Thailand-Indonesia sector. We employed the GRBR network to receive VHF and UHF signals from polar low-Earth-orbit satellites. The TEC offset is an unknown parameter in the absolute TEC estimation process. We propose a new technique based on the two-station method to estimate the offset for the latitudinal TEC estimation, and it works better than the original method for a sparse network. The TEC estimation system requires two iterations to minimize the root-mean-square error (RMSE). Once the RMSE reaches the global minimum, the absolute TECs are estimated simultaneously over five GRBR stations. GPS-TECs from local stations are used as the initial guess of the offset estimation. The height of the ionospheric pierce point is determined from the ionosonde hmF2. As a result, the latitudinal GRBR-TEC was successfully estimated from the polar orbit satellites. The two EIA humps were clearly captured by the GRBR-TEC. The result was well verified with the TEC reconstructed from the C/NOFS density data and the ionosonde bottomside data. This is a significant step showing that the GRBR is a useful tool for the study of low-latitude ionospheric features.

  15. 47 CFR 101.145 - Interference to geostationary-satellites.

    Science.gov (United States)

    2010-10-01

    ... in the bands 2655-2690 MHz, 5925-7075 MHz, and 12.7-13.25 GHz on board geostationary-space stations... in these bands on board geostationary space stations. (b) 2655 to 2690 MHz and 5925 to 7075 MHz. No... degrees of the geostationary-satellite orbit, taking into account atmospheric refraction....

  16. Digital, Satellite-Based Aeronautical Communication

    Science.gov (United States)

    Davarian, F.

    1989-01-01

    Satellite system relays communication between aircraft and stations on ground. System offers better coverage with direct communication between air and ground, costs less and makes possible new communication services. Carries both voice and data. Because many data exchanged between aircraft and ground contain safety-related information, probability of bit errors essential.

  17. 7 CFR 611.22 - Availability of satellite imagery.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Availability of satellite imagery. 611.22 Section 611... § 611.22 Availability of satellite imagery. Cloud-free maps of the United States based on imagery received from a satellite are prepared and released to the pubic by NRCS. The maps offer the first image...

  18. 47 CFR 76.123 - Satellite syndicated program exclusivity.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Satellite syndicated program exclusivity. 76... Exclusivity and Sports Blackout § 76.123 Satellite syndicated program exclusivity. (a) Upon receiving notification pursuant to paragraph (d) of this section, a satellite carrier shall not deliver, to...

  19. Design and implementation of the CAPS receiver

    Science.gov (United States)

    Hu, Yonghui; Hua, Yu; Hou, Lei; Wei, Jingfa; Wu, Jianfeng

    2009-03-01

    In this paper, based on analyses of the Chinese Area Positioning System (CAPS) satellite (GEO satellite) resources and signal properties, the signal power at the port of the receiver antenna is estimated, and the implementation projects are presented for a switching band C to band L CAPS C/A code receiver integrated with GPS receiver suite and for a CAPS dual frequency P code receiver. A microstrip receiving antenna is designed with high sensitivity and wide beam orientation, the RF front end of the C/A code and P code receivers, and a processor is designed for the navigation baseband. A single frequency CAPS C/A code receiver and a CAPS dual frequency P code receiver are built at the same time. A software process flow is provided, and research on relatively key techniques is also conducted, such as signal searching, code loop and carrier loop algorithms, a height assistant algorithm, a dual frequency difference speed measurement technique, a speed measurement technique using a single frequency source with frequency assistance, and a CAPS time correcting algorithm, according to the design frame of the receiver hardware. Research results show that the static plane positioning accuracy of the CAPS C/A code receiver is 20.5-24.6 m, height accuracy is 1.2-12.8 m, speed measurement accuracy is 0.13-0.3 m/s, dynamic plane positioning accuracy is 24.4 m, height accuracy is 3.0 m, and speed measurement accuracy is 0.24 m/s. In the case of C/A code, the timing accuracy is 200 ns, and it is also shown that the positioning accuracy of the CAPS precise code receiver (1 σ) is 5 m from south to north, and 0.8 m from east to west. Finally, research on positioning accuracy is also conducted.

  20. Design and implementation of the CAPS receiver

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, based on analyses of the Chinese Area Positioning System (CAPS) satellite (GEO satellite) resources and signal properties, the signal power at the port of the receiver antenna is estimated, and the implementation projects are presented for a switching band C to band L CAPS C/A code receiver integrated with GPS receiver suite and for a CAPS dual frequency P code receiver. A microstrip receiving antenna is designed with high sensitivity and wide beam orientation, the RF front end of the C/A code and P code receivers, and a processor is designed for the navigation baseband. A single frequency CAPS C/A code receiver and a CAPS dual frequency P code receiver are built at the same time. A software process flow is provided, and research on relatively key techniques is also conducted, such as signal searching, code loop and carrier loop algorithms, a height assistant algorithm, a dual frequency difference speed measurement technique, a speed measurement technique using a single frequency source with frequency assistance, and a CAPS time correcting algorithm, according to the design frame of the receiver hardware. Research results show that the static plane positioning accuracy of the CAPS C/A code receiver is 20.5-24.6 m, height accuracy is 1.2-12.8 m, speed measurement accuracy is 0.13-0.3 m/s, dynamic plane positioning accuracy is 24.4 m, height accuracy is 3.0 m, and speed measurement accuracy is 0.24 m/s. In the case of C/A code, the timing accuracy is 200 ns, and it is also shown that the positioning accuracy of the CAPS precise code receiver (1σ ) is 5 m from south to north, and 0.8 m from east to west. Finally, research on positioning accuracy is also conducted.

  1. The 136 MHZ/400 MHz earth station antenna-noise temperature prediction program for RAE-B

    Science.gov (United States)

    Taylor, R. E.; Fee, J. J.; Chin, M.

    1972-01-01

    A simulation study was undertaken to determine the 136 MHz and 400 MHz noise temperature of the ground network antennas which will track the RAE-B satellite during data transmission periods. Since the noise temperature of the antenna effectively sets the signal-to-noise ratio of the received signal, a knowledge of SNR will be helpful in locating the optimum time windows for data transmission during low noise periods. Antenna noise temperatures will be predicted for selected earth-based ground stations which will support RAE-B. Telemetry data acquisition will be at 400 MHz; tracking support at 136 MHz will be provided by the Goddard Range and Range Rate (RARR) stations. The antenna-noise temperature predictions will include the effects of galactic-brightness temperature, the sun, and the brightest radio stars. Predictions will cover the ten-month period from March 1, 1973 to December 31, 1973.

  2. 3D-RTK Capability of Single Gnss Receivers

    Science.gov (United States)

    Stempfhuber, W.

    2013-08-01

    GNSS data processed with the RTK method can be provided in standardised NMEA format. Through the reduced shadowing effects of the aerial objects, GNSS external factors such as multipath cause few problems. With L1 carrier phase analysis, the baseline computation must nevertheless remain limited at the range of a few kilometres. With distances of more than 5 kilometres between the reference station and the rover station position, mistakes arise in the decimetre area. The overall modular system consists of a low-cost, single-frequency receiver (e.g. uBlox LEA4T or 6T receiver), a L1 antenna (e.g. the Trimble Bullet III), a developed data logger including an integrated WLAN communication module for storage and securing of the raw data as well as a power supply. Optimisation of the L1 antenna has shown that, in this instance, many problems relating to signal reception can be reduced. A calibration of the choke-ring adaptors for various antenna calibration facilities results in good and homogeneous antenna parameters. In this situation, the real-time algorithm from the Open Source project RTKLib [Takasu, 2010] generally runs on a small computer at the reference station. In this case, the data transfer from the L1 receiver to the PC is realisable through a serial cable. The rover station can transfer the raw data to the computing algorithm over a WLAN network or through a data radio. Of course, this computational algorithm can also be adapted to an integrated computing module for L1 carrier phase resolutions. The average time to first fix (TTFF) amounts to a few minutes depending on the satellite constellation. Different test series in movement simulators and in moving objects have shown that a stable, fixed solution is achieved with a normal satellite constellation. A test series with a Microdrones quadrocopter could also be conducted. In comparison of the RTK positions with a geodetic dual frequency receiver, differences are in millimetre ranges. In addition, reference

  3. Research Supporting Satellite Communications Technology

    Science.gov (United States)

    Horan Stephen; Lyman, Raphael

    2005-01-01

    This report describes the second year of research effort under the grant Research Supporting Satellite Communications Technology. The research program consists of two major projects: Fault Tolerant Link Establishment and the design of an Auto-Configurable Receiver. The Fault Tolerant Link Establishment protocol is being developed to assist the designers of satellite clusters to manage the inter-satellite communications. During this second year, the basic protocol design was validated with an extensive testing program. After this testing was completed, a channel error model was added to the protocol to permit the effects of channel errors to be measured. This error generation was used to test the effects of channel errors on Heartbeat and Token message passing. The C-language source code for the protocol modules was delivered to Goddard Space Flight Center for integration with the GSFC testbed. The need for a receiver autoconfiguration capability arises when a satellite-to-ground transmission is interrupted due to an unexpected event, the satellite transponder may reset to an unknown state and begin transmitting in a new mode. During Year 2, we completed testing of these algorithms when noise-induced bit errors were introduced. We also developed and tested an algorithm for estimating the data rate, assuming an NRZ-formatted signal corrupted with additive white Gaussian noise, and we took initial steps in integrating both algorithms into the SDR test bed at GSFC.

  4. Advanced satellite communication system

    Science.gov (United States)

    Staples, Edward J.; Lie, Sen

    1992-01-01

    The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

  5. ACSSB land mobile earth station

    Science.gov (United States)

    Taira, Shinichi; Ikegami, Tetsushi; Suzuki, Ryutaro; Suzuki, Shoichi; Kawahara, Hideki; Tada, Shun-Ichi

    1990-03-01

    This paper describes the performance of the land mobile earth station using the Amplitude Companded Single Sideband (ACSSB) modulation technique developed for mobile satellite communications and results of the field experiments which were conducted in rural, suburban, and urban areas. This ACSSB system uses a 3-kHz pilot tone, and the voice frequency band is from 300 to 2500 Hz. The experiments show that the required C/N0 for voice communications is 40 dBHz and the required C/N0 for pilot signal tracking is 34 dBHz. Voice quality in rural and suburban areas was degraded slightly. In urban areas shadowings due to the presence of large buildings and trees caused signal losses. A comparison of the ACSSB system with the conventional narrow-band frequency-modulation system indicates that the ACSSB system can transmit voice signals more efficiently.

  6. A Review on Inter-satellite Link in Inter-satellite Optical Wireless Communication

    Science.gov (United States)

    Arora, Heena; Goyal, Rakesh

    2017-06-01

    In this paper, inter-satellite optical wireless communication (IsOWC) system is proposed, one of the imperative utilizations of free space optics/wireless space optics (FSO)/WSO innovation. IsOWC frameworks give a high bandwidth, small size, small weight, low power and minimal effort different option for present microwave satellite frameworks. Optical communications systems have evolved from lengthy fibers to powerful wireless system. This has hence resulted in the use of optical wireless communication system in space communications. As the quantity of satellites circling the Earth expands year by year, a system between the satellites gives a strategy to them to correspond with one another. This is vital for satellites to send data to each other furthermore to hand off the data starting with one satellite then onto the next satellite and after that to the ground stations. By utilizing laser satellite correspondence, the satellites can be joined with information rates up to a few Gbps. The system performance including bit rates, input power, wavelength and distance on an inter-satellite link was analyzed. Various issues such as bit rates, input power, wavelength and distance were presented in IsOWC.

  7. A MEO Tracking and Data Relay Satellite System Constellation Scheme for China

    Institute of Scientific and Technical Information of China (English)

    WU Ting-yong; WU Shi-qi; LING Xiang

    2005-01-01

    A medium earth orbit (MEO) tracking and data relay satellite system (TDRSS) constellation scheme for China is proposed. This system consists of MEO satellite constellation, inter-satellite links (ISLs) and terrestrial gateway station, which can provide continuous bidirectional data transmission links between low altitude spacecrafts and the terrestrial gateway station in China. Theoretical analysis and simulation results indicate that the proposed constellation can cover the global low altitude space sphere and earth surface of China continuously, and has a preferable practical perspective.

  8. Permanent GNSS Observations at Agh-Ust Satellite Observatory

    Science.gov (United States)

    Kudrys, Jacek

    2016-06-01

    GPS satellite observations at the Faculty of Mining Surveying and Environmental Engineering AGH-UST are conducted since the early 90s of the last century. In 2001, efforts have been made on getting permanently functioning GPS station. At present, observatory is EPN operational center for two GNSS stations KRAW and KRA1. Moreover, KRA1 station is one of fundamental control points in polish horizontal network. The article gives the history and scope of the research carried out in the satellite observatory AGH-UST during the period 2001 - 2015.

  9. Engineering Test Satellite VI (ETS-VI)

    Science.gov (United States)

    Horii, M.; Funakawa, K.

    1991-01-01

    The Engineering Test Satellite-VI (ETS-VI) is being developed as the third Japanese three-axis stabilized engineering test satellite to establish the 2-ton geostationary operational satellite bus system and to demonstrate the high performance satellite communication technology for future operational satellites. The satellite is expected to be stationed at 154 deg east latitude. It will be launched from the Tanegashima Space Center in Japan by a type H-II launch vehicle. The Deep Space Network (DSN) will support the prelaunch compatibility test, data interface verification testing, and launch rehersals. The DSN primary support period is from launch through the final AEF plus 1 hour. Contingency support is from final AEF plus 1 hour until launch plus 1 month. The coverage will consist of all the 26-m antennas as prime and the 34-m antennas at Madrid and Canberra as backup. Maximum support will consist of two 8-hour tracks per station for a 7-day period, plus the contingency support, if required. Information is given in tabular form for DSN support, telemetry, command, and tracking support responsibility.

  10. Non-Coop Station History

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Station history documentation for stations outside the US Cooperative Observer network. Primarily National Weather Service stations assigned WBAN station IDs. Other...

  11. Highly Sensitive Optical Receivers

    CERN Document Server

    Schneider, Kerstin

    2006-01-01

    Highly Sensitive Optical Receivers primarily treats the circuit design of optical receivers with external photodiodes. Continuous-mode and burst-mode receivers are compared. The monograph first summarizes the basics of III/V photodetectors, transistor and noise models, bit-error rate, sensitivity and analog circuit design, thus enabling readers to understand the circuits described in the main part of the book. In order to cover the topic comprehensively, detailed descriptions of receivers for optical data communication in general and, in particular, optical burst-mode receivers in deep-sub-µm CMOS are presented. Numerous detailed and elaborate illustrations facilitate better understanding.

  12. TELE-X and its role in a future operational Nordic satellite system

    Science.gov (United States)

    Anderson, Lars

    In the middle of 1987 it is planned to launch TELE-X, the first Nordic telecommunications satellite. The Swedish-Norwegian company NOTELSAT (Nordic Telecommunications Satellite Corporation) will be responsible for the operation of the TELE-X system. Via the experimental TELE-X satellite the Nordic countries will get access to direct broadcasting of two TV-programs and at least four digital sound programs in stereo by use of two transponders in the 12.2 to 12.5 GHz band. The programs are planned to be composed of nationally produced programs in Norway. Sweden and Finland. By means of distributing these programs via satellite they will reach up to 4 times as many viewers and listernes as presently in the terrestrial national systems. The basic motivations for exchanging programs are to strengthen the cultural ties between the Nordic countries and to give the individuals more freedom in the choice of programs. Another goal is to give the public a better sound and picture quality than can be achieved today. These quality improvements shall be met by using small receiver parabolas of less than 1 m in diameter. Contributing to the improved quality is the choice of the C-MAC (Multiplexed Analoque Components) modulation system. TELE-X is a multipurpose satellite which besides the two TV-transponders will have two transponders for data/video communication in the frequency band 12.5 to 12.75 GHz. The choice of system for data and video is based on the philosophy of thin-route traffic between small and low cost earth stations (1.8 to 2.5 m) placed directly at the subscribers premises. The system includes an advanced Data/Video Control Station which automatically connects the traffic stations with standarized transmission speeds up to 2 Mbps. The system which is based on the SCPC/DAMA method can be expanded up to 5000 traffic stations. Numerous data/video applications will be investigated in the initial experimental phase of the project which also will be used for market

  13. Stanwell power station project

    Energy Technology Data Exchange (ETDEWEB)

    Mills, David R; J Dey, Christopher [University of Sidney, Sidney (Australia); Morrison, Graham L [University of New South Wales, Sidney (Australia)

    2000-07-01

    This paper describes the Compact Linear Fresnel Reflector (CLFR) being developed for installation at the Stanwell power station in Queensland Australia. Stanwell Corporation Limited (SCL). Solahart International, Solsearch Pty. Ltd. And the universities of Sidney and New South Wales are cooperating in the project, and this first plant being partly funded by the Australian Greenhouse Office. The solar plant will be attached to a 1440 MW(e) coal fired plant. The 17000 m{sup 2} array will be the largest array in Australia, producing a peak of 13 MW of thermal energy which will offset the use of coal in the generation of electricity. It will use direct steam generation and will feed either steam or hot water at 265 Celsius degrees directly into the power station preheating cycle. The CLFR system, first developed by the University of Sidney and Solsearch Pty. Ltd., is simple and offers small reflector size, low structural cost, fixed receiver geometry. Initial installed plant costs are approximately US$1000 per kWe, but this includes the effect of high up-front design costs and the cost should drop substantially in the second and subsequent plants. [Spanish] Proyecto de la Planta Electrica Stanwell este articulo describe el Reflector Lineal Compacto Fresnel (CLFR, siglas en ingles) que se esta desarrollando para la instalacion de la planta electrica Stanwell en Queensland, Australia. La Corporacion Stanwell Limited (SCL), Solahart International, Solsearch Pty. Ltd., las universidades de Sidney y de New South Wales estan cooperando en este proyecto, y esta primera planta esta parcialmente auspiciada por la Australian Greenhouse Office. La planta solar sera anexa a una planta de carbon de 1440 MW(e). Este arreglo de 17000 m{sup 2} sera el mayor en Australia y producira un maximo de 13 MW en energia termica la cual contrarrestara el uso del carbon en la generacion de electricidad. Utilizara generacion con vapor directo y alimentara ya sea vapor o agua caliente a 265 grados

  14. Geostationary Satellite (GOES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from radiometer instruments on SMS (ATS) and GOES satellites in geostationary orbit. These satellites produced...

  15. Internet-to-orbit gateway and virtual ground station: A tool for space research and scientific outreach

    Science.gov (United States)

    Jaffer, Ghulam; Nader, Ronnie; Koudelka, Otto

    2011-09-01

    Students in higher education, and scientific and technological researchers want to communicate with the International Space Station (ISS), download live satellite images, and receive telemetry, housekeeping and science/engineering data from nano-satellites and larger spacecrafts. To meet this need the Ecuadorian Civilian Space Agency (EXA) has recently provided the civilian world with an internet-to-orbit gateway (Hermes-A/Minotaur) Space Flight Control Center (SFCC) available for public use. The gateway has a maximum range of tracking and detection of 22,000 km and sensitivity such that it can receive and discriminate the signals from a satellite transmitter with power˜0.1 W. The capability is enough to receive the faintest low-earth-orbit (LEO) satellites. This gateway virtually connects participating internet clients around the world to a remote satellite ground station (GS), providing a broad community for multinational cooperation. The goal of the GS is to lower financial and engineering barriers that hinder access to science and engineering data from orbit. The basic design of the virtual GS on a user side is based on free software suites. Using these and other software tools the GS is able to provide access to orbit for a multitude of users without each having to go through the costly setups. We present the design and implementation of the virtual GS in a higher education and scientific outreach settings. We also discuss the basic architecture of the single existing system and the benefits of a proposed distributed system. Details of the software tools and their applicability to synchronous round-the-world tracking, monitoring and processing performed by students and teams at Graz University of Technology, Austria, EXA-Ecuador, University of Michigan, USA and JAXA who have participated in various mission operations and have investigated real-time satellite data download and image acquisition and processing. Students and other remote users at these

  16. Neptune's small satellites

    Science.gov (United States)

    Thomas, P.

    1992-04-01

    The small satellites of Neptune and other planets discovered during the Voyager 2 mission are discussed in terms of their composition and relationship to the planetary systems. The satellite Proteus is described in terms of its orbit, five other satellites are described, and they are compared to ther small satellites and systems. Neptune's satellites are hypothesized to be related to the ring system, and the satellite Galatea is related to the confinement of the rings.

  17. Cooperative Station History Forms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Various forms, photographs and correspondence documenting the history of Cooperative station instrumentation, location changes, inspections, and...

  18. Amtrak Rail Stations (National)

    Data.gov (United States)

    Department of Transportation — Updated database of the Federal Railroad Administration's (FRA) Amtrak Station database. This database is a geographic data set containing Amtrak intercity railroad...

  19. Estimating Zenith Tropospheric Delays from BeiDou Navigation Satellite System Observations

    Directory of Open Access Journals (Sweden)

    Xin Sui

    2013-04-01

    Full Text Available The GNSS derived Zenith Tropospheric Delay (ZTD plays today a very critical role in meteorological study and weather forecasts, as ZTDs of thousands of GNSS stations are operationally assimilated into numerical weather prediction models. Recently, the Chinese BeiDou Navigation Satellite System (BDS was officially announced to provide operational services around China and its neighborhood and it was demonstrated to be very promising for precise navigation and positioning. In this contribution, we concentrate on estimating ZTD using BDS observations to assess its capacity for troposphere remote sensing. A local network which is about 250 km from Beijing and comprised of six stations equipped with GPS- and BDS-capable receivers is utilized. Data from 5 to 8 November 2012 collected on the network is processed in network mode using precise orbits and in Precise Point Positioning mode using precise orbits and clocks. The precise orbits and clocks are generated from a tracking network with most of the stations in China and several stations around the world. The derived ZTDs are compared with that estimated from GPS data using the final products of the International GNSS Service (IGS. The comparison shows that the bias and the standard deviation of the ZTD differences are about 2 mm and 5 mm, respectively, which are very close to the differences of GPS ZTD estimated using different software packages.

  20. Estimating zenith tropospheric delays from BeiDou navigation satellite system observations.

    Science.gov (United States)

    Xu, Aigong; Xu, Zongqiu; Ge, Maorong; Xu, Xinchao; Zhu, Huizhong; Sui, Xin

    2013-04-03

    The GNSS derived Zenith Tropospheric Delay (ZTD) plays today a very critical role in meteorological study and weather forecasts, as ZTDs of thousands of GNSS stations are operationally assimilated into numerical weather prediction models. Recently, the Chinese BeiDou Navigation Satellite System (BDS) was officially announced to provide operational services around China and its neighborhood and it was demonstrated to be very promising for precise navigation and positioning. In this contribution, we concentrate on estimating ZTD using BDS observations to assess its capacity for troposphere remote sensing. A local network which is about 250 km from Beijing and comprised of six stations equipped with GPS- and BDS-capable receivers is utilized. Data from 5 to 8 November 2012 collected on the network is processed in network mode using precise orbits and in Precise Point Positioning mode using precise orbits and clocks. The precise orbits and clocks are generated from a tracking network with most of the stations in China and several stations around the world. The derived ZTDs are compared with that estimated from GPS data using the final products of the International GNSS Service (IGS). The comparison shows that the bias and the standard deviation of the ZTD differences are about 2 mm and 5 mm, respectively, which are very close to the differences of GPS ZTD estimated using different software packages.

  1. Low complexity MIMO receivers

    CERN Document Server

    Bai, Lin; Yu, Quan

    2014-01-01

    Multiple-input multiple-output (MIMO) systems can increase the spectral efficiency in wireless communications. However, the interference becomes the major drawback that leads to high computational complexity at both transmitter and receiver. In particular, the complexity of MIMO receivers can be prohibitively high. As an efficient mathematical tool to devise low complexity approaches that mitigate the interference in MIMO systems, lattice reduction (LR) has been widely studied and employed over the last decade. The co-authors of this book are world's leading experts on MIMO receivers, and here they share the key findings of their research over years. They detail a range of key techniques for receiver design as multiple transmitted and received signals are available. The authors first introduce the principle of signal detection and the LR in mathematical aspects. They then move on to discuss the use of LR in low complexity MIMO receiver design with respect to different aspects, including uncoded MIMO detection...

  2. Global satellite composites - 20 years of evolution

    Science.gov (United States)

    Kohrs, Richard A.; Lazzara, Matthew A.; Robaidek, Jerrold O.; Santek, David A.; Knuth, Shelley L.

    2014-01-01

    For two decades, the University of Wisconsin Space Science and Engineering Center (SSEC) and the Antarctic Meteorological Research Center (AMRC) have been creating global, regional and hemispheric satellite composites. These composites have proven useful in research, operational forecasting, commercial applications and educational outreach. Using the Man computer Interactive Data System (McIDAS) software developed at SSEC, infrared window composites were created by combining Geostationary Operational Environmental Satellite (GOES), and polar orbiting data from the SSEC Data Center and polar data acquired at McMurdo and Palmer stations, Antarctica. Increased computer processing speed has allowed for more advanced algorithms to address the decision making process for co-located pixels. The algorithms have evolved from a simplistic maximum brightness temperature to those that account for distance from the sub-satellite point, parallax displacement, pixel time and resolution. The composites are the state-of-the-art means for merging/mosaicking satellite imagery.

  3. Delphi Accounts Receivable Module -

    Data.gov (United States)

    Department of Transportation — Delphi accounts receivable module contains the following data elements, but are not limited to customer information, cash receipts, line of accounting details, bill...

  4. Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2016 April-July

    Science.gov (United States)

    Warner, Brian D.

    2016-10-01

    Lightcurves for 31 near-Earth asteroids (NEAs), obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2016 April-July, were analyzed for rotation period and signs of satellites or tumbling.

  5. Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2016 October-December

    Science.gov (United States)

    Warner, Brian D.

    2017-04-01

    Lightcurves for 33 near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2016 October through December were analyzed for rotation period and signs of satellites or tumbling.

  6. Geo-spatial distribution of cloud cover and influence of cloud induced attenuation and noise temperature on satellite signal propagation over Nigeria

    Science.gov (United States)

    Ojo, Joseph Sunday

    2017-05-01

    The study of the influence of cloud cover on satellite propagation links is becoming more demanding due to the requirement of larger bandwidth for different satellite applications. Cloud attenuation is one of the major factors to consider for optimum performance of Ka/V and other higher frequency bands. In this paper, the geo-spatial distribution of cloud coverage over some chosen stations in Nigeria has been considered. The substantial scale spatial dispersion of cloud cover based on synoptic meteorological data and the possible impact on satellite communication links at higher frequency bands was also investigated. The investigation was based on 5 years (2008-2012) achieved cloud cover data collected by the Nigerian Meteorological Agency (NIMET) Federal Ministry of Aviation, Oshodi Lagos over four synoptic hours of the day covering day and night. The performances of satellite signals as they traverse through the cloud and cloud noise temperature at different seasons and over different hours of days at Ku/W-bands frequency are also examined. The overall result shows that the additional total atmospheric noise temperature due to the clear air effect and the noise temperature from the cloud reduces the signal-to-noise ratio of the satellite receiver systems, leading to more signal loss and if not adequately taken care of may lead to significant outage. The present results will be useful for Earth-space link budgeting, especially for the proposed multi-sensors communication satellite systems in Nigeria.

  7. Technical Design Report, Second Target Station

    Energy Technology Data Exchange (ETDEWEB)

    Galambos, John D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anderson, David E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bechtol, D. [HDR, Inc., Chattanooga, TN (United States); Bethea, Katie L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brown, N. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Carden, W. F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chae, Steven M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Clark, A. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Counce, Deborah M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Craft, K. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Crofford, Mark T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Collins, Richard M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cousineau, Sarah M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Curry, Douglas E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cutler, Roy I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dayton, Michael J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dean, Robert A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Deibele, Craig E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Doleans, Marc [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dye, T. [HDR, Inc., Chattanooga, TN (United States); Eason, Bob H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eckroth, James A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fincrock, C. [HDR, Inc., Chattanooga, TN (United States); Fritts, S. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Gallmeier, Franz X. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gawne, Ken R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hartman, Steven M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hess, S. [HDR, Inc., Chattanooga, TN (United States); Holmes, Jeffrey A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Horak, Charlie M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Matthew P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Iverson, Erik B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jacobs, Lorelei L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jones, Larry C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, B. [HDR, Inc., Chattanooga, TN (United States); Johnson, S. [HDR, Inc., Chattanooga, TN (United States); Kasemir, Kay [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kim, Sang-Ho [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Laughon, Gregory J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lu, W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mahoney, Kelly L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mammosser, John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McManamy, T. [McManamy Consulting, Inc., Knoxville, TN (United States); Michilini, M. [HDR, Inc., Chattanooga, TN (United States); Middendorf, Mark E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); O' Neal, Ed [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nemec, B. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Peters, Roy Cecil [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Plum, Michael A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Reagan, G. [Barge Waggoner Sumner & Cannon, Inc., Nashville, TN (United States); Remec, Igor [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rennich, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Riemer, Bernie [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Saethre, Robert B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schubert, James Phillip [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shishlo, Andrei P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smith, C. Craig [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Strong, William Herb [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tallant, Kathie M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tennant, David Alan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Thibadeau, Barbara M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Trumble, S. [HDR, Inc., Chattanooga, TN (United States); Trotter, Steven M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Z. [Institute of Modern Physics (IMP), Chinese Academy of Sciences (China); Webb, Steven B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Derrick C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); White, Karen S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Jinkui [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-01-01

    The Second Target Station (STS) is a proposed upgrade for SNS. It includes a doubling of the accelerator power and an additional instrument hall. The new instrument hall will receive a 467 kW 10 Hz beam. The parameters and preliminary design aspects of the STS are presented for the accelerator, target systems, instrument hall, instruments and civil construction aspects.

  8. Code and codeless ionospheric measurements with NASA's Rogue GPS Receiver

    Science.gov (United States)

    Srinivasan, Jeff M.; Meehan, Tom K.; Young, Lawrence E.

    1989-01-01

    The NASA/JPL Rogue Receiver is an 8-satellite, non-multiplexed, highly digital global positioning system (GPS) receiver that can obtain dual frequency data either with or without knowledge of the P-code. In addition to its applications for high accuracy geodesy and orbit determination, the Rogue uses GPS satellite signals to measure the total electron content (TEC) of the ionosphere along the lines of sight from the receiver to the satellites. These measurements are used by JPL's Deep Space Network (DSN) for calibrating radiometric data. This paper will discuss Rogue TEC measurements, emphasizing the advantages of a receiver that can use the P-code, when available, but can also obtain reliable dual frequency data when the code is encrypted.

  9. Visibility conflict resolution for multiple antennae and multi-satellites via genetic algorithm

    Science.gov (United States)

    Lee, Junghyun; Hyun, Chung; Ahn, Hyosung; Wang, Semyung; Choi, Sujin; Jung, Okchul; Chung, Daewon; Ko, Kwanghee

    Satellite mission control systems typically are operated by scheduling missions to the visibility between ground stations and satellites. The communication for the mission is achieved by interacting with satellite visibility and ground station support. Specifically, the satellite forms a cone-type visibility passing over a ground station, and the antennas of ground stations support the satellite. When two or more satellites pass by at the same time or consecutively, the satellites may generate a visibility conflict. As the number of satellites increases, solving visibility conflict becomes important issue. In this study, we propose a visibility conflict resolution algorithm of multi-satellites by using a genetic algorithm (GA). The problem is converted to scheduling optimization modeling. The visibility of satellites and the supports of antennas are considered as tasks and resources individually. The visibility of satellites is allocated to the total support time of antennas as much as possible for users to obtain the maximum benefit. We focus on a genetic algorithm approach because the problem is complex and not defined explicitly. The genetic algorithm can be applied to such a complex model since it only needs an objective function and can approach a global optimum. However, the mathematical proof of global optimality for the genetic algorithm is very challenging. Therefore, we apply a greedy algorithm and show that our genetic approach is reasonable by comparing with the performance of greedy algorithm application.

  10. UAS CNPC Satellite Link Performance - Sharing Spectrum with Terrestrial Systems

    Science.gov (United States)

    Kerczewski, Robert J.; Wilson, Jeffrey D.; Bishop, William D.

    2016-01-01

    In order to provide for the safe integration of unmanned aircraft systems into the National Airspace System, the control and non-payload communications (CNPC) link connecting the ground-based pilot with the unmanned aircraft must be highly reliable. A specific requirement is that it must operate using aviation safety radiofrequency spectrum. The 2012 World Radiocommunication Conference (WRC-12) provided a potentially suitable allocation for radio line-of-sight (LOS), terrestrial based CNPC link at 5030-5091 MHz. For a beyond radio line-of-sight (BLOS), satellite-based CNPC link, aviation safety spectrum allocations are currently inadequate. Therefore, the 2015 WRC will consider the use of Fixed Satellite Service (FSS) bands to provide BLOS CNPC under Agenda Item 1.5. This agenda item requires studies to be conducted to allow for the consideration of how unmanned aircraft can employ FSS for BLOS CNPC while maintaining existing systems. Since there are terrestrial Fixed Service systems also using the same frequency bands under consideration in Agenda Item 1.5 one of the studies required considered spectrum sharing between earth stations on-board unmanned aircraft and Fixed Service station receivers. Studies carried out by NASA have concluded that such sharing is possible under parameters previously established by the International Telecommunications Union. As the preparation for WRC-15 has progressed, additional study parameters Agenda Item 1.5 have been proposed, and some studies using these parameters have been added. This paper examines the study results for the original parameters as well as results considering some of the more recently proposed parameters to provide insight into the complicated process of resolving WRC-15 Agenda Item 1.5 and achieving a solution for BLOS CNPC for unmanned aircraft.

  11. Secure base stations

    NARCIS (Netherlands)

    Bosch, Peter; Brusilovsky, Alec; McLellan, Rae; Mullender, Sape; Polakos, Paul

    2009-01-01

    With the introduction of the third generation (3G) Universal Mobile Telecommunications System (UMTS) base station router (BSR) and fourth generation (4G) base stations, such as the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Evolved Node B (eNB), it has become important to se

  12. SPS rectifier stations

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    The first of the twelves SPS rectifier stations for the bending magnets arrived at CERN at the end of the year. The photograph shows a station with the rectifiers on the left and in the other three cubicles the chokes, capacitors and resistor of the passive filter.

  13. "Inventive" Learning Stations

    Science.gov (United States)

    Jarrett, Olga

    2010-01-01

    Learning stations can be used for myriad purposes--to teach concepts, integrate subject matter, build interest, and allow for inquiry--the possibilities are limited only by the imagination of the teacher and the supplies available. In this article, the author shares suggestions and a checklist for setting up successful learning stations. In…

  14. "Inventive" Learning Stations

    Science.gov (United States)

    Jarrett, Olga

    2010-01-01

    Learning stations can be used for myriad purposes--to teach concepts, integrate subject matter, build interest, and allow for inquiry--the possibilities are limited only by the imagination of the teacher and the supplies available. In this article, the author shares suggestions and a checklist for setting up successful learning stations. In…

  15. Meyrin Petrol Station

    CERN Multimedia

    2006-01-01

    Please note that the Meyrin petrol station will be closed for maintenance work on Tuesday 19 and Wednesday 20 December 2006. If you require petrol during this period we invite you to use the Prévessin petrol station, which will remain open. TS-IC-LO Section Tel.: 77039 - 73793

  16. MOBILLAB-NIVA - a complete station for monitoring water quality

    OpenAIRE

    A. Henriksen; Røgeberg, E.; Andersen, S.; Veidel, A.

    1986-01-01

    MOBILLAB-NIVA is a complete mobile station for monitoring water quality with telemetric transmission of recorded data to a central receiving station. It is intended for use in studies of rapid changes in water quality and its effects on aquatic life and short term studies to decide on water quality monitoring strategy. The present version of Mobillab-niva is specially designed to study effects of acid inputs on water chemistry, fish and invertebrates. The station is equipped with physical and...

  17. The Roman stational liturgy

    Directory of Open Access Journals (Sweden)

    Janusz Mieczkowski

    2012-03-01

    Full Text Available The papal stational liturgy in Rome was a particular kind of worship service from the Christian Antiquity to the XIV century. Its essential elements are four. Its always took place under the leadership of the pope or his representative. This form of liturgy was mobile: it was celebrated in different basilicas or churches of Rome. Third, the choice of church depended on the feast, liturgical seasons or commemoration being celebrated. Fourth, the stational liturgy was the urban liturgical celebration of the day. The highpoint of this system was Lent. Throughout the entire system Church of Rome manifested its own unity. The station was usually the Pope’s solemn mass in the stational church for the whole city. But on certain days in the year the Pope went in another church (collecta, from which a solemn procession was made to the stational church.

  18. Central Station Design Options

    DEFF Research Database (Denmark)

    2011-01-01

    The purpose of EDISON Work Package 4.1 is the evaluation of possible Central (charging) Stations design options for making possible the public charging of Electric Vehicles (EVs). A number of scenarios for EVs are assessed, with special emphasis on the options of Fast Charging and Battery Swapping....... The work identifies the architecture, sizing and siting of prospective Central Stations in Denmark, which can be located at shopping centers, large car parking lots or gas stations. Central Stations are planned to be integrated in the Danish distribution grid. The Danish island of Bornholm, where a high.......g. due to vandalism, the charge supply circuit is disconnected. More electrical vehicles on the market are capable today of quick charging up to 50 kW power level. The feasibility of Central Stations with fast charging/swapping option, their capacity, design, costs and grid impact, as well as battery...

  19. Transportable optical ground station for high-speed free-space laser communication

    Science.gov (United States)

    Shrestha, Amita; Brechtelsbauer, Martin

    2012-10-01

    Near real-time data downlinks from aircrafts, satellites and high altitude platforms via high-speed laser commu- nication links is an important research topic at the Institute of Communications and Navigation of the German Aerospace Center (DLR). Ground stations for such scenarios are usually fixed at a certain location. With a mo- tivation to provide a ground station that is quickly and easily deployed anywhere in the world, a transportable optical ground station (TOGS) has been developed. TOGS features a pneumatically deployable Cassegrain-type telescope with main mirror diameter of 60 cm, including optical tracking and receiving system. For calibration of position and attitude, multiple sensors like dual-antenna GPS and inclination sensors have been installed. In order to realize these systems, robust software that operates and controls them is essential. The software is platform independent and is aimed to be used on both mobile and ground terminals. It includes implementa- tion of accurate pointing, acquisition and tracking algorithms, hardware drivers, and user interfaces. Important modules of the software are GPS tracking, optical tracking, star- and satellite tracking, and calibration of the TOGS itself. Recently, a first successful data-downlink from an aircraft to TOGS using GPS tracking has been performed. To streamline the software development and testing process, some simulation environments like mount simulator, aircraft path simulator, tracking camera simulator and tracking error analysis tool have also been developed. This paper presents the overall hardware/software structure of the TOGS, and gives results of the tracking accuracy improvement techniques like GPS extrapolation and optical tracking.

  20. A GPS Receiver for Lunar Missions

    Science.gov (United States)

    Bamford, William A.; Heckler, Gregory W.; Holt, Greg N.; Moreau, Michael C.

    2008-01-01

    Beginning with the launch of the Lunar Reconnaissance Orbiter (LRO) in October of 2008, NASA will once again begin its quest to land humans on the Moon. This effort will require the development of new spacecraft which will safely transport people from the Earth to the Moon and back again, as well as robotic probes tagged with science, re-supply, and communication duties. In addition to the next-generation spacecraft currently under construction, including the Orion capsule, NASA is also investigating and developing cutting edge navigation sensors which will allow for autonomous state estimation in low Earth orbit (LEO) and cislunar space. Such instruments could provide an extra layer of redundancy in avionics systems and reduce the reliance on support and on the Deep Space Network (DSN). One such sensor is the weak-signal Global Positioning System (GPS) receiver "Navigator" being developed at NASA's Goddard Space Flight Center (GSFC). At the heart of the Navigator is a Field Programmable Gate Array (FPGA) based acquisition engine. This engine allows for the rapid acquisition/reacquisition of strong GPS signals, enabling the receiver to quickly recover from outages due to blocked satellites or atmospheric entry. Additionally, the acquisition algorithm provides significantly lower sensitivities than a conventional space-based GPS receiver, permitting it to acquire satellites well above the GPS constellation. This paper assesses the performance of the Navigator receiver based upon three of the major flight regimes of a manned lunar mission: Earth ascent, cislunar navigation, and entry. Representative trajectories for each of these segments were provided by NASA. The Navigator receiver was connected to a Spirent GPS signal generator, to allow for the collection of real-time, hardware-in-the-loop results for each phase of the flight. For each of the flight segments, the Navigator was tested on its ability to acquire and track GPS satellites under the dynamical

  1. Concept design of HAYATE : Small satellite for supporting Antarctic geophysical observation

    OpenAIRE

    Yoshihara, Keisuke; Sugiura, Yoshiki; Sekiguchi,Masato; Ui, Kyoichi; Tsurumi,Singo; Nakaya, Koji; Mori, Makoto; Matsunaga, Saburo; Ohkami, Yoshiaki

    1999-01-01

    This paper presents the results of conceptual design of a small communication satellite (HAYATE) for supporting research in Antarctica and remote islands. The HAY ATE satellite collects environmental data from unmanned probes located on the Antarctic ice plate and also transmits data from Syowa Station in Antarctica to Japan and the United States. Through the satellite mission analyses, we confirmed that the HAYATE satellite would be able to gather data for GPS baseline analysis and to observ...

  2. The power relay satellite

    Science.gov (United States)

    Glaser, Peter E.

    The availability and use of renewable energy sources compatible with reducing risks to the global environment are key to sustainable development. Large-scale, renewable energy resources at undeveloped or underutilized sites are potentially available on several continents. The Power Relay Satellite (PRS) concept has the potential to access these remote energy resources by coupling primary electricity generation from terrestrial transmission lines. A global PRS network can be envisioned to provide a high degree of flexibility for supplying energy demands worldwide with wireless power transmitted from sites on Earth to geosynchronous orbit and then reflected to receivers interfacing with terrestrial power transmision networks. Past developments in wireless power transmission (WPT) are reviewed and recent successful results are noted. The origins of the PRS concept, and a possible configuration are discussed, principles of WPT at microwave frequencies, functional requirements, and system design contraints are outlined, and space transportation concepts presented. PRS assessments including applicable technologies, economic projections, and societal issues are highlighted. It is concluded that the PRS provides a promising option to access renewable resources at great distances from major markets, and represents an important stage in the future development in the future of solar power satellites.

  3. Preliminary Electrical Designs for CTEX and AFIT Satellite Ground Station

    Science.gov (United States)

    2010-03-01

    activated failsafe marker != 0 = 0 Tube 2 Tube 3 Shutdown Describes the primary operation of the experiment control system. [DiS01] Tube Processes: Each...the 400-1,200 nm range. This band is known to contain peaks for Hematites , Geothites and other iron bearing minerals [2]. Looking at this data and...Motion Controllers Motor Amplifier PSU DCCU Power 12-30V DC 56V AC USB General Purpose I/O 32-PIN Proprietary Connection Ethernet Primary Data

  4. Al-Manar and Alhurra: Competing Satellite Stations and Ideologies

    Science.gov (United States)

    2006-10-01

    Other programmes for children include American movies such as Rain Man and Disney cartoons.53 Some programmes are religiously-oriented. One game...are from the point of the view of that enemy, rubbing salt in the wound, as it were. Al-Manar does not conform to stereotypes of it (or of Hizbullah

  5. NUTS: Ground station with GNU Radio and USRP

    OpenAIRE

    Vea, Karl David

    2015-01-01

    Study and describe GNU Radio together with USRP as alternative ground station. Describe and analyze GMSK signal. NGHam link protcol implementation. Simulation on demodulation considering how frequency synchronization can be achieved. Discuss if and how GNU Radio suits the uneversity satellite project.

  6. 47 CFR 22.507 - Number of transmitters per station.

    Science.gov (United States)

    2010-10-01

    ..., stand-alone transmitter is linked to the system via a control/repeater facility or by satellite... 47 Telecommunication 2 2010-10-01 2010-10-01 false Number of transmitters per station. 22.507 Section 22.507 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES...

  7. An enhanced algorithm to estimate BDS satellite's differential code biases

    Science.gov (United States)

    Shi, Chuang; Fan, Lei; Li, Min; Liu, Zhizhao; Gu, Shengfeng; Zhong, Shiming; Song, Weiwei

    2016-02-01

    This paper proposes an enhanced algorithm to estimate the differential code biases (DCB) on three frequencies of the BeiDou Navigation Satellite System (BDS) satellites. By forming ionospheric observables derived from uncombined precise point positioning and geometry-free linear combination of phase-smoothed range, satellite DCBs are determined together with ionospheric delay that is modeled at each individual station. Specifically, the DCB and ionospheric delay are estimated in a weighted least-squares estimator by considering the precision of ionospheric observables, and a misclosure constraint for different types of satellite DCBs is introduced. This algorithm was tested by GNSS data collected in November and December 2013 from 29 stations of Multi-GNSS Experiment (MGEX) and BeiDou Experimental Tracking Stations. Results show that the proposed algorithm is able to precisely estimate BDS satellite DCBs, where the mean value of day-to-day scattering is about 0.19 ns and the RMS of the difference with respect to MGEX DCB products is about 0.24 ns. In order to make comparison, an existing algorithm based on IGG: Institute of Geodesy and Geophysics, China (IGGDCB), is also used to process the same dataset. Results show that, the DCB difference between results from the enhanced algorithm and the DCB products from Center for Orbit Determination in Europe (CODE) and MGEX is reduced in average by 46 % for GPS satellites and 14 % for BDS satellites, when compared with DCB difference between the results of IGGDCB algorithm and the DCB products from CODE and MGEX. In addition, we find the day-to-day scattering of BDS IGSO satellites is obviously lower than that of GEO and MEO satellites, and a significant bias exists in daily DCB values of GEO satellites comparing with MGEX DCB product. This proposed algorithm also provides a new approach to estimate the satellite DCBs of multiple GNSS systems.

  8. 75 FR 44198 - Implementation of Section 203 of the Satellite Television Extension and Localism Act of 2010...

    Science.gov (United States)

    2010-07-28

    ...\\ See Cable Television Report and Order, FCC 72-108, 37 FR 3252, February 3, 1972 (adopting the concept... precondition to satellite carriage of the HD programming of an SV station affiliated with the same network. We... signal of a broadcast station access to broadcast programming via satellite.\\19\\ The 1988 SHVA...

  9. Automatic Detection of Omega Signals Captured by the Poynting Flux Analyzer (PFX) on Board the Akebono Satellite

    CERN Document Server

    Suarjaya, I Made Agus Dwi; Goto, Yoshitaka

    2016-01-01

    The Akebono satellite was launched in 1989 to observe the Earth's magnetosphere and plasmasphere. Omega was a navigation system with 8 ground stations transmitter and had transmission pattern that repeats every 10 s. From 1989 to 1997, the PFX on board the Akebono satellite received signals at 10.2 kHz from these stations. Huge amounts of PFX data became valuable for studying the propagation characteristics of VLF waves in the ionosphere and plasmasphere. In this study, we introduce a method for automatic detection of Omega signals from the PFX data in a systematic way, it involves identifying a transmission station, calculating the delay time, and estimating the signal intensity. We show the reliability of the automatic detection system where we able to detect the omega signal and confirmed its propagation to the opposite hemisphere along the Earth's magnetic field lines. For more than three years (39 months), we detected 43,734 and 111,049 signals in the magnetic and electric field, respectively, and demons...

  10. Automatic Detection of Omega Signals Captured by the Poynting Flux Analyzer (PFX on Board the Akebono Satellite

    Directory of Open Access Journals (Sweden)

    Made Agus Dwi Suarjaya

    2016-10-01

    Full Text Available The Akebono satellite was launched in 1989 to observe the Earth’s magnetosphere and plasmasphere. Omega was a navigation system with 8 ground stations transmitter and had transmission pattern that repeats every 10 s. From 1989 to 1997, the PFX on board the Akebono satellite received signals at 10.2 kHz from these stations. Huge amounts of PFX data became valuable for studying the propagation characteristics of VLF waves in the ionosphere and plasmasphere. In this study, we introduce a method for automatic detection of Omega signals from the PFX data in a systematic way, it involves identifying a transmission station, calculating the delay time, and estimating the signal intensity. We show the reliability of the automatic detection system where we able to detect the omega signal and confirmed its propagation to the opposite hemisphere along the Earth’s magnetic field lines. For more than three years (39 months, we detected 43,734 and 111,049 signals in the magnetic and electric field, respectively, and demonstrated that the proposed method is powerful enough for the statistical analyses.

  11. Satellite B-ISDN traffic analysis

    Science.gov (United States)

    Shyy, Dong-Jye; Inukai, Thomas

    1991-01-01

    The impact of asynchronous transfer mode (ATM) traffic on the advanced satellite broadband integrated services digital network (B-ISDN) with onboard processing is reported. Simulation models were built to analyze the cell transfer performance through the statistical multiplexer at the earth station and the fast packet switch at the satellite. The effectiveness of ground ATM cell preprocessing was established, as well as the performance of several schemes for improving the down-link beam utilization when the space segment employs a fast packet switch.

  12. Robust Satellite Communications Under Hostile Interference

    Science.gov (United States)

    2015-01-08

    Gaussian Noise BER Bit Error Rate BLER Block Error Rate BPSK Binary Phase Shift Keying CODEC Coder and Decoder CRC Cyclic Redundancy Check dB...Satellite Communication SNR Signal to Noise Ratio STK Systems Took Kit TDRS Tracking and Data Relay Satellite Toff Idle Time of a Transmitter Ton...Received Signal-to- Noise Ratio at the Jammer ...................................................... 15  3.2.2  SNR Threshold for Repeating the Signal

  13. Relative receiver autonomous integrity monitoring for future GNSS-based aircraft navigation

    Science.gov (United States)

    Gratton, Livio Rafael

    The Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of flight for more than a decade. Intense research is currently devoted to extending the use of Global Navigation Satellite Systems (GNSS), including GPS, to precision approach and landing operations. In this context, this work is focused on the development, analysis, and verification of the concept of Relative Receiver Autonomous Integrity Monitoring (RRAIM) and its potential applications to precision approach navigation. RRAIM fault detection algorithms are developed, and associated mathematical bounds on position error are derived. These are investigated as possible solutions to some current key challenges in precision approach navigation, discussed below. Augmentation systems serving continent-size areas (like the Wide Area Augmentation System or WAAS) allow certain precision approach operations within the covered region. More and better satellites, with dual frequency capabilities, are expected to be in orbit in the mid-term future, which will potentially allow WAAS-like capabilities worldwide with a sparse ground station network. Two main challenges in achieving this goal are (1) ensuring that navigation fault detection functions are fast enough to alert worldwide users of hazardously misleading information, and (2) minimizing situations in which navigation is unavailable because the user's local satellite geometry is insufficient for safe position estimation. Local augmentation systems (implemented at individual airports, like the Local Area Augmentation System or LAAS) have the potential to allow precision approach and landing operations by providing precise corrections to user-satellite range measurements. An exception to these capabilities arises during ionospheric storms (caused by solar activity), when hazardous situations can exist with residual range errors several orders of magnitudes higher than nominal. Until dual

  14. Space vehicle field unit and ground station system

    Energy Technology Data Exchange (ETDEWEB)

    Judd, Stephen; Dallmann, Nicholas; Delapp, Jerry; Proicou, Michael; Seitz, Daniel; Michel, John; Enemark, Donald

    2017-09-19

    A field unit and ground station may use commercial off-the-shelf (COTS) components and share a common architecture, where differences in functionality are governed by software. The field units and ground stations may be easy to deploy, relatively inexpensive, and be relatively easy to operate. A novel file system may be used where datagrams of a file may be stored across multiple drives and/or devices. The datagrams may be received out of order and reassembled at the receiving device.

  15. Space vehicle field unit and ground station system

    Science.gov (United States)

    Judd, Stephen; Dallmann, Nicholas; Delapp, Jerry; Proicou, Michael; Seitz, Daniel; Michel, John; Enemark, Donald

    2016-10-25

    A field unit and ground station may use commercial off-the-shelf (COTS) components and share a common architecture, where differences in functionality are governed by software. The field units and ground stations may be easy to deploy, relatively inexpensive, and be relatively easy to operate. A novel file system may be used where datagrams of a file may be stored across multiple drives and/or devices. The datagrams may be received out of order and reassembled at the receiving device.

  16. The Galilean Satellites

    Science.gov (United States)

    1998-01-01

    This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. The Galilean satellites were first seen by the Italian astronomer Galileo Galilei in 1610. Shown from left to right in order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto.The order of these satellites from the planet Jupiter helps to explain some of the visible differences among the moons. Io is subject to the strongest tidal stresses from the massive planet. These stresses generate internal heating which is released at the surface and makes Io the most volcanically active body in our solar system. Europa appears to be strongly differentiated with a rock/iron core, an ice layer at its surface, and the potential for local or global zones of water between these layers. Tectonic resurfacing brightens terrain on the less active and partially differentiated moon Ganymede. Callisto, furthest from Jupiter, appears heavily cratered at low resolutions and shows no evidence of internal activity.North is to the top of this composite picture in which these satellites have all been scaled to a common factor of 10 kilometers (6 miles) per picture element.The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft acquired the Io and Ganymede images in June 1996, the Europa images in September 1996, and the Callisto images in November 1997.Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission

  17. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  18. Vertical profiling of atmospheric refractivity using GPS STD data from a single ground-based station: Simulations and applications

    Science.gov (United States)

    Zus, F.; Dick, G.; Heise, S.; Wickert, J.; Ramatschi, M.

    2013-12-01

    We developed a ray-tracing operator to compute the signal travel time delay due to the neutral atmosphere, known as Slant Total Delay (STD), between a GPS satellite and a ground-based receiving station. Having developed a rapid and precise forward operator we constructed the tangent-linear (adjoint) operator to estimate refractivity in the vicinity of a single station. The refractivity retrievals potentially complement refractivity retrievals from radio occultation data and can be considered a valuable input for Numerical Weather Prediction. In a first experiment (simulation) we study the feasibility for vertical profiling of refractivity using STDs from a single station. The simulation cycle consists of the computation of STDs given a refractivity profile, the addition of noise to mimic observation errors and the retrieval of a refractivity profile from the artificial STDs by a non-linear least-square analysis. Clearly, besides the noise level, the elevation range plays an important role regarding the quality of the refractivity retrieval; near-horizon STDs corrupted by noise allow a significantly better refractivity retrieval than STDs close to the zenith without any noise. The simulation study suggests that near-horizon STDs provide additional information when compared to Zenith Total Delays (ZTDs). In a second experiment (application) we replace the artificial STDs in the simulation by STDs retrieved from GPS phase-observations. The procedure is repeated station-by-station for 200 stations in Germany. We do not find a significant benefit from STDs over ZTDs in the retrieved refractivity profile since near-horizon STDs are rarely available and representative errors due to asymmetry are non-negligable. We attempt to mitigate the latter problem by the additional estimation of horizontal gradients, and indeed, we find strong evidence that STDs retrieved from GPS phase-observations contain asymmetric information. The former problem still poses a serious limitation

  19. Waste Transfer Stations

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund

    2011-01-01

    tion and transport is usually the most costly part of any waste management system; and when waste is transported over a considerable distance or for a long time, transferring the waste from the collection vehicles to more efficient transportation may be economically beneficial. This involves...... a transfer station where the transfer takes place. These stations may also be accessible by private people, offering flexibility to the waste system, including facilities for bulky waste, household hazardous waste and recyclables. Waste transfer may also take place on the collection route from small...... describes the main features of waste transfer stations, including some considerations about the economical aspects on when transfer is advisable....

  20. Space station operations management

    Science.gov (United States)

    Cannon, Kathleen V.

    1989-01-01

    Space Station Freedom operations management concepts must be responsive to the unique challenges presented by the permanently manned international laboratory. Space Station Freedom will be assembled over a three year period where the operational environment will change as significant capability plateaus are reached. First Element Launch, Man-Tended Capability, and Permanent Manned Capability, represent milestones in operational capability that is increasing toward mature operations capability. Operations management concepts are being developed to accomodate the varying operational capabilities during assembly, as well as the mature operational environment. This paper describes operations management concepts designed to accomodate the uniqueness of Space Station Freedoom, utilizing tools and processes that seek to control operations costs.

  1. Integration of Quantum Cryptography through Satellite Networks Transmission

    Directory of Open Access Journals (Sweden)

    Skander Aris

    2011-01-01

    Full Text Available Problem statement: The security of the telecommunications satellite has become a crucial issue. The telecommunications can be set using the classical cryptography. But this so-called classical cryptography provides cryptographic security. This means that security is based on the difficulty of some mathematics problems. On the other hand, quantum cryptography provides security without conditions based on the law of quantum physics. This method, called the theoretic information security is evidenced using the theory of information. Approach: In this study, we study whether quantum cryptography can be applied in the frame of the satellite telecommunications network. To do this in our project, we present theories regarding the following issues: Telecommunications Station and Satellite Communication Networks, Quantum Key Distribution, Open Space and Satellites, Analyses in different Scenarios between the Satellite and Earth station. Results: Quantum communications offers many advantages for secure data transmission, in our implementation study, we presented different scenarios of quantum key exchange between satellites and ground stations for possible approach to subsystem with quantum communication in space, capable of generating and detecting entangled photons as well as faint laser pulses. Conclusion: The use of satellites to distribute quantum photon provides a unique solution for long-distance. Moreover, quantum cryptography is a satisfactory solution to improve the safety problem. So, the quantum transmissions are the future of telecommunications.

  2. Analyses for a Modernized GNSS Radio Occultation Receiver

    Science.gov (United States)

    Griggs, Erin R.

    Global Navigation Satellite System (GNSS) radio occultation (RO) is a remote sensing technique that exploits existing navigation signals to make global, real-time observations of the Earth's atmosphere. A specialized RO receiver makes measurements of signals originating from a transmitter onboard a GNSS spacecraft near the Earth's horizon. The radio wave is altered during passage through the Earth's atmosphere. The changes in the received signals are translated to the refractivity characteristics of the intervening medium, which enable the calculation of atmospheric pressure, temperature, and humidity. Current satellite missions employing GNSS RO have provided invaluable and timely information for weather and climate applications. Existing constellations of occultation satellites, however, are aging and producing fewer quality measurements. Replacement fleets of RO satellites are imperative to sustain and improve the global coverage and operational impact achieved by the current generation of RO satellites. This dissertation describes studies that facilitate the development of next generation RO receivers and satellite constellations. Multiple research efforts were conducted that aim to improve the quantity and quality of measurements made by a future satellite-based RO collection system. These studies range in magnitude and impact, and begin with a receiver development study using ground-based occultation data. Future RO constellations and collection opportunities were simulated and autonomous occultation prediction and scheduling capabilities were implemented. Finally, a comprehensive study was conducted to characterize the stability of the GNSS atomic frequency standards. Oscillator stability for a subset of satellites in the GNSS was found to be of insufficient quality at timescales relevant to RO collections and would degrade the atmospheric profiling capabilities of an RO system utilizing these signals. Recommendations for a high-rate clock correction network

  3. Satellite clock corrections estimation to accomplish real time ppp: experiments for brazilian real time network

    Science.gov (United States)

    Marques, Haroldo; Monico, João; Aquino, Marcio; Melo, Weyller

    2014-05-01

    The real time PPP method requires the availability of real time precise orbits and satellites clocks corrections. Currently, it is possible to apply the solutions of clocks and orbits available by BKG within the context of IGS Pilot project or by using the operational predicted IGU ephemeris. The accuracy of the satellite position available in the IGU is enough for several applications requiring good quality. However, the satellites clocks corrections do not provide enough accuracy (3 ns ~ 0.9 m) to accomplish real time PPP with the same level of accuracy. Therefore, for real time PPP application it is necessary to further research and develop appropriated methodologies for estimating the satellite clock corrections in real time with better accuracy. Currently, it is possible to apply the real time solutions of clocks and orbits available by Federal Agency for Cartography and Geodesy (BKG) within the context of IGS Pilot project. The BKG corrections are disseminated by a new proposed format of the RTCM 3.x and can be applied in the broadcasted orbits and clocks. Some investigations have been proposed for the estimation of the satellite clock corrections using GNSS code and phase observable at the double difference level between satellites and epochs (MERVAT, DOUSA, 2007). Another possibility consists of applying a Kalman Filter in the PPP network mode (HAUSCHILD, 2010) and it is also possible the integration of both methods, using network PPP and observables at double difference level in specific time intervals (ZHANG; LI; GUO, 2010). For this work the methodology adopted consists in the estimation of the satellite clock corrections based on the data adjustment in the PPP mode, but for a network of GNSS stations. The clock solution can be solved by using two types of observables: code smoothed by carrier phase or undifferenced code together with carrier phase. In the former, we estimate receiver clock error; satellite clock correction and troposphere, considering

  4. An Investigation on Advantages of Utilizing Adaptive Bit Rate for LEO Satellite Link Engineering

    Directory of Open Access Journals (Sweden)

    Mehdi Hosseini

    2012-09-01

    Full Text Available The paper aims to investigate the advantages of using adaptive bit rate in the communication link of a LEO satellite. While doing the study, it is assumed that there is a communication subsystem on-board responsible for gathering the information sent by a number of ground user terminals. The subsystem which operates based on Store-and-Forward (SAF Scenario, contains two communication links, one for receiving data from user terminals (store case, and the other for forwarding the stored data to an Earth station (forward case. In fact, the current work aims to improve the volume of the data forwarded to Earth station. To this end, the Forward case bit rate is varied adaptively, and then by analyzing the power budget in a practical condition, the improvement achieved is evaluated. The results specifically obtained for a sample LEO satellite shows that utilizing adaptive bit rate instead of fixed bit rate can increase the daily data exchange up to about 100%.

  5. Signal Station Inspection Reports

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Handwritten reports resulting from detailed inspections of US Army Signal Service Stations, 1871-1889. Features reported included instrument exposure and condition,...

  6. FEMA DFIRM Station Start

    Data.gov (United States)

    Minnesota Department of Natural Resources — This table contains information about station starting locations. These locations indicate the reference point that was used as the origin for distance measurements...

  7. "Central Station" Londonis

    Index Scriptorium Estoniae

    2000-01-01

    Londoni galeriis Milch seitsme läti, leedu ja eesti kunstniku projekt "Central Station". Kuraatorid Lisa Panting, Sally Tallant. Eestist osalevad Hanno Soans (Catarina Campinoga koostöös valminud video), Kiwa, Kai Kaljo

  8. Realtime USGS Streamflow Stations

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Approximately 5,000 of the 6,900 U.S. Geological Survey sampling stations are equipped with telemetry to transmit data on streamflow, temperature, and other...

  9. "Central Station" Londonis

    Index Scriptorium Estoniae

    2000-01-01

    Londoni galeriis Milch seitsme läti, leedu ja eesti kunstniku projekt "Central Station". Kuraatorid Lisa Panting, Sally Tallant. Eestist osalevad Hanno Soans (Catarina Campinoga koostöös valminud video), Kiwa, Kai Kaljo

  10. ASOS Station Photos

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The images contained in this library are of stations in the Automated Surface Observing System (ASOS) network. These images were taken between 1998-2001 for the ASOS...

  11. Master Station History Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Standard/Legacy MSHR, formally identified as the DSI-9767 dataset, is the legacy dataset/report sorted by NCDC Station ID and period of record. This...

  12. Materials Test Station

    Data.gov (United States)

    Federal Laboratory Consortium — When completed, the Materials Test Station at the Los Alamos Neutron Science Center will meet mission need. MTS will provide the only fast-reactor-like irradiation...

  13. Natural Weathering Exposure Station

    Data.gov (United States)

    Federal Laboratory Consortium — The Corps of Engineers' Treat Island Natural Weathering Exposure Station is a long-term natural weathering facility used to study concrete durability. Located on the...

  14. Station Management Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The following plan is the result of a recent initiative in Region 5 to produce general management guidance based on stated objectives for individual field stations....

  15. Maine Field Station

    Data.gov (United States)

    Federal Laboratory Consortium — In 2000 NOAA's National Marine Fisheries Service established the Maine Field Station in Orono, ME to have more direct involvement in the conservation of the living...

  16. Electrostatic pickup station

    CERN Multimedia

    CERN PhotoLab

    1982-01-01

    Electrostatic pickup station, with 4 interleaved electrodes, to measure beam position in the horizontal and vertical plane. This type is used in the transfer lines leaving the PS (TT2, TT70, TTL2). See also 7904075.

  17. USRCRN Station Information

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Documentation of United States Regional Climate Reference Network (USRCRN) installations in 2009. Installations documented are for USRCRN pilot project stations in...

  18. Space Station Food System

    Science.gov (United States)

    Thurmond, Beverly A.; Gillan, Douglas J.; Perchonok, Michele G.; Marcus, Beth A.; Bourland, Charles T.

    1986-01-01

    A team of engineers and food scientists from NASA, the aerospace industry, food companies, and academia are defining the Space Station Food System. The team identified the system requirements based on an analysis of past and current space food systems, food systems from isolated environment communities that resemble Space Station, and the projected Space Station parameters. The team is resolving conflicts among requirements through the use of trade-off analyses. The requirements will give rise to a set of specifications which, in turn, will be used to produce concepts. Concept verification will include testing of prototypes, both in 1-g and microgravity. The end-item specification provides an overall guide for assembling a functional food system for Space Station.

  19. Mukilteo Research Station

    Data.gov (United States)

    Federal Laboratory Consortium — Research at the Mukilteo Research Station focuses on understanding the life cycle of marine species and the impacts of ecosystem stressors on anadromous and marine...

  20. TV Analog Station Transmitters

    Data.gov (United States)

    Department of Homeland Security — This file is an extract from the Consolidated Database System (CDBS) licensed by the Media Bureau. It consists of Analog Television Stations (see Rule Part47 CFR...

  1. Public Transit Stations

    Data.gov (United States)

    Department of Homeland Security — fixed rail transit stations within the Continental United States, Alaska, Hawaii, the District of Columbia, and Puerto Rico. The modes of transit that are serviced...

  2. Routes and Stations

    Data.gov (United States)

    Department of Homeland Security — he Routes_Stations table is composed of fixed rail transit systems within the Continental United States, Alaska, Hawaii, the District of Columbia, and Puerto Rico....

  3. Active Marine Station Metadata

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Active Marine Station Metadata is a daily metadata report for active marine bouy and C-MAN (Coastal Marine Automated Network) platforms from the National Data...

  4. Design and implementation of the CAPS receiver

    Institute of Scientific and Technical Information of China (English)

    HU YongHui; HUA Yu; HOU Lei; WEI JingFa; WU JianFeng

    2009-01-01

    In this paper,baaed on analyses of the Chinese Area Positioning System (CAPS) satellite (GEO satellite) resources and signal properties,the signal power at the port of the receiver antenna is estimated,and the implementation projects are presented for a switching band C to band L CAPS C/A code receiver integrated with GPS receiver suite and for a CAPS dual frequency P code receiver.A microstrip receiving antenna is designed with high sensitivity and wide beam orientation,the RF front end of the C/A code and P code receivers,and a processor is designed for the navigation baseband.A single frequency CAPS C/A code receiver and a CAPS dual frequency P code receiver are built at the same time.A software process flow is provided,and research on relatively key techniques is also conducted,such as signal searching,code loop and carrier loop algorithms,a height assistant algorithm,a dual frequency difference speed measurement technique,a speed measurement technique using a single frequency source with frequency assistance,and a CAPS time correcting algorithm,according to the design frame of the receiver hardware.Research results show that the static plane positioning accuracy of the CAPS C/A code receiver is 20.5-24.6 m,height accuracy is 1.2-12.8 m,speed measurement accuracy is 0.13-0.3 m/s,dynamic plane positioning accuracy is 24.4 m,height accuracy is 3.0 m,and speed measurement accuracy is 0.24 m/s.In the case of C/A code,the timing accuracy is 200 ha,and it is also shown that the positioning accuracy of the CAPS precise code receiver (1σ) is 5 m from south to north,and 0.8 m from east to west.Finally,research on positioning accuracy is also conducted.

  5. The Lizard Wireless Station of Guglielmo Marconi

    Science.gov (United States)

    Montstein, Christian

    2014-08-01

    During the vacation with my wife in Cornwall, we by chance were walking by the Lizard wireless station, originally installed by Guglielmo Marconi and recently refurbished by The National Trust/UK. Fortunately the shed was open for public visitors and a student was present telling stories about the station and its history. The historic equipment was demonstrated by sending some Morse codes. The high voltage sparks and its sound were quite impressive while in the background the Morse code receiver punched dots and dashes onto the strip chart.

  6. Enhanced Master Station History Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Enhanced Master Station History Report (EMSHR) is a compiled list of basic, historical information for every station in the station history database, beginning...

  7. LARES succesfully launched in orbit: satellite and mission description

    CERN Document Server

    Paolozzi, Antonio

    2013-01-01

    On February 13th 2012, the LARES satellite of the Italian Space Agency (ASI) was launched into orbit with the qualification flight of the new VEGA launcher of the European Space Agency (ESA). The payload was released very accurately in the nominal orbit. The name LARES means LAser RElativity Satellite and summarises the objective of the mission and some characteristics of the satellite. It is, in fact, a mission designed to test Einstein's General Relativity Theory (specifically 'frame dragging' and Lense-Thirring effect). The satellite is passive and covered with optical retroreflectors that send back laser pulses to the emitting ground station. This allows accurate positioning of the satellite, which is important for measuring the very small deviations from Galilei-Newton's laws. In 2008, ASI selected the prime industrial contractor for the LARES system with a heavy involvement of the universities in all phases of the programme, from the design to the construction and testing of the satellite and separation...

  8. Olympus receiver evaluation and phase noise measurements

    Science.gov (United States)

    Campbell, Richard L.; Wang, Huailiang; Sweeney, Dennis

    1990-01-01

    A set of measurements performed by the Michigan Tech Sensing and Signal Processing Group on the analog receiver built by the Virginia Polytechnic Institute (VPI) and the Jet Propulsion Laboratory (JPL) for propagation measurements using the Olympus Satellite is described. Measurements of local oscillator (LO) phase noise were performed for all of the LOs supplied by JPL. In order to obtain the most useful set of measurements, LO phase noise measurements were made using the complete VPI receiver front end. This set of measurements demonstrates the performance of the receiver from the Radio Frequency (RF) input through the high Intermediate Frequency (IF) output. Three different measurements were made: LO phase noise with DC on the voltage controlled crystal oscillator (VCXO) port; LO phase noise with the 11.381 GHz LO locked to the reference signal generator; and a reference measurement with the JPL LOs out of the system.

  9. Centimeter-Level Robust Gnss-Aided Inertial Post-Processing for Mobile Mapping Without Local Reference Stations

    Science.gov (United States)

    Hutton, J. J.; Gopaul, N.; Zhang, X.; Wang, J.; Menon, V.; Rieck, D.; Kipka, A.; Pastor, F.

    2016-06-01

    For almost two decades mobile mapping systems have done their georeferencing using Global Navigation Satellite Systems (GNSS) to measure position and inertial sensors to measure orientation. In order to achieve cm level position accuracy, a technique referred to as post-processed carrier phase differential GNSS (DGNSS) is used. For this technique to be effective the maximum distance to a single Reference Station should be no more than 20 km, and when using a network of Reference Stations the distance to the nearest station should no more than about 70 km. This need to set up local Reference Stations limits productivity and increases costs, especially when mapping large areas or long linear features such as roads or pipelines. An alternative technique to DGNSS for high-accuracy positioning from GNSS is the so-called Precise Point Positioning or PPP method. In this case instead of differencing the rover observables with the Reference Station observables to cancel out common errors, an advanced model for every aspect of the GNSS error chain is developed and parameterized to within an accuracy of a few cm. The Trimble Centerpoint RTX positioning solution combines the methodology of PPP with advanced ambiguity resolution technology to produce cm level accuracies without the need for local reference stations. It achieves this through a global deployment of highly redundant monitoring stations that are connected through the internet and are used to determine the precise satellite data with maximum accuracy, robustness, continuity and reliability, along with advance algorithms and receiver and antenna calibrations. This paper presents a new post-processed realization of the Trimble Centerpoint RTX technology integrated into the Applanix POSPac MMS GNSS-Aided Inertial software for mobile mapping. Real-world results from over 100 airborne flights evaluated against a DGNSS network reference are presented which show that the post-processed Centerpoint RTX solution agrees with

  10. Leadership at Antarctic Stations.

    Science.gov (United States)

    1987-03-01

    Claseification 6. No. Pegees LEADERSHIP AT ANTARTIC STATIONS hxIs i4 5, C =r~eta(C), 17 Rfs~W (R, Udusiied U)J 7. No Refs 8. Author(s) Edocumesnt I...whether there is a "best" approach to leadership at an Antartic Station and what leadership style may have the most to offer. 3~~ __ ___ Tipesis to be

  11. LAERTIS, a multidisciplinary station

    Science.gov (United States)

    Aggouras, G.; Anassontzis, E. G.; Ball, A. E.; Chinowsky, W.; Fahrun, E.; Grammatikakis, G.; Green, C.; Grieder, P.; Katrivanos, P.; Koske, P.; Markopoulos, E.; Minkowsky, P.; Nygren, D.; Papageorgiou, K.; Przybylski, G.; Resvanis, L. K.; Siotis, I.; Sopher, J.; Tsagli, V.; Zhukov, V. A.

    2006-11-01

    LAERTIS, designed to collect environmental data from the deep-sea, is operated since 1999 and has been deployed several time at 4000 m depth at the NESTOR site. Power and data were transferred through a 30-km electro-optical cable to the Shore Station. In this report, we describe briefly the LAERTIS instrumentation and present typical data that were collected successfully during those deployment demonstrating the importance of a deep-sea station permanently connected to shore.

  12. Re-establishment of the IMS Hydroacoustic Station HA03, Robinson Crusoe Island, Chile

    Science.gov (United States)

    Haralabus, Georgios; Stanley, Jerry; Zampolli, Mario; Pautet, Lucie

    2015-04-01

    Water column hydrophone stations of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) International Monitoring System (IMS) comprise typically two triplets of moored hydrophones deployed on both sides of an island. Triplet distances vary approximately between 50 - 200 km from the island, with each triplet connected to the receiving shore equipment by fibre-optic submarine data cables. Once deployed, the systems relay underwater acoustic waveforms in the band 1 - 100 Hz in real time to Vienna via a shore based satellite link. The design life of hydroacoustic (HA) stations is at least 20 years, without need for any maintenance of the underwater system (UWS). The re-establishment of hydrophone station HA03 at Robinson Crusoe Island (670 km West of the Chilean mainland) is presented here. The station was destroyed in February 2010 by a Tsunami induced by an 8.8 magnitude earthquake. After a major engineering and logistical undertaking HA03 is now back in operation since April 2014. The main phases of the project are presented: (i) the installation of a shore facility for the reception of the hydrophone data from the UWS, which also relays the data back to the CTBTO International Data Center (IDC) in Vienna via a real-time satellite connection, (ii) the manufacturing and testing of the system to meet the stringent requirements of the Nuclear-Test-Ban Treaty, and (iii) the installation of the UWS with a state-of-the-art cable ship. Examples of data acquired by HA03 are also presented. These include hydroacoustic signals from the 1 April 2014 magnitude 8.2 earthquake in Northern Chile, bursting underwater bubbles from a submarine volcano near the Mariana Islands (15,000 Km away from the station), and vocalizations from the numerous marine mammals which transit in the vicinity of HA03. The use of CTBTO data for scientific purposes is possible via the virtual Data Exploitation Centre (vDEC), which is a platform that enables registered researchers to access

  13. Satellite ATM Networks: Architectures and Guidelines Developed

    Science.gov (United States)

    vonDeak, Thomas C.; Yegendu, Ferit

    1999-01-01

    An important element of satellite-supported asynchronous transfer mode (ATM) networking will involve support for the routing and rerouting of active connections. Work published under the auspices of the Telecommunications Industry Association (http://www.tiaonline.org), describes basic architectures and routing protocol issues for satellite ATM (SATATM) networks. The architectures and issues identified will serve as a basis for further development of technical specifications for these SATATM networks. Three ATM network architectures for bent pipe satellites and three ATM network architectures for satellites with onboard ATM switches were developed. The architectures differ from one another in terms of required level of mobility, supported data rates, supported terrestrial interfaces, and onboard processing and switching requirements. The documentation addresses low-, middle-, and geosynchronous-Earth-orbit satellite configurations. The satellite environment may require real-time routing to support the mobility of end devices and nodes of the ATM network itself. This requires the network to be able to reroute active circuits in real time. In addition to supporting mobility, rerouting can also be used to (1) optimize network routing, (2) respond to changing quality-of-service requirements, and (3) provide a fault tolerance mechanism. Traffic management and control functions are necessary in ATM to ensure that the quality-of-service requirements associated with each connection are not violated and also to provide flow and congestion control functions. Functions related to traffic management were identified and described. Most of these traffic management functions will be supported by on-ground ATM switches, but in a hybrid terrestrial-satellite ATM network, some of the traffic management functions may have to be supported by the onboard satellite ATM switch. Future work is planned to examine the tradeoffs of placing traffic management functions onboard a satellite as

  14. Parameter Impact on Sharing Studies Between UAS CNPC Satellite Transmitters and Terrestrial Systems

    Science.gov (United States)

    Kerczewski, Robert J.; Wilson, Jeffrey D.; Bishop, William D.

    2015-01-01

    In order to provide a control and non-payload communication (CNPC) link for civil-use unmanned aircraft systems (UAS) when operating in beyond-line-of-sight (BLOS) conditions, satellite communication links are generally required. The International Civil Aviation Organization (ICAO) has determined that the CNPC link must operate over protected aviation safety spectrum allocations. Although a suitable allocation exists in the 5030-5091 MHz band, no satellites provide operations in this band and none are currently planned. In order to avoid a very lengthy delay in the deployment of UAS in BLOS conditions, it has been proposed to use existing satellites operating in the Fixed Satellite Service (FSS), of which many operate in several spectrum bands. Regulatory actions by the International Telecommunications Union (ITU) are needed to enable such a use on an international basis, and indeed Agenda Item (AI) 1.5 for the 2015 World Radiocommunication Conference (WRC) was established to decide on the enactment of possible regulatory provisions. As part of the preparation for AI 1.5, studies on the sharing FSS bands between existing services and CNPC for UAS are being contributed by NASA and others. These studies evaluate the potential impact of satellite CNPC transmitters operating from UAS on other in-band services, and on the potential impact of other in-band services on satellite CNPC receivers operating on UAS platforms. Such studies are made more complex by the inclusion of what are essentially moving FSS earth stations, compared to typical sharing studies between fixed elements. Hence, the process of determining the appropriate technical parameters for the studies meets with difficulty. In order to enable a sharing study to be completed in a less-than-infinite amount of time, the number of parameters exercised must be greatly limited. Therefore, understanding the impact of various parameter choices is accomplished through selectivity analyses. In the case of sharing

  15. The Princess Elisabeth Station

    Science.gov (United States)

    Berte, Johan

    2012-01-01

    Aware of the increasing impact of human activities on the Earth system, Belgian Science Policy Office (Belspo) launched in 1997 a research programme in support of a sustainable development policy. This umbrella programme included the Belgian Scientific Programme on Antarctic Research. The International Polar Foundation, an organization led by the civil engineer and explorer Alain Hubert, was commissioned by the Belgian Federal government in 2004 to design, construct and operate a new Belgian Antarctic Research Station as an element under this umbrella programme. The station was to be designed as a central location for investigating the characteristic sequence of Antarctic geographical regions (polynia, coast, ice shelf, ice sheet, marginal mountain area and dry valleys, inland plateau) within a radius of 200 kilometers (approx.124 miles) of a selected site. The station was also to be designed as "state of the art" with respect to sustainable development, energy consumption, and waste disposal, with a minimum lifetime of 25 years. The goal of the project was to build a station and enable science. So first we needed some basic requirements, which I have listed here; plus we had to finance the station ourselves. Our most important requirement was that we decided to make it a zero emissions station. This was both a philosophical choice as we thought it more consistent with Antarctic Treaty obligations and it was also a logistical advantage. If you are using renewable energy sources, you do not have to bring in all the fuel.

  16. Applications of two-way satellite time and frequency transfer in the BeiDou navigation satellite system

    Science.gov (United States)

    Zhou, ShanShi; Hu, XiaoGong; Liu, Li; Guo, Rui; Zhu, LingFeng; Chang, ZhiQiao; Tang, ChengPan; Gong, XiuQiang; Li, Ran; Yu, Yang

    2016-10-01

    A two-way satellite time and frequency transfer (TWSTFT) device equipped in the BeiDou navigation satellite system (BDS) can calculate clock error between satellite and ground master clock. TWSTFT is a real-time method with high accuracy because most system errors such as orbital error, station position error, and tropospheric and ionospheric delay error can be eliminated by calculating the two-way pseudorange difference. Another method, the multi-satellite precision orbit determination (MPOD) method, can be applied to estimate satellite clock errors. By comparison with MPOD clock estimations, this paper discusses the applications of the BDS TWSTFT clock observations in satellite clock measurement, satellite clock prediction, navigation system time monitor, and satellite clock performance assessment in orbit. The results show that with TWSTFT clock observations, the accuracy of satellite clock prediction is higher than MPOD. Five continuous weeks of comparisons with three international GNSS Service (IGS) analysis centers (ACs) show that the reference time difference between BeiDou time (BDT) and golbal positoning system (GPS) time (GPST) realized IGS ACs is in the tens of nanoseconds. Applying the TWSTFT clock error observations may obtain more accurate satellite clock performance evaluation in the 104 s interval because the accuracy of the MPOD clock estimation is not sufficiently high. By comparing the BDS and GPS satellite clock performance, we found that the BDS clock stability at the 103 s interval is approximately 10-12, which is similar to the GPS IIR.

  17. Applicability of Virtual Reference Stations for Static and Kinematic Positioning

    Science.gov (United States)

    Kalita, Jakub; Rzepecka, Zofia

    2013-04-01

    There is a possibility to generate artificial observations for a particular position by using a known Virtual Reference Station technique. It is done by transferring the observations from a physical reference station and interpolating the biases, usually using a network of reference stations. Theoretically, the measurements can replace the physical reference receiver and both, simplify and improve the processing of static and kinematic measurements. Here, the VRS is used as a control station for static and kinematic post-processing taking advantage of the network of reference stations by interpolating ionospheric and tropospheric biases to location of measurement. However previous computational experiments showed that the generated virtual observations are strongly correlated with the observations gathered at the nearest physical reference station. The previous studies were performed at close vicinity of the physical reference station. For further investigations of these correlations, and the issue of how do they influence processing results, a field experiment was designed and performed, in which the real measurements were taken at various distances from the physical reference station. Basing on these measurements, the correlations between the reference station and VRS stations were studied. The unknown physical stations were determined and used as a comparison for VRS measurements. Also, the applicability of VRS observations for static and kinematic processing was validated. To assure independence of calculations and results, besides commercial software (GNSS Solutions and LGO) chosen Precise Point Positioning services were used. The VRS data were obtained from the POZGEO-D service of the ASG-EUPOS network.

  18. Use of a Closed-Loop Tracking Algorithm for Orientation Bias Determination of an S-Band Ground Station

    Science.gov (United States)

    Welch, Bryan W.; Schrage, Dean S.; Piasecki, Marie T.

    2015-01-01

    The Space Communications and Navigation (SCaN) Testbed project completed installation and checkout testing of a new S-Band ground station at the NASA Glenn Research Center in Cleveland, Ohio in 2015. As with all ground stations, a key alignment process must be conducted to obtain offset angles in azimuth (AZ) and elevation (EL). In telescopes with AZ-EL gimbals, this is normally done with a two-star alignment process, where telescope-based pointing vectors are derived from catalogued locations with the AZ-EL bias angles derived from the pointing vector difference. For an antenna, the process is complicated without an optical asset. For the present study, the solution was to utilize the gimbal control algorithms closed-loop tracking capability to acquire the peak received power signal automatically from two distinct NASA Tracking and Data Relay Satellite (TDRS) spacecraft, without a human making the pointing adjustments. Briefly, the TDRS satellite acts as a simulated optical source and the alignment process proceeds exactly the same way as a one-star alignment. The data reduction process, which will be discussed in the paper, results in two bias angles which are retained for future pointing determination. Finally, the paper compares the test results and provides lessons learned from the activity.

  19. Evaluation Of Geo-Spatial Proximity Of Mobile Communication GSM Base Transceiver Stations To Buildings In Ile-Ife Nigeria

    Directory of Open Access Journals (Sweden)

    Badru

    2015-08-01

    Full Text Available Efficient placement of radio facilities for the communication base transceiver station CBS of the two small global system for mobile communication GSM has being an area of research due to fast growing of GSM market in Nigeria. In line with this development Nigerian Communication Commission NCC and Nigeria Environmental Standard and Regulation Enforcement Agency NESREA have stated the setback between communication base station and the nearest infrastructure as 5 m and 10 m respectively. To evaluate the degree of the implementation of these setbacks in Ile-Ife the study area the research study identified the spatial locations of the CBS using a global communication for satellite GPS receiver and also employed the use of a high resolution satellite imagery which were processed using geo-spatial techniques. The results of this study revealed that 45.6 and 59.5 of the CBS had setback to building structures at 5 m and 10 m respectively with spatial variability between 30 m to 17074 m at elevation between 193 m to 377 m.

  20. Antenna unit and radio base station therewith

    Science.gov (United States)

    Kuwahara, Mikio; Doi, Nobukazu; Suzuki, Toshiro; Ishida, Yuji; Inoue, Takashi; Niida, Sumaru

    2007-04-10

    Phase and amplitude deviations, which are generated, for example, by cables connecting an array antenna of a CDMA base station and the base station, are calibrated in the baseband. The base station comprises: an antenna apparatus 1; couplers 2; an RF unit 3 that converts a receive signal to a baseband signal, converts a transmit signal to a radio frequency, and performs power control; an A/D converter 4 for converting a receive signal to a digital signal; a receive beam form unit 6 that multiplies the receive signal by semi-fixed weight; a despreader 7 for this signal input; a time-space demodulator 8 for demodulating user data; a despreader 9 for probe signal; a space modulator 14 for user data; a spreader 13 for user signal; a channel combiner 12; a Tx calibrater 11 for controlling calibration of a signal; a D/A converter 10; a unit 16 for calculation of correlation matrix for generating a probe signal used for controlling an Rx calibration system and a TX calibration system; a spreader 17 for probe signal; a power control unit 18; a D/A converter 19; an RF unit 20 for probe signal; an A/D converter 21 for signal from the couplers 2; and a despreader 22.