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Sample records for radio frequency spectrum

  1. Spread spectrum compressed sensing MRI using chirp radio frequency pulses

    CERN Document Server

    Qu, Xiaobo; Zhuang, Xiaoxing; Yan, Zhiyu; Guo, Di; Chen, Zhong

    2013-01-01

    Compressed sensing has shown great potential in reducing data acquisition time in magnetic resonance imaging (MRI). Recently, a spread spectrum compressed sensing MRI method modulates an image with a quadratic phase. It performs better than the conventional compressed sensing MRI with variable density sampling, since the coherence between the sensing and sparsity bases are reduced. However, spread spectrum in that method is implemented via a shim coil which limits its modulation intensity and is not convenient to operate. In this letter, we propose to apply chirp (linear frequency-swept) radio frequency pulses to easily control the spread spectrum. To accelerate the image reconstruction, an alternating direction algorithm is modified by exploiting the complex orthogonality of the quadratic phase encoding. Reconstruction on the acquired data demonstrates that more image features are preserved using the proposed approach than those of conventional CS-MRI.

  2. THE LOW-FREQUENCY RADIO CATALOG OF FLAT-SPECTRUM SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Giroletti, M. [INAF Istituto di Radioastronomia, Via Gobetti 101, I-40129 Bologna (Italy); D' Abrusco, R.; Paggi, A.; Cowperthwaite, Philip S. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Masetti, N. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy); Funk, S., E-mail: fmassaro79@gmail.com [Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States)

    2014-07-01

    A well known property of the γ-ray sources detected by Cos-B in the 1970s, by the Compton Gamma-Ray Observatory in the 1990s, and recently by the Fermi observations is the presence of radio counterparts, particularly for those associated with extragalactic objects. This observational evidence is the basis of the radio-γ-ray connection established for the class of active galactic nuclei known as blazars. In particular, the main spectral property of the radio counterparts associated with γ-ray blazars is that they show a flat spectrum in the GHz frequency range. Our recent analysis dedicated to search blazar-like candidates as potential counterparts for the unidentified γ-ray sources allowed us to extend the radio-γ-ray connection in the MHz regime. We also showed that blazars below 1 GHz maintain flat radio spectra. Thus, on the basis of these new results, we assembled a low-frequency radio catalog of flat-spectrum sources built by combining the radio observations of the Westerbork Northern Sky Survey and of the Westerbork in the southern hemisphere catalog with those of the NRAO Very Large Array Sky survey (NVSS). This could be used in the future to search for new, unknown blazar-like counterparts of γ-ray sources. First, we found NVSS counterparts of Westerbork Synthesis Radio Telescope radio sources, and then we selected flat-spectrum radio sources according to a new spectral criterion, specifically defined for radio observations performed below 1 GHz. We also described the main properties of the catalog listing 28,358 radio sources and their logN-logS distributions. Finally, a comparison with the Green Bank 6 cm radio source catalog was performed to investigate the spectral shape of the low-frequency flat-spectrum radio sources at higher frequencies.

  3. Hybrid spread spectrum radio system

    Science.gov (United States)

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  4. Integrated Common Radio Resource Management with Spectrum Aggregation over Non-Contiguous Frequency Bands

    DEFF Research Database (Denmark)

    Cabral, Orlando; Meucci, Filippo; Mihovska, Albena D.;

    2011-01-01

    This paper proposes an integrated Common Radio Resource Management (iCRRM). The iCRRM performs classic CRRM functionalities jointly with Spectrum Aggregation (SA), being able to switch users between non-contiguous frequency bands. The SA scheduling is obtained with an optimised General Multi......-Band Scheduling (GMBS) algorithm with the aim of cell throughput maximisation. In particular, we investigate the dependence of the throughput on the cell coverage distance for the allocation of users over the 2 and 5 GHz bands for a single operator scenario under a constant average Signal to Interference...

  5. Automatic DGD and GVD compensation at 640 Gb/s based on scalar radio-frequency spectrum measurement

    DEFF Research Database (Denmark)

    Paquot, Yvan; Schröder, Jochen; Palushani, Evarist;

    2013-01-01

    of separate GVD and DGD compensators using an impairment monitor based on an integrated all-optical radio-frequency (RF) spectrum analyzer. We show that low-bandwidth measurement of only a single tone in the RF spectrum is sufficient for automatic compensation for multiple degrees of freedom using...

  6. High-frequency excess in the radio continuum spectrum of the type-1 Seyfert galaxy NGC 985

    CERN Document Server

    Doi, Akihiro

    2016-01-01

    The Seyfert galaxy NGC 985 is known to show a high-frequency excess in its radio continuum spectrum in a milli-Jansky level on the basis of previous observations at 1.4--15 GHz; a steep spectrum at low frequencies (a spectral index of $\\alpha=-1.10 \\pm 0.03$) changes at ~10 GHz into an inverted spectrum at higher frequencies ($\\alpha=+0.86 \\pm 0.09$). We conduct new observations at 15--43 GHz using the Very Large Array and at 100 GHz using the Nobeyama Millimeter Array. As a result, the high-frequency excess continuing at even higher radio frequencies up to 43 GHz has been confirmed. The non-detection at 100 GHz was not so strong constraint, and therefore the spectral behavior above 43 GHz remains unclear. The astrometric position of the high-frequency excess component coincides with the optical position of the Seyfert nucleus and the low-frequency radio position to an accuracy of 0.1 arcsec, corresponding to ~80 pc; the radio source size is constrained to be <0.02 arcsec, corresponding to <16 pc. We di...

  7. Photonic-chip-based radio-frequency spectrum analyser with terahertz bandwidth

    Science.gov (United States)

    Pelusi, Mark; Luan, Feng; Vo, Trung D.; Lamont, Michael R. E.; Madden, Steven J.; Bulla, Douglas A.; Choi, Duk-Yong; Luther-Davies, Barry; Eggleton, Benjamin J.

    2009-03-01

    Signal processing at terahertz speeds calls for an enormous leap in bandwidth beyond the current capabilities of electronics, for which practical operation is currently limited to tens of gigahertz. This can be achieved through all-optical schemes making use of the ultrafast response of χ(3) nonlinear waveguides. Towards this objective, we have developed compact planar rib waveguides based on As2S3 glass, providing a virtual `lumped' high nonlinearity in a monolithic platform capable of integrating multiple functions. Here, we apply it to demonstrate, for the first time, a photonic-chip-based, all-optical, radio-frequency spectrum analyser with the performance advantages of distortion-free, broad measurement bandwidth (>2.5 THz) and flexible wavelength operation (that is, colourless). The key to this is the waveguide's high optical nonlinearity and dispersion-shifted design. Using the device, we characterize high-bit-rate (320 Gb s-1) optical signals impaired by various distortions. The demonstrated ultrafast, broadband capability highlights the potential for integrated chip-based signal processing at bit rates approaching and beyond Tb s-1.

  8. Radio frequency detection assembly and method for detecting radio frequencies

    Science.gov (United States)

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  9. Visibility based angular power spectrum estimation in low frequency radio interferometric observations

    CERN Document Server

    Choudhuri, Samir; Ghosh, Abhik; Ali, SK Saiyad

    2014-01-01

    We present two estimators to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio interferometric observations. This is relevant for both the foregrounds and the cosmological 21-cm signal buried therein. The discussion here is restricted to the Galactic synchrotron radiation, the most dominant foreground component after point source removal. Our theoretical analysis is validated using simulations at 150 MHz, mainly for GMRT and also briefly for LOFAR. The Bare Estimator uses pairwise correlations of the measured visibilities, while the Tapered Gridded Estimator uses the visibilities after gridding in the uv plane. The former is very precise, but computationally expensive for large data. The latter has a lower precision, but takes less computation time which is proportional to the data volume. The latter also allows tapering of the sky response leading to sidelobe suppression, an useful ingredient for foreground removal. Both estimators avoid the positive bias ...

  10. Spectrum access games for cognitive radio networks

    CSIR Research Space (South Africa)

    Masonta, MT

    2010-09-01

    Full Text Available Cognitive Radio (CR) is seen as a key enabling technology for addressing current under-utilization and inefficient use of radio frequency spectrum. The use of CR will see most of the spectrum white spaces being used opportunistically without causing...

  11. Radio quite site qualification for the Brasilian Southern Space Observatory by monitoring the low frequency 10-240 MHz Eletromagnetic Spectrum

    Science.gov (United States)

    da Rosa, Guilherme Simon; Schuch, Nelson Jorge; Espindola Antunes, Cassio; Gomes, Natanael

    The monitoring of the level of the radio interference in the Site of the Brazilian Southern Space Observatory - SSO/CRS/CIE/INPE - MCT, (29S, 53W), São Martinho da Serra, RS, in south a of Brazil, aims to gather spectral data for the Observatory's Site qualification as a radio quite site for installation of Radio Astronomy instrumentation, free of radio noise. The determination of the radio interference level is being conducted by using a spectrum analyzer and Omni directional antennas remotely controlled through a GPIB interface, via IEEE 488 bus, and programs written in C language. That procedure allows the scanning of the Electromagnetic Spectrum power over the examined frequency range from 10 - 240MHz. The methodology for these tests was to amplify the radio signal from the antenna by a block amplifier. Subsequently, the received signals are evaluated by the spectrum analyzer. A dedicated PC computer is used for the control and data acquisition, with the developed software. The data are instantly stored in digital format and remotely transferred via VNC software from the SSO-Observatory Site to the Radio Frequency and Telecommunication Laboratory at the Southern Regional Space Research Center - CRS/CIE/INPE - MCT, in Santa Maria, RS, for analysis and storage on the radio interference data base for long period. It is compared the SSO's Electromagnetic Spectrum data obtained since the beginning of the 1990's decade, before the Site constructions, with the current observed data. Some radio transmissions were found in the observed frequency range due to some local FMs, mostly between 93.5 MHz to 105.7 MHz, which were observed in previous monitoring. A good evidence of the site quality is the fact that the power of the Electromagnetic Spectrum is much lower than that measured at the Radio Frequency and Telecommunication Laboratory, in Santa Maria, RS, where the signals do not exceed -60 dB. On the Site of the SSO, due to the low power observed, weak radio signals

  12. Smart Radio Spectrum Management for Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Partha Pratim Bhattacharya

    2011-08-01

    Full Text Available Today’s wireless networks are characterized by fixed spectrum assignment policy. The limited availablespectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm toexploit the existing wireless spectrum opportunistically. Cognitive radio is a paradigm for wirelesscommunication in which either a network or a wireless node changes its transmission or receptionparameters to communicate efficiently avoiding interference with licensed or unlicensed users. It cancapture best available spectrum to meet user communication requirements (spectrum management. Inthis work, a fuzzy logic based system for spectrum management is proposed where the radio can shareunused spectrum depending on parameters like distance, signal strength, node velocity and availabilityof unused spectrum. The system is simulated and is found to give satisfactory results.

  13. Steep Spectrum Radio Sources in Galaxy Clusters

    Science.gov (United States)

    Clarke, Tracy E.

    2012-05-01

    Steep spectrum radio emission associated with galaxy clusters comes from compact central active galactic nuclei (AGN) driven radio sources in dense cool core clusters as well as from large regions of diffuse (halo and relic) emission associated with dynamically complex merging systems. These radio halos and relics are best traced at low radio frequencies where details of their morphology, location and spectral index distribution can be used to probe the underlying acceleration mechanism(s) as well as important details of large scale structure formation. Low frequency radio observations also play an important role in the study of AGN feedback into the intracluster medium and the regulation of cooling cores. While spectacular results are coming from the current generation of low frequency instruments, there will soon be a new revolution in studies of steep spectrum sources with the upcoming generation of low frequency interferometers on Earth and ultimately the moon.

  14. Tapering the sky response for angular power spectrum estimation from low-frequency radio-interferometric data.

    Science.gov (United States)

    Choudhuri, Samir; Bharadwaj, Somnath; Roy, Nirupam; Ghosh, Abhik; Ali, Sk Saiyad

    2016-06-11

    It is important to correctly subtract point sources from radio-interferometric data in order to measure the power spectrum of diffuse radiation like the Galactic synchrotron or the Epoch of Reionization 21-cm signal. It is computationally very expensive and challenging to image a very large area and accurately subtract all the point sources from the image. The problem is particularly severe at the sidelobes and the outer parts of the main lobe where the antenna response is highly frequency dependent and the calibration also differs from that of the phase centre. Here, we show that it is possible to overcome this problem by tapering the sky response. Using simulated 150 MHz observations, we demonstrate that it is possible to suppress the contribution due to point sources from the outer parts by using the Tapered Gridded Estimator to measure the angular power spectrum Cℓ of the sky signal. We also show from the simulation that this method can self-consistently compute the noise bias and accurately subtract it to provide an unbiased estimation of Cℓ.

  15. Tapering the sky response for angular power spectrum estimation from low-frequency radio-interferometric data

    CERN Document Server

    Choudhuri, Samir; Roy, Nirupam; Ghosh, Abhik; Ali, Sk Saiyad

    2016-01-01

    It is important to correctly subtract point sources from radio-interferometric data in order to measure the power spectrum of diffuse radiation like the Galactic synchrotron or the Epoch of Reionization 21-cm signal. It is computationally very expensive and challenging to image a very large area and accurately subtract all the point sources from the image. The problem is particularly severe at the sidelobes and the outer parts of the main lobe where the antenna response is highly frequency dependent and the calibration also differs from that of the phase center. Here we show that it is possible to overcome this problem by tapering the sky response. Using simulated 150 MHz observations, we demonstrate that it is possible to suppress the contribution due to point sources from the outer parts by using the Tapered Gridded Estimator to measure the angular power spectrum C_l of the sky signal. We also show from the simulation that this method can self-consistently compute the noise bias and accurately subtract it t...

  16. Site Evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408-10 GHz for a GEM polarized galactic radio emission experiment

    CERN Document Server

    Fonseca, R; Cupido, L; dos Santos, D M; Smoot, G F; Tello, C A S

    2004-01-01

    We probed for Radio Frequency Interference (RFI) for the three potential Galactic Emission Mapping Experiment (GEM) sites at Portugal using custom made omnidirectional disconic antennas. For the installation of a 10-meter dish dedicated to the mapping of Polarized Galactic Emission foreground planned for 2005-2007 in the 5-10 GHz band, the three sites chosen as suitable to host the antenna were surveyed for local radio pollution in the frequency range [0.01-10] GHz. Tests were done to look for radio broadcasting and mobile phone emission lines in the radio spectrum. The results show one of the sites to be almost entirely RFI clean and showing good conditions to host the experiment.

  17. Multi-Frequency Monitoring of the Flat Spectrum Radio Quasar PKS 1222+216 in 2008–2015

    Directory of Open Access Journals (Sweden)

    Ivan Troitskiy

    2016-11-01

    Full Text Available We analyze the broadband activity of the flat spectrum radio quasar PKS 1222+216 from 2008 to 2015 using multi-frequency monitoring which involves γ-ray data from the Fermi Large Area Telescope, total intensity and linear polarization observations from different optical telescopes in R band, and imaging of the inner jet structure with the Very Long Baseline Array (VLBA at 43 GHz. During the observations, the source showed several dramatic flares at γ rays and optical bands, with the rising branch of a γ-ray flare accompanied by a rapid rotation of the polarization position angle (EVPA, a fast increase of the degree of polarization in the optical band, brightening of the VLBI core, and appearance of a new superluminal component in the parsec-scale jet. The rapid variability of the optical linear polarization may be explained by a strong turbulence in the jet plasma. We find a correlation between the γ rays, optical R band, and 43 GHz variability on a long-term scale (months and years, and a good general alignment between EVPAs in R band and at 43 GHz, while the correlation between short-term variations (days and weeks is weaker. Synchronous activity across the bands supports the idea that the emission regions responsible for the γ-ray and optical flares are co-spatial and located in the vicinity of the mm-wave core of the parsec-scale jet. However, these connections do not completely explain the challenging behaviour of PKS 1222+216, since there are some γ-ray flares which are not accompanied by jet events, and vice versa. We need a continuation of multi-frequency monitoring along with high resolution imaging of the parsec-scale jet to understand in detail the origin of high energy emission in blazars.

  18. Radio frequency ion source

    CERN Document Server

    Shen Guan Ren; Gao Fu; LiuNaiYi

    2001-01-01

    The study on Radio Frequency Ion Source is mainly introduced, which is used for CIAE 600kV ns Pulse Neutron Generator; and obtained result is also presented. The RF ion source consists of a diameter phi 25 mm, length 200 mm, coefficient of expansion =3.5 mA, beam current on target >=1.5 mA, beam spot =100 h.

  19. Radio Frequency Spectrum Management

    Science.gov (United States)

    1980-03-01

    ed.). Approaches to Organizational Design. University of Pittsburg Press, 1971. Vroom , Victor H . Methods of Organizational Research. Uni- versity of...electromagnetic compatability standards for new system developments. The Director also has 82 C-, E- E-4 - 1-4 U E-44 0 0 J1b ci00 E- g -- 4 H ccn zc...00 z 000- E E- 0 .4 E 𔃾u - 0zn 04 E- C-7 c zz zi- 9xH 83 H the responsibility for determiing current and future require- ments for communications

  20. Radio resource allocation and dynamic spectrum access

    CERN Document Server

    Benmammar , Badr

    2013-01-01

    We are currently witnessing an increase in telecommunications norms and standards given the recent advances in this field. The increasing number of normalized standards paves the way for an increase in the range of services available for each consumer. Moreover, the majority of available radio frequencies have already been allocated. This explains the emergence of cognitive radio (CR) - the sharing of the spectrum between a primary user and a secondary user.In this book, we will present the state of the art of the different techniques for spectrum access using cooperation and competit

  1. Radio Frequency Identification

    Indian Academy of Sciences (India)

    V Rajaraman

    2017-06-01

    Radio Frequency Identification (RFID) has been around sinceearly 2000. Its use has currently become commonplace as thecost of RFID tags has rapidly decreased. RFID tags have alsobecome more ‘intelligent’ with the incorporation of processorsand sensors in them. They are widely used now in manyinnovative ways. RFIDs are an integral part of Internet ofThings (IOT) and IT systems of smart cities. In this article,we introduce the technology used by RFID systems, illustratetheir use in several applications, and discuss problems of privacyand security when they are used.

  2. Smart radio: spectrum access for first responders

    Science.gov (United States)

    Silvius, Mark D.; Ge, Feng; Young, Alex; MacKenzie, Allen B.; Bostian, Charles W.

    2008-04-01

    This paper details the Wireless at Virginia Tech Center for Wireless Telecommunications' (CWT) design and implementation of its Smart Radio (SR) communication platform. The CWT SR can identify available spectrum within a pre-defined band, rendezvous with an intended receiver, and transmit voice and data using a selected quality of service (QoS). This system builds upon previous cognitive technologies developed by CWT for the public safety community, with the goal of providing a prototype mobile communications package for military and public safety First Responders. A master control (MC) enables spectrum awareness by characterizing the radio environment with a power spectrum sensor and an innovative signal detection and classification module. The MC also enables spectrum and signal memory by storing sensor results in a knowledge database. By utilizing a family radio service (FRS) waveform database, the CWT SR can create a new communication link on any designated FRS channel frequency using FM, BPSK, QPSK, or 8PSK modulations. With FM, it supports analog voice communications with legacy hand-held FRS radios. With digital modulations, it supports IP data services, including a CWT developed CVSD-based VoIP protocol. The CWT SR coordinates spectrum sharing between analog primary users and digital secondary users by applying a simple but effective channel-change protocol. It also demonstrates a novel rendezvous protocol to facilitate the detection and initialization of communications links with neighboring SR nodes through the transmission of frequency-hopped rendezvous beacons. By leveraging the GNU Radio toolkit, writing key modules entirely in Python, and utilizing the USRP hardware front-end, the CWT SR provides a dynamic spectrum test bed for future smart and cognitive radio research.

  3. Wideband spectrum analysis of ultra-high frequency radio-wave signals due to advanced one-phonon non-collinear anomalous light scattering.

    Science.gov (United States)

    Shcherbakov, Alexandre S; Arellanes, Adan Omar

    2017-04-20

    We present a principally new acousto-optical cell providing an advanced wideband spectrum analysis of ultra-high frequency radio-wave signals. For the first time, we apply a recently developed approach with the tilt angle to a one-phonon non-collinear anomalous light scattering. In contrast to earlier cases, now one can exploit a regime with the fixed optical wavelength for processing a great number of acoustic frequencies simultaneously in the linear regime. The chosen rutile-crystal combines a moderate acoustic velocity with low acoustic attenuation and allows us wide-band data processing within GHz-frequency acoustic waves. We have created and experimentally tested a 6-cm aperture rutile-made acousto-optical cell providing the central frequency 2.0 GHz, frequency bandwidth ∼0.52  GHz with the frequency resolution about 68.3 kHz, and ∼7620 resolvable spots. A similar cell permits designing an advanced ultra-high-frequency arm within a recently developed multi-band radio-wave acousto-optical spectrometer for astrophysical studies. This spectrometer is intended to operate with a few parallel optical arms for processing the multi-frequency data flows within astrophysical observations. Keeping all the instrument's advantages of the previous schematic arrangement, now one can create the highest-frequency arm using the developed rutile-based acousto-optical cell. It permits optimizing the performances inherent in that arm via regulation of both the central frequency and the frequency bandwidth for spectrum analysis.

  4. Radio Frequency Anechoic Chamber Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports the design, manufacture, and test of antenna systems. The facility is also used as an electromagnetic compatibility/radio frequency interference...

  5. Spectrum Sensing for Cognitive Radio Based on Multiple Antennas

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; De Carvalho, Elisabeth; Prasad, Ramjee

    2012-01-01

    Spectrum sensing is a key component for enabling the cognitive radio paradigm. In this paper, we propose a novel totally-blind spectrum sensing technique for cognitive radio device equipped with multiple antennas, namely the Space Frequency Cross Product Sensing (SFCPS) algorithm. Existing...

  6. Maximizing the utility of radio spectrum: Broadband spectrum measurements and occupancy model for use by cognitive radio

    Science.gov (United States)

    Petrin, Allen J.

    Radio spectrum is a vital national asset; proper management of this finite resource is essential to the operation and development of telecommunications, radio-navigation, radio astronomy, and passive remote sensing services. To maximize the utility of the radio spectrum, knowledge of its current usage is beneficial. As a result, several spectrum studies have been conducted in urban Atlanta, suburban Atlanta, and rural North Carolina. These studies improve upon past spectrum studies by resolving spectrum usage by nearly all its possible parameters: frequency, time, polarization, azimuth, and location type. The continuous frequency range from 400MHz to 7.2 GHz was measured with a custom-designed system. More than 8 billion spectrum measurements were taken over several months of observation. A multi-parameter spectrum usage detection method was developed and analyzed with data from the spectrum studies. This method was designed to exploit all the characteristics of spectral information that was available from the spectrum studies. Analysis of the spectrum studies showed significant levels of underuse. The level of spectrum usage in time and azimuthal space was determined to be only 6.5 % for the urban Atlanta, 5.3 % for suburban Atlanta, and 0.8 % for the rural North Carolina spectrum studies. Most of the frequencies measured never experienced usage. Interference was detected in several protected radio astronomy and sensitive radio navigation bands. A cognitive radio network architecture to share spectrum with fixed microwave systems was developed. The architecture uses a broker-based sharing method to control spectrum access and investigate interference issues.

  7. Spread Spectrum Mobile Radio Communications.

    Science.gov (United States)

    1984-09-15

    seconds, yielding Z Y a =XMZ m M .-m The sequence of operacions is illustrated by the matrices of figures ’--3- and 1-3b. Each matrix is either a...sequence of K-bit numbers (code word, address, detection matrix) or a frequency-time spectrogram (traasmit spectrum, receive spectrum). The matrices pertain...and a reduced rank-sum receiver. In figure 3-1, we show the operation of a MRSR by means of matrices . 3-1 Reduced Rank-Sum Receiver With the values of

  8. MEASURING THE JET POWER OF FLAT-SPECTRUM RADIO QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Shabala, S. S.; Santoso, J. S. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, TAS 7001 (Australia); Godfrey, L. E. H. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

    2012-09-10

    We use frequency-dependent position shifts of flat-spectrum radio cores to estimate the kinetic power of active galactic nucleus (AGN) jets. We find a correlation between the derived jet powers and AGN narrow-line luminosity, consistent with the well-known relation for radio galaxies and steep spectrum quasars. This technique can be applied to intrinsically weak jets even at high redshift.

  9. Low Frequency Radio Experiment (LORE)

    Science.gov (United States)

    Manoharan, P. K.; Naidu, Arun; Joshi, B. C.; Roy, Jayashree; Kate, G.; Pethe, Kaiwalya; Galande, Shridhar; Jamadar, Sachin; Mahajan, S. P.; Patil, R. A.

    2016-03-01

    In this paper, we present a case study of Low Frequency Radio Experiment (LORE) payload to probe the corona and the solar disturbances at solar offsets greater than 2 solar radii, i.e., at frequencies below 30 MHz. The LORE can be complimentary to the planned Indian solar mission, “Aditya-L1” and its other payloads as well as synergistic to ground-based interplanetary scintillation (IPS) observations, which are routinely carried out by the Ooty Radio Telescope. We discuss the baseline design and technical details of the proposed LORE and its particular suitability for providing measurements on the detailed time and frequency structure of fast drifting type-III and slow drifting type-II radio bursts with unprecedented time and frequency resolutions. We also brief the gonio-polarimetry, which is possible with better-designed antennas and state-of-the-art electronics, employing FPGAs and an intelligent data management system. These would enable us to make a wide range of studies, such as nonlinear plasma processes in the Sun-Earth distance, in-situ radio emission from coronal mass ejections (CMEs), interplanetary CME driven shocks, nature of ICMEs driving decelerating IP shocks and space weather effects of solar wind interaction regions.

  10. Radio frequency propagation made easy

    CERN Document Server

    Faruque, Saleh

    2015-01-01

    This book introduces Radio Frequency Propagation to a broad audience.  The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications.  The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  11. Radio Frequency Solid State Amplifiers

    CERN Document Server

    Jacob, J

    2015-01-01

    Solid state amplifiers are being increasingly used instead of electronic vacuum tubes to feed accelerating cavities with radio frequency power in the 100 kW range. Power is obtained from the combination of hundreds of transistor amplifier modules. This paper summarizes a one hour lecture on solid state amplifiers for accelerator applications.

  12. LEP radio-frequency cavity

    CERN Multimedia

    1991-01-01

    One of the copper radio-frequency accelerating cavities installed for the first phase of LEP (1989-1995). Bunches of electrons and positrons circulated in LEP in opposite directions and were accelerated in eight different sets of 16 cavities (situated on either side of the four experiments), gaining 400 million volts of accelerating power per turn.

  13. Radio frequency modulation made easy

    CERN Document Server

    Faruque, Saleh

    2017-01-01

    This book introduces Radio Frequency Modulation to a broad audience. The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications. The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  14. Economic Analysis of the Radio Spectrum for Regulatory Purposes

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza

    the user value as long as there is no market for trade in frequency licenses. The economic value of the radio spectrum has been calculated for six different service applications (fixed links, Maritime and aeronautic applications, broadcasting services, mobile services, private mobile radio network services...... and military services). For each application the economic value is calculated for both use of the application and production of equipments related to each application. The paper draws on an extensive study of the economic value of the Danish radio spectrum prepared for the Danish Telecom Agency (Danish Telecom...

  15. The radio-frequency quadrupole

    CERN Document Server

    Vretenar, Maurizio

    2013-01-01

    Radio-frequency quadrupole (RFQ) linear accelerators appeared on the accelerator scene in the late 1970s and have since revolutionized the domain of low-energy proton and ion acceleration. The RFQ makes the reliable production of unprecedented ion beam intensities possible within a compact radio-frequency (RF) resonator which concentrates the three main functions of the low-energy linac section: focusing, bunching and accelerating. Its sophisticated electrode structure and strict beam dynamics and RF requirements, however, impose severe constraints on the mechanical and RF layout, making the construction of RFQs particularly challenging. This lecture will introduce the main beam optics, RF and mechanical features of a RFQ emphasizing how these three aspects are interrelated and how they contribute to the final performance of the RFQ.

  16. Impact of Different Air Protocols on the Use of the Radio Spectrum by Radio Frequency Identification (RFID Devices in the 860 to 960 MHz Bands

    Directory of Open Access Journals (Sweden)

    Mike Marsh

    2007-07-01

    Full Text Available This article shows measured results of the different spectra of different protocols using advanced spectrum analyzers and signal generators. These results allow an understanding of the issues involved and indicate why a change from certain protocols that are currently promoted needs to be made as the industry matures. This paper shows that RFID systems operating in the 860 to 960 MHz UHF bands will have the optimum performance.

  17. Energy-Efficient Spectrum Sensing for Cognitive Radio Networks

    NARCIS (Netherlands)

    Maleki, S.

    2013-01-01

    Dynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licens

  18. Energy-Efficient Spectrum Sensing for Cognitive Radio Networks

    NARCIS (Netherlands)

    Maleki, S.

    2013-01-01

    Dynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licens

  19. LEP Radio Frequency Copper Cavity

    CERN Multimedia

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  20. Mars' radio spectrum and the flying dust.

    NARCIS (Netherlands)

    Roos-Serote, M.; Stam, D.M.; Fender, R.P.

    2004-01-01

    Mars' radio spectrum at centimeter wavelengths is produced by thermal radiation from the surface and sub-surface. Observations at 2.8 cm made in the 1975 and 1978 show variations of its radio brightness as a function of longitude on the planet (Doherty et al. , ApJ 233, 1979). In addition, an overal

  1. Mars' radio spectrum and the flying dust.

    NARCIS (Netherlands)

    M. Roos-Serote; D.M. Stam; R.P. Fender

    2004-01-01

    Mars' radio spectrum at centimeter wavelengths is produced by thermal radiation from the surface and sub-surface. Observations at 2.8 cm made in the 1975 and 1978 show variations of its radio brightness as a function of longitude on the planet (Doherty et al. , ApJ 233, 1979). In addition, an overal

  2. Compressive Wideband Spectrum Sensing for Fixed Frequency Spectrum Allocation

    CERN Document Server

    Liu, Yipeng

    2010-01-01

    Too high sampling rate is the bottleneck to wideband spectrum sensing for cognitive radio (CR). As the survey shows that the sensed signal has a sparse representation in frequency domain in the mass, compressed sensing (CS) can be used to transfer the sampling burden to the digital signal processor. An analog to information converter (AIC) can randomly sample the received signal with sub-Nyquist rate to obtained the random measurements. Considering that the static frequency spectrum allocation of primary radios means the bounds between different primary radios is known in advance, here we incorporate information of the spectrum boundaries between different primary user as a priori information to obtain a mixed l2/l1 norm denoising operator (MNDO). In the MNDO, the estimated power spectrum density (PSD) vector is divided into block sections with bounds corresponding different allocated primary radios. Different from previous standard l1-norm constraint on the whole PSD vector, a sum of the l2 norm of each sect...

  3. Differentially-Enhanced Sideband Imaging via Radio-frequency Encoding

    CERN Document Server

    Fard, A M; Jalali, B

    2015-01-01

    We present a microscope paradigm that performs differential interference imaging with high sensitivity via optical amplification and radio-frequency (RF) heterodyne detection. This method, termed differentially-enhanced sideband imaging via radio-frequency encoding (DESIRE), uniquely exploits frequency-to-space mapping technique to encode the image of an object onto the RF sidebands of an illumination beam. As a proof-of-concept, we show validation experiment by implementing radio frequency (f = 15 GHz) phase modulation in conjunction with spectrally-encoded laser scanning technique to acquire one-dimensional image of a barcode-like object using a commercial RF spectrum analyzer.

  4. A novel spectrum sharing scheme for cognitive radios

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel approach, which combines spectrum adaptation and orthogonal frequency division multiplexing (OFDM), is proposed to share the licensed spectrum dynamically for cognitive radio systems. Given spectrum sensing and channel estimation information by the receiver, an improved model due to signal power thresholds is adopted to achieve spectrum adaptation for unlicensed users. In order to efficiently allocate the unlicensed signal power, a dynamic power allocation algorithm is also proposed. Simulation results indicate that the propositional scheme solves the partial interference problem of interference temperature model (ITM) and improves the spectrum utilization.

  5. Cooperative Wideband Spectrum Sensing for the Centralized Cognitive Radio Network

    CERN Document Server

    Zhang, Peng

    2011-01-01

    Various primary user (PU) radios have been allocated into fixed frequency bands in the whole spectrum. A cognitive radio network (CRN) should be able to perform the wideband spectrum sensing (WSS) to detect temporarily unoccupied frequency bands. We summarize four occupancy features for the frequency bands. 1. The occupancy is sparse; 2. The frequency band allocation information is fixed and common; 3. There are three categories for the frequency band usages; 4. The occupied frequency bands are common in the CRN. For the first time, we consider all features as the prior knowledge in the compressed sensing based cooperative WSS (CWSS) algorithm design for a centralized CRN. We propose a modified orthogonal matching pursuit (Mod-OMP) algorithm and a modified simultaneous orthogonal matching pursuit (Mod-SOMP) algorithm for the CWSS. We compare the CWSS performance of Mod-OMP/Mod-SOMP with the original OMP/SOMP and show the performance improvements.

  6. Radio Frequency Power Load and Associated Method

    Science.gov (United States)

    Srinivasan, V. Karthik (Inventor); Freestone, Todd M. (Inventor); Sims, William Herbert, III (Inventor)

    2014-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus may include a container with an ionized fluid therein. The apparatus may include one conductor immersed in a fluid and another conductor electrically connected to the container. A radio frequency transmission system may include a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus may include a fluid having an ion source therein, one conductor immersed in a fluid, and another conductor electrically connected to the container. A method of dissipating power generated by a radio frequency transmission system may include constructing a waveguide with ionized fluid in a container and connecting the waveguide to an amplifier of the transmission system.

  7. Radio frequency integrated circuit design

    CERN Document Server

    Rogers, John W M

    2010-01-01

    This newly revised and expanded edition of the 2003 Artech House classic, Radio Frequency Integrated Circuit Design, serves as an up-to-date, practical reference for complete RFIC know-how. The second edition includes numerous updates, including greater coverage of CMOS PA design, RFIC design with on-chip components, and more worked examples with simulation results. By emphasizing working designs, this book practically transports you into the authors' own RFIC lab so you can fully understand the function of each design detailed in this book. Among the RFIC designs examined are RF integrated LC

  8. The very steep spectrum radio halo in Abell 697

    CERN Document Server

    Macario, Giulia; Brunetti, Gianfranco; Dallacasa, Daniele; Giacintucci, Simona; Cassano, Rossella; Bardelli, Sandro; Athreya, Ramana

    2010-01-01

    In this paper we present a detailed study of the giant radio halo in the galaxy cluster Abell 697, with the aim to constrain its origin and connection with the cluster dynamics. We performed high sensitivity GMRT observations at 325 MHz, which showed that the radio halo is much brighter and larger at this frequency, compared to previous 610 MHz observations. In order to derive the integrated spectrum in the frequency range 325 MHz--1.4 GHz, we re--analysed archival VLA data at 1.4 GHz and made use of proprietary GMRT data at 610 MHz. {Our multifrequency analysis shows that the total radio spectrum of the giant radio halo in A\\,697 is very steep, with $\\alpha_{\\rm~325 MHz}^{\\rm~1.4 GHz} \\approx 1.7-1.8$. %\\pm0.1$. Due to energy arguments, a hadronic origin of the halo is disfavoured by such steep spectrum. Very steep spectrum halos in merging clusters are predicted in the case that the emitting electrons are accelerated by turbulence, observations with the upcoming low frequency arrays will be able to test the...

  9. PERFORMANCE OPTIMIZATION OF COGNITIVE RADIO WITH WIDEBAND SPECTRUM SENSING

    Directory of Open Access Journals (Sweden)

    E. Saraniya

    2014-09-01

    Full Text Available Cognitive radio (CR technology allows the unlicensed user to access the licensed spectrum bands. Spectrum sensing is an essential function in cognitive radio to detect the spectrum holes and opportunistically use the underutilized frequency bands without causing interference to primary user (PU. In this paper we are maximizing the throughput capacity of cognitive radio user and hence the performance of spectrum sensing and protection to licensed user improves over a wideband spectrum sensing band. The simulation of cognitive radio is done by analyzing the performance of energy detector spectrum sensing technique to detect primary user and to formulate the optimization using multiband joint detection method (MJD to achieve suitable trade- off between secondary user access and primary user network. The main aim of this paper is to maximize the probability of detection and to decrease the probabilities of miss detection and false alarm. To maximize the throughput it requires minimizing the throughput loss caused by miss detection and the significant reduction in probability of false alarm helps in achieving the spectral efficiency from the secondary user’s perspective. The simulation results show that the performance increases with the MJD method.

  10. Tecnologia radio cognitiva en la banda ultra high frequency (UHF

    Directory of Open Access Journals (Sweden)

    Hernán Paz Penagos

    2014-01-01

    Full Text Available Mobile cellular communication companies in Colombia require more spectrum resources to expand their portfolio of services. However, additional frequency bands for that particular purpose are scarce, yet it is well known that there are many underutilized licensed bands. Therefore new radio technologies are being studied in order to solve this problem, e.g. Software Defined Radio SDR Cognitive Radio CR and Dynamic Spectrum Access DSA. These strategies recommend mobility across the radio spectrum to meet various needs and achieve greater efficiency when managing such a scarce resource. In this context, a case study is presented in an attempt to examine the require¬ments that must be met for the implementation of cognitive radio networks in Bogota. The case study includes evaluation for the possibility of migration from cellular communications to cognitive radio since the bands assigned to UltraHigh Frequency UHF television offer possible free-of-interference coexistence between the two services (i.e. Cellular and TV. The study shows feasibility to migration; however, the implementations of cognitive radio need availability of hardware, software and flexible radio platforms.

  11. Radio Frequency Interference Mitigation at the WSRT

    CERN Document Server

    Fridman, P A; Millenaar, R P

    2010-01-01

    The sensitivity of radio astronomical stations is often limited by man-made radio frequency interference (RFI) due to a variety of terrestrial activities. An RFI mitigation subsystem (RFIMS) based on real-time digital signalprocessing is proposed here for the Westerbork Synthesis Radio Telescope based on a powerful field programmable gate array processor. In this system the radio astronomy signals polluted by RFI are "cleaned" with the RFIMS before routine back-end correlation processing takes place. The high temporal and frequency resolution of RFIMS allows the detection and excision of RFI better than do standard radio telescope back-end configurations.

  12. Radio Spectrum Management Development in India : A Framework for Strengthening Radio Spectrum Management and Policies

    OpenAIRE

    World Bank

    2006-01-01

    This report provides a detailed review of the current spectrum management regime in India; provides a perspective on best practice as may be applied in India and in addition provides a consideration of measures which could be taken to enhance spectrum management activities in India. The radio spectrum in India is a national resource, owned and managed by the Government. The authority for day-to-day spectrum management activities is vested Wireless Planning and Coordination (WPC) in New Delhi....

  13. Dynamic Spectrum Access in Cognitive Radio Networks with RF Energy Harvesting

    OpenAIRE

    Lu, Xiao; Wang,Ping; Dusit, Niyato; Ekram, Hossain

    2014-01-01

    Spectrum efficiency and energy efficiency are two critical issues in designing wireless networks. Through dynamic spectrum access, cognitive radios can improve the spectrum efficiency and capacity of wireless networks. On the other hand, radio frequency (RF) energy harvesting has emerged as a promising technique to supply energy to wireless networks and thereby increase their energy efficiency. Therefore, to achieve both spectrum and energy efficiencies, the secondary users in a cognitive rad...

  14. Low Frequency Radio Astronomy Summary: A Festschrift For Bill Erickson

    Science.gov (United States)

    Clark, B. G.; Kassim, N. E.; Perez, M. R.

    2005-12-01

    The science and technological issues presented at this workshop in honor of Bill Erickson's 74th birthday, are certainly opening up a new window of astronomical observations at the low end of the radio frequency spectrum. We briefly review some of the contributions concentrating our comments on the topics of science, technology, and history.

  15. Localized radio frequency communication using asynchronous transfer mode protocol

    Science.gov (United States)

    Witzke, Edward L.; Robertson, Perry J.; Pierson, Lyndon G.

    2007-08-14

    A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.

  16. Cooperative cognitive radio networks the complete spectrum cycle

    CERN Document Server

    Ibnkahla, Mohamed

    2014-01-01

    PrefaceAcknowledgmentsAuthorIntroduction to Cognitive RadioIntroductionCognitive Radio FrameworkDefinition of Cognitive RadioFunctions of Cognitive Radio FrameworkTransceiver ArchitectureCritical Design ChallengesFunctions of the Spectrum Management ProcessParadigms of Cognitive RadioInterweave ParadigmUnderlay ParadigmOverlay ParadigmSummaryOrganization of This BookReferencesSpectrum SensingIntroductionSpectrum SensingMatched Filtering (Coherent Detector)Energy DetectorFeature DetectionComparisonDesign Trade-Off and ChallengesMultiband Spectrum SensingIntroductionSerial Spectrum Sensing Techn

  17. Orbiting low frequency array for radio astronomy

    NARCIS (Netherlands)

    Rajan, Rai Thilak; Rajan, Raj; Engelen, Steven; Bentum, Marinus Jan; Verhoeven, Chris

    2011-01-01

    Recently new and interesting science drivers have emerged for very low frequency radio astronomy from 0.3 MHz to 30 MHz. However Earth bound radio observations at these wavelengths are severely hampered by ionospheric distortions, man made interference, solar flares and even complete reflection belo

  18. Orbiting low frequency array for radio astronomy

    NARCIS (Netherlands)

    Rajan, Rai Thilak; Engelen, Steven; Bentum, Mark; Verhoeven, Chris

    2011-01-01

    Recently new and interesting science drivers have emerged for very low frequency radio astronomy from 0.3 MHz to 30 MHz. However Earth bound radio observations at these wavelengths are severely hampered by ionospheric distortions, man made interference, solar flares and even complete reflection belo

  19. Kinerja Spectrum Sensing Dengan Metode Cyclostationary Feature Detector Pada Radio Kognitif

    Directory of Open Access Journals (Sweden)

    HENDRY CAHYO

    2017-06-01

    Full Text Available   Abstrak Perkembangan dalam dunia telekomunikasi nirkabel terutama spektrum frekuensi adalah hal yang perlu mendapatkan perhatian penting. Spektrum frekuensi merupakan sumber daya yang terbatas, penggunaannya harus dilakukan secara efisien dan se-maksimal mungkin. Penelitian ini membahas teknik spectrum sensing pada radio kognitif untuk menghadapi masalah keterbatasan penggunaan spektrum frekuensi. Radio kognitif merupakan sistem radio cerdas yang bisa mengatur parameternya seperti frekuensi kerja, daya pancar, dan skema modulasi secara optimal dalam melakukan proses komunikasi. Spectrum sensing merupakan teknik untuk memaksimalkan penggunaan spektrum frekuensi. Penelitian ini membandingkan kinerja metode cyclostationary feature detection dan metode energy detection pada teknik spectrum sensing menggunakan software matlab sehingga dapat diketahui bahwa kinerja cyclostationary feature detection untuk nilai Pd = 0,85 lebih handal sebesar 0,2 untuk fungsi probability of false dan lebih handal sebesar 2 dB untuk fungsi signal to noise ratio daripada energy detection. Kata kunci: radio kognitif, spectrum sensing, cyclostationary feature detection, energy detection, probability of false alarm.   Abstract Developments in the world of wireless telecommunications specially frequency spectrum is an important thing to get attention. Frequency spectrum is afinite resource, its use must be efficiently and as maximum as possible. This study discuss the technique of spectrum sensing in cognitive radio to faces the problem using restrictiveness of frequency spectrum. Cognitive radio is a smart radio system that can adjust its parameters like work frequency, emission power, and modulation scheme are optimal in the communication process. Spectrum sensing is a technique to maximize the use of the frequency spectrum. This study compared performance of cyclostationary feature detection methodh with energy detection methodh in spectrum sensing technique using

  20. High spectral purity Kerr frequency comb radio frequency photonic oscillator.

    Science.gov (United States)

    Liang, W; Eliyahu, D; Ilchenko, V S; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2015-08-11

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than -60 dBc Hz(-1) at 10 Hz, -90 dBc Hz(-1) at 100 Hz and -170 dBc Hz(-1) at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10(-10) at 1-100 s integration time-orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption.

  1. SPECTRUM SENSING IN COGNITIVE RADIO NETWORKS: QOS CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    Nabil Giweli

    2015-12-01

    Full Text Available The rapidly growing number of wireless communication devices has led to massive increases in radio traffic density, resulting in a noticeable shortage of available spectrum. To address this shortage, the Cognitive Radio (CR technology offers promising solutions that aim to improve the spectrum utilization. The operation of CR relies on detecting the so-called spectrum holes, the frequency bands that remain unoccupied by their licensed operators. The unlicensed users are then allowed to communicate using these spectrum holes. As such, the performance of CR is highly dependent on the employed spectrum sensing methods. Several sensing methods are already available. However, no individual method can accommodate all potential CR operation scenarios. Hence, it is fair to ascertain that the performance of a CR device can be improved if it is capable of supporting several sensing methods. It should obviously also be able to select the most suitable method. In this paper, several spectrum sensing methods are compared and analyzed, aiming to identify their advantages and shortcomings in different CR operating conditions. Furthermore, it identifies the features that need to be considered while selecting a suitable sensing method from the catalog of available methods.

  2. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

    NARCIS (Netherlands)

    Harwood, Jeremy J.; Croston, Judith H.; Intema, Huib T.; Stewart, Adam J.; Ineson, Judith; Hardcastle, Martin J.; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K.; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W.

    2016-01-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at

  3. Opportunistic spectrum sharing in cognitive radio networks

    CERN Document Server

    Wang, Zhe

    2015-01-01

    This Springer Brief investigates spectrum sharing with limited channel feedback in various cognitive radio systems, such as point-to-point, broadcast scheduling and ad-hoc networks. The design aim is to optimally allocate the secondary resources to improve the throughput of secondary users while maintaining a certain quality of service for primary users. The analytical results of optimal resource allocation are derived via optimization theory and are verified by the numerical results. The results demonstrate the secondary performance is significantly improved by limited feedback and is further improved by more feedback bits, more secondary receivers and more primary side information.

  4. Economic Analysis of the Radio Spectrum for Regulatory Purposes

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza

    will be necessary to ensure efficient and harmonised patterns of usage across countries. In this respect an assessment of the economic value of various applications is an important input. This paper measures the economic value in terms of contribution to GDP. We use this approach, as it is very difficult to assess...... not a purely technical matter. Economic considerations must be taken into account as well. A free market approach may be suitable for assigning frequency bands between operators within the same application, but is less suitable for allocation between various applications. Here regulatory intervention...... the user value as long as there is no market for trade in frequency licenses. The economic value of the radio spectrum has been calculated for six different service applications (fixed links, Maritime and aeronautic applications, broadcasting services, mobile services, private mobile radio network services...

  5. The Late Radio Spectrum of SN1993J

    CERN Document Server

    Pérez-Torres, M A; Marcaide, J M

    2002-01-01

    We present VLA radio continuum measurements of SN1993J in M81 at the frequencies of 0.32 (P-band), 1.3 and 1.7 (L-band), 4.9 (C-band), 8.5 (X-band), and 14.9 (U-band) GHz carried out on December 17 and 21, 2000, about 2820 days after the supernova explosion. We find that a power-law spectrum, free-free absorbed by an homogeneous --or clumpy, but not a mixture of both-- distribution of ionized gas, yields the best fit to the radio data. This result contrasts with the modeling of the early ($t \\lessim $230 days) radio emission from SN1993J, where a mixture of homogeneous and clumpy absorbers appeared to be necessary to adequately describe the behavior of the light curves, and thus gives support to the suggestion that a change in the mass-loss properties of the progenitor star took place in the last stages of its evolution. The radio spectrum of supernova SN1993J between 0.32 and 14.9 GHz is well characterized by $\\alpha = -0.67 \\pm 0.02 $ ($S_\

  6. Radio frequency integrated circuit design for cognitive radio systems

    CERN Document Server

    Fahim, Amr

    2015-01-01

    This book fills a disconnect in the literature between Cognitive Radio systems and a detailed account of the circuit implementation and architectures required to implement such systems.  Throughout the book, requirements and constraints imposed by cognitive radio systems are emphasized when discussing the circuit implementation details.  In addition, this book details several novel concepts that advance state-of-the-art cognitive radio systems.  This is a valuable reference for anybody with background in analog and radio frequency (RF) integrated circuit design, needing to learn more about integrated circuits requirements and implementation for cognitive radio systems. ·         Describes in detail cognitive radio systems, as well as the circuit implementation and architectures required to implement them; ·         Serves as an excellent reference to state-of-the-art wideband transceiver design; ·         Emphasizes practical requirements and constraints imposed by cognitive radi...

  7. Let Cognitive Radios Imitate: Imitation-based Spectrum Access for Cognitive Radio Networks

    CERN Document Server

    Iellamo, Stefano; Coupechoux, Marceau

    2011-01-01

    In this paper, we tackle the problem of opportunistic spectrum access in large-scale cognitive radio networks, where the unlicensed Secondary Users (SU) access the frequency channels partially occupied by the licensed Primary Users (PU). Each channel is characterized by an availability probability unknown to the SUs. We apply evolutionary game theory to model the spectrum access problem and develop distributed spectrum access policies based on imitation, a behavior rule widely applied in human societies consisting of imitating successful behavior. We first develop two imitation-based spectrum access policies based on the basic Proportional Imitation (PI) rule and the more advanced Double Imitation (DI) rule given that a SU can imitate any other SUs. We then adapt the proposed policies to a more practical scenario where a SU can only imitate the other SUs operating on the same channel. A systematic theoretical analysis is presented for both scenarios on the induced imitation dynamics and the convergence proper...

  8. Effect of economic techniques on radio frequency utilization

    Science.gov (United States)

    Fox, Richard N.

    1991-03-01

    This thesis compares the efficacy of spectrum assignment and allocation using a market based system with the current government controlled regulatory system. In making this comparison, a brief review of the spectrum and its radio communication uses is given. An examination of the current system--historical, organizational and political--is also presented. The spectrum is then discussed as a resource in relation to its economic characteristics: supply, demand, opportunity costs, prices, externalities and property rights. Although the spectrum is a unique resource as compared to most other natural resources, this conclusion is no valid reason for not allowing the establishment of a spectrum market exists. An examination of how such a market might be established and operated, and the implications of such a market are then discussed, with an example of how this market would operate in the Land Mobile Radio Services. To better illustrate this point, a brief history of land mobile radio, its technology and applications, and current allocation and assignment mechanisms is also presented. This study concludes by discussing the importance of the frequency spectrum to economic growth, summarizes the advantages and disadvantages of both marketplace and government regulation, and proposes that a market trial be instituted to test the viability of a spectral market.

  9. Spread Spectrum Communication with Chaotic Frequency Modulation

    Science.gov (United States)

    Volkovskii, Alexander R.; Tsimring, Lev S.; Rulkov, Nikolai F.; Langmore, Ian; Young, Stephen C.

    We describe two different approaches to employ chaotic signals in spread-spectrum (SS) communication systems with phase and frequency modulation. In the first one a chaotic signal is used as a carrier. We demonstrate that using a feedback loop controller, the local chaotic oscillator in the receiver can be synchronized to the transmitter. The information can be transmitted using phase or frequency modulation of the chaotic carrier signal. In the second system the chaotic signal is used for frequency modulation of a voltage controlled oscillator (VCO) to provide a SS signal similar to frequency hopping systems. We show that in a certain parameter range the receiver VCO can be synchronized to the transmitter VCO using a relatively simple phase lock loop (PLL) circuit. The same PLL is used for synchronization of the chaotic oscillators. The information signal can be transmitted using a binary phase shift key (BPSK) or frequency shift key (BFSK) modulation of the frequency modulated carrier signal. Using an experimental circuit operating at radio frequency band and a computer modeling we study the bit error rate (BER) performance in a noisy channel as well as multiuser capability of the system.

  10. Population density effect on radio frequencies interference (RFI) in radio astronomy

    Science.gov (United States)

    Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin; Hassan, Mohd Saiful Rizal; Rosli, Zulfazli; Hamidi, Zety Shahrizat

    2012-06-01

    Radio astronomical observation is infected by wide range of Radio Frequency Interference (RFI). We will also use information gathered from on-site RFI level measurements on selected 'good' areas generated by this study. After investigating a few suitable sites we will commence to the site and construct the RFI observation. Eventually, the best area we will be deciding from the observations soon. The result of this experiment will support our planning to build the first radio telescope in Malaysia. Radio observatories normally are located in remote area, in order to combat RFI from active spectrum users and radio noise produced in industrial or residential areas. The other solution for this problem is regulating the use of radio frequencies in the country (spectrum management). Measurement of RFI level on potential radio astronomical site can be done to measure the RFI levels at sites. Seven sites are chosen divide by three group, which is A, B and C. In this paper, we report the initial testing RFI survey for overall spectrum (0-2GHz) for those sites. The averaged RFI level above noise level at the three group sites are 19.0 (+/-1.79) dBm, 19.5 (+/-3.71) dBm and 17.0 (+/-3.71) dBm and the averaged RFI level above noise level for without main peaks are 20.1 (+/-1.77) dBm, 19.6 (+/-3.65) dBm and 17.2 (+/-1.43) dBm respectively.

  11. Radio Frequency Fragment Separator at NSCL

    Energy Technology Data Exchange (ETDEWEB)

    Bazin, D. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States)], E-mail: bazin@nscl.msu.edu; Andreev, V. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Becerril, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States); Doleans, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Mantica, P.F. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Ottarson, J. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Schatz, H. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States); Stoker, J.B. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Vincent, J. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States)

    2009-07-21

    A new device has been designed and built at NSCL which provides additional filtering of radioactive beams produced via projectile fragmentation. The Radio Frequency Fragment Separator (RFFS) uses the time micro structure of the beams accelerated by the cyclotrons to deflect particles according to their time-of-flight, in effect producing a phase filtering. The transverse RF (Radio Frequency) electric field of the RFFS has superior filtering performance compared to other electrostatic devices, such as Wien filters. Such filtering is critical for radioactive beams produced on the neutron-deficient side of the valley of stability, where strong contamination occurs at intermediate energies from 50 to 200 MeV/u.

  12. Radio-frequency integrated-circuit engineering

    CERN Document Server

    Nguyen, Cam

    2015-01-01

    Radio-Frequency Integrated-Circuit Engineering addresses the theory, analysis and design of passive and active RFIC's using Si-based CMOS and Bi-CMOS technologies, and other non-silicon based technologies. The materials covered are self-contained and presented in such detail that allows readers with only undergraduate electrical engineering knowledge in EM, RF, and circuits to understand and design RFICs. Organized into sixteen chapters, blending analog and microwave engineering, Radio-Frequency Integrated-Circuit Engineering emphasizes the microwave engineering approach for RFICs. Provide

  13. Radio Frequency Fragment Separator at NSCL

    Science.gov (United States)

    Bazin, D.; Andreev, V.; Becerril, A.; Doléans, M.; Mantica, P. F.; Ottarson, J.; Schatz, H.; Stoker, J. B.; Vincent, J.

    2009-07-01

    A new device has been designed and built at NSCL which provides additional filtering of radioactive beams produced via projectile fragmentation. The Radio Frequency Fragment Separator (RFFS) uses the time micro structure of the beams accelerated by the cyclotrons to deflect particles according to their time-of-flight, in effect producing a phase filtering. The transverse RF (Radio Frequency) electric field of the RFFS has superior filtering performance compared to other electrostatic devices, such as Wien filters. Such filtering is critical for radioactive beams produced on the neutron-deficient side of the valley of stability, where strong contamination occurs at intermediate energies from 50 to 200 MeV/u.

  14. LOFAR, a new low frequency radio telescope

    CERN Document Server

    Röttgering, H J A

    2003-01-01

    LOFAR, the Low Frequency Array, is a large radio telescope consisting of approximately 100 soccer-field sized antenna stations spread over a region of 400 km in diameter. It will operate at frequencies from ~10 to 240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will allow for studies of a broad range of astrophysical topics, including reionisation, transient radio sources and cosmic rays, distant galaxies and AGNs. In this contribution a status rapport of the LOFAR project and an overview of the science case is presented.

  15. Multislot Simultaneous Spectrum Sensing and Energy Harvesting in Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2016-07-01

    Full Text Available In cognitive radio (CR, the spectrum sensing of the primary user (PU may consume some electrical power from the battery capacity of the secondary user (SU, resulting in a decrease in the transmission power of the SU. In this paper, a multislot simultaneous spectrum sensing and energy harvesting model is proposed, which uses the harvested radio frequency (RF energy of the PU signal to supply the spectrum sensing. In the proposed model, the sensing duration is divided into multiple sensing slots consisting of one local-sensing subslot and one energy-harvesting subslot. If the PU is detected to be present in the local-sensing subslot, the SU will harvest RF energy of the PU signal in the energy-harvesting slot, otherwise, the SU will continue spectrum sensing. The global decision on the presence of the PU is obtained through combining local sensing results from all the sensing slots by adopting “Or-logic Rule”. A joint optimization problem of sensing time and time splitter factor is proposed to maximize the throughput of the SU under the constraints of probabilities of false alarm and detection and energy harvesting. The simulation results have shown that the proposed model can clearly improve the maximal throughput of the SU compared to the traditional sensing-throughput tradeoff model.

  16. A Survey on Dynamic Spectrum Access Techniques for Cognitive Radio

    CERN Document Server

    Garhwal, Anita

    2012-01-01

    Cognitive radio (CR) is a new paradigm that utilizes the available spectrum band. The key characteristic of CR system is to sense the electromagnetic environment to adapt their operation and dynamically vary its radio operating parameters. The technique of dynamically accessing the unused spectrum band is known as Dynamic Spectrum Access (DSA). The dynamic spectrum access technology helps to minimize unused spectrum bands. In this paper, main functions of Cognitive Radio (CR) i.e. spectrum sensing, spectrum management, spectrum mobility and spectrum sharing are discussed. Then DSA models are discussed along with different methods of DSA such as Command and Control, Exclusive-Use, Shared Use of Primary Licensed User and Commons method. Game-theoretic approach using Bertrand game model, Markovian Queuing Model for spectrum allocation in centralized architecture and Fuzzy logic based method are also discussed and result are shown.

  17. Correlation between the Flux Density and Polarization for Flat Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Fei-Peng Pi; Yong-Xiang Wang; Jing Pan

    2011-03-01

    In this paper, using the preliminary database of the University of Michigan Radio Astronomy Observatory (UMRAO) at the radio frequencies, we calculated the weighted polarization at 8 GHz and investigated the correlation between the polarization and the flux density for 92 flat spectrum radio quasars (FSRQs). We found that the two observations are closely and positively correlated for FSRQs. This is perhaps from a relativistic beaming effect.

  18. Matched Filter Based Spectrum Sensing on Cognitive Radio for OFDM WLANs

    Directory of Open Access Journals (Sweden)

    R.Saravanan

    2013-02-01

    Full Text Available For the unlicensed users to use the licensed spectrum, unused frequency bands called white spaces need to be detected. Cognitive radio does this task by dynamic spectrum access. This requires intelligent spectrum sensing techniques. In this paper such unused spectrum for OFDM WLAN (IEEE 802.11a is predicted by exploring the signals presence in minimum time using matched filter based detection incorporating optimal threshold selection, thereby increasing the sensing accuracy andinterference reduction of secondary network.

  19. Spectrum access and management for cognitive radio networks

    CERN Document Server

    2017-01-01

    This book presents cutting-edge research contributions that address various aspects of network design, optimization, implementation, and application of cognitive radio technologies. It demonstrates how to make better utilization of the available spectrum, cognitive radios and spectrum access to achieve effective spectrum sharing between licensed and unlicensed users. The book provides academics and researchers essential information on current developments and future trends in cognitive radios for possible integration with the upcoming 5G networks. In addition, it includes a brief introduction to cognitive radio networks for newcomers to the field.

  20. Spectrum management and radio resource management considering cognitive radio systems

    NARCIS (Netherlands)

    Haartsen, Jaap C.; Wieweg, Lasse; Huschke, Jörg

    2005-01-01

    International fora and some national administrations define a cognitive radio (CR) as a pioneering radio communication system that would be capable of altering and adapting its transmitter and receiver parameters based on communication and the exchange of information with related detectable radio co

  1. Spectrum Occupancy Statistics in the Context of Cognitive Radio

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Chandra, Ashok

    2011-01-01

    Cognitive radio (CR), a disruptive technology, has come out as a promising solution to the problem of spectrum scarcity and which will facilitate the flexible spectrum use in future. In this paradigm, the spectrum utilization is improved by opportunistic spectrum use by unlicensed users without i...

  2. Radio frequency source coding made easy

    CERN Document Server

    Faruque, Saleh

    2015-01-01

    This book introduces Radio Frequency Source Coding to a broad audience. The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications. The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  3. Radio frequency channel coding made easy

    CERN Document Server

    Faruque, Saleh

    2016-01-01

    This book introduces Radio Frequency Channel Coding to a broad audience. The author blends theory and practice to bring readers up-to-date in key concepts, underlying principles and practical applications of wireless communications. The presentation is designed to be easily accessible, minimizing mathematics and maximizing visuals.

  4. Cost cutting using radio frequency inventory control.

    Science.gov (United States)

    Weber, J

    1992-05-01

    Bar coding should be a staple in every hospital by now--but it's not. The author tells how bar coding and the use of radio frequency transmission of inventory data direct to their mainframe computer has saved them time and money.

  5. Radio Frequency Identifiers: What are the Possibilities?

    CERN Document Server

    Elmorshidy, Ahmed

    2010-01-01

    This paper defines the components of radio frequency identifiers (RFID). It also explores the different areas and sectors where RFID can be beneficial. The paper discusses the uses and advantages of RFID in deference, consumer packaged goods (CPG), healthcare, logistics, manufacturing, and retail.

  6. Graphene for radio frequency electronics

    Directory of Open Access Journals (Sweden)

    Lei Liao

    2012-07-01

    Full Text Available Graphene is emerging as an attractive electronic material for future electronics. With the highest carrier mobility, high saturation velocity, high critical current densities, and single atomic thickness, graphene has great potential for ultra-high speed transistors, with the highest projected cut-off frequency exceeding 1 THz. However, the fabrication of high speed graphene transistors is of significant challenge, since conventional electronic fabrication processes often introduce undesirable defects into graphene lattices. Significant efforts have made to mitigate these challenges. Here we review the opportunities, challenges, as well as the recent advances in the development of high speed graphene transistors and circuits.

  7. A Radio Frequency Charge Parity Meter

    OpenAIRE

    Schroer, M. D.; Jung, M.; Petersson, K. D.; Petta, J. R.

    2012-01-01

    We demonstrate a total charge parity measurement by detecting the radio frequency signal that is reflected by a lumped element resonator coupled to a single InAs nanowire double quantum dot. The high frequency response of the circuit is used to probe the effects of the Pauli exclusion principle at interdot charge transitions. Even parity charge transitions show a striking magnetic field dependence that is due to a singlet-triplet transition, while odd parity transitions are relatively insensi...

  8. Estimation and Coordination of Sequence Patterns for Frequency Hopping Dynamic Spectrum Access Networks

    Science.gov (United States)

    2014-03-27

    than one node. A separate effort demonstrated applicability of these algorithms via hardware implementation on the GNU radio test bed [30]. It also...Spectrum Company showed in a survey of Radio Frequency (RF) bands that underutilization of spectrum has resulted from current frequency management...division based protocols where radios always share their environment information. Larger networks, on the other hand, function best when a dispute-based

  9. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    2000-01-01

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  10. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  11. High Temperature Radio Frequency Loads

    CERN Document Server

    Federmann, S; Grudiev, A; Montesinos, E; Syratchev, I

    2011-01-01

    In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet withmore than 150 ◦C and high pressure has a higher value than water with 50 ◦C under low pressure. Conventional RF power loads containing dielectric and magnetic materials as well as sensitive ceramic windows usually do not permit going much higher than 90 ◦C. Here we present and discuss several design concepts for "metal only" RF high power loads. One concept is the application of magnetic steel corrugated waveguides near cutoff – this concept could find practical use above several GHz. Another solution are resonant structures made of steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage of the rather high losses of normal steel may also be used in coaxial line geometries with large di...

  12. Low Frequency Radio Transients in the Galactic Center

    Science.gov (United States)

    Hyman, S. D.; Bartleson, A. L.; Lazio, T. J. W.; Kassim, N. E.

    2001-12-01

    We report the detection of a new radio transient source, GCRT J1746-2757, located only 1.1 degrees north of the Galactic center. Consistent with other radio transients toward the Galactic center, this source brightened and faded on a time scale of a few months. No X-ray counterpart was detected, but upper limits suggest that GCRT J1746-2757 may have been a "fast" transient, with a time scale of days. We also report new 0.33 GHz measurements of the radio counterpart to the X-ray transient source, XTE J1748-288, previously detected and monitored at higher radio frequencies. We show that the spectrum of XTE J1748-288 steepened considerably during a period of a few months after its peak. We also discuss the need for a more efficient means of finding additional radio transients. This research is supported by funding from the Jeffress Memorial Trust, Research Corporation, and the Sweet Briar College Faculty Grants program. Basic research in radio astronomy at NRL is supported by the Office of Naval Research.

  13. Auction based spectrum management of cognitive radio networks

    DEFF Research Database (Denmark)

    Chang, H. B.; Chen, K.-C.; Prasad, Ramjee

    2009-01-01

    (PS-MSs), and we therefore construct a cognitive radio network (CRN) consisting of a PRN with multiple CR-MSs. We propose a spectrum management policy framework such that CR-MSs can compete in utilization of the PRN spectrum bands available to opportunistic transmission of CR-MSs by Vickrey auction......Cognitive radio (CR) technology is considered as an effective solution to enhance overall spectrum efficiency, especially primary radio network (PRN) typically having relatively low spectrum utilization. However, to realize CR concept, it is essential to provide enough incentives to PRN and extra...... to the PRN, the overall spectrum utilization, the profit of the service provider, the spectrum access opportunity of the CR-MSs are increased to achieve cowin situation for every party in cognitive radio networks....

  14. Mapping the Orion Molecular Cloud Complex in Radio Frequencies

    Science.gov (United States)

    Castelaz, Michael W.; Lemly, C.

    2013-01-01

    The purpose of this research project was to create a large-scale intensity map of the Orion Molecular Cloud Complex at a radio frequency of 1420 MHz. A mapping frequency of 1420 MHz was chosen because neutral hydrogen, which is the primary component of the Orion Molecular Complex, naturally emits radio waves at this frequency. The radio spectral data for this project were gathered using a 4.6-m radio telescope whose spectrometer was tuned to 1420 MHz and whose beam width was 2.7 degrees. The map created for this project consisted of an eight-by-eight grid centered on M42 spanning 21.6 degrees per side. The grid consisted of 64 individual squares spanning 2.7 degrees per side (corresponding to the beam width of the telescope). Radio spectra were recorded for each of these individual squares at an IF gain of 18. Each spectrum consisted of intensity on an arbitrary scale from 0 to 10 plotted as a function frequencies ranging from -400 kHz to +100 kHz around the origin of 1420 MHz. The data from all 64 radio spectra were imported into Wolfram Alpha, which was used to fit Gaussian functions to the data. The peak intensity and the frequency at which this peak intensity occurs could then be extracted from the Gaussian functions. Other helpful quantities that could be calculated from the Gaussian functions include flux (integral of Gaussian function over frequency range), average value of intensity (flux integral divided by frequency range), and half maximum of intensity. Because all of the radio spectra were redshifted, the velocities of the hydrogen gas clouds of the Orion Molecular Cloud Complex could be calculated using the Doppler equation. The data extracted from the Gaussian functions were then imported into Mathcad to create 2D grayscale maps with right ascension (RA) on the x-axis, declination on the y-axis, and intensity (or flux, etc.) represented on a scale from black to white (with white representing the highest intensities). These 2D maps were then imported

  15. GMRT 150 MHz follow up of diffuse steep spectrum radio emission in galaxy clusters

    CERN Document Server

    Macario, G; Dallacasa, D; Giacintucci, S; Brunetti, G; Cassano, R; Ishwara-Chandra, C H; Athreya, R

    2011-01-01

    It has been recently found that a few galaxy clusters host diffuse radio halo emission with very steep synchrotron spectra ($\\alpha$ > 1.6), which may be classified as Ultra Steep Spectrum Radio Halos (USSRHs). USSRHs are expected in the turbulence re-acceleration model for the origin of cluster radio halos, and are best discovered and studied at low frequencies. We performed GMRT follow up observations of three galaxy clusters at 150MHz, selected from the GMRT radio halo survey, which are known to host an USSRH or candidate very steep spectrum diffuse emission. This project is aimed to characterize the low frequency spectrum of USSRHs for a detailed study of their origin and connection with cluster mergers. We present preliminary results at 150 MHz of the cluster A697.

  16. Detection efficiency of cooperative spectrum sensing in cognitive radio network

    Institute of Scientific and Technical Information of China (English)

    CHEN Xing; BIE Zhi-song; WU Wei-ling

    2008-01-01

    Sensing the spectrum in a reliable and efficient manner is crucial to cognitive radio. To combat the channel fading suffered by the single radio, cooperative spectrum sensing is employed, to associate the detection of multiple radios. In this article, the optimization problem of detection efficiency under the constraint of detection probability is investigated, and an algorithm to evaluate the required radio number and sensing time for maximal detection efficiency is presented. To show the effect of cooperation on the detection efficiency, the proposed algorithm is applied to cooperative sensing using the spectral correlation detector under the Rayleigh flat fading channel.

  17. Spectrum Allocation Based on Game Theory in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Qiufen Ni

    2013-03-01

    Full Text Available As a kind of intelligent communication technology, the characteristic of dynamic spectrum allocation of cognitive radio provides feasible scheme for sharing with the spectrum resources among the primary user and secondary users, which solves the current spectrum resource scarcity problem. In this paper, we comprehensively explored the cognitive radio spectrum allocation models based on game theory from cooperative game and non-cooperative game, which provide detailed overview and analysis on the state of the art of spectrum allocation based on game theory. In order to provide flexible and efficient spectrum allocation in wireless networks, this paper also provides the general framework model based on game theory for cognitive radio spectrum allocation.

  18. Radio Frequency Based Water Level Monitor and Controller for ...

    African Journals Online (AJOL)

    Radio Frequency Based Water Level Monitor and Controller for Residential Applications. ... Nigerian Journal of Technology ... This paper elucidates a radio frequency (RF) based transmission and reception system used to remotely monitor ...

  19. SITE TECHNOLOGY CAPSULE: IITRI RADIO FREQUENCY HEATING TECHNOLOGY

    Science.gov (United States)

    Radio frequency heating (RFH) technologies use electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. Contaminants are removed from in situ soils and transfe...

  20. Performance Analysis of Cognitive Radio for Wi-Fi Signals Using Cyclostationary Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    Mandeep Singh

    2014-08-01

    Full Text Available The need for radio spectrum usage is increasing day by day with recent advancements in wireless system. But there is limited amount of spectrum available. So that for solving this problem Cognitive Radio (CR is used for purpose of the spectrum utilization properly. Basically the Licensed users use the licensed bands but the unlicensed users should always check spectrum with the help of CR technology. The main aim of cognitive radio is to sense the spectrum continuously. In this paper, we have provided the proposal that how the capacity of the system can be increased by reuse the unused licensed band by simulating a Cognitive radio system. The secondary users can occupy free space (spectrum holes and also licensed bands by continuously monitoring the spectrum. The requirements of cognitive radio systems will be investigated by considering spectrum sensing techniques. To achieve this, a Cyclostationary Spectrum Sensing technique is studied and applied to detect OFDM signals in a noisy environment. The results are obtained for the applications employed in high frequency, such as, Wi-Fi.

  1. Ultra-Wideband Radio Frequency Identification Systems

    CERN Document Server

    Nekoogar, Faranak

    2012-01-01

    Ultra-Wideband Radio Frequency Identification Systems describes the essentials of radio frequency identification systems as well as their target markets. The authors provide a study of commercially available RFID systems and characterizes their performance in terms of read range and reliability in the presence of conductive and dielectric materials. The capabilities and limitations of some commercial RFID systems are reported followed by comprehensive discussions of the advantages and challenges of using ultra-wideband technology for tag/reader communications. The book presents practical aspects of UWB RFID system such as: pulse generation, remote powering, tag and reader antenna design, as well as special applications of  UWB RFIDs in a simple and easy-to-understand language.

  2. Graphene radio frequency receiver integrated circuit.

    Science.gov (United States)

    Han, Shu-Jen; Garcia, Alberto Valdes; Oida, Satoshi; Jenkins, Keith A; Haensch, Wilfried

    2014-01-01

    Graphene has attracted much interest as a future channel material in radio frequency electronics because of its superior electrical properties. Fabrication of a graphene integrated circuit without significantly degrading transistor performance has proven to be challenging, posing one of the major bottlenecks to compete with existing technologies. Here we present a fabrication method fully preserving graphene transistor quality, demonstrated with the implementation of a high-performance three-stage graphene integrated circuit. The circuit operates as a radio frequency receiver performing signal amplification, filtering and downconversion mixing. All circuit components are integrated into 0.6 mm(2) area and fabricated on 200 mm silicon wafers, showing the unprecedented graphene circuit complexity and silicon complementary metal-oxide-semiconductor process compatibility. The demonstrated circuit performance allow us to use graphene integrated circuit to perform practical wireless communication functions, receiving and restoring digital text transmitted on a 4.3-GHz carrier signal.

  3. An Introduction to Radio Frequency Engineering

    Science.gov (United States)

    Coleman, Christopher

    2004-06-01

    Using an easily understood approach combined with numerous worked examples, illustrations and homework problems, this textbook focuses on minimizing the mathematics needed to grasp radio frequency engineering. The book includes broad coverage of RF systems, circuit design, antennas, propagation and digital techniques. Written for upper level undergraduate courses, it will also provide an excellent introduction to the subject for graduate students, researchers and practicing engineers.

  4. TOUTATIS: A radio frequency quadrupole code

    OpenAIRE

    Romuald Duperrier

    2000-01-01

    A cw high power linear accelerator can only work with very low particle losses and structure activation. At low energy, the radio frequency quadrupole (RFQ) is an accelerator element that is very sensitive to losses. To design this structure, a good understanding of the beam dynamics is required. Generally, the reference code PARMTEQM is enough to design the accelerator. TOUTATIS has been written with the goals of cross-checking results and obtaining more reliable dynamics. This paper relates...

  5. Novel Spectrum Sensing Algorithms for OFDM Cognitive Radio Networks.

    Science.gov (United States)

    Shi, Zhenguo; Wu, Zhilu; Yin, Zhendong; Cheng, Qingqing

    2015-06-15

    Spectrum sensing technology plays an increasingly important role in cognitive radio networks. Consequently, several spectrum sensing algorithms have been proposed in the literature. In this paper, we present a new spectrum sensing algorithm "Differential Characteristics-Based OFDM (DC-OFDM)" for detecting OFDM signal on account of differential characteristics. We put the primary value on channel gain θ around zero to detect the presence of primary user. Furthermore, utilizing the same method of differential operation, we improve two traditional OFDM sensing algorithms (cyclic prefix and pilot tones detecting algorithms), and propose a "Differential Characteristics-Based Cyclic Prefix (DC-CP)" detector and a "Differential Characteristics-Based Pilot Tones (DC-PT)" detector, respectively. DC-CP detector is based on auto-correlation vector to sense the spectrum, while the DC-PT detector takes the frequency-domain cross-correlation of PT as the test statistic to detect the primary user. Moreover, the distributions of the test statistics of the three proposed methods have been derived. Simulation results illustrate that all of the three proposed methods can achieve good performance under low signal to noise ratio (SNR) with the presence of timing delay. Specifically, the DC-OFDM detector gets the best performance among the presented detectors. Moreover, both of the DC-CP and DC-PT detector achieve significant improvements compared with their corresponding original detectors.

  6. Steep-spectrum sources and the duty cycle of the radio emission

    CERN Document Server

    Orienti, M

    2010-01-01

    It is currently accepted that intrinsically compact and bright radio sources characterized by a convex spectrum peaking at frequencies ranging from 100 MHz to a few GHz are young objects. Following the evolutionary models, these objects would evolve into the population of classical radio galaxies. However, the fraction of young radio sources in flux density-limited samples is much larger than what expected from the number counts of large radio sources. This may suggest that for some reason a significant fraction of young objects would never become large radio galaxies with sizes up to a few Mpc. The discovery of the young radio source PKS 1518+047 characterized by an uncommonly steep spectrum confirms that the radio emission may switch off shortly after its onset. Then the source spectrum steepens and evolves due to energy losses. If the interruption is not temporary, the fate of the fading sources is to disappear at frequencies lower than those explored by current radio telescopes. Fossils of past activities...

  7. Inkjet Printed Radio Frequency Passive Components

    KAUST Repository

    McKerricher, Garret

    2015-12-01

    Inkjet printing is a mature technique for colourful graphic arts. It excels at customized, large area, high resolution, and small volume production. With the developments in conductive, and dielectric inks, there is potential for large area inkjet electronics fabrication. Passive radio frequency devices can benefit greatly from a printing process, since the size of these devices is defined by the frequency of operation. The large size of radio frequency passives means that they either take up expensive space “on chip” or that they are fabricated on a separate lower cost substrate and somehow bonded to the chips. This has hindered cost-sensitive high volume applications such as radio frequency identification tags. Substantial work has been undertaken on inkjet-printed conductors for passive antennas on microwave substrates and even paper, yet there has been little work on the printing of the dielectric materials aimed at radio frequency passives. Both the conductor and dielectric need to be integrated to create a multilayer inkjet printing process that is capable of making quality passives such as capacitors and inductors. Three inkjet printed dielectrics are investigated in this thesis: a ceramic (alumina), a thermal-cured polymer (poly 4 vinyl phenol), and a UV-cured polymer (acrylic based). For the conductor, both a silver nanoparticle ink as well as a custom in-house formulated particle-free silver ink are explored. The focus is on passives, mainly capacitors and inductors. Compared to low frequency electronics, radio frequency components have additional sensitivity regarding skin depth of the conductor and surface roughness, as well as dielectric constant and loss tangent of the dielectric. These concerns are investigated with the aim of making the highest quality components possible and to understand the current limitations of inkjet-fabricated radio frequency devices. An inkjet-printed alumina dielectric that provides quality factors of 200 and high

  8. Characteristics of Collision, Capacitive Radio Frequency Sheath

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu; DingWanYu; Wang Wenchun; Liu JinYuan; Wang Xiaogang; Liu Yue

    2005-01-01

    A simple collisional radio frequency (rf) sheath fluid model, which is not restricted by the ratio of rf frequency to ion plasma frequency (β=ωrf/ωpi), was established and solved numerically. In the ion balance equation, the effect of the collision on the ion and the ion velocity is assumed to be a direct ratio to ion velocity. The ion energy distributions (IEDs) calculated in the model in comparison with the experimental data [M. A. Sobolewski, J. K. Olthoff, and Y.C. Wang, J. Appl. Phys. 85, 3966 (1999)], proved the validity of the model. And the effect of the collision on the sheath characteristic was obtained and discussed. This paper demonstrates that the collision frequency is another crucial parameter as well as the ratio β to determine the rf sheath characteristics and the shape of IE Ds.

  9. Radio-frequency scanning tunnelling microscopy.

    Science.gov (United States)

    Kemiktarak, U; Ndukum, T; Schwab, K C; Ekinci, K L

    2007-11-01

    The scanning tunnelling microscope (STM) relies on localized electron tunnelling between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25-year period since its invention, the STM has helped uncover a wealth of phenomena in diverse physical systems--ranging from semiconductors to superconductors to atomic and molecular nanosystems. A severe limitation in scanning tunnelling microscopy is the low temporal resolution, originating from the diminished high-frequency response of the tunnel current readout circuitry. Here we overcome this limitation by measuring the reflection from a resonant inductor-capacitor circuit in which the tunnel junction is embedded, and demonstrate electronic bandwidths as high as 10 MHz. This approximately 100-fold bandwidth improvement on the state of the art translates into fast surface topography as well as delicate measurements in mesoscopic electronics and mechanics. Broadband noise measurements across the tunnel junction using this radio-frequency STM have allowed us to perform thermometry at the nanometre scale. Furthermore, we have detected high-frequency mechanical motion with a sensitivity approaching approximately 15 fm Hz(-1/2). This sensitivity is on par with the highest available from nanoscale optical and electrical displacement detection techniques, and the radio-frequency STM is expected to be capable of quantum-limited position measurements.

  10. Transition characteristics from radio-frequency discharge to arc in hollow cathode configuration

    Institute of Scientific and Technical Information of China (English)

    许建平; 巩春志; 吴明忠; 田修波

    2014-01-01

    The technique ofglow discharges in radio frequency configuration was applied to ignite hollow cathode vacuum arc discharge.The effect of discharge parameters on the building up of hollow cathode arc discharge was investigated.The emission spectrum during the vacuum arc ignition process was measured to disclose the discharge dynamics.There exists a threshold radio frequency power (300 W),beyond which hollow cathode is in γmode discharge status while radio frequency discharge changes into the arc discharge.With the increase of the radio frequency power,the plasma temperature and electronic density increase,and the discharge mode transits more rapidly.The ignition time ofhollow cathode vacuum arc discharge is less than 4 s with a radio frequency power of700 W.

  11. The polarimetric multi-frequency radio sources properties

    CERN Document Server

    Galluzzi, V

    2016-01-01

    The polarization properties of extragalactic radio sources at frequencies higher than 20 GHz are still poorly constrained. However, their characterization would provide invaluable information about the physics of the emission processes and is crucial to estimate their contamination as foregrounds of the polarized cosmic microwave background (CMB) angular power spectrum on scales 200 mJy (at 20 GHz) carried out with the Australia Telescope Compact Array between 5.5 and 38 GHz. The analysis clearly shows that polarization properties cannot be simply inferred from total intensity ones, as the spectral behaviors of the two signals are typically different.

  12. Spectrum Utilisation and Management in Cognitive Radio Networks

    DEFF Research Database (Denmark)

    Patil, Kishor P.

    satisfy new market demands and increase spectrum efficiency. Evaluation of the spectrum usage is the first step toward the future deployment of cognitive radio. Several spectrum usage measurement campaigns have been performed mainly in USA and Europe. The results of these campaigns are not directly...... assigned to different services and it is very much difficult for the emerging wireless technologies to get entry due to rigid spectrum policy and heavy opportunity cost. The inefficient prevailing spectrum management causes the artificial spectrum scarcity. The measurement campaigns conducted worldwide...

  13. Radio Frequency Simulation System (RFSS) Capabilities Summary

    Science.gov (United States)

    1977-04-01

    S- 0LEVEL-- TECHNICAL REPORT TD -77-8 RADIO FREQUENCY SIMULATION SYSTEM (RFSS) CAPABILITIES SUMMARY 00 SAeroballistios Directorate Advanced Simulation...gAttn: DRDMT - TD /AMCMS 63 303.214131101 RedstngArj gUAl. Alabmt 35809______________ It CONTITL.uNG OFFICE NAME AND ADDRESS CoMuaa ner US Army Missile...r ~- -- 0 0 0 1 N -4 -- -~ *5 0 - 5e41 -A I: a 00 I I. S Jto cc iI us V A U. II I’~z’LF~iJ - - - - -> 3-cc dc -4 -.40 =! Jo -AZC 4 C - 442q 0 M~A $Ji a

  14. Radio frequency driven multicusp sources (invited)

    Science.gov (United States)

    Leung, Ka-Ngo

    1998-02-01

    The radio frequency (rf)-driven multicusp source was originally developed for use in the superconducting super collider injector. The source can routinely provide 30 mA of H˜ beam at 0.1% duty factor. By adding a minute quantity of cesium to the discharge, H- beam current in excess of 100 mA and e/H˜1 has been achieved. The rf-driven H˜ source is being further developed for 6% duty factor operation to be used in the national spallation neutron source. Application of the rf-driven multicusp source has been extended to radioactive ion beam production, ion projection lithography, and compact neutron tubes.

  15. Radio frequency transistors principles and practical applications

    CERN Document Server

    Dye, Norm

    1993-01-01

    Cellular telephones, satellite communications and radar systems are adding to the increasing demand for radio frequency circuit design principles. At the same time, several generations of digitally-oriented graduates are missing the essential RF skills. This book contains a wealth of valuable design information difficult to find elsewhere.It's a complete 'tool kit' for successful RF circuit design. Written by experienced RF design engineers from Motorola's semiconductors product section.Book covers design examples of circuits (e.g. amplifiers; oscillators; switches; pulsed power; modular syst

  16. Strategies for improvement of spectrum capacity for WiMax cellular systems by Cognitive Radio Technology supported by Relay Stations

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2007-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context will be presented and discussed in this paper. Ideas to improve the wireless transmission by orthogonal OFDM-based communication and to increase the c...

  17. Strategies for improvement of spectrum capacity for WiMax cellular systems by Cognitive Radio Technology supported by Relay Stations

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2007-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context will be presented and discussed in this paper. Ideas to improve the wireless transmission by orthogonal OFDM-based communication and to increase...

  18. Extragalactic radio sources with sharply inverted spectrum at metre wavelengths

    CERN Document Server

    Gopal-Krishna,; Mhaskey, Mukul; Ranadive, Pritesh; Wiita, Paul J; Goyal, A; Kantharia, N G; Ishwara-Chandra, C H

    2014-01-01

    We present the first results of a systematic search for the rare extragalactic radio sources showing an inverted (integrated) spectrum, with spectral index $\\alpha \\ge +2.0$, a previously unexplored spectral domain. The search is expected to yield strong candidates for $\\alpha \\ge +2.5$, for which the standard synchrotron self-absorption (characterized by a single power-law energy distribution of relativistic electron population) would not be a plausible explanation, even in an ideal case of a perfectly homogeneous source of incoherent synchrotron radiation. Such sharply inverted spectra, if found, would require alternative explanations, e.g., free-free absorption, or non-standard energy distribution of relativistic electrons which differs from a power-law (e.g., Maxwellian). The search was carried out by comparing two sensitive low-frequency radio surveys made with sub-arcminute resolution, namely, the WISH survey at 352 MHz and TGSS/DR5 at 150 MHz. The overlap region between these two surveys contains 7056 ...

  19. Genetic spectrum assignment model with constraints in cognitive radio networks

    Directory of Open Access Journals (Sweden)

    Fang Ye

    2011-06-01

    Full Text Available The interference constraints of genetic spectrum assignment model in cognitive radio networks are analyzed in this paper. An improved genetic spectrum assignment model is proposed. The population of genetic algorithm is divided into two sets, the feasible spectrum assignment strategies and the randomly updated spectrum assignment strategies. The penalty function is added to the utility function to achieve the spectrum assignment strategy that satisfies the interference constraints and has better fitness. The proposed method is applicable in both the genetic spectrum assignment model and the quantum genetic spectrum assignment mode. It can ensure the randomness of partial chromosomes in the population to some extent, and reduce the computational complexity caused by the constraints-free procedure after the update of population. Simulation results show that the proposed method can achieve better performance than the conventional genetic spectrum assignment model and quantum genetic spectrum assignment model

  20. Oscillation Maps in the Broadband Radio Spectrum of the 1 August 2010 Event

    Science.gov (United States)

    Karlický, M.; Rybák, J.

    2017-01-01

    We search for indications of waves in the 25 - 2000 MHz radio spectrum of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast propagating waves in the solar corona with periods of 181, 69, and 40 seconds were detected in UV observations. Using the wavelet technique, we construct a new type of oscillation map for selected periods in the whole domain of the radio spectrum. While an oscillation with a period of 181 seconds was recognized in the whole 25 - 2000 MHz radio spectrum, oscillations with periods of 69 and 40 seconds were only confirmed in the 250 - 870 MHz frequency range. In the 800 - 2000 MHz range we found periods of 50 and 80 seconds. Moreover, in the 250 - 870 MHz frequency range, an oscillation with a period of about 420 seconds was detected. We also made maps of phases of the 181-second oscillations in order to analyze their frequency drift. At the beginning of the radio event, the phase of the 181-second oscillation in the 2000 - 500 MHz frequency range drifts toward lower frequencies. On the other hand, we found that the phase is nearly synchronous at frequencies 25 - 500 MHz. While the phase drift at higher frequencies can be interpreted as being caused by the UV wave, the synchronization of the phase on lower frequencies is explained by the fast electron beams, whose acceleration is modulated by the UV wave. Owing to this modulation, the electron beams are accelerated with the period of the UV wave (181 seconds). These beams propagate upward through the solar corona and generate the 25 - 500 MHz radio emission with the 181-second period. The 25 - 500 MHz radio emission, which corresponds to a large interval of heights in the solar corona, is nearly synchronous because of the high beam velocity ({≈} c/3, where c is the light speed).

  1. Generalized Block Sparse Constraint Based Compressive Wideband Spectrum Sensing for Cognitive Radio

    CERN Document Server

    Liu, Yipeng

    2010-01-01

    Wideband spectrum sensing detects the unused spectrum holes for dynamic spectrum access of cognitive radios. However the too high sampling rate is the challenge for application. As the survey shows that the monitoring primary signal has sparse representation in frequency domain, compressive sensing can be used to transfer the sampling burden to the digital signal processor. An analog to information converter can randomly sample the received signal with sub-Nyquist rate to obtain the random measurements. In the spectrum recovery, to match the practical situation, an improved block sparse signal model can be formulated in that the static frequency spectrum allocation of primary radios means the bounds between di?erent primary radios is known. The whole monitoring spectrum is divided sections of di?erent length in accordance with di?erent allocated primary radios. The minimization of the l2 norm can encourage the dense distribution locally, while the l1 norm of the l2 norms can give the sparse distribution of th...

  2. Spectrum sensing using single-radio switched-beam antenna systems

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Wilcox, David; De Carvalho, Elisabeth

    2012-01-01

    The paper describes spectrum sensing using single-radio switched-beam arrays with reactance-loaded parasitic elements. At a given frequency, the antenna's loading conditions (reactive loads) are optimized for maximum average beamforming gain in the beampattern look direction. Circular permutations...

  3. Two perspectives on trading in radio spectrum usage rights: coase and commons compared

    NARCIS (Netherlands)

    Lemstra, Wolter; Groenewegen, John; Vries, de Piet; Akalu, Rajen

    2014-01-01

    In this contribution, we address the introduction of private property rights and market trades in the use of the radio frequency spectrum. We discuss the UK case being inspired by the ideas of Coase. We discuss how an appropriate design of property rights and a secondary market would look like and h

  4. Spectrum sensing using single-radio switched-beam antenna systems

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Wilcox, David; De Carvalho, Elisabeth

    2012-01-01

    The paper describes spectrum sensing using single-radio switched-beam arrays with reactance-loaded parasitic elements. At a given frequency, the antenna's loading conditions (reactive loads) are optimized for maximum average beamforming gain in the beampattern look direction. Circular permutations...

  5. Discovery of ultra-steep spectrum giant radio galaxy with recurrent radio jet activity in Abell 449

    CERN Document Server

    Hunik, D

    2016-01-01

    We report a discovery of a 1.3 Mpc diffuse radio source with extremely steep spectrum fading radio structures in the vicinity of the Abell 449 cluster of galaxies. Its extended diffuse lobes are bright only at low radio frequencies and their synchrotron age is about 160 Myr. The parent galaxy of the extended relic structure, which is the dominant galaxy within the cluster, is starting a new jet activity. There are three weak X-rays sources in the vicinity of the cluster as found in the ROSAT survey, however it is not known if they are connected with this cluster of galaxies. Just a few radio galaxy relics are currently known in the literature, as finding them requires sensitive and high angular resolution low-frequency radio observations. Objects of this kind, which also are starting a new jet activity, are important for understanding the life cycle and evolution of active galactic nuclei. A new 613 MHz map as well as the archival radio data pertaining to this object are presented and analyzed.

  6. DISCOVERY OF ULTRA-STEEP SPECTRUM GIANT RADIO GALAXY WITH RECURRENT RADIO JET ACTIVITY IN ABELL 449

    Energy Technology Data Exchange (ETDEWEB)

    Hunik, Dominika; Jamrozy, Marek, E-mail: dominika.hunik@uj.edu.pl [Obserwatorium Astronomiczne, Uniwersytet Jagielloński, ul. Orla 171, 30-244 Kraków (Poland)

    2016-01-20

    We report a discovery of a 1.3 Mpc diffuse radio source with extremely steep spectrum fading radio structures in the vicinity of the Abell 449 cluster of galaxies. Its extended diffuse lobes are bright only at low radio frequencies and their synchrotron age is about 160 Myr. The parent galaxy of the extended relic structure, which is the dominant galaxy within the cluster, is starting a new jet activity. There are three weak X-rays sources in the vicinity of the cluster as found in the ROSAT survey, however it is not known if they are connected with this cluster of galaxies. Just a few radio galaxy relics are currently known in the literature, as finding them requires sensitive and high angular resolution low-frequency radio observations. Objects of this kind, which also are starting a new jet activity, are important for understanding the life cycle and evolution of active galactic nuclei. A new 613 MHz map as well as the archival radio data pertaining to this object are presented and analyzed.

  7. Digital Receivers for Low-Frequency Radio Telescopes UTR-2, URAN, GURT

    Science.gov (United States)

    Zakharenko, V.; Konovalenko, A.; Zarka, P.; Ulyanov, O.; Sidorchuk, M.; Stepkin, S.; Koliadin, V.; Kalinichenko, N.; Stanislavsky, A.; Dorovskyy, V.; Shepelev, V.; Bubnov, I.; Yerin, S.; Melnik, V.; Koval, A.; Shevchuk, N.; Vasylieva, I.; Mylostna, K.; Shevtsova, A.; Skoryk, A.; Kravtsov, I.; Volvach, Y.; Plakhov, M.; Vasilenko, N.; Vasylkivskyi, Y.; Vavriv, D.; Vinogradov, V.; Kozhin, R.; Kravtsov, A.; Bulakh, E.; Kuzin, A.; Vasilyev, A.; Ryabov, V.; Reznichenko, A.; Bortsov, V.; Lisachenko, V.; Kvasov, G.; Mukha, D.; Litvinenko, G.; Brazhenko, A.; Vashchishin, R.; Pylaev, O.; Koshovyy, V.; Lozinsky, A.; Ivantyshyn, O.; Rucker, H. O.; Panchenko, M.; Fischer, G.; Lecacheux, A.; Denis, L.; Coffre, A.; Grießmeier, J.-M.

    This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. Since 1998, digital receivers performing on-the-fly dynamic spectrum calculations or waveform data recording without data loss have been used at the UTR-2 radio telescope, the URAN VLBI system, and the GURT new generation radio telescope. Here, we detail these receivers developed for operation in the strong interference environment that prevails in the decameter wavelength range. Data collected with these receivers allowed us to discover numerous radio astronomical objects and phenomena at low frequencies, a summary of which is also presented.

  8. World Administrative Radio Conference. Issues for US International Spectrum Policy

    Science.gov (United States)

    1991-11-01

    U.S. preparations for the 1992 World Administrative Radio Conference to be held in Spain, February 1992 are examined. WARC-92 will attempt to reassign radio frequencies internationally in order to take advantage of new radio-based technologies and applications, such as digital audio broadcasting, high definition television, and personal communications services, while still accommodating the needs of existing users and services. The impacts of the realignment will be felt throughout the U.S. economy and around the world, and the agreements reached at WARC-92 will influence the development of radio-based systems and services well into the next century.

  9. Market-driven spectrum sharing in cognitive radio

    CERN Document Server

    Yi, Changyan

    2016-01-01

    This brief focuses on the current research on mechanism design for dynamic spectrum sharing in cognitive radio (CR) networks. Along with a review of CR architectures and characteristics, this brief presents the motivations, significances and unique challenges of implementing algorithmic mechanism design for encouraging both primary spectrum owners and secondary spectrum users to participate in dynamic spectrum sharing. The brief then focuses on recent advances in mechanism design in CR networks. With an emphasis on dealing with the uncertain spectrum availabilities, mechanisms based on spectrum recall, two-stage spectrum sharing and online spectrum allocation are introduced with the support of theoretic analyses and numerical illustrations. The brief concludes with a discussion of potential research directions and interests, which will motivate further studies on mechanism design for wireless communications. This brief is concise and approachable for researchers, professionals and advanced-level students in w...

  10. Radio emission of extensive air showers at microwave frequencies

    Science.gov (United States)

    Filonenko, A. D.

    2016-05-01

    It is found that the power of the incoherent radiation of ionization electrons of an extensive air shower in the frequency range of 150 GHz is more than 10-24 W/m2Hz, with the shower energy ~1018 eV at a distance of 5 km from its axis. This means that, unlike fluorescent detectors, a radio telescope with an effective area of more than 300 m2 can monitor the trajectory of showers with an energy higher than 1018 eV at any time of the day regardless of the weather. The spectrum maximum near the frequency of 150 GHz is roughly three orders of magnitude higher than the value experimentally measured in the characteristic band (~5-10 GHz).

  11. Distributed opportunistic spectrum sharing in cognitive radio networks

    KAUST Repository

    Hawa, Mohammed

    2016-05-19

    In cases where the licensed radio spectrum is underutilized, cognitive radio technology enables cognitive devices to sense and then dynamically access this scarce resource making the most out of it. In this work, we introduce a simple and intuitive, yet powerful and efficient, technique that allows opportunistic channel access in cognitive radio systems in a completely distributed fashion. Our proposed method achieves very high values of spectrum utilization and throughput. It also minimizes interference between cognitive base stations and the primary users licensed to use the spectrum. The algorithm responds quickly and efficiently to variations in the network parameters and also achieves a high degree of fairness between cognitive base stations. © 2016 John Wiley & Sons, Ltd.

  12. Target tracking based on frequency spectrum amplitude

    Institute of Scientific and Technical Information of China (English)

    Guo Huidong; Zhang Xinhua; Xia Zhijun

    2006-01-01

    The amplitude of frequency spectrum can be integrated with probabilistic data association (PDA) to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The probabilistic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.

  13. Radio frequency multicusp ion source development (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Leung, K.N. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

    1996-03-01

    The radio-frequency (rf) driven multicusp source was originally developed for use in the Superconducting Super Collider injector. It has been demonstrated that the source can meet the H{sup {minus}} beam current and emittance requirements for this application. By employing a porcelain-coated antenna, a clean plasma discharge with very long-life operation can be achieved. Today, the rf source is used to generate both positive and negative hydrogen ion beams and has been tested in various particle accelerator laboratories throughout the world. Applications of this ion source have been extended to other fields such as ion beam lithography, oil-well logging, ion implantation, accelerator mass spectrometry and medical therapy machines. This paper summarizes the latest rf ion source technology and development at the Lawrence Berkeley National Laboratory. {copyright} {ital 1996 American Institute of Physics.}

  14. Radio frequency driven multicusp sources (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Leung, K. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road-MS 5/119, University of California, Berkeley, California 94720 (United States)

    1998-02-01

    The radio frequency (rf)-driven multicusp source was originally developed for use in the superconducting super collider injector. The source can routinely provide 30 mA of H{sup {approximately}} beam at 0.1{percent} duty factor. By adding a minute quantity of cesium to the discharge, H{sup {minus}} beam current in excess of 100 mA and e/H{approximately}1 has been achieved. The rf-driven H{approximately} source is being further developed for 6{percent} duty factor operation to be used in the national spallation neutron source. Application of the rf-driven multicusp source has been extended to radioactive ion beam production, ion projection lithography, and compact neutron tubes.{copyright} {ital 1998 American Institute of Physics.}

  15. Radio frequency multicusp ion source development (invited)

    Science.gov (United States)

    Leung, K. N.

    1996-03-01

    The radio-frequency (rf) driven multicusp source was originally developed for use in the Superconducting Super Collider injector. It has been demonstrated that the source can meet the H- beam current and emittance requirements for this application. By employing a porcelain-coated antenna, a clean plasma discharge with very long-life operation can be achieved. Today, the rf source is used to generate both positive and negative hydrogen ion beams and has been tested in various particle accelerator laboratories throughout the world. Applications of this ion source have been extended to other fields such as ion beam lithography, oil-well logging, ion implantation, accelerator mass spectrometry and medical therapy machines. This paper summarizes the latest rf ion source technology and development at the Lawrence Berkeley National Laboratory.

  16. SMART TRAVELLING WITH RADIO FREQUENCY IDENTIFICATION

    Directory of Open Access Journals (Sweden)

    Zainab Rasheed Fahad Mirza

    2013-01-01

    Full Text Available Radio Frequency Identification (RFID technology is being widely used now-a-days and is becoming more popular with every passing day. There are varied applications of this technology in various fields such as industry, communication, travel and transportation. Roads, rail ways, air traffic and container vessel shipping all share underlying abstractions of transportation nets with hubs. This study is concerned with applications of RFID technology with Cloud computing, innovation in the field of travelling and its applications for different modes of transportation at Harbors, airports, train stations, road intersections providing security, coordination, to the users. Combined with other technologies, RFID technology is being used for modern airports baggage system, for railroad car identification, in container transportation systems, for fuel supply control of vehicles, in traffic management system and in travelling information system.

  17. TOUTATIS: A radio frequency quadrupole code

    Directory of Open Access Journals (Sweden)

    Romuald Duperrier

    2000-12-01

    Full Text Available A cw high power linear accelerator can only work with very low particle losses and structure activation. At low energy, the radio frequency quadrupole (RFQ is an accelerator element that is very sensitive to losses. To design this structure, a good understanding of the beam dynamics is required. Generally, the reference code PARMTEQM is enough to design the accelerator. TOUTATIS has been written with the goals of cross-checking results and obtaining more reliable dynamics. This paper relates the different numerical methods used in the code. It is time based, using multigrids methods and adaptive mesh for a fine description of the forces without being time consuming. The field is calculated through a Poisson solver and the vanes are fully described, allowing it to properly simulate the coupling gaps and the RFQs extremities. Theoretical and experimental tests are also described and show a good agreement between simulations and reference cases.

  18. An amplitude modulated radio frequency plasma generator

    Science.gov (United States)

    Lei, Fan; Li, Xiaoping; Liu, Yanming; Liu, Donglin; Yang, Min; Xie, Kai; Yao, Bo

    2017-04-01

    A glow discharge plasma generator and diagnostic system has been developed to study the effects of rapidly variable plasmas on electromagnetic wave propagation, mimicking the plasma sheath conditions encountered in space vehicle reentry. The plasma chamber is 400 mm in diameter and 240 mm in length, with a 300-mm-diameter unobstructed clear aperture. Electron densities produced are in the mid 1010 electrons/cm3. An 800 W radio frequency (RF) generator is capacitively coupled through an RF matcher to an internally cooled stainless steel electrode to form the plasma. The RF power is amplitude modulated by a waveform generator that operates at different frequencies. The resulting plasma contains electron density modulations caused by the varying power levels. A 10 GHz microwave horn antenna pair situated on opposite sides of the chamber serves as the source and detector of probe radiation. The microwave power feed to the source horn is split and one portion is sent directly to a high-speed recording oscilloscope. On mixing this with the signal from the pickup horn antenna, the plasma-induced phase shift between the two signals gives the path-integrated electron density with its complete time dependent variation. Care is taken to avoid microwave reflections and extensive shielding is in place to minimize electronic pickup. Data clearly show the low frequency modulation of the electron density as well as higher harmonics and plasma fluctuations.

  19. Spectrum handoff algorithm with imperfect spectrum sensing incognitive radio networks

    Science.gov (United States)

    Ma, Bin; Bao, Xiao-min; Xie, Xian-zhong

    2016-10-01

    To guarantee the quality of service of licensed users, the unlicensed users must vacate the occupied channel by spectrum handoff if licensed users appear in the licensed spectrum. However, spectrum sensing with false alarm and missed detection may lead to more inaccuracy problems when unlicensed users perform spectrum handoff. To improve the problems mentioned before, we utilize PRP M/G/1 queuing network model to propose a spectrum handoff algorithm with error data retransmission mechanism and analyze its performance by transmission delay and extended data delivery time. In addition, we discuss the relationship between false alarm probability, extended data delivery time and user traffic load and verify the effectiveness of the proposed algorithm.

  20. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, H.J.; Fomin, F.V.; Pyatkin, A.V.; Woeginer, G.J.

    2007-01-01

    A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least 2. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the so

  1. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, H.J.; Fomin, F.V.; Pyatkin, A.V.; Woeginer, G.J.

    2002-01-01

    A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least 2. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the

  2. Radio labeling with pre-assigned frequencies

    NARCIS (Netherlands)

    Bodlaender, H.L.; Broersma, Haitze J.; Fomin, F.V.; Pyatkin, A.V.; Woeginger, Gerhard

    2002-01-01

    A radio labeling of a graph $G$ is an assignment of pairwise distinct, positive integer labels to the vertices of $G$ such that labels of adjacent vertices differ by at least $2$. The radio labeling problem (\\mbox{\\sc RL}) consists in determining a radio labeling that minimizes the maximum label

  3. Oscillation Maps in the Broadband Radio Spectrum of the 1 August 2010 Event

    CERN Document Server

    Karlicky, M

    2016-01-01

    We search for indications of waves in the 25-2000 MHz radio spectrum of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast propagating waves in the solar corona with the periods of 181, 69, and 40 seconds were detected in UV observations. Using the wavelet technique we construct a new type of map of oscillations for selected periods in the whole domain of the radio spectrum. While the oscillation with the period of 181 seconds was recognized in the whole 25-2000 MHz radio spectrum, oscillations with periods of 69 and 40 seconds were confirmed only in the 250-870 MHz frequency range. In the 800-2000 MHz range we found periods of 50 and 80 seconds. Moreover, in the 250-870 MHz frequency range, the oscillation with the period of about 420 seconds was detected. We also made maps of phases of the 181-second oscillations in order to analyze their frequency drift. At the beginning of the radio event, in the 2000-500 MHz frequency range the phase of the 181-second oscillation drifts towards lower fr...

  4. Dispersion by pulsars, magnetars, fast radio bursts and massive electromagnetism at very low radio frequencies

    CERN Document Server

    Bentum, Mark J; Spallicci, Alessandro D A M

    2016-01-01

    Our understanding of the universe relies mostly on electromagnetism. As photons are the messengers, fundamental physics is concerned in testing their properties. Photon mass upper limits have been earlier set through pulsar observations, but new investigations are offered by the excess of dispersion measure (DM) sometimes observed with pulsar and magnetar data at low frequencies, or with the fast radio bursts (FRBs), of yet unknown origin. Arguments for the excess of DM do not reach a consensus, but are not mutually exclusive. Thus, we remind that for massive electromagnetism, dispersion goes as the inverse of the frequency squared. Thereby, new avenues are offered also by the recently operating ground observatories in 10-80 MHz domain and by the proposed Orbiting Low Frequency Antennas for Radio astronomy (OLFAR). The latter acts as a large aperture dish by employing a swarm of nano-satellites observing the sky for the first time in the 0.1 - 15 MHz spectrum. The swarm must be deployed sufficiently away from...

  5. Dispersion by pulsars, magnetars, fast radio bursts and massive electromagnetism at very low radio frequencies

    Science.gov (United States)

    Bentum, Mark J.; Bonetti, Luca; Spallicci, Alessandro D. A. M.

    2017-01-01

    Our understanding of the universe relies mostly on electromagnetism. As photons are the messengers, fundamental physics is concerned in testing their properties. Photon mass upper limits have been earlier set through pulsar observations, but new investigations are offered by the excess of dispersion measure (DM), sometimes observed with pulsar and magnetar data at low frequencies, or with the fast radio bursts (FRBs), of yet unknown origin. Arguments for the excess of DM do not reach a consensus, but are not mutually exclusive. Thus, we remind that for massive electromagnetism, dispersion goes as the inverse of the frequency squared. Thereby, new avenues are offered also by the recently operating ground observatories in 10-80 MHz domain and by the proposed Orbiting Low Frequency Antennas for Radio astronomy (OLFAR). The latter acts as a large aperture dish by employing a swarm of nano-satellites observing the sky for the first time in the 0.1-15 MHz spectrum. The swarm must be deployed sufficiently away from the ionosphere to avoid distorsions from terrestrial interference, especially during solar maxima, and offer stable conditions for calibration during observations.

  6. Trirotron: triode rotating beam radio frequency amplifier

    Science.gov (United States)

    Lebacqz, Jean V.

    1980-01-01

    High efficiency amplification of radio frequencies to very high power levels including: establishing a cylindrical cloud of electrons; establishing an electrical field surrounding and coaxial with the electron cloud to bias the electrons to remain in the cloud; establishing a rotating electrical field that surrounds and is coaxial with the steady field, the circular path of the rotating field being one wavelength long, whereby the peak of one phase of the rotating field is used to accelerate electrons in a beam through the bias field in synchronism with the peak of the rotating field so that there is a beam of electrons continuously extracted from the cloud and rotating with the peak; establishing a steady electrical field that surrounds and is coaxial with the rotating field for high-energy radial acceleration of the rotating beam of electrons; and resonating the rotating beam of electrons within a space surrounding the second field, the space being selected to have a phase velocity equal to that of the rotating field to thereby produce a high-power output at the frequency of the rotating field.

  7. Ultra Steep Spectrum radio sources in the Lockman Hole: SERVS identifications and redshift distribution at the faintest radio fluxes

    CERN Document Server

    Afonso, J; Ibar, E; Grossi, M; Simpson, C; Chapman, S; Jarvis, M J; Rottgering, H; Norris, R P; Dunlop, J; Ivison, R J; Messias, H; Pforr, J; Vaccari, M; Seymour, N; Best, P; González-Solares, E; Farrah, D; Fernandes, C A C; Huang, J -S; Lacy, M; Marastron, C; Marchetti, L; Mauduit, J -C; Oliver, S; Rigopoulou, D; Stanford, S A; Surace, J; Zeimann, G

    2011-01-01

    Ultra Steep Spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z>~2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610 MHz integrated fluxes above 100 microJy, is assembled. Deep infrared data at 3.6 and 4.5 micron from the Spitzer Extragalactic Representative Volume Survey (SERVS) is used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6](AB)=19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of...

  8. Kinerja Spectrum Sensing dengan Metode Matched Filter Detector pada Radio Kognitif

    Directory of Open Access Journals (Sweden)

    BAYU ANGGA

    2017-06-01

    Full Text Available Abstrak Evolusi sistem nirkabel dan teknologi saat ini telah membuat dampak besar pada masyarakat. Namun, disaat yang sama pengelolaan dan pemanfaatan kelangkaan spektrum tidak efisien. Radio kognitif adalah paradigma baru dalam merancang sistem komunikasi nirkabel yang bertujuan untuk meningkatkan pemanfaatan spektrum frekuensi radio (RF dan mengurangi seminimal mungkin kelangkaan spektrum. Spectrum sensing adalah langkah utama yang akan memungkinkan jaringan radio kognitif, yaitu untuk menentukan status spektrum dan aktivitas pengguna utama secara berkala, dengan menggunakan metode matched filter detector dan energy detector sebagai pembandingnya. Hasil dari kinerja spectrum sensing berdasarkan simulasi, menunjukan kinerja matched filter detector membutuhkan SNR = 15 dB untuk mencapai probability detection (Pd sebesar 100%, dengan probability false alarm sebesar 0,01, sedangkan energy detector hanya membutuhkan SNR = 14,2 dB. Secara keseluruhan untuk deteksi sinyal yang optimal kinerja matched filter detector tidak lebih baik dibanding kinerja energy detector. Kata kunci: spectrum sensing, radio kognitif, probability detection, matched filter detector, energy detector. Abstract The evolution of wireless systems and current technology has made a huge impact on society. However, at the same time the management and utilization of spectrum scarcity is not efficient. Cognitive Radio is a new paradigm in designing wireless communication system that aims to improve the utilization of the radio frequency spectrum (RF and reduce to a minimum the scarcity of spectrum. Spectrum sensing is a major step that will allow the cognitive radio networks, namely to determine the status of the spectrum and activity of the primary user at regular intervals, using the method of matched filter detector and energy detector as a comparison. The results of the performance spectrum sensing based on simulations, indicates the performance matched filter detector requires

  9. Performance Analysis of Ad Hoc Dispersed Spectrum Cognitive Radio Networks over Fading Channels

    Directory of Open Access Journals (Sweden)

    Mohammad Muneer

    2011-01-01

    Full Text Available Cognitive radio systems can utilize dispersed spectrum, and thus such approach is known as dispersed spectrum cognitive radio systems. In this paper, we first provide the performance analysis of such systems over fading channels. We derive the average symbol error probability of dispersed spectrum cognitive radio systems for two cases, where the channel for each frequency diversity band experiences independent and dependent Nakagami- fading. In addition, the derivation is extended to include the effects of modulation type and order by considering M-ary phase-shift keying ( -PSK and M-ary quadrature amplitude modulation -QAM schemes. We then consider the deployment of such cognitive radio systems in an ad hoc fashion. We consider an ad hoc dispersed spectrum cognitive radio network, where the nodes are assumed to be distributed in three dimension (3D. We derive the effective transport capacity considering a cubic grid distribution. Numerical results are presented to verify the theoretical analysis and show the performance of such networks.

  10. DEMONSTRATION BULLETIN: RADIO FREQUENCY HEATING - KAI TECHNOLOGIES, INC.

    Science.gov (United States)

    Radio frequency heating (RFH) is a process that uses electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. An RFH system developed by KAI Technologies, I...

  11. Experimental radio frequency link for Ka-band communications applications

    Science.gov (United States)

    Fujikawa, Gene; Conray, Martin J.; Saunders, Alan L.; Pope, Dale E.

    1988-01-01

    An experimental radio frequency link has been demonstrated to provide two-way communication between a remote user ground terminal and a ground-based Ka-band transponder. Bit-error-rate performance and radio frequency characteristics of the communication link were investigated.

  12. 47 CFR 80.927 - Antenna radio frequency indicator.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna radio frequency indicator. 80.927... Boats § 80.927 Antenna radio frequency indicator. The transmitter must be equipped with a device which provides visual indication whenever the transmitter is supplying power to the antenna. ...

  13. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna radio frequency indicator. 80.1019... Act § 80.1019 Antenna radio frequency indicator. Each nonportable bridge-to-bridge transmitter must be... indication when the transmitter is supplying power to the antenna transmission line or, in lieu thereof, a...

  14. `Fingerprint' Fine Structure in the Solar Decametric Radio Spectrum Solar Physics

    Science.gov (United States)

    Zlotnik, E. Y.; Zaitsev, V. V.; Melnik, V. N.; Konovalenko, A. A.; Dorovskyy, V. V.

    2015-07-01

    We study a unique fine structure in the dynamic spectrum of the solar radio emission discovered by the UTR-2 radio telescope (Kharkiv, Ukraine) in the frequency band of 20 - 30 MHz. The structure was observed against the background of a broadband type IV radio burst and consisted of parallel drifting narrow bands of enhanced emission and absorption on the background emission. The observed structure differs from the widely known zebra pattern at meter and decimeter wavelengths by the opposite directions of the frequency drift within a single stripe at a given time. We show that the observed properties can be understood in the framework of the radiation mechanism by virtue of the double plasma resonance effect in a nonuniform coronal magnetic trap. We propose a source model providing the observed frequency drift of the stripes.

  15. Radio-frequency measurement in semiconductor quantum computation

    Science.gov (United States)

    Han, TianYi; Chen, MingBo; Cao, Gang; Li, HaiOu; Xiao, Ming; Guo, GuoPing

    2017-05-01

    Semiconductor quantum dots have attracted wide interest for the potential realization of quantum computation. To realize efficient quantum computation, fast manipulation and the corresponding readout are necessary. In the past few decades, considerable progress of quantum manipulation has been achieved experimentally. To meet the requirements of high-speed readout, radio-frequency (RF) measurement has been developed in recent years, such as RF-QPC (radio-frequency quantum point contact) and RF-DGS (radio-frequency dispersive gate sensor). Here we specifically demonstrate the principle of the radio-frequency reflectometry, then review the development and applications of RF measurement, which provides a feasible way to achieve high-bandwidth readout in quantum coherent control and also enriches the methods to study these artificial mesoscopic quantum systems. Finally, we prospect the future usage of radio-frequency reflectometry in scaling-up of the quantum computing models.

  16. Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies

    NARCIS (Netherlands)

    Labiano, A.; O'Dea, C. P.; Barthel, P. D.; Vries, W. H. de; Baum, S. A.

    2007-01-01

    Abstract: AIMS: Search for star formation regions in the hosts of potentially young radio galaxies (Gigahertz Peaked Spectrum and Compact Steep Spectrum sources). METHODS: Near-UV imaging with the Hubble Space Telescope Advanced Camera for Surveys.} RESULTS: We find near-UV light which could be the

  17. Radio spectrum evolution and magnetic field in extreme GPS radio sources. The case of RXJ1459+3337

    CERN Document Server

    Orienti, M

    2007-01-01

    Aims: The knowledge of the properties of the youngest radio sources is very important in order to trace the earliest phase of the evolution of the radio emission. RXJ1459+3337, with its high turnover frequency (~25 GHz) provides a unique opportunity to study this class of extreme objects. Methods: High-sensitivity multi-frequency VLA observations have been carried out to measure the flux-density with high accuracy, while multi-frequency VLBA observations were performed, aimed at determining the pc-scale structure. Archival ROSAT data have been used to infer the X-ray luminosity. Results: The comparison between our new VLA data and those available in the literature shows a steady increment of the flux-density in the optically-thick part of the spectrum and a decrement of the turnover frequency. In the optically-thin regime, the source flux density has already started to decrease. Such a variability can be explained in terms of an adiabatically-expanding homogeneous radio component. The frequency range spanned ...

  18. Radio Frequency Heating for Soil Remediation.

    Science.gov (United States)

    Price, Stephen L; Kasevich, Raymond S; Johnson, Mark A; Wiberg, Dan; Marley, Michael C

    1999-02-01

    Radio frequency heating (RFH) is a technology that increases the cost-effectiveness of a variety of site remediation technologies by accelerating the rate of contaminant removal. Heating makes the physical, chemical, and biological properties of materials such as contaminants, soil, and groundwater more amenable to remediation. RFH brings controlled heating to the subsurface, enhancing the removal of contaminants by soil vapor extraction (SVE), groundwater aeration (air sparging), bioremediation, and product recovery. The results presented are from a bench-scale study and a field demonstration that both used RFH to enhance the performance of SVE. The bench-scale study performed on PCE-contaminated soil revealed an increase, by a factor of 8, in the removal rate when RFH was used to heat soil to 90 °C. The application of RFH for a three-week period at a former gasoline station near St. Paul, MN, resulted in raising the ambient soil temperature from 8 °C to 100 °C in the immediate vicinity of the RFH applicator and to 40 °C 1.5 m (5 ft) away. Most significantly, the use of an integrated RFH/SVE system achieved an overall 50% reduction in gasoline range organics (GRO) in soil over a two- to three-month period. The discussion includes applications of RFH for enhancing bioremediation and product recovery.

  19. Moessbauer absorption by thick ferromagnets in radio-frequency magnetic field

    CERN Document Server

    Dzyublik, A Y

    2002-01-01

    The dynamical scattering theory is developed for transmission of the Moessbauer radiation through a ferromagnetic absorber of arbitrary thickness whose magnetization periodically reverses under the influence of an external radio-frequency (RF) magnetic field. The thickness dependence of the Moessbauer absorption spectrum as well as the time dependence and energy distribution of the transmitted beam are analyzed. The transmitted spectrum as a function of the frequency of transmitted gamma-quanta, reveals a sideband structure separated by twice the frequency of the RF field, which collapses to a single line at high frequencies.

  20. A survey of spectrum prediction methods in cognitive radio networks

    Science.gov (United States)

    Wu, Jianwei; Li, Yanling

    2017-04-01

    Spectrum prediction technology is an effective way to solve the problems of processing latency, spectrum access, spectrum collision and energy consumption in cognitive radio networks. Spectral prediction technology is divided into three categories according to its nature, namely, spectral prediction method based on regression analysis, spectrum prediction method based on Markov model and spectrum prediction method based on machine learning. By analyzing and comparing the three kinds of prediction models, the author hopes to provide some reference for the later researchers. In this paper, the development situation, practical application and existent problems of three kinds of forecasting models are analyzed and summarized. On this basis, this paper discusses the development trend of the next step.

  1. Spectrum sensing and resource allocation for multicarrier cognitive radio systems under interference and power constraints

    Science.gov (United States)

    Dikmese, Sener; Srinivasan, Sudharsan; Shaat, Musbah; Bader, Faouzi; Renfors, Markku

    2014-12-01

    Multicarrier waveforms have been commonly recognized as strong candidates for cognitive radio. In this paper, we study the dynamics of spectrum sensing and spectrum allocation functions in cognitive radio context using very practical signal models for the primary users (PUs), including the effects of power amplifier nonlinearities. We start by sensing the spectrum with energy detection-based wideband multichannel spectrum sensing algorithm and continue by investigating optimal resource allocation methods. Along the way, we examine the effects of spectral regrowth due to the inevitable power amplifier nonlinearities of the PU transmitters. The signal model includes frequency selective block-fading channel models for both secondary and primary transmissions. Filter bank-based wideband spectrum sensing techniques are applied for detecting spectral holes and filter bank-based multicarrier (FBMC) modulation is selected for transmission as an alternative multicarrier waveform to avoid the disadvantage of limited spectral containment of orthogonal frequency-division multiplexing (OFDM)-based multicarrier systems. The optimization technique used for the resource allocation approach considered in this study utilizes the information obtained through spectrum sensing and knowledge of spectrum leakage effects of the underlying waveforms, including a practical power amplifier model for the PU transmitter. This study utilizes a computationally efficient algorithm to maximize the SU link capacity with power and interference constraints. It is seen that the SU transmission capacity depends critically on the spectral containment of the PU waveform, and these effects are quantified in a case study using an 802.11-g WLAN scenario.

  2. A Zynq-based Cluster Cognitive Radio

    OpenAIRE

    Rooks, Kurtis M.

    2014-01-01

    Traditional hardware radios provide very rigid solutions to radio problems. Intelligent software defined radios, also known as cognitive radios, provide flexibility and agility compared to hardware radio systems. Cognitive radios are well suited for radio applications in a changing radio frequency environment, such as dynamic spectrum access. In this thesis, a cognitive radio is demonstrated where the system self reconfigures to dem...

  3. Optimization of Ta2O5 optical thin film deposited by radio frequency magnetron sputtering.

    Science.gov (United States)

    Shakoury, R; Willey, Ronald R

    2016-07-10

    Radio frequency magnetron sputtering has been used here to find the parameters at which to deposit Ta2O5 optical thin films with negligible absorption in the visible spectrum. The design of experiment methodology was employed to minimize the number of experiments needed to find the optimal results. Two independent approaches were used to determine the index of refraction n and k values.

  4. A Modified Energy Detection Based Spectrum Sensing Algorithm for Green Cognitive Radio Communication

    Directory of Open Access Journals (Sweden)

    Sidra Rajput

    2015-10-01

    Full Text Available Spectrum Sensing is the first and fundamental function of Cognitive Cycle which plays a vital role in the success of CRs (Cognitive Radios. Spectrum Sensing indicate the presence and absence of PUs (Primary Users in RF (Radio Frequency spectrum occupancy measurements. In order to correctly determine the presence and absence of Primary Users, the algorithms in practice include complex mathematics which increases the computational complexity of the algorithm, thus shifted the CRs to operate as ?green? communication systems. In this paper, an energy efficient and computationally less complex, energy detection based Spectrum Sensing algorithm have been proposed. The design goals of the proposed algorithm are to save the processing and sensing energies. At first, by using less MAC (Multiply and Accumulate operation, it saves the processing energy needed to determine the presence and absence of PUs. Secondly, it saves the sensing energy by providing a way to find lowest possible sensing time at which spectrum is to be sensed. Two scenarios have been defined for testing the proposed algorithm i.e. simulate detection capability of Primary Users in ideal and noisy scenarios. Detection of PUs in both of these scenarios have been compared to obtain the probability of detection. Energy Efficiency of the proposed algorithm has been proved by making performance comparison between the proposed (less complex algorithm and the legacy energy detection algorithm. With reduced complexity, the proposed spectrum sensing algorithm can be considered under the paradigm of Green Cognitive Radio Communication

  5. RAP Framework for Spectrum Management in Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Kishore V. Krishnan

    2014-03-01

    Full Text Available The Spectrum Management schemes currently in use overlook the need for interference measurements at the receiver end. The negligence culminates in an underwhelming performance of the Cognitive Radio Network (CRN due to the presence of hidden/exposed primary senders. Our aim was to implement the RAP framework for spectrum management in a cognitive Radio. The scheme chosen deems it a necessity to take into consideration the inaccuracy of spectrum sensing in order to achieve the desired optimal performance. Unlike the widely used schemes which solely depend on local interference measurements, the proposed probabilistic framework aims at enhancing the CRN good put by incorporating interference measurements performed at the receiver into the protocol. Moreover, the spectrum management scheme, discussed in the study, makes most of the least exploitable spectral opportunities by relying on low power rate communication robust to interference. The issued spectrum access policy ensures fair distribution of spectral opportunity to its multiple secondary users. It, in contrast to the existing greedy spectrum access policies, prevents any user from monopolizing the available spectral opportunity as it is regulated and operated in a strictly probabilistic framework. It also diligently makes useful, provisions in the policy to ensure that every spectral opportunity, even while being exploited, appear available at all times to see to it that no Secondary User (SU misidentifies the spectral opportunity as unavailable.

  6. Inductively coupled radio frequency methane plasma simulation

    Science.gov (United States)

    Bera, K.; Farouk, B.; Vitello, P.

    2001-05-01

    A self-consistent two-dimensional radio frequency inductively coupled glow discharge model has been developed in cylindrical coordinates using a fluid model. The objective of the study is to provide insight into charged species dynamics and investigate their effects on plasma process for a methane discharge. The model includes continuity and energy equations for electrons and continuity, momentum and energy equations for positive and negative ions. An electromagnetic model that considers the electric field due to the space charge within the plasma and due to inductive power coupling is also incorporated. For an inductively coupled methane discharge we expect to find higher fluxes of ions and radicals to the cathode, and hence a higher deposition/etch rate for a high-density plasma. The independent control of ion energy to the cathode in an inductively coupled discharge will facilitate control on film deposition/etch rate and uniformity on the wafer. Swarm data as a function of the electron energy are provided as input to the model. The model predicts the electron density, ion density and their fluxes and energies to the cathode. The radical and neutral densities in the discharge are calculated using a gas phase chemistry model. The diamond-like-carbon thin-film deposition/etch rate is predicted using a surface chemistry model. The gas phase chemistry model considers the diffusion of radicals and neutrals along with creation and loss terms. The surface deposition/etching process involves adsorption-desorption, adsorption layer reaction, ion stitching, direct ion incorporation and carbon sputtering.

  7. High Radio Frequency Properties and Variability of Brightest Cluster Galaxies

    CERN Document Server

    Hogan, M T; Geach, J E; Grainge, K J B; Hlavacek-Larrondo, J; Hovatta, T; Karim, A; McNamara, B R; Rumsey, C; Russell, H R; Salomé, P; Aller, H D; Aller, M F; Benford, D J; Fabian, A C; Readhead, A C S; Sadler, E M; Saunders, R D E

    2015-01-01

    We consider the high radio frequency (15 GHz - 353 GHz) properties and variability of 35 Brightest Cluster Galaxies (BCGs). These are the most core-dominated sources drawn from a parent sample of more than 700 X-ray selected clusters, thus allowing us to relate our results to the general population. We find that >6.0% of our parent sample (>15.1% if only cool-core clusters are considered) contain a radio-source at 150 GHz of at least 3mJy (~1x10^23 W/Hz at our median redshift of z~0.13). Furthermore, >3.4% of the BCGs in our parent sample contain a peaked component (Gigahertz Peaked Spectrum, GPS) in their spectra that peaks above 2 GHz, increasing to >8.5% if only cool-core clusters are considered. We see little evidence for strong variability at 15 GHz on short (week-month) time-scales although we see variations greater than 20% at 150 GHz over 6-month times-frames for 4 of the 23 sources with multi-epoch observations. Much more prevalent is long-term (year-decade time-scale) variability, with average annua...

  8. A novel weighed cooperative bandwidth spectrum sensing for spectrum occupancy of cognitive radio network

    Institute of Scientific and Technical Information of China (English)

    刘鑫; 陈琨奇; 闫钧华

    2016-01-01

    In cognitive radio network (CRN), a secondary user (SU) may utilize the spectrum resource of the primary user (PU) and avoid causing harmful interference to the primary network (PN) via spectrum sensing. In the traditional time spectrum sensing, the SU cannot detect the PU’s presence during its transmission, thus increasing interference to the PN. In this work, a novel weighed cooperative bandwidth spectrum sensing method is proposed, which allows multiple SUs to use part of the bandwidth to perform cooperative spectrum sensing throughout the whole frame in order to detect the PU’s reappearance in time. The SU’s spectrum efficiency is maximized by jointly optimizing sensing bandwidth proportion, number of cooperative SUs and detection probability, subject to the constraints on the SU’s interference and the false alarm probability. Simulation results show significant decrease on the interference and improvement on the spectrum efficiency using the proposed weighed cooperative bandwidth spectrum sensing method.

  9. Total Variation Minimization Based Compressive Wideband Spectrum Sensing for Cognitive Radios

    CERN Document Server

    Liu, Yipeng

    2011-01-01

    Wideband spectrum sensing is a critical component of a functioning cognitive radio system. Its major challenge is the too high sampling rate requirement. Compressive sensing (CS) promises to be able to deal with it. Nearly all the current CS based compressive wideband spectrum sensing methods exploit only the frequency sparsity to perform. Motivated by the achievement of a fast and robust detection of the wideband spectrum change, total variation mnimization is incorporated to exploit the temporal and frequency structure information to enhance the sparse level. As a sparser vector is obtained, the spectrum sensing period would be shorten and sensing accuracy would be enhanced. Both theoretical evaluation and numerical experiments can demonstrate the performance improvement.

  10. Sgr A* at low radio frequencies: GMRT observations

    CERN Document Server

    Roy, S; Roy, Subhashis

    2004-01-01

    The central region of the Galaxy has been observed at 580, 620 and 1010 MHz with the Giant Metrewave Radio Telescope (GMRT). We detect emission from Sgr-A*, the compact object at the dynamical centre of the Galaxy, and estimate its flux density at 620 MHz to be 0.5 +/- 0.1 Jy. This is the first detection of Sgr A* below 1 GHz (Roy & Rao 2002, 2003), which along with a possible detection at 330 MHz (Nord et al. 2004) provides its spectrum below 1 GHz. Comparison of the 620 MHz map with maps made at other frequencies indicates that most parts of the Sgr A West HII region have optical depth 2. However, Sgr A*, which is seen in the same region in projection, shows a slightly inverted spectral index between 1010 MHz and 620 MHz. This is consistent with its high frequency spectral index, and indicates that Sgr A* is located in front of the Sgr A West complex, and rules out any low frequency turnover around 1 GHz, as suggested by Davies et al. (1976).

  11. Energy harvesting from radio frequency propagation using piezoelectric cantilevers

    Science.gov (United States)

    Ahmad, Mahmoud Al; Alshareef, H. N.

    2012-02-01

    This work reports an induced strain in a piezoelectric cantilever due to radio frequency signal propagation. The piezoelectric actuator is coupled to radio frequency (RF) line through a gap of 0.25 mm. When a voltage signal of 10 Vpp propagates in the line it sets an alternating current in the actuator electrodes. This flowing current drives the piezoelectric cantilever to mechanical movement, especially when the frequency of the RF signal matches the mechanical resonant frequency of the cantilever. Output voltage signals versus frequency for both mechanical vibrational and RF signal excitations have been measured using different loads.

  12. Energy harvesting from radio frequency propagation using piezoelectric cantilevers

    KAUST Repository

    Al Ahmad, Mahmoud

    2012-02-01

    This work reports an induced strain in a piezoelectric cantilever due to radio frequency signal propagation. The piezoelectric actuator is coupled to radio frequency (RF) line through a gap of 0.25 mm. When a voltage signal of 10 Vpp propagates in the line it sets an alternating current in the actuator electrodes. This flowing current drives the piezoelectric cantilever to mechanical movement, especially when the frequency of the RF signal matches the mechanical resonant frequency of the cantilever. Output voltage signals versus frequency for both mechanical vibrational and RF signal excitations have been measured using different loads.© 2011 Elsevier Ltd. All rights reserved.

  13. EFFICIENT SPECTRUM UTILIZATION IN COGNITIVE RADIO THROUGH REINFORCEMENT LEARNING

    Directory of Open Access Journals (Sweden)

    Dhananjay Kumar

    2013-09-01

    Full Text Available Machine learning schemes can be employed in cognitive radio systems to intelligently locate the spectrum holes with some knowledge about the operating environment. In this paper, we formulate a variation of Actor Critic Learning algorithm known as Continuous Actor Critic Learning Automaton (CACLA and compare this scheme with Actor Critic Learning scheme and existing Q–learning scheme. Simulation results show that our CACLA scheme has lesser execution time and achieves higher throughput compared to other two schemes.

  14. The angular power spectrum of radio emission at 2.3 GHz

    CERN Document Server

    Giardino, G; Fosalba, P; Górski, K M; Jonas, J L; O'Mullane, W; Tauber, J A

    2001-01-01

    We have analysed the Rhodes/HartRAO survey at 2326 MHz and derived the global angular power spectrum of Galactic continuum emission. In order to measure the angular power spectrum of the diffuse component, point sources were removed from the map by median filtering. A least-square fit to the angular power spectrum of the entire survey with a power law spectrum C_l proportional to l^{-alpha}, gives alpha = 2.43 +/- 0.01 for l = 2-100. The angular power spectrum of radio emission appears to steepen at high Galactic latitudes and for observed regions with |b| > 20 deg, the fitted spectral index is alpha = 2.92 +/- 0.07. We have extrapolated this result to 30 GHz (the lowest frequency channel of Planck) and estimate that no significant contribution to the sky temperature fluctuation is likely to come from synchrotron at degree-angular scales

  15. High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars

    CERN Document Server

    Giroletti, M; D'Abrusco, R; Lico, R; Burlon, D; Hurley-Walker, N; Johnston-Hollitt, M; Morgan, J; Pavlidou, V; Bell, M; Bernardi, G; Bhat, R; Bowman, J D; Briggs, F; Cappallo, R J; Corey, B E; Deshpande, A A; Ewall-Rice, A; Emrich, D; Gaensler, B M; Goeke, R; Greenhill, L J; Hazelton, B J; Hindson, L; Kaplan, D L; Kasper, J C; Kratzenberg, E; Feng, L; Jacobs, D; Kurdryavtseva, N; Lenc, E; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Offringa, A R; Ord, S M; Pindor, B; Prabu, T; Procopio, P; Riding, J; Rogers, A E E; Roshi, A; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Waterson, M; Wayth, R B; Webster, R L; Whitney, A R; Williams, A; Williams, C L

    2016-01-01

    Low-frequency radio arrays are opening a new window for the study of the sky, both to study new phenomena and to better characterize known source classes. Being flat-spectrum sources, blazars are so far poorly studied at low radio frequencies. We characterize the spectral properties of the blazar population at low radio frequency compare the radio and high-energy properties of the gamma-ray blazar population, and search for radio counterparts of unidentified gamma-ray sources. We cross-correlated the 6,100 deg^2 Murchison Widefield Array Commissioning Survey catalogue with the Roma blazar catalogue, the third catalogue of active galactic nuclei detected by Fermi-LAT, and the unidentified members of the entire third catalogue of gamma-ray sources detected by \\fermilat. When available, we also added high-frequency radio data from the Australia Telescope 20 GHz catalogue. We find low-frequency counterparts for 186 out of 517 (36%) blazars, 79 out of 174 (45%) gamma-ray blazars, and 8 out of 73 (11%) gamma-ray bl...

  16. Low frequency follow up of radio halos and relics in the GMRT Radio Halo Cluster Survey

    CERN Document Server

    Venturi, Tiziana; Dallacasa, Daniele; Cassano, Rossella; Brunetti, Gianfranco; Macario, Giulia; Athreya, Ramana

    2012-01-01

    We performed GMRT low frequency observations of the radio halos, relics and new candidates belonging to the GMRT Radio Halo Cluster Sample first observed at 610 MHz. High sensitivity imaging was performed using the GMRT at 325 MHz and 240 MHz. The properties of the diffuse emission in each cluster were compared to our 610 MHz images and/or literature information available at other frequencies, in order to derive the integrated spectra over a wide frequency range.Beyond the classical radio halos, whose spectral index $\\alpha$ is in the range $\\sim1.2\\div1.3$ (S$\\propto\

  17. Radio Frequency Micro Ion Thruster for Precision Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek proposes to develop radio frequency discharge, gridded micro-ion thruster that produces sub-mN thrust precisely adjustable over a wide dynamic thrust range....

  18. Radio Frequency Micro Ion Thruster for Precision Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek proposes to continue development of an engineering model radio frequency discharge, gridded micro ion thruster that produces sub-mN to mN thrust precisely...

  19. Plasma processing of superconducting radio frequency cavities

    Science.gov (United States)

    Upadhyay, Janardan

    The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb SRF cavities. In the process of developing plasma etching technology, an apparatus was built and a method was developed to plasma etch a single cell Pill Box cavity. The plasma characterization was done with the help of optical emission spectroscopy. The Nb etch rate at various points of this cavity was measured before processing the SRF cavity. Cylindrical ring-type samples of Nb placed on the inner surface of the outer wall were used to measure the dependence of the process parameters on plasma etching. The measured etch rate dependence on the pressure, rf power, dc bias, temperature, Cl2 concentration and diameter of the inner electrode was determined. The etch rate mechanism was studied by varying the temperature of the outer wall, the dc bias on the inner electrode and gas conditions. In a coaxial plasma reactor, uniform plasma etching along the cylindrical structure is a challenging task due to depletion of the active radicals along the gas flow direction. The dependence of etch rate uniformity along the cylindrical axis was determined as a function of process parameters. The formation of dc self-biases due to surface area asymmetry in this type of plasma and its variation on the pressure, rf power and gas composition was measured. Enhancing the surface area of the inner electrode to reduce the

  20. Three-dimensional effects for radio frequency antenna modeling

    Energy Technology Data Exchange (ETDEWEB)

    Carter, M.D.; Batchelor, D.B.; Stallings, D.C.

    1993-12-31

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  1. Three-dimensional effects for radio frequency antenna modeling

    Science.gov (United States)

    Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

    1994-10-01

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  2. Three-dimensional effects for radio frequency antenna modeling

    Energy Technology Data Exchange (ETDEWEB)

    Carter, M.D.; Batchelor, D.B.; Stallings, D.C. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821-8071 (United States))

    1994-10-15

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

  3. The Radio Frequency Environment at 240-270 MHz with Application to Signal-of-Opportunity Remote Sensing

    Science.gov (United States)

    Piepmeier, Jeffrey R.; Vega, Manuel; Fritts, Matthew; Du Toit, Cornelis; Knuble, Joseph; Lin, Yao-Cheng; Nold, Benjamin; Garrison, James

    2017-01-01

    Low frequency observations are desired for soil moisture and biomass remote sensing. Long wavelengths are needed to penetrate vegetation and Earths land surface. In addition to the technical challenges of developing Earth observing spaceflight instruments operating at low frequencies, the radio frequency spectrum allocated to remote sensing is limited. Signal-of-opportunity remote sensing offers the chance to use existing signals exploiting their allocated spectrum to make Earth science measurements. We have made observations of the radio frequency environment around 240-270 MHz and discuss properties of desired and undesired signals.

  4. Solar system radio emissions studies with the largest low-frequency radio telescopes

    Science.gov (United States)

    Zakharenko, V.; Konovalenko, A.; Litvinenko, G.; Kolyadin, V.; Zarka, P.; Mylostna, K.; Vasylieva, I.; Griessmeier, J.-M.; Sidorchuk, M.; Rucker, H.; Fischer, G.; Cecconi, B.; Coffre, A.; Denis, L.; Shevchenko, V.; Nikolaenko, V.

    2014-04-01

    We describe the trends and tasks in the field of lowfrequency studies of radio emission from the Solar system's objects. The world's largest decameter radio telescopes UTR-2 and URAN have a unique combination of sensitivity and time/frequency resolution parameters, providing the capability of the most detailed studies of various types of solar and planetary emissions.

  5. A Survey of Worldwide Spectrum Occupancy Measurement Campaigns for Cognitive Radio

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Prasad, Ramjee; Skouby, Knud Erik

    2011-01-01

    Cognitive radio is the emerging technology which provide the innovative approach to improve the spectrum utilization and alleviate the spectrum scarcity. Evaluation of the spectrum occupancy is the step toward the future deployment of cognitive radio. Worldwide several spectrum occupancy measurem...... in India....

  6. OPTIMIZATION OF SPECTRUM UTILIZATION IN COGNITIVE RADIO SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li Hongjiang; Zhu Qi

    2011-01-01

    In Cognitive Radio (CR) networks,CR user has to detect the spectrum channel periodically to make sure that the channel is idle during data transmission frame in order to avoid the collisions to the primary users.Hence recent research has been focused on the interference avoidance problem.Quality of Service (QoS) requirement of CR user will affect the time of data transmission in each frame.In this paper,in order to solve the interference avoidance and spectrum utilization problems without cooperation among CR users,a new scheme to obtain the optimal duration of data transmission frame is proposed to maximize the spectrum utilization and guarantee the protection to the primary users.The main advantages of our proposed scheme include the followings:(1) QoS requirement of CR user is concerned; (2) p-persistent Media Access Control (MAC) random access is used to avoid the collisions among CR users; (3) CR network system capacity is considered.We develop a Markov chain of the primary spectrum channel states and an exponential distribution of the CR user's traffic model to analyze the performance of our proposed scheme.Computer simulation shows that there is an optimal data transmission time to maximize the spectrum utilization.However,the regulatory constraint of the collision rate to the primary users has to be satisfied at the expense of spectrum utilization.And also the tradeoff between the spectrum utilization and the capacity of the CR system is taken into account.

  7. Planetary and exoplanetary low frequency radio observations from the Moon

    Science.gov (United States)

    Zarka, P.; Bougeret, J.-L.; Briand, C.; Cecconi, B.; Falcke, H.; Girard, J.; Grießmeier, J.-M.; Hess, S.; Klein-Wolt, M.; Konovalenko, A.; Lamy, L.; Mimoun, D.; Aminaei, A.

    2012-12-01

    We analyze the planetary and exoplanetary science that can be carried out with precursor as well as future low frequency radio instruments on the Moon, assessing the limiting noise sources, comparing them to the average and peak spectra of all planetary radio components as they will be seen from the Lunar surface or orbit. We identify which objectives will be accessible with each class of instrument, and discuss the interest of these observations compared to observations by planetary probes and to ground-based observations by large low-frequency radio arrays. The interest of goniopolarimetry is emphasized for pathfinder missions.

  8. Cooperative spectrum sensing and Detection efficiency in cognitive radio network

    Directory of Open Access Journals (Sweden)

    Nishant Dev Khaira

    2012-01-01

    Full Text Available —Spectrum sensing is required for better utilization of spectrum and preventing interference with licensed users. However, detection performance in practice is often compromised with multipath fading, shadowing and receiver uncertainty issues. To mitigate the impact of these issues, cooperative spectrum sensing has been shown to be an effective method to improve the detection performance by exploiting spatial diversity. While cooperative gain such as improved detection performance and relaxed sensitivity requirement can be obtained, cooperative sensing can incur cooperation overhead. The overhead refers to any extra sensing time, delay, energy, and operations devoted to cooperative sensing and any performance degradation caused by cooperative sensing. Specifically, the cooperation method is analyzed by the fundamental components called the elements of cooperative sensing, including cooperation models, sensing techniques, hypothesis testing, data fusion, control channel and reporting, user selection, and knowledge base. To combat the channel fading suffered by the single radio, cooperative spectrum sensing is employed, to associate the detection of multiple radios. In this article, the optimization problem of detection efficiency under the constraint of detection probability is investigated.

  9. Towards the Realization of Graphene Based Flexible Radio Frequency Receiver

    Directory of Open Access Journals (Sweden)

    Maruthi N. Yogeesh

    2015-11-01

    Full Text Available We report on our progress and development of high speed flexible graphene field effect transistors (GFETs with high electron and hole mobilities (~3000 cm2/V·s, and intrinsic transit frequency in the microwave GHz regime. We also describe the design and fabrication of flexible graphene based radio frequency system. This RF communication system consists of graphite patch antenna at 2.4 GHz, graphene based frequency translation block (frequency doubler and AM demodulator and graphene speaker. The communication blocks are utilized to demonstrate graphene based amplitude modulated (AM radio receiver operating at 2.4 GHz.

  10. Generalized detector as a spectrum sensor in cognitive radio networks

    Directory of Open Access Journals (Sweden)

    M.S.Shbat

    2015-06-01

    Full Text Available The implementation of the generalized detector (GD in cognitive radio (CR systems allows us to improve the spectrum sensing performance in comparison with employment of the conventional detectors. We analyze the spectrum sensing performance for the uncorrelated and spatially correlated receive antenna array elements. Addi¬tionally, we consider a practical case when the noise power at the output of GD linear systems (the preliminary and additional filters is differed by value. The choice of the optimal GD threshold based on the minimum total error rate criterion is also discussed. Simulation results demonstrate superiority of GD implementation in CR sys¬tem as spectrum sensor in comparison with the energy detector (ED, weighted ED (WED, maximum-minimum eigenvalue (MME detector, and generalized likelihood ratio test (GLRT detector

  11. Blind Spectrum Sensing by Information Theoretic Criteria for Cognitive Radios

    CERN Document Server

    Wang, Rui

    2010-01-01

    Spectrum sensing is a fundamental and critical issue for opportunistic spectrum access in cognitive radio networks. Among the many spectrum sensing methods, the information theoretic criteria (ITC) based method is a promising blind method which can reliably detect the primary users while requiring little prior information. In this paper, we provide an intensive treatment on the ITC sensing method. To this end, we first introduce a new over-determined channel model constructed by applying multiple antennas or over sampling at the secondary user in order to make the ITC applicable. Then, a simplified ITC sensing algorithm is introduced, which needs to compute and compare only two decision values. Compared with the original ITC sensing algorithm, the simplified algorithm significantly reduces the computational complexity without losing any performance. Applying the recent advances in random matrix theory, we then derive closed-form expressions to tightly approximate both the probability of false alarm and probab...

  12. Spectrum Hole Prediction And White Space Ranking For Cognitive Radio Network Using An Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Sunday Iliya

    2015-08-01

    Full Text Available Abstract With spectrum becoming an ever scarcer resource it is critical that new communication systems utilize all the available frequency bands as efficiently as possible in time frequency and spatial domain. rHowever spectrum allocation policies most of the licensed spectrums grossly underutilized while the unlicensed spectrums are overcrowded. Hence all future wireless communication devices beequipped with cognitive capability to maximize quality of service QoS require a lot of time and energartificial intelligence and machine learning in cognitive radio deliver optimum performance. In this paper we proposed a novel way of spectrum holes prediction using artificial neural network ANN. The ANN was trained to adapt to the radio spectrum traffic of 20 channels and the trained network was used for prediction of future spectrum holes. The input of the neural network consist of a time domain vector of length six i.e. minute hour date day week and month. The output is a vector of length 20 each representing the probability of the channel being idle. The channels are ranked in order of decreasing probability of being idleminimizing We assumed that all the channels have the same noise and quality of service and only one vacant channel is needed for communication. The result of the spectrum holes search using ANN was compared with that of blind linear and blind stochastic search and was found to be superior. The performance of the ANN that was trained to predict the probability of the channels being idle outperformed the ANN that will predict the exact channel states busy or idle. In the ANN that was trained to predict the exact channels states all channels predicted to be idle are randomly searched until the first spectrum hole was found no information about search direction regarding which channel should be sensed first.

  13. RF Spectrum Sensing Based on an Overdamped Nonlinear Oscillator Ring for Cognitive Radios

    Science.gov (United States)

    Tang, Zhi-Ling; Li, Si-Min; Yu, Li-Juan

    2016-01-01

    Existing spectrum-sensing techniques for cognitive radios require an analog-to-digital converter (ADC) to work at high dynamic range and a high sampling rate, resulting in high cost. Therefore, in this paper, a spectrum-sensing method based on a unidirectionally coupled, overdamped nonlinear oscillator ring is proposed. First, the numerical model of such a system is established based on the circuit of the nonlinear oscillator. Through numerical analysis of the model, the critical condition of the system’s starting oscillation is determined, and the simulation results of the system’s response to Gaussian white noise and periodic signal are presented. The results show that once the radio signal is input into the system, it starts oscillating when in the critical region, and the oscillating frequency of each element is fo/N, where fo is the frequency of the radio signal and N is the number of elements in the ring. The oscillation indicates that the spectrum resources at fo are occupied. At the same time, the sampling rate required for an ADC is reduced to the original value, 1/N. A prototypical circuit to verify the functionality of the system is designed, and the sensing bandwidth of the system is measured. PMID:27294928

  14. Low-frequency study of two giant radio galaxies: 3C 35 and 3C 223

    Science.gov (United States)

    Orrù, E.; Murgia, M.; Feretti, L.; Govoni, F.; Giovannini, G.; Lane, W.; Kassim, N.; Paladino, R.

    2010-06-01

    Aims: Radio galaxies with a projected linear size ⪆1 Mpc are classified as giant radio sources. According to the current interpretation these are old sources which have evolved in a low-density ambient medium. Because radiative losses are negligible at low frequency, extending spectral aging studies in this frequency range will allow us to determine the zero-age electron spectrum injected and then to improve the estimate of the synchrotron age of the source. Methods: We present Very Large Array images at 74 MHz and 327 MHz of two giant radio sources: 3C 35 and 3C 223. We performed a spectral study using 74, 327, 608 and 1400 GHz images. The spectral shape is estimated in different positions along the source. Results: The radio spectrum follows a power-law in the hotspots, while in the inner region of the lobe the shape of the spectrum shows a curvature at high frequencies. This steepening agrees with synchrotron aging of the emitting relativistic electrons. In order to estimate the synchrotron age of the sources, the spectra were fitted with a synchrotron model of emission. They show that 3C 35 is an old source of 143 ± 20 Myr, while 3C 223 is a younger source of 72 ± 4 Myr.

  15. Spectrum Assignment with Non-Deterministic Bandwidth of Spectrum Holein Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Huang Jie

    2016-01-01

    Full Text Available The spectrum allocation for cognitive radio networks (CRNs has received considerable studies under the assumption that the bandwidth of spectrum holes is static. However, in practice, the bandwidth of spectrum holes is time-varied due to primary user/secondary user (PU/SU activity and mobility, which result in non-determinacy. This paper studies the spectrum allocation for CRNs with non-deterministic bandwidth of spectrum holes. We present a novel probability density function (PDF model through order statistic to describe the non-deterministic bandwidth of spectrum holes and provide a bound to approximate it. After that, a statistical spectrum allocation model based on stochastic multiple knapsack problem (MKP is established for spectrum allocation with non-deterministic bandwidth of spectrum holes. To reduce the computational complexity, we transform this stochastic programming probleminto a constant MKP though exploiting the properties of cumulative distribution function (CDF, which can be solved via MTHG algorithm by using auxiliary variable. Simulation results illustrate that the proposed statistical spectrum allocation algorithm can achieve better performances compared to the existing algorithms when the bandwidth of spectrum holes istime-varied.

  16. Current Trends and Research Challenges in Spectrum-Sensing for Cognitive Radios

    Directory of Open Access Journals (Sweden)

    Roopali Garg

    2016-07-01

    Full Text Available The ever increasing demand of wireless communication systems has led to search of suitable spectrum bands for transmission of data. The research in the past has revealed that radio spectrum is under-utilized in most of the scenarios. This prompted the scientist to seek a solution to utilize the spectrum efficiently. Cognitive Radios provided an answer to the problem by sensing the idle (licensed bands and allowing (secondary users to transmit in these idle spaces. Spectrum sensing forms the main block of cognition cycle. This paper reviews the current trends in research in the domain of spectrum sensing. The author describes the type of channel being modelled, diversity combining schemes used, optimal algorithms applied at fusion centre, spectrum sensing techniques employed. Further, the research challenges are discussed. It is presented that various attributes like sensing time, throughput, rate reliability, optimum cooperative users, sensing frequency etc. needs to be addressed. A trade-off needs to be established to optimize two opposing parameters like sensing and throughput.

  17. The statistics of low frequency radio interference at the Murchison Radio-astronomy Observatory

    CERN Document Server

    Sokolowski, Marcin; Lewis, Morgan

    2016-01-01

    We characterize the low frequency radio-frequency interference (RFI) environment at the Murchison Radio-astronomy Observatory (MRO), the location selected for the low-frequency component of the Square Kilometre Array. Data were collected from the BIGHORNS instrument, located at the MRO, which records a contiguous bandwidth between 70 and 300 MHz, between November 2014 to March 2015 inclusive. The data were processed to identify RFI, and we describe a series of statistics in both the time and frequency domain, including modeling of the RFI occupancy and signal power as a series of distribution functions, with the goal of aiding future scientists and operation staff in observation planning.

  18. Low-Frequency Radio Bursts and Space Weather

    Science.gov (United States)

    Gopalswamy, N.

    2016-01-01

    Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the solar system. Substantial progress has been made in the past two decades, because of the continuous and uniform data sets available from space-based radio and white-light instrumentation. This paper highlights some recent results obtained on IP radio phenomena. In particular, the source of type IV radio bursts, the behavior of type III storms, shock propagation in the IP medium, and the solar-cycle variation of type II radio bursts are considered. All these phenomena are closely related to solar eruptions and active region evolution. The results presented were obtained by combining data from the Wind and SOHO missions.

  19. MULTI-FREQUENCY STUDIES OF RADIO RELICS IN THE GALAXY CLUSTERS A4038, A1664, AND A786

    Energy Technology Data Exchange (ETDEWEB)

    Kale, Ruta; Dwarakanath, K. S., E-mail: ruta@iucaa.ernet.in [Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080 (India)

    2012-01-01

    We present a multi-frequency study of radio relics associated with the galaxy clusters A4038, A1664, and A786. Radio images, integrated spectra, spectral index maps, and fits to the integrated spectra in the framework of the adiabatic compression model are presented. Images of the relic in A4038 at 150, 240, and 606 MHz with the Giant Meterwave Radio Telescope have revealed extended ultra-steep spectrum ({alpha} {approx} -1.8 to -2.7) emission of extent 210 Multiplication-Sign 80 kpc{sup 2}. The model of passively evolving radio lobes compressed by a shock fits the integrated spectrum best. The relic with a circular morphology at the outskirts of the cluster A1664 has an integrated spectral index of {approx} - 1.10 {+-} 0.06 and is best fit by the model of radio lobes lurking for {approx}4 Multiplication-Sign 10{sup 7} yr. The relic near A786 has a curved spectrum and is best fit by a model of radio lobes lurking for {approx}3 Multiplication-Sign 10{sup 7} yr. At 4.7 GHz, a compact radio source, possibly the progenitor of the A786 relic, is detected near the center of the radio relic. The A786 radio relic is thus likely a lurking radio galaxy rather than a site of cosmological shock as has been considered in earlier studies.

  20. Compressed Measurements Based Spectrum Sensing for Wideband Cognitive Radio Systems

    Directory of Open Access Journals (Sweden)

    Taha A. Khalaf

    2015-01-01

    Full Text Available Spectrum sensing is the most important component in the cognitive radio (CR technology. Spectrum sensing has considerable technical challenges, especially in wideband systems where higher sampling rates are required which increases the complexity and the power consumption of the hardware circuits. Compressive sensing (CS is successfully deployed to solve this problem. Although CS solves the higher sampling rate problem, it does not reduce complexity to a large extent. Spectrum sensing via CS technique is performed in three steps: sensing compressed measurements, reconstructing the Nyquist rate signal, and performing spectrum sensing on the reconstructed signal. Compressed detectors perform spectrum sensing from the compressed measurements skipping the reconstruction step which is the most complex step in CS. In this paper, we propose a novel compressed detector using energy detection technique on compressed measurements sensed by the discrete cosine transform (DCT matrix. The proposed algorithm not only reduces the computational complexity but also provides a better performance than the traditional energy detector and the traditional compressed detector in terms of the receiver operating characteristics. We also derive closed form expressions for the false alarm and detection probabilities. Numerical results show that the analytical expressions coincide with the exact probabilities obtained from simulations.

  1. Radio frequency powering of microelectronic sensor modules

    Energy Technology Data Exchange (ETDEWEB)

    Boegel, Gerd vom; Meyer, Frederic; Kemmerling, Martin [Fraunhofer-Institut fuer Mikroelektronische Schaltungen und Systeme, Duisburg (Germany)

    2013-03-01

    In RFID applications the power supply of transponders via electromagnetic field is state-of-the-art. In this presentation the use of electromagnetic energy will be discussed for the operation of sensor modules. Starting with the question, whether the omnipresent radiation from power supply networks, radio transmitters, and mobile phone base stations is useable (energy harvesting), the feasibility of the operation of self-sufficient sensor modules is explained. Ancillary conditions of typical applications (e.g. operating range) and technology are considered. (orig.)

  2. Estimation of Black Hole Masses from Steep Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Ye Chen; Zhi-Fu Chen; Yi-Ping Qin; You-Bing Li

    2011-03-01

    In this work, we employ a sample of 185 steep-spectrum radio quasars (SSRQs) to estimate their black hole masses from broad emission lines. Our black hole masses are compared with the virial black hole masses estimated by Shen (2010). We find that there is a large deviation between the two kinds of values if the black hole masses are estimated from broad emission line of CIV. However, both values are in agreement if the black hole masses are estimated from broad emission line of MgII or H.

  3. Magnetoreception in birds: the effect of radio-frequency fields.

    Science.gov (United States)

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-02-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field.

  4. ULTRA STEEP SPECTRUM RADIO SOURCES IN THE LOCKMAN HOLE: SERVS IDENTIFICATIONS AND REDSHIFT DISTRIBUTION AT THE FAINTEST RADIO FLUXES

    Energy Technology Data Exchange (ETDEWEB)

    Afonso, J.; Bizzocchi, L.; Grossi, M.; Messias, H.; Fernandes, C. A. C. [Observatorio Astronomico de Lisboa, Faculdade de Ciencias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal); Ibar, E.; Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Simpson, C. [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom); Chapman, S.; Gonzalez-Solares, E. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Jarvis, M. J. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Rottgering, H. [Leiden Observatory, Leiden University, Oort Gebouw, P.O. Box 9513, 2300 RA Leiden (Netherlands); Norris, R. P. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Dunlop, J.; Best, P. [SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Pforr, J. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Vaccari, M. [Department of Astronomy, University of Padova, vicolo Osservatorio 3, 35122 Padova (Italy); Seymour, N. [Mullard Space Science Laboratory, UCL, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Farrah, D. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Huang, J.-S., E-mail: jafonso@oal.ul.pt [Department of Astrophysics, Oxford University, Keble Road, Oxford OX1 3RH (United Kingdom); and others

    2011-12-20

    Ultra steep spectrum (USS) radio sources have been successfully used to select powerful radio sources at high redshifts (z {approx}> 2). Typically restricted to large-sky surveys and relatively bright radio flux densities, it has gradually become possible to extend the USS search to sub-mJy levels, thanks to the recent appearance of sensitive low-frequency radio facilities. Here a first detailed analysis of the nature of the faintest USS sources is presented. By using Giant Metrewave Radio Telescope and Very Large Array radio observations of the Lockman Hole at 610 MHz and 1.4 GHz, a sample of 58 USS sources, with 610 MHz integrated fluxes above 100 {mu}Jy, is assembled. Deep infrared data at 3.6 and 4.5 {mu}m from the Spitzer Extragalactic Representative Volume Survey (SERVS) are used to reliably identify counterparts for 48 (83%) of these sources, showing an average total magnitude of [3.6]{sub AB} = 19.8 mag. Spectroscopic redshifts for 14 USS sources, together with photometric redshift estimates, improved by the use of the deep SERVS data, for a further 19 objects, show redshifts ranging from z = 0.1 to z = 2.8, peaking at z {approx} 0.6 and tailing off at high redshifts. The remaining 25 USS sources, with no redshift estimate, include the faintest [3.6] magnitudes, with 10 sources undetected at 3.6 and 4.5 {mu}m (typically [3.6] {approx}> 22-23 mag from local measurements), which suggests the likely existence of higher redshifts among the sub-mJy USS population. The comparison with the Square Kilometre Array Design Studies Simulated Skies models indicates that Fanaroff-Riley type I radio sources and radio-quiet active galactic nuclei may constitute the bulk of the faintest USS population, and raises the possibility that the high efficiency of the USS technique for the selection of high-redshift sources remains even at the sub-mJy level.

  5. Energy and spectrum efficiency in rural areas based on cognitive radio technology

    CSIR Research Space (South Africa)

    Masonta, MT

    2009-09-01

    Full Text Available The rapid growth and development observed in wireless communications has resulted in the overcrowding of the radio spectrum used as a communication medium in wireless networks. In many countries, governmental agencies regulate the use of the radio...

  6. AURA - A radio frequency extension to IceCube

    CERN Document Server

    Ruckman, L

    2008-01-01

    The excellent radio frequency transparency of cold polar ice, combined with the coherent Cherenkov emission produced by neutrino-induced showers when viewed at wavelengths longer than a few centimeters, has spurred considerable interest in a large-scale radio-wave neutrino detector array. The AURA (Askaryan Under-ice Radio Array) experimental effort, within the IceCube collaboration, seeks to take advantage of the opportunity presented by IceCube drilling through 2010 to establish the radio frequency technology needed to achieve 100-1000 km^3 effective volumes. In the 2006-2007 Austral summer 3 deep in-ice radio frequency (RF) clusters were deployed at depths of 1300m and 300m on top of the IceCube strings. Additional 3 clusters will be deployed in the Austral summer of 2008-2009. Verification and calibration results from the current deployed clusters are presented, and the detector design and performances are discussed. Augmentation of IceCube with large-scale 1000km^3sr radio and acoustic arrays would exten...

  7. Spectrum Sensing in Cognitive Radio Networks: Performance Evaluation and Optimization

    CERN Document Server

    Xiong, Gang; Yener, Aylin

    2012-01-01

    This paper studies cooperative spectrum sensing in cognitive radio networks where secondary users collect local energy statistics and report their findings to a secondary base station, i.e., a fusion center. First, the average error probability is quantitively analyzed to capture the dynamic nature of both observation and fusion channels, assuming fixed amplifier gains for relaying local statistics to the fusion center. Second, the system level overhead of cooperative spectrum sensing is addressed by considering both the local processing cost and the transmission cost. Local processing cost incorporates the overhead of sample collection and energy calculation that must be conducted by each secondary user; the transmission cost accounts for the overhead of forwarding the energy statistic computed at each secondary user to the fusion center. Results show that when jointly designing the number of collected energy samples and transmission amplifier gains, only one secondary user needs to be actively engaged in sp...

  8. Development of A Pulse Radio-Frequency Plasma Jet

    Science.gov (United States)

    Wang, Shou-Guo; Zhao, Ling-Li; Yang, Jing-Hua

    2013-09-01

    A small pulse plasma jet was driven by new developed radio-frequency (RF) power supply of 6.78 MHz. In contrast to the conventional RF 13.56 MHz atmospheric pressure plasma jet (APPJ), the power supply was highly simplified by eliminating the matching unit of the RF power supply and using a new circuit, moreover, a pulse controller was added to the circuit to produce the pulse discharge. The plasma jet was operated in a capacitively coupled manner and exhibited low power requirement of 5 W at atmospheric pressure using argon as a carrier gas. The pulse plasma plume temperature remained at less than 45 °C for an extended period of operation without using water to cool the electrodes. Optical emission spectrum measured at a wide range of 200-1000 nm indicated various excited species which were helpful in applying the plasma jet for surface sterilization to human skin or other sensitive materials. Institude of Plasma Physics, Chinese Academy of Science, Hefei, China.

  9. Three-dimensional effects for radio frequency antenna modeling

    Energy Technology Data Exchange (ETDEWEB)

    Carter, M.D.; Batchelor, D.B.; Stallings, D.C.

    1993-09-01

    Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. Comparisons with experiments indicate that these 2-D calculations can overestimate the loading of the antenna and fail to give the correct reactive behavior. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform 3-D modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap, conducting sidewalls, and finite phase velocity are considered. The plasma impedance matrix for the loading calculation is generated by use of the ORION-1D code. The 3-D model is benchmarked with the 2-D model in the 2-D limit. For finite-length antennas, inductance calculations are found to be in much more reasonable agreement with experiments for 3-D modeling than for the 2-D estimates. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna sidewalls rather than in the plasma as in the 2-D model. Thus, the feeders have much more influence than the plasma on the currents that return in the sidewall. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model.

  10. Unlicensed Spectrum Sharing Game Between LEO Satellites and Terrestrial Cognitive Radio Networks

    Institute of Scientific and Technical Information of China (English)

    XIE Zhuochen; MA Lu; LIANG Xuwen

    2012-01-01

    By cognitive radio,the low Earth orbit (LEO) satellites may prefer to operate in the unlicensed spectrum which is open to all the users,and compete for the limited resources with terrestrial cognitive radio networks (CRNs).The competition can be regarded as a game and analyzed with game theory.This particular unlicensed spectrum sharing problem is modeled here,and the special properties of “spatially-distinguished-interference” and the short period of the interactions between satellites and terrestrial CRNs are explored.Then,the problem is formulated as a “partially-blind” finitely repeated prisoner's dilemma by game theory.Finally,we begin with two promising spectrum sharing schemes,which can be used to enforce the frequency reuse among the remotely located terrestrial CRN players as well as to overcome the observation noise.By analysis and comparison,it is proposed that the novel refreshing-contrite-tit-for-tat (R-CTFT) is the optimal spectrum sharing scheme.Simulation results verify that it can be used to utilize the spectrum most efficiently.

  11. Spectrum sharing in cognitive radio networks--an auction-based approach.

    Science.gov (United States)

    Wang, Xinbing; Li, Zheng; Xu, Pengchao; Xu, Youyun; Gao, Xinbo; Chen, Hsiao-Hwa

    2010-06-01

    Cognitive radio is emerging as a promising technique to improve the utilization of the radio frequency spectrum. In this paper, we consider the problem of spectrum sharing among primary (or "licensed") users (PUs) and secondary (or "unlicensed") users (SUs). We formulate the problem based on bandwidth auction, in which each SU makes a bid for the amount of spectrum and each PU may assign the spectrum among the SUs by itself according to the information from the SUs without degrading its own performance. We show that the auction is a noncooperative game and that Nash equilibrium (NE) can be its solution. We first consider a single-PU network to investigate the existence and uniqueness of the NE and further discuss the fairness among the SUs under given conditions. Then, we present a dynamic updating algorithm in which each SU achieves NE in a distributed manner. The stability condition of the dynamic behavior for this spectrum-sharing scheme is studied. The discussion is generalized to the case in which there are multiple PUs in the network, where the properties of the NE are shown under appropriate conditions. Simulations were used to evaluate the system performance and verify the effectiveness of the proposed algorithm.

  12. Nonreciprocal Radio Frequency Transduction in a Parametric Mechanical Artificial Lattice

    Science.gov (United States)

    Huang, Pu; Zhang, Liang; Zhou, Jingwei; Tian, Tian; Yin, Peiran; Duan, Changkui; Du, Jiangfeng

    2016-07-01

    Generating nonreciprocal radio frequency transduction plays important roles in a wide range of research and applications, and an aspiration is to integrate this functionality into microcircuits without introducing a magnetic field, which, however, remains challenging. By designing a 1D artificial lattice structure with a neighbor interaction engineered parametrically, we predicted a nonreciprocity transduction with a large unidirectionality. We then experimentally demonstrated the phenomenon on a nanoelectromechanical chip fabricated by conventional complementary metal-silicon processing. A unidirectionality with isolation as high as 24 dB is achieved, and several different transduction schemes are realized by programing the control voltage topology. Apart from being used as a radio frequency isolator, the system provides a way to build a practical on-chip programmable device for broad research and applications in the radio frequency domain.

  13. Radio frequency interference protection of communications between the Deep Space Network and deep space flight projects

    Science.gov (United States)

    Johnston, D. W. H.

    1981-01-01

    The increasing density of electrical and electronic circuits in Deep Space Station systems for computation, control, and numerous related functions has combined with the extension of system performance requirements calling for higher speed circuitry along with broader bandwidths. This has progressively increased the number of potential sources of radio frequency interference inside the stations. Also, the extension of spectrum usage both in power and frequency as well as the greater density of usage at all frequencies for national and international satellite communications, space research, Earth resource operations and defense, and particularly the huge expansion of airborne electronic warfare and electronic countermeasures operations in the Mojave area have greatly increased the potential number and severity of radio frequency interference incidents. The various facets of this problem and the efforts to eliminate or minimize the impact of interference on Deep Space Network support of deep space flight projects are described.

  14. Spectrum Occupancy Statistics in the Context of Cognitive Radio

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Chandra, Ashok

    2011-01-01

    measurements conducted in the frequency band from 700 MHz to 2700 MHz in an outdoor environment in the suburban of Mumbai, India. The measurement results of two weekdays campaign shows considerably low occupation with great potential for dynamic usage of spectrum. Further we discuss CR potentials based...

  15. A Radio-Frequency-over-Fiber link for large-array radio astronomy applications

    CERN Document Server

    Mena, Juan; Cliche, Jean-Francois; Dobbs, Matt; Gilbert, Adam; Tang, Qing Yang

    2013-01-01

    A prototype 425-850 MHz Radio-Frequency-over-Fiber (RFoF) link for the Canadian Hydrogen Intensity Mapping Experiment (CHIME) is presented. The design is based on a directly modulated Fabry-Perot (FP) laser, operating at ambient temperature, and a single-mode fiber. The dynamic performance, gain stability, and phase stability of the RFoF link are characterized. Tests on a two-element interferometer built at the Dominion Radio Astrophysical Observatory for CHIME prototyping demonstrate that RFoF can be successfully used as a cost-effective solution for analog signal transport on the CHIME telescope and other large-array radio astronomy applications

  16. On the high frequency polarization of pulsar radio emission

    CERN Document Server

    Von Hoensbroech, A; Krawczyk, A

    1998-01-01

    We have analyzed the polarization properties of pulsars at an observing frequency of 4.9 GHz. Together with low frequency data, we are able to trace polarization profiles over more than three octaves into an interesting frequency regime. At those high frequencies the polarization properties often undergo important changes such as significant depolarization. A detailed analysis allowed us to identify parameters, which regulate those changes. A significant correlation was found between the integrated degree of polarization and the loss of rotational energy E^dot. The data were also used to review the widely established pulsar profile classification scheme of core- and cone-type beams. We have discovered the existence of pulsars which show a strongly increasing degree of circular polarization towards high frequencies. Previously unpublished average polarization profiles, recorded at the 100m Effelsberg radio telescope, are presented for 32 radio pulsars at 4.9 GHz. The data were used to derive polarimetric param...

  17. Steering Wheel Shaped Frequency Reconfigurable Antenna for Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Harbinder Singh

    2014-05-01

    Full Text Available This paper depicts an outline to design a novel compact and low profile frequency reconfigurable microstrip patch antenna for possible applications in cognitive radio systems to act as a fast switching antenna capable of operating in seven different frequencies in the range of 6.25 to 8.25 GHz. The antenna structure comprises a center rectangular encircled patch, in which rectangular patch is driven patch and the encirclement is for frequency reconfigure ability. The reconfiguration ability of the antenna is obtained by placing four radio frequency micro-electromechanical system (RF-MEMS switches in between encircled patch and driven patch. Different switch configurations were investigated and the same was evaluated for diverse frequency ranges.

  18. Design of UWB pulse radio transceiver using statistical correlation technique in frequency domain

    Directory of Open Access Journals (Sweden)

    M. Anis

    2007-06-01

    Full Text Available In this paper, we propose a new technique to extract low power UWB pulse radio signals, near to noise level, using statistical correlation technique in frequency domain. The receiver consists of many narrow bandpass filters which extract energy either from transmitted UWB signal, interfering channels or noise. Transmitted UWB data can be eliminated by statistical correlation of multiple bandpass filter outputs. Super-regenerative oscillators, tuned within UWB spectrum, are designed as bandpass filters. Summers and comparators perform statistical correlation.

  19. The MHz-peaked radio spectrum of the unusual gamma-ray source PMN J1603-4904

    CERN Document Server

    Müller, C; Schulz, R; Coppejans, R; Falcke, H; Intema, H; Kadler, M; Krauß, F; Ojha, R

    2016-01-01

    Context. The majority of bright extragalactic gamma-ray sources are blazars. Only a few radio galaxies have been detected by Fermi/LAT. Recently, the GHz-peaked spectrum source PKS 1718-649 was confirmed to be gamma-ray bright, providing further evidence for the existence of a population of gamma-ray loud, compact radio galaxies. A spectral turnover in the radio spectrum in the MHz to GHz range is a characteristic feature of these objects, which are thought to be young due to their small linear sizes. The multiwavelength properties of the gamma-ray source PMN J1603-4904 suggest that it is a member of this source class. Aims. The known radio spectrum of PMN J1603-4904 can be described by a power law above 1 GHz. Using observations from the Giant Metrewave Radio Telescope (GMRT) at 150, 325, and 610 MHz, we investigate the behaviour of the spectrum at lower frequencies to search for a low-frequency turnover. Methods. Data from the TIFR GMRT Sky Survey (TGSS ADR) catalogue and archival GMRT observations were use...

  20. Multi-frequency studies of radio relics in the galaxy clusters A4038, A1664 and A786

    CERN Document Server

    Kale, Ruta

    2011-01-01

    We present a multi-frequency study of radio relics associated with the galaxy clusters A4038, A1664 and A786. Radio images, integrated spectra, spectral index maps and fits to the integrated spectra in the framework of the adiabatic compression model are presented. Images of the relic in A4038 at 150, 240 and 606 MHz with the Giant Metrewave Radio Telescope have revealed extended ultra-steep spectrum (\\alpha ~ -1.8 to -2.7) emission of an extent 210 x 80 kpc^2. The model of passively evolving radio lobes compressed by a shock best fits the integrated spectrum. The relic with a circular morphology at the outskirts of the cluster A1664 has an integrated spectral index of -1.10+/-0.06 and is best fit by the model of radio lobes lurking for ~ 4x10^7 yr. The relic near A786 has a curved spectrum and is best fit by a model of radio lobes lurking for ~ 3x10^7 yr. At 4.7 GHz, a compact radio source, possibly the progenitor of the A786 relic, is detected near the center of the radio relic. The A786 radio relic is thus...

  1. Radio Frequency Interference mitigation using deep convolutional neural networks

    CERN Document Server

    Akeret, Joel; Lucchi, Aurelien; Refregier, Alexandre

    2016-01-01

    We propose a novel approach for mitigating radio frequency interference (RFI) signals in radio data using the latest advances in deep learning. We employ a special type of Convolutional Neural Network, the U-Net, that enables the classification of clean signal and RFI signatures in 2D time-ordered data acquired from a radio telescope. We train and assess the performance of this network using the HIDE & SEEK radio data simulation and processing packages, as well as data collected at the Bleien Observatory. We find that our U-Net implementation can outperform classical RFI mitigation algorithms such as SEEK's SumThreshold implementation. We publish our U-Net software package on GitHub under GPLv3 license.

  2. Radio frequency interference mitigation using deep convolutional neural networks

    Science.gov (United States)

    Akeret, J.; Chang, C.; Lucchi, A.; Refregier, A.

    2017-01-01

    We propose a novel approach for mitigating radio frequency interference (RFI) signals in radio data using the latest advances in deep learning. We employ a special type of Convolutional Neural Network, the U-Net, that enables the classification of clean signal and RFI signatures in 2D time-ordered data acquired from a radio telescope. We train and assess the performance of this network using the HIDE &SEEK radio data simulation and processing packages, as well as early Science Verification data acquired with the 7m single-dish telescope at the Bleien Observatory. We find that our U-Net implementation is showing competitive accuracy to classical RFI mitigation algorithms such as SEEK's SUMTHRESHOLD implementation. We publish our U-Net software package on GitHub under GPLv3 license.

  3. Analytical Simulation and Performance Optimization for Spectrum Sensing in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Ayman A. El-Saleh

    2011-02-01

    Full Text Available Dynamic spectrum allocation (DSA solutions such as cognitive radio networks (CRNs have been proposed as a key technology to exploit the frequency segments that are spectrally underutilized. In this paper, the performance of cooperative CRNs has been analyzed under two different operational modes, namely, constant primary user protection (CPUP and constant secondary user spectrum usability (CSUSU. The CRN performance metrics have been selected to be the overall CRN capacity and the overall interference from CRN to the primary users under CPUP and CSUSU scenario, respectively. Computer simulations are invoked to evaluate the CRN performance with varying the sensing time as well as the number of cooperating users in the network and the observations have been presented. Finally, particle swarm ptimization algorithm has been used to jointly optimize the sensing time duration and cooperation level of spectrum sensing in CRNs. The simulation results show that the CRN performance can be noticeably improved by applying suitable optimization algorithms.

  4. Calibration of low-frequency radio telescopes using the galactic background radiation

    Science.gov (United States)

    Dulk, G. A.; Erickson, W. C.; Manning, R.; Bougeret, J.-L.

    2001-01-01

    We consider the calibration of flux densities of radio bursts from decametric to kilometric wavelengths using ground-based and space-based data. The method we derive is applicable to low-frequency radio telescopes where galactic background radiation is the principal contribution to system temperature. It can be particularly useful for telescopes of low angular resolution observing spectra of radio bursts from the Sun and the planets because absolute calibration of these telescopes is very difficult with conventional techniques. Here we apply the method to observations from about 7 to 47 MHz that were made on the ground with the Bruny Island Radio Spectrometer located in Tasmania, Australia, and those from about 20 kHz to 13.8 MHz were made with the radio experiment WAVES on the WIND spacecraft. The spectrum of the galactic background radiation from 30 MHz has been carefully measured with low-resolution telescopes, starting more than a decade ago. We use this known spectrum to calibrate both BIRS and WAVES on an absolute scale. The accuracy we achieve is about a factor of two, whereas the flux densities of solar and planetary radio sources vary by many orders of magnitude. Our method permits inter-calibration of ground-based and space-based observations, and allows corrections to be made for instrumental uncertainties on both radio experiments. In addition, on the ground, it allows the spectra to be corrected for ionospheric absorption and partial ground reflections. As an application we show the spectrum of a solar type III burst observed from 47 MHz to 20 kHz. Its flux density was largest, S~ 10-17 W m-2 Hz-1, at about 3 MHz, while at 60 kHz and at 47 MHz it was lower by a factor of about 300.

  5. FR II radio galaxies at low frequencies I: morphology, magnetic field strength and energetics

    CERN Document Server

    Harwood, Jeremy J; Intema, Huib T; Stewart, Adam J; Ineson, Judith; Hardcastle, Martin J; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W

    2016-01-01

    Due to their steep spectra, low-frequency observations of FR II radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths has meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C452 and 3C223. We find that the morphology of 3C452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total ...

  6. Economics and computer science of a radio spectrum reallocation.

    Science.gov (United States)

    Leyton-Brown, Kevin; Milgrom, Paul; Segal, Ilya

    2017-07-11

    The recent "incentive auction" of the US Federal Communications Commission was the first auction to reallocate radio frequencies between two different kinds of uses: from broadcast television to wireless Internet access. The design challenge was not just to choose market rules to govern a fixed set of potential trades but also, to determine the broadcasters' property rights, the goods to be exchanged, the quantities to be traded, the computational procedures, and even some of the performance objectives. An essential and unusual challenge was to make the auction simple enough for human participants while still ensuring that the computations would be tractable and capable of delivering nearly efficient outcomes.

  7. Radio Frequency Radiation Dosimetry Handbook (Fifth Edition)

    Science.gov (United States)

    2009-07-01

    high-level RF fields. Lossy-line systems work best for frequencies above 100 MHz. For high fields below 100 MHz, line burnout may be a problem. Fiber...overexposures to the head could result in a post-concussion syndrome (IEEE COMAR, 2002). Delayed effects are adverse effects that don‘t show up...individual received an overexposure to his head, it is also possible for signs and symptoms similar to that of a post-concussion syndrome to develop

  8. Scattering of radio frequency waves by turbulence in fusion plasmas

    Science.gov (United States)

    Ram, Abhay K.

    2016-10-01

    In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments and incoherent fluctuations due to turbulence are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on RF waves has not been quantified experimentally, there are telltale signs, arising from differences between results from simulations and from experiments, that fluctuations can modify the spectrum of RF waves. Any effect on RF waves in the scrape-off layer can have important experimental consequences. For example, electron cyclotron waves are expected to stabilize the deleterious neoclassical tearing mode (NTM) in ITER. Spectral and polarization changes due to scattering will modify the spatial location and profile of the current driven by the RF waves, thereby affecting the control of NTMs. Pioneering theoretical studies and complementary computer simulations have been pursued to elucidate the impact of fluctuations on RF waves. From the full complement of Maxwell's equations for cold, magnetized plasmas, it is shown that the Poynting flux in the wake of filaments develops spatial structure due to diffraction and shadowing. The uniformity of power flow into the plasma is affected by side-scattering, modifications to the wave spectrum, and coupling to plasma waves other than the incident RF wave. The Snell's law and the Fresnel equations have been reformulated within the context of magnetized plasmas. They are distinctly different from their counterparts in scalar dielectric media, and reveal new and important physical insight into the scattering of RF waves. The Snell's law and Fresnel equations are the basis for the Kirchhoff approximation necessary to determine properties of the scattered waves. Furthermore, this theory is also relevant for studying back

  9. LOFAR: A new radio telescope for low frequency radio observations: Science and project status

    CERN Document Server

    Röttgering, H J A; Fender, R P; Kuijpers, J; Van Haarlem, M P; Johnston-Hollitt, M; Miley, G K

    2003-01-01

    LOFAR, the Low Frequency Array, is a large radio telescope consisting about 100 soccer field sized antenna stations spread over a region of 400 km in diameter. It will operate in the frequency range from ~10 to 240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will allow for a broad range of astrophysical studies. In this contribution we first discuss four major areas of astrophysical research in which LOFAR will undoubtedly make important contributions: reionisation, distant galaxies and AGNs, transient radio sources and cosmic rays. Subsequently, we will discuss the technical concept of the instrument and the status of the LOFAR project

  10. Design, Implementation, and Evaluation of a Hybrid DS/FFH Spread-Spectrum Radio Transceiver

    Energy Technology Data Exchange (ETDEWEB)

    Olama, Mohammed M [ORNL; Killough, Stephen M [ORNL; Kuruganti, Teja [ORNL; Carroll, Thomas E. [Pacific Northwest National Laboratory (PNNL)

    2014-01-01

    In recent years there has been great interest in using hybrid spread-spectrum (HSS) techniques for commercial applications, particularly in the Smart Grid, in addition to their inherent uses in military communications. This is because HSS can accommodate high data rates with high link integrity, even in the presence of significant multipath effects and interfering signals. A highly useful form of this transmission technique for many types of command, control, and sensing applications is the specific code-related combination of standard direct-sequence modulation with "fast" frequency-hopping, denoted hybrid DS/FFH, wherein multiple frequency hops occur within a single data-bit time. In this paper, we present the efforts carried out at Oak Ridge National Laboratory toward exploring the design, implementation, and evaluation of a hybrid DS/FFH spread-spectrum radio transceiver using a single Field Programmable Gate Array (FPGA). The FPGA allows the various subsystems to quickly communicate with each other and thereby maintain tight synchronization. We also investigate various hopping sequences against robustness to interference and jamming. Experimental results are presented that show the receiver sensitivity, radio data-rate/bit-error evaluations, and jamming and interference rejection capabilities of the implemented hybrid DS/FFH spread-spectrum system under widely varying design parameters.

  11. Simultaneous wireless information and power transfer for spectrum sharing in cognitive radio communication systems

    KAUST Repository

    Benkhelifa, Fatma

    2016-07-26

    In this paper, we consider the simultaneous wireless information and power transfer for the spectrum sharing (SS) in cognitive radio (CR) systems with a multi-antenna energy harvesting (EH) primary receiver (PR). The PR uses the antenna switching (AS) technique that assigns a subset of the PR\\'s antennas to harvest the energy from the radio frequency (RF) signals sent by the secondary transmitter (ST), and assigns the rest of the PR\\'s antennas to decode the information data. In this context, the primary network allows the secondary network to use the spectrum as long as the interference induced by the secondary transmitter (ST)\\'s signals is beneficial for the energy harvesting process at the PR side. The objective of this work is to show that the spectrum sharing is beneficial for both the SR and PR sides and leads to a win-win situation. To illustrate the incentive of the spectrum sharing cognitive system, we evaluate the mutual outage probability (MOP) introduced in [1] which declares an outage event if the PR or the secondary receiver (SR) is in an outage. Through the simulation results, we show that the performance of our system in terms of the MOP is always better than the performance of the system in the absence of ST and improves as the ST-PR interference increases. © 2016 IEEE.

  12. Authentication of Radio Frequency Identification Devices Using Electronic Characteristics

    Science.gov (United States)

    Chinnappa Gounder Periaswamy, Senthilkumar

    2010-01-01

    Radio frequency identification (RFID) tags are low-cost devices that are used to uniquely identify the objects to which they are attached. Due to the low cost and size that is driving the technology, a tag has limited computational capabilities and resources. This limitation makes the implementation of conventional security protocols to prevent…

  13. Radio frequency power sensor based on MEMS technology

    NARCIS (Netherlands)

    Fernandez, L.J.; Visser, Eelke; Sesé, J.; Wiegerink, Remco J.; Jansen, Henricus V.; Flokstra, Jan; Flokstra, Jakob; Elwenspoek, Michael Curt

    2003-01-01

    We present the first measurement results of a power sensor for radio frequency (rf) signals (50 kHz - 40 GHz) with almost no dissipation during the measurement. This sensor is, therefore, a 'through' power sensor, that means that the rf signal is available during the measurement of its power. The

  14. INNOVATIVE TECHNOLOGY EVALUATION REPORT: RADIO FREQUENCY HEATING, KAI TECHNOLOGIES, INC.

    Science.gov (United States)

    A demonstration of KAI Technologies in-situ radio frequency heating system for soil treatment was conducted from January 1994 to July 1994 at Kelly Air Force Base in San Antonio, Texas. This demonstration was conducted as a joint effort between the USEPA and the USAF. The technol...

  15. Modelling of Voids in Complex Radio Frequency Plasmas

    NARCIS (Netherlands)

    W. J. Goedheer,; Land, V.; Venema, J.

    2009-01-01

    In this paper hydrodynamic and kinetic approaches to model low pressure capacitively coupled complex radio-frequency discharges are discussed and applied to discharges under microgravity. Experiments in the PKE-Nefedov reactor on board the International Space Station, as well as discharges in which

  16. How can radio frequency identification technology impact nursing practice?

    Science.gov (United States)

    Billingsley, Luanne; Wyld, David

    2014-12-01

    Radio frequency identification (RFID) technology can save nurses time, improve quality of care, en hance patient and staff safety, and decrease costs. However, without a better understanding of these systems and their benefits to patients and hospitals, nurses may be slower to recommend, implement, or adopt RFID technology into practice.

  17. Topology optimization of radio frequency and microwave structures

    DEFF Research Database (Denmark)

    Aage, Niels

    This thesis focuses on topology optimization of conductor-based microwave and radio frequency electromagnetic devices. The research is motivated by the ever increasing usage of small hand-held, or autonomous, electric devices, which have lead to a series of new challenges for the design...

  18. Monitoring of tumor radio frequency ablation using derivative spectroscopy

    NARCIS (Netherlands)

    Spliethoff, J.W.; Tanis, E.; Evers, Daniel James; Hendriks, B.H.; Prevoo, W.; Ruers, T.J.M.

    2014-01-01

    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffus

  19. Eddy current imaging with an atomic radio-frequency magnetometer

    CERN Document Server

    Wickenbrock, Arne; Blanchard, John W; Budker, Dmitry

    2016-01-01

    We use a radio-frequency $^{85}$Rb alkali-vapor cell magnetometer based on a paraffin-coated cell with long spin-coherence time and a small, low-inductance driving coil to create highly resolved conductivity maps of different objects. We resolve sub-mm features in conductive objects, we characterize the frequency response of our technique, and by operating at frequencies up to 250 kHz we are able to discriminate between differently conductive materials based on the induced response. The method is suited to cover a wide range of driving frequencies and can potentially be used for detecting non-metallic objects with low DC conductivity.

  20. Use of GIS in Radio Frequency and Positioning Applications

    OpenAIRE

    Jewell, Victoria Rose

    2014-01-01

    GIS are geoprocessing programs that are commonly used to store and perform calculations on terrain data, maps, and other geospatial data. GIS offers the latest terrain and building data as well as tools to process this data. This thesis considers three applications of GIS data and software: a Large Scale Radio Frequency (RF) Model, a Medium Scale RF Model, and Indoor Positioning. The Large Scale RF Model estimates RF propagation using the latest terrain data supplied in GIS for frequencies ra...

  1. INFLUENCE OF CONSTRUCTIVE AND TECHNOLOGICAL DEFECTS ON COAXIAL RADIO-FREQUENCY CABLE IMPEDANCE

    Directory of Open Access Journals (Sweden)

    G.V. Bezprozvannych

    2013-04-01

    Full Text Available Coaxial user's radio-frequency cables belong to a category of cable television network elements parameters of which essentially specify the system capabilities as a whole. The cable working frequency spectrum spreading to 1000 MHz along with digital television and soundtrack signals transmission and high-definition television introduction causes more rigid requirements for wave impedance and, consequently, for the cable design. The established norms on user's cable impedance deviations fail to answer the state-of-the-art requirements for granting a complex of interactive services. On the basis of calculations performed, values of internal and external conductor diameters deviations as well as dielectric permeability of the insulation material are validated. For up-to-date user's radio-frequency cables, the impedance deviation from the normalized average value of 75 Ohm should not exceed ± 2 Ohm.

  2. LOFAR MSSS: The scaling relation between AGN cavity power and radio luminosity at low radio frequencies

    Science.gov (United States)

    Kokotanekov, G.; Wise, M.; Heald, G. H.; McKean, J. P.; Bîrzan, L.; Rafferty, D. A.; Godfrey, L. E. H.; de Vries, M.; Intema, H. T.; Broderick, J. W.; Hardcastle, M. J.; Bonafede, A.; Clarke, A. O.; van Weeren, R. J.; Röttgering, H. J. A.; Pizzo, R.; Iacobelli, M.; Orrú, E.; Shulevski, A.; Riseley, C. J.; Breton, R. P.; Nikiel-Wroczyński, B.; Sridhar, S. S.; Stewart, A. J.; Rowlinson, A.; van der Horst, A. J.; Harwood, J. J.; Gürkan, G.; Carbone, D.; Pandey-Pommier, M.; Tasse, C.; Scaife, A. M. M.; Pratley, L.; Ferrari, C.; Croston, J. H.; Pandey, V. N.; Jurusik, W.; Mulcahy, D. D.

    2017-09-01

    We present a new analysis of the widely used relation between cavity power and radio luminosity in clusters of galaxies with evidence for strong AGN feedback. We studied the correlation at low radio frequencies using two new surveys - the first alternative data release of the TIFR GMRT Sky Survey (TGSS ADR1) at 148 MHz and LOFAR's firstall-sky survey, the Multifrequency Snapshot Sky Survey (MSSS) at 140 MHz. We find a scaling relation Pcav ∝ Lβ148, with a logarithmic slope of β = 0.51 ± 0.14, which is in good agreement with previous results based on data at 327 MHz. The large scatter present in this correlation confirms the conclusion reached at higher frequencies that the total radio luminosity at a single frequency is a poor predictor of the total jet power. Previous studies have shown that the magnitude of this scatter can be reduced when bolometric radio luminosity corrected for spectral aging is used. We show that including additional measurements at 148 MHz alone is insufficient to improve this correction and further reduce the scatter in the correlation. For a subset of four well-resolved sources, we examined the detected extended structures at low frequencies and compare with the morphology known from higher frequency images and Chandra X-ray maps. In the case of Perseus we discuss details in the structures of the radio mini-halo, while in the 2A 0335+096 cluster we observe new diffuse emission associated with multiple X-ray cavities and likely originating from past activity. For A2199 and MS 0735.6+7421, we confirm that the observed low-frequency radio lobes are confined to the extents known from higher frequencies. This new low-frequency analysis highlights the fact that existing cavity power to radio luminosity relations are based on a relatively narrow range of AGN outburst ages. We discuss how the correlation could be extended using low frequency data from the LOFAR Two-metre Sky Survey (LoTSS) in combination with future, complementary deeper X

  3. The Scale Invariant Synchrotron Jet of Flat Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    L. M. Du; J. M. Bai; Z. H. Xie; T. F. Yi; Y. B. Xu; R. Xue; X. H. Wang

    2015-06-01

    In this paper, the scale invariance of the synchrotron jet of Flat Spectrum Radio Quasars has been studied using a sample of combined sources from FKM04 and from SDSS DR3 catalogue. Since the research of scale invariance has been focused on sub-Eddington cases that can be fitted onto the fundamental plane, while near-Eddington sources such as FSRQs have not been explicitly studied. The extracted physical properties of synchrotron jet of FSRQs have been shown to be scale invariant using our sample. The results are in good agreement with theoretical expectations of Heinz & Sunyaev (2003). Therefore, the jet synchrotron is shown to be scale independent, regardless of the accretion modes. Results in this article thus lend support to the scale invariant model of the jet synchrotron throughout the mass scale of black hole systems.

  4. Eigenvalue based Spectrum Sensing Algorithms for Cognitive Radio

    CERN Document Server

    Zeng, Yonghong

    2008-01-01

    Spectrum sensing is a fundamental component is a cognitive radio. In this paper, we propose new sensing methods based on the eigenvalues of the covariance matrix of signals received at the secondary users. In particular, two sensing algorithms are suggested, one is based on the ratio of the maximum eigenvalue to minimum eigenvalue; the other is based on the ratio of the average eigenvalue to minimum eigenvalue. Using some latest random matrix theories (RMT), we quantify the distributions of these ratios and derive the probabilities of false alarm and probabilities of detection for the proposed algorithms. We also find the thresholds of the methods for a given probability of false alarm. The proposed methods overcome the noise uncertainty problem, and can even perform better than the ideal energy detection when the signals to be detected are highly correlated. The methods can be used for various signal detection applications without requiring the knowledge of signal, channel and noise power. Simulations based ...

  5. Time variation in the low frequency spectrum of Vela-like pulsar B1800-21

    CERN Document Server

    Basu, Rahul; Lewandowski, Wojciech; Kijak, Jarosław; Dembska, Marta

    2016-01-01

    We report the flux measurement of the Vela like pulsar B1800-21 at the low radio frequency regime over multiple epochs spanning several years. The spectrum shows a turnover around the GHz frequency range and represents a typical example of gigahertz-peaked spectrum (GPS) pulsar. Our observations revealed that the pulsar spectrum show a significant evolution during the observing period with the low frequency part of the spectrum becoming steeper, with a higher turnover frequency, for a period of several years before reverting back to the initial shape during the latest measurements. The spectral change over times spanning several years requires dense structures, with free electron densities around 1000--20000 cm$^{-3}$ and physical dimensions ~220 AU, in the interstellar medium (ISM) traversing across the pulsar line of sight. We look into the possible sites of such structures in the ISM and likely mechanisms particularly the thermal free-free absorption as possible explanations for the change.

  6. Measurements of radio frequent cavity volt ages by X-ray spectrum measurements

    Directory of Open Access Journals (Sweden)

    Toprek Dragan

    2005-01-01

    Full Text Available This paper deals with X-ray spectrum measurement as a method for the measurement of radio frequent cavity voltage and the theory of X-ray spectrum calculation. Experimental results at 72 MHz for three different values of the radio frequent power of ACCEL K250 super conducting cyclotron are being presented.

  7. Radio Frequency Interference Suppression for Landmine Detection by Quadrupole Resonance

    Directory of Open Access Journals (Sweden)

    Liu Guoqing

    2006-01-01

    Full Text Available The quadrupole resonance (QR technology can be used as a confirming sensor for buried plastic landmine detection by detecting the explosives within the mine. We focus herein on the detection of TNT mines via the QR sensor. Since the frequency of the QR signal is located within the AM radio frequency band, the QR signal can be corrupted by strong radio frequency interferences (RFIs. Hence to detect the very weak QR signal, RFI mitigation is essential. Reference antennas, which receive RFIs only, can be used together with the main antenna, which receives both the QR signal and the RFIs, for RFI mitigation. The RFIs are usually colored both spatially and temporally, and hence exploiting only the spatial diversity of the antenna array may not give the best performance. We exploit herein both the spatial and temporal correlations of the RFIs to improve the TNT detection performance.

  8. Relativistic runaway breakdown in low-frequency radio

    DEFF Research Database (Denmark)

    Fullekrug, M.; Roussel-Dupre, R.; Symbalisty, E.M.D.

    2011-01-01

    is characterized by consecutive broadband pulses in the low-frequency radio range from similar to 10 to 300 kHz at a distance of similar to 800 km. Experimental evidence for the existence of consecutive broadband pulses is provided by low-frequency radio observations of sprite-producing lightning discharges...... at a distance of similar to 550 km. The measured broadband pulses occur similar to 4-9 ms after the sprite-producing lightning discharge, they exhibit electromagnetic radiation which mainly spans the frequency range from similar to 50 to 350 kHz, and they exhibit complex waveforms without the typical...... ionospheric reflection of the first hop sky wave. Two consecutive pulses occur similar to 4.5 ms and similar to 3 ms after the causative lightning discharge and coincide with the sprite luminosity. It is concluded that relativistic runaway breakdown within the Earth's atmosphere can emit broadband...

  9. Addressed qubit manipulation in radio-frequency dressed lattices

    Science.gov (United States)

    Sinuco-León, G. A.; Garraway, B. M.

    2016-03-01

    Precise control over qubits encoded as internal states of ultracold atoms in arrays of potential wells is a key element for atomtronics applications in quantum information, quantum simulation and atomic microscopy. Here we theoretically study atoms trapped in an array of radio-frequency dressed potential wells and propose a scheme for engineering fast and high-fidelity single-qubit gates with low error due to cross-talk. In this proposal, atom trapping and qubit manipulation relies exclusively on long-wave radiation making it suitable for atom-chip technology. We demonstrate that selective qubit addressing with resonant microwaves can be programmed by controlling static and radio-frequency currents in microfabricated conductors. These results should enable studies of neutral-atom quantum computing architectures, powered by low-frequency electromagnetic fields with the benefit of simple schemes for controlling individual qubits in large ensembles.

  10. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    Science.gov (United States)

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-03-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

  11. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    Science.gov (United States)

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-01-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification. PMID:28272492

  12. Spectrum Sensing For Cognitive Radios Through Differential Entropy

    Directory of Open Access Journals (Sweden)

    Sanjeev Gurugopinath

    2016-04-01

    Full Text Available In this work, we present a novel Goodness-of-Fit Test driven by differential entropy for spectrum sensing in cognitive radios, under three different noise models – Gaussian, Laplacian and mixture of Gaussians. We analyze the proposed detector under Gaussian noise which models the worst-case. We then analyze by considering the Laplacian noise process which has tails heavier than that of the Gaussian. We generalize the analysis considering the noise to be a mixture of Gaussians, which is often the case with noise and interference in communication systems. We analyze the performance under each of these cases for a large class of practically relevant fading channel models and primary signal models, with emphasis on low Signal-to-Noise ratio regimes. Towards this end, we derive closed form expressions for the distribution of the test statistic under the null hypothesis and the detection threshold that satisfies a constraint on the probability of false-alarm. Through Monte Carlo simulations, we demonstrate that our detection strategy outperforms an existing spectrum sensing technique based on order statistics.

  13. Phase responses of harmonics reflected from radio-frequency electronics

    Science.gov (United States)

    Mazzaro, Gregory J.; McGowan, Sean F.; Gallagher, Kyle A.; Sherbondy, Kelly D.; Martone, Anthony F.; Narayanan, Ram M.

    2016-05-01

    The phase responses of nonlinear-radar targets illuminated by stepped frequencies are studied. Data is presented for an experimental radar and two commercial electronic targets at short standoff ranges. The amplitudes and phases of harmonics generated by each target at each frequency are captured over a 100-MHz-wide transmit band. As in the authors' prior work, target detection is demonstrated by receiving at least one harmonic of at least one transmit frequency. In the present work, experiments confirm that the phase of a harmonic reflected from a radio-frequency electronic target at a standoff distance is linear versus frequency. Similar to traditional wideband radar, the change of the reflected phase with respect to frequency indicates the range to the nonlinear target.

  14. Implementation Aspects of a Flexible Frequency Spectrum Usage Algorithm for Cognitive OFDM Systems

    DEFF Research Database (Denmark)

    Sacchi, Claudio; Tonelli, Oscar; Cattoni, Andrea Fabio

    2011-01-01

    (A) frameworks, and its hardware feasibility on FPGA. In particular, a modified version of the Spectrum Load Balancing (SLB) Frequency Spectrum Usage (FSU) algorithm [1] is implemented in a commercial Software-Defined Radio (SDR) framework. Simulations will be carried out on the basis of the WiMAX IEEE 802...... time on a shared spectrum chunk, emphasizes the role of resource allocation as a critical system design issue. This work is aimed at analyzing the practical issues related to the Software Defined Radio (SDR)-based implementation of a dynamic spectrum allocation algorithm, designed for OFDM...... on a Xilinx ML506 development board is performed. The main novelty proposed in this paper consists in the SDR-based implementation of a computationally-sustainable resource allocation algorithm for FSU on low-cost commercial FPGA platforms. The proposed implementation is competitive with respect to other ones...

  15. Relativistic runaway breakdown in low-frequency radio

    Science.gov (United States)

    Füllekrug, Martin; Roussel-Dupré, Robert; Symbalisty, Eugene M. D.; Chanrion, Olivier; Odzimek, Anna; van der Velde, Oscar; Neubert, Torsten

    2010-01-01

    The electromagnetic radiation emitted by an electron avalanche beam resulting from relativistic runaway breakdown within the Earth's atmosphere is investigated. It is found from theoretical modeling with a computer simulation that the electron beam emits electromagnetic radiation which is characterized by consecutive broadband pulses in the low-frequency radio range from ˜10 to 300 kHz at a distance of ˜800 km. Experimental evidence for the existence of consecutive broadband pulses is provided by low-frequency radio observations of sprite-producing lightning discharges at a distance of ˜550 km. The measured broadband pulses occur ˜4-9 ms after the sprite-producing lightning discharge, they exhibit electromagnetic radiation which mainly spans the frequency range from ˜50 to 350 kHz, and they exhibit complex waveforms without the typical ionospheric reflection of the first hop sky wave. Two consecutive pulses occur ˜4.5 ms and ˜3 ms after the causative lightning discharge and coincide with the sprite luminosity. It is concluded that relativistic runaway breakdown within the Earth's atmosphere can emit broadband electromagnetic pulses and possibly generates sprites. The source location of the broadband pulses can be determined with an interferometric network of wideband low-frequency radio receivers to lend further experimental support to the relativistic runaway breakdown theory.

  16. Photonics-based tunable and broadband radio frequency converter

    Science.gov (United States)

    Borges, Ramon Maia; Mazzer, Daniel; Rufino Marins, Tiago Reis; Sodré, Arismar Cerqueira

    2016-03-01

    This paper is regarding the concept and development of a photonics-based tunable and broadband radio frequency converter (PBRC). It employs an external modulation technique to generate and reconfigure its output frequency, a digital circuit to manage the modulators' bias voltages, and an optical interface for connecting it to optical-wireless networks based on radio-over-fiber technology. The proposed optoelectronic device performs photonics-based upconversion and downconversion as a function of the local oscillator frequency and modulators' bias points. Experimental results demonstrate a radiofrequency (RF) carrier conversion with spectral purity over the frequency range from 750 MHz to 6.0 GHz, as well as the integration of the photonics-based converter with an optical backhaul based on a 1.5-km single-mode fiber from a geographically distributed optical network. Low phase noise and distortion absence illustrate its applicability for convergent and reconfigurable optical wireless communications. A potential application relies on the use of PBRC in convergent optical wireless networks to dynamically provide RF carriers as a function of the telecom operator demand and radio propagation environment.

  17. Low Frequency Spectral Structure of X-shaped Radio Sources

    Science.gov (United States)

    Lal, D. V.; Rao, A. P.

    2005-12-01

    X-shaped radio galaxies are attributed to be formed by galactic mergers as the black holes of two galaxies fall into the merged system and form a bound system. Recent analysis of Giant Metrewave Radio Telescope low frequency data for an X-shaped source, 3C 223.1 has revealed an unusual result (Lal & Rao 2004). The radio morphologies of it at 240 and 610 MHz show well defined X-shape with a pair of active jets along the north-south axis and a pair of wings along the east-west axis, that pass symmetrically through the undetected radio core. The wings (or low surface brightness jets) have flatter spectral indices with respect to the high surface brightness jets, which confirms the earlier marginal result obtained at high frequency by Dennett-Thorpe et al. (2002). Although unusual, it is a valuable result which puts stringent constraints on the formation models and nature of these sources. We present preliminary results for two such sources.

  18. Fiber Bragg-grating strain sensor interrogation using laser radio-frequency modulation.

    Science.gov (United States)

    Gagliardi, G; Salza, M; Ferraro, P; De Natale, P

    2005-04-04

    We demonstrate the possibility of using radio-frequency modulation spectroscopic techniques for interrogation of fiber Bragg-grating (FBG) structures. Sidebands at 2 GHz are superimposed onto the output spectrum of a 1560-nm DFB diode laser. The power reflected by an FBG is demodulated at multiples of the sideband frequency. The sideband-to-carrier beat signal is shown to be extremely sensitive to Bragg wavelength shifts due to mechanical stress. Using this method, both static and dynamic strain measurements can be performed, with a noise-equivalent sensitivity of the order of 150 nepsilon/ radicalHz, in the quasi-static domain (2 Hz), and 1.6 nepsilon/ radicalHz at higher frequencies (1 kHz). The measured frequency response is presently limited at 20 kHz only by the test device bandwidth. A long-term reproducibility in strain measurements within 100 nepsilon is estimated from laser frequency drift referred to molecular absorption lines.

  19. Vacuum arc localization in CLIC prototype radio frequency accelerating structures

    CERN Document Server

    AUTHOR|(CDS)2091976; Koivunen, Visa

    2016-04-04

    A future linear collider capable of reaching TeV collision energies should support accelerating gradients beyond 100 MV/m. At such high fields, the occurrence of vacuum arcs have to be mitigated through conditioning, during which an accelerating structure’s resilience against breakdowns is slowly increased through repeated radio frequency pulsing. Conditioning is very time and resource consuming, which is why developing more efficient procedures is desirable. At CERN, conditioning related research is conducted at the CLIC high-power X-band test stands. Breakdown localization is an important diagnostic tool of accelerating structure tests. Abnormal position distributions highlight issues in structure design, manufacturing or operation and may consequently help improve these processes. Additionally, positioning can provide insight into the physics of vacuum arcs. In this work, two established positioning methods based on the time-difference-ofarrival of radio frequency waves are extended. The first method i...

  20. Final report: In situ radio frequency heating demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Jarosch, T.R.; Beleski, R.J.; Faust, D.

    1994-01-05

    A field demonstration of in situ radio frequency heating was performed at the Savannah River Site (SRS) as part of the US Department of Energy-Office of Technology Development`s Integrated Demonstration. The objective of the demonstration was to investigate the effectiveness of in situ radio frequency (RF) heating as an enhancement to vacuum extraction of residual solvents (primarily trichloroethylene and perchloroethylene) held in vadose zone clay deposits. Conventional soil vacuum extraction techniques are mass transfer limited because of the low permeabilities of the clays. By selectively heating the clays to temperatures at or above 100{degrees}C, the release or transport of the solvent vapors will be enhanced as a result of several factors including an increase in the contaminant vapor pressure and diffusivity and an increase in the effective permeability of the formation with the release of water vapor.

  1. Impact of cognitive radio on radio astronomy

    NARCIS (Netherlands)

    Bentum, M.J.; Boonstra, A.J.; Baan, W.A.

    2010-01-01

    The introduction of new communication techniques requires an increase in the efficiency of spectrum usage. Cognitive radio is one of the new techniques that fosters spectrum efficiency by using unoccupied frequency spectrum for communications. However, cognitive radio will increase the transmission

  2. Radio Frequency (RF) Measurements for Human Detection, Tracking, and Identification

    Science.gov (United States)

    2007-10-01

    of tick bites and the potential for Lyme disease . Insect repellent will be available at the test site and we will ask volunteers to inspect...2003, 150 (4). 6. Chen, Victor C.; Ling, Hao. Time Frequency for Radar Imaging and Signal Analysis; Artech House, 2002. 7. Natecz, Marek ; Rytel... disease that is the direct result of participating in this project (under the provisions of AR 40-38 and AR 70-25). Title of Research Project: Radio

  3. Base Level Management of Radio Frequency Radiation Protection Program

    Science.gov (United States)

    1989-04-01

    with a healti h....:d. V. STANDARDS A. The Basis of Our Permissible Exposure Limits (PELs). 1. What level of RFR is safe? It’s a big question, and a lot...mobile lifting equipment, hand-held radios, climbing gear, etc. b. Check out your equipment. Is the calibration current? Does the probe frequency range...CH--Hazardous levels possible, but only in areas that require climbing . GH--Ground-level hazardous exposures possible. DL--Transmitter dummy loaded. SH

  4. Integration of Radio Frequency Identification and Wireless Sensor Networks

    OpenAIRE

    2013-01-01

    ABSTRACT: Radio frequency identification (RFID) system is used for detecting and identifying the tagged objects by electromagnetic signals. The main components of RFID are tag (transponder), reader (transceiver) and a host computer. RFID can be implemented in wide applications such as supply chain, car access, animal tracking and smart cards. Wireless sensor network (WSN), which consists of a huge numbers of nodes, can monitor the condition of the environment including pressure, humidity, and...

  5. Radio Frequency Radiation (RFR) Measurements in Operational Settings.

    Science.gov (United States)

    1984-12-01

    1NURAT0 OF -HSAG Deport No. 84-028CV111ARA USAF OCCUPATIONAL AND ENVIRONMENTAL HEALTH LABORATORY Brooks AFB, Texas 78235 RADIO FREQUENCY RADIATION (RFR...with a 60 Watt/cm3 peak power burnout rating. First attempts to use these early instruments (Model 8300). in the investigation of an alleged...an aside, Narda also makes several other probe series for measurements to as low as 300 Kiz. All Narda probes are susceptible to burnout when exposed

  6. Large-N correlator systems for low frequency radio astronomy

    Science.gov (United States)

    Foster, Griffin

    Low frequency radio astronomy has entered a second golden age driven by the development of a new class of large-N interferometric arrays. The low frequency array (LOFAR) and a number of redshifted HI Epoch of Reionization (EoR) arrays are currently undergoing commission and regularly observing. Future arrays of unprecedented sensitivity and resolutions at low frequencies, such as the square kilometer array (SKA) and the hydrogen epoch of reionization array (HERA), are in development. The combination of advancements in specialized field programmable gate array (FPGA) hardware for signal processing, computing and graphics processing unit (GPU) resources, and new imaging and calibration algorithms has opened up the oft underused radio band below 300 MHz. These interferometric arrays require efficient implementation of digital signal processing (DSP) hardware to compute the baseline correlations. FPGA technology provides an optimal platform to develop new correlators. The significant growth in data rates from these systems requires automated software to reduce the correlations in real time before storing the data products to disk. Low frequency, widefield observations introduce a number of unique calibration and imaging challenges. The efficient implementation of FX correlators using FPGA hardware is presented. Two correlators have been developed, one for the 32 element BEST-2 array at Medicina Observatory and the other for the 96 element LOFAR station at Chilbolton Observatory. In addition, calibration and imaging software has been developed for each system which makes use of the radio interferometry measurement equation (RIME) to derive calibrations. A process for generating sky maps from widefield LOFAR station observations is presented. Shapelets, a method of modelling extended structures such as resolved sources and beam patterns has been adapted for radio astronomy use to further improve system calibration. Scaling of computing technology allows for the

  7. Longitudinal capture in the radio-frequency-quadrupole structure

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, S.

    1980-03-01

    The radio-frequency-quadrupole (RFQ) linac structure not only can attain easily transverse focusing in the low-beta region, but also can obtain very high capture efficiency because of its low beta-lambda and low-particle rigidity. An optimization study of the zero space-charge longitudinal capture in an RFQ linac that yields configurations with large capture efficiency is described.

  8. Radio frequency heating for in-situ remediation of DNAPL

    Energy Technology Data Exchange (ETDEWEB)

    Kasevich, R.S. [KAI Technologies, Woburn, MA (United States)

    1996-08-01

    In-situ radio frequency (RF) heating technology for treating soils contaminated with dense nonaqueous phase liquids (DNAPLs) is described. RF imparts heat to non-conducting materials through the application of carefully controlled RF transmissions, improving contaminant flow characteristics and facilitating separation and removal from subsurface soils. The paper outlines advantages and limitations of RF remediation, process operations, general technology considerations, low permeability media considerations, commercial availability, and costs. Two case histories of RF remediation are briefly summarized. 13 refs., 10 figs.

  9. SIGNAL IDENTIFICATION AND ISOLATION UTILIZING RADIO FREQUENCY PHOTONICS

    Science.gov (United States)

    2017-09-01

    AFRL-RY-WP-TR-2017-0158 SIGNAL IDENTIFICATION AND ISOLATION UTILIZING RADIO FREQUENCY PHOTONICS Preetpaul S. Devgan RF/EO Subsystems Branch...MATERIEL COMMAND UNITED STATES AIR FORCE NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data included in this document for...ABW) Public Affairs Office (PAO) and is available to the general public, including foreign nationals. Copies may be obtained from the Defense

  10. On the integrated continuum radio-spectrum of supernova remnant W44 (G34.7-0.4): new insights from Planck's data

    CERN Document Server

    Onić, D

    2015-01-01

    In this paper, the integrated continuum radio-spectrum of supernova remnant (SNR) W44 was analyzed up to 70 GHz, testing the different emission models that can be responsible for its particular shape. {\\it Planck's} observations made possible to analyze the high frequency part of radio-emission from SNRs. Although the quality of radio-continuum spectrum (a high scatter of data points at same frequencies) prevents us to make definite conclusions, we emphasize the possibility of spinning-dust emission detection towards this remnant. In addition, a concave-down feature, due to synchrotron losses, can not be definitely dismissed by the present knowledge of the integrated radio continuum spectrum of this SNR.

  11. Imaging Interplanetary CMEs at Radio Frequency From Solar Polar Orbit

    Science.gov (United States)

    Wu, Ji; Sun, Weiying; Zheng, Jianhua; Zhang, Cheng; Wang, Chi; Wang, C. B.; Wang, S.

    Coronal mass ejections (CMEs) are violent discharges of plasma and magnetic fields from the Sun's corona. They have come to be recognized as the major driver of physical conditions in the Sun-Earth system. Consequently, the detection of CMEs is important for un-derstanding and ultimately predicting space weather conditions. The Solar Polar Orbit Radio Telescope (SPORT) is a proposed mission to observe the propagation of interplanetary CMEs from solar polar orbit. The main payload (radio telescope) on board SPORT will be an in-terferometric imaging radiometer working at the meter wavelength band, which will follow the propagation of interplanetary CMEs from a distance of a few solar radii to near 1 AU from solar polar orbit. The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind plasma experiment, a solar wind ion composition instrument, an energetic particle detector, a wave detector, a mag-netometer and an interplanetary radio burst tracker. In this paper, we first describe the current shortage of interplanetary CME observations. Next, the scientific motivation and objectives of SPORT are introduced. We discuss the basic specifications of the main radio telescope of SPORT with reference to the radio emission mechanisms and the radio frequency band to be observed. Finally, we discuss the key technologies of the SPORT mission, including the con-ceptual design of the main telescope, the image retrieval algorithm and the solar polar orbit injection. Other payloads and their respective observation objectives are also briefly discussed. Key words: Interplanetary CMEs; Interferometric imaging; Solar polar orbit; Radiometer.

  12. The highest-frequency detection of a radio relic: 16-GHz AMI observations of the `Sausage' cluster

    CERN Document Server

    Stroe, Andra; Harwood, Jeremy J; van Weeren, Reinout; Röttgering, Huub J A; Saunders, Richard D E; Sobral, David; Perrott, Yvette C; Schammel, Michel P

    2014-01-01

    We observed the cluster CIZA J2242.8+5301 with the Arcminute Microkelvin Imager at $16$ GHz and present the first high radio-frequency detection of diffuse, non-thermal cluster emission. This cluster hosts a variety of bright, extended, steep-spectrum synchrotron-emitting radio sources, associated with the intra-cluster medium, called radio relics. Most notably, the northern, Mpc-wide, narrow relic provides strong evidence for diffusive shock acceleration in clusters. We detect a puzzling, flat-spectrum, diffuse extension of the southern relic, which is not visible in the lower radio-frequency maps. The northern radio relic is unequivocally detected and measures an integrated flux of $1.2\\pm0.3$ mJy. While the low-frequency ($<2$ GHz) spectrum of the northern relic is well represented by a power-law, it clearly steepens towards $16$ GHz. This result is inconsistent with diffusive shock acceleration predictions of ageing plasma behind a uniform shock front. The steepening could be caused by an inhomogeneous...

  13. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

    Science.gov (United States)

    Harwood, Jeremy J.; Croston, Judith H.; Intema, Huib T.; Stewart, Adam J.; Ineson, Judith; Hardcastle, Martin J.; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K.; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W.

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  14. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics.

    Science.gov (United States)

    Harwood, Jeremy J; Croston, Judith H; Intema, Huib T; Stewart, Adam J; Ineson, Judith; Hardcastle, Martin J; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  15. Radio-frequency interference mitigating hyperspectral L-band radiometer

    Science.gov (United States)

    Toose, Peter; Roy, Alexandre; Solheim, Frederick; Derksen, Chris; Watts, Tom; Royer, Alain; Walker, Anne

    2017-02-01

    Radio-frequency interference (RFI) can significantly contaminate the measured radiometric signal of current spaceborne L-band passive microwave radiometers. These spaceborne radiometers operate within the protected passive remote sensing and radio-astronomy frequency allocation of 1400-1427 MHz but nonetheless are still subjected to frequent RFI intrusions. We present a unique surface-based and airborne hyperspectral 385 channel, dual polarization, L-band Fourier transform, RFI-detecting radiometer designed with a frequency range from 1400 through ≈ 1550 MHz. The extended frequency range was intended to increase the likelihood of detecting adjacent RFI-free channels to increase the signal, and therefore the thermal resolution, of the radiometer instrument. The external instrument calibration uses three targets (sky, ambient, and warm), and validation from independent stability measurements shows a mean absolute error (MAE) of 1.0 K for ambient and warm targets and 1.5 K for sky. A simple but effective RFI removal method which exploits the large number of frequency channels is also described. This method separates the desired thermal emission from RFI intrusions and was evaluated with synthetic microwave spectra generated using a Monte Carlo approach and validated with surface-based and airborne experimental measurements.

  16. The radio-frequency design of an iris-type coupler for the CPHS radio-frequency quadrupole

    Institute of Scientific and Technical Information of China (English)

    XIONG Zheng-Feng; ZHENG Shu-Xin; XING Qing-Zi; GUAN Xia-Ling

    2012-01-01

    The Compact Pulsed Hadron Source (CPHS) project is a university-based proton accelerator platform (13 MeV,16 kW,50 mA peak current,0.5 ms pulse width at 50 Hz) for multi-disciplinary neutron and proton applications.The CPHS linac consists of a 3 MeV radio frequency quadrupole (RFQ) linac and a 13 MeV drift tube linac (DTL).Both the RFQ and DTL share a 325 MHz,2.1 MW klystron source.A single iris-type radio-frequency (RF) coupler is used to feed 537 kW of RF power to the RFQ cavity.Threedimensional electromagnetic models of the ridge-loaded tapered waveguide (RLWG) and the coupler-cavity system are presented,and the design process and results of the RLWG and iris plate are described in detail.

  17. The radio-frequency design of an iris-type coupler for the CPHS radio-frequency quadrupole

    Science.gov (United States)

    Xiong, Zheng-Feng; Zheng, Shu-Xin; Xing, Qing-Zi; Guan, Xia-Ling

    2012-01-01

    The Compact Pulsed Hadron Source (CPHS) project is a university-based proton accelerator platform (13 MeV, 16 kW, 50 mA peak current, 0.5 ms pulse width at 50 Hz) for multi-disciplinary neutron and proton applications. The CPHS linac consists of a 3 MeV radio-frequency quadrupole (RFQ) linac and a 13 MeV drift tube linac (DTL). Both the RFQ and DTL share a 325 MHz, 2.1 MW klystron source. A single iris-type radio-frequency (RF) coupler is used to feed 537 kW of RF power to the RFQ cavity. Three-dimensional electromagnetic models of the ridge-loaded tapered waveguide (RLWG) and the coupler-cavity system are presented, and the design process and results of the RLWG and iris plate are described in detail.

  18. Performance analysis of spectrum sharing mechanisms in cognitive radio networks

    Directory of Open Access Journals (Sweden)

    Peipei Chen

    2011-01-01

    Full Text Available Abstract In this article, a non-preemptive (NP mechanism is proposed to improve the quality-of-service (QoS of secondary users (SUs in joint leasing and sensing-based cognitive radio networks (CRNs. In this spectrum-sharing mechanism, a primary user (PU could not forcibly terminate a SU with ongoing transmission. Both the typical preemptive and the proposed NP mechanisms are modeled by multi-dimensional Markov chains with three state variables. A decomposition-approximated method is used to derive the closed-form solutions of the steady-state probabilities in the Markov chains. The analytical results are verified by numerical results. System parameters that affect performance metrics are also investigated in these two mechanisms. The simulation results show that in the proposed mechanism the performance metrics of SUs such as force-termination probability and mean system delay are improved significantly, with an acceptable loss of PUs' QoS in terms of mean waiting time and blocking probability. A QoS tradeoff can be achieved between the primary and the secondary systems. For QoS improvement of SUs, the proposed NP mechanism outperforms the preemptive mechanism in joint leasing and sensing-based CRNs.

  19. ENERGY EFFICIENT COOPERATIVE SPECTRUM SENSING IN COGNITIVE RADIO

    Directory of Open Access Journals (Sweden)

    Ramzi Saifan

    2016-03-01

    Full Text Available Sensing in cognitive radio (CR protects the primary user (PU from bad interference. Therefore, it is assumed to be a requirement. However, sensing has two main challenges; first the CR is required to sense the PU under very low signal to noise ratios which will take longer sensing time, and second, some CR nodes may suffer from deep fading and shadowing effects. Cooperative spectrum sensing (CSS is supposed to solve these challenges. However, CSS adds extra energy consumption due to CRs send the sensing result to the fusion center and receive the final decision from the fusion center. This is in addition to the sensing energy itself. Therefore, CSS may consume considerable energy out of the battery of the CR node. Therefore in this paper, we try to find jointly the sensing time required from each CR node and the number of CR nodes who should perform sensing such that the energy and energy efficiency (i.e., ratio of throughput to energy consumed are optimized. Simulation results show that the joint optimization achieves better in terms of energy efficiency than other approaches that perform separate optimization.

  20. Magnetic Field Amplification and Flat Spectrum Radio Quasars

    CERN Document Server

    Chen, Xuhui; Zhang, Haocheng; Pohl, Martin; Fossati, Giovanni; Boettcher, Markus; Bailyn, Charles D; Bonning, Erin W; Buxton, Michelle; Coppi, Paolo; Isler, Jedidah; Maraschi, Laura; Urry, Meg

    2014-01-01

    We perform time-dependent, spatially-resolved simulations of blazar emission to evaluate several flaring scenarios related to magnetic-field amplification and enhanced particle acceleration. The code explicitly accounts for light-travel-time effects and is applied to flares observed in the flat spectrum radio quasar (FSRQ) PKS 0208-512, which show optical/{\\gamma}-ray correlation at some times, but orphan optical flares at other times. Changes in both the magnetic field and the particle acceleration efficiency are explored as causes of flares. Generally, external Compton emission appears to describe the available data better than a synchrotron self-Compton scenario, and in particular orphan optical flares are difficult to produce in the SSC framework. X-ray soft-excesses, {\\gamma}-ray spectral hardening, and the detections at very high energies of certain FSRQs during flares find natural explanations in the EC scenario with particle acceleration change. Likewise, optical flares with/without {\\gamma}-ray count...

  1. RFID Transponders' Radio Frequency Emissions in Aircraft Communication and Navigation Radio Bands

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Williams, Reuben A.; Koppen, Sandra V.; Salud, Maria Theresa P.

    2006-01-01

    Radiated emissions in aircraft communication and navigation bands are measured from several active radio frequency identification (RFID) tags. The individual tags are different in design and operations. They may also operate in different frequency bands. The process for measuring the emissions is discussed, and includes tag interrogation, reverberation chamber testing, and instrument settings selection. The measurement results are described and compared against aircraft emission limits. In addition, interference path loss for the cargo bays of passenger aircraft is measured. Cargo bay path loss is more appropriate for RFID tags than passenger cabin path loss. The path loss data are reported for several aircraft radio systems on a Boeing 747 and an Airbus A320.

  2. Eddy current imaging with an atomic radio-frequency magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Wickenbrock, Arne, E-mail: wickenbr@uni-mainz.de [Johannes Gutenberg-Universität Mainz, 55128 Mainz (Germany); Leefer, Nathan; Blanchard, John W. [Helmholtz Institut Mainz, 55099 Mainz (Germany); Budker, Dmitry [Johannes Gutenberg-Universität Mainz, 55128 Mainz (Germany); Helmholtz Institut Mainz, 55099 Mainz (Germany); Department of Physics, University of California, Berkeley, California 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2016-05-02

    We use a radio-frequency {sup 85}Rb alkali-vapor cell magnetometer based on a paraffin-coated cell with long spin-coherence time and a small, low-inductance driving coil to create highly resolved conductivity maps of different objects. We resolve sub-mm features in conductive objects, we characterize the frequency response of our technique, and by operating at frequencies up to 250 kHz we are able to discriminate between differently conductive materials based on the induced response. The method is suited to cover a wide range of driving frequencies and can potentially be used for detecting non-metallic objects with low DC conductivity.

  3. Properties of flat-spectrum radio-loud Narrow-Line Seyfert 1 Galaxies

    CERN Document Server

    Foschini, L; Caccianiga, A; Ciroi, S; Cracco, V; Peterson, B M; Angelakis, E; Braito, V; Fuhrmann, L; Gallo, L; Grupe, D; Järvelä, E; Kaufmann, S; Komossa, S; Kovalev, Y Y; Lähteenmäki, A; Lisakov, M M; Lister, M L; Mathur, S; Richards, J L; Romano, P; Sievers, A; Tagliaferri, G; Tammi, J; Tibolla, O; Tornikoski, M; Vercellone, S; La Mura, G; Maraschi, L; Rafanelli, P

    2014-01-01

    We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio frequencies to X-rays, and supplement these with information available from online catalogs and the literature in order to cover the full electromagnetic spectrum. This is the largest known multiwavelength survey for this type of source. We detected 90% of the sources in X-rays and found 17% at gamma rays. Extreme variability at high energies was also found, down to timescales as short as hours. In some sources, dramatic spectral and flux changes suggest interplay between a relativistic jet and the accretion disk. The estimated masses of the central black holes are in the range $\\sim 10^{6-8}M_{\\odot}$, smaller than those of blazars, while the accretion luminosities span a range from $\\sim 0.01$ to $\\sim 0.49$ times the Eddington limit, with an outlier at $0.003$. The distribu...

  4. Model of the Radio Frequency (RF) Excitation Response from Monopole and Dipole Antennas in a Large Scale Tank

    Science.gov (United States)

    Wilson, Jeffrey D.; Zimmerli, Gregory A.

    2012-01-01

    Good antenna-mode coupling is needed for determining the amount of propellant in a tank through the method of radio frequency mass gauging (RFMG). The antenna configuration and position in a tank are important factors in coupling the antenna to the natural electromagnetic modes. In this study, different monopole and dipole antenna mounting configurations and positions were modeled and responses simulated in a full-scale tank model with the transient solver of CST Microwave Studio (CST Computer Simulation Technology of America, Inc.). The study was undertaken to qualitatively understand the effect of antenna design and placement within a tank on the resulting radio frequency (RF) tank spectrum.

  5. On the high frequency spectrum of a classical accretion disc

    CERN Document Server

    Balbus, Steven A

    2014-01-01

    We derive simple and explicit expressions for the high frequency spectrum of a classical accretion disc. Both stress-free and finite stress inner boundaries are considered. A classical accretion disc spectrum with a stress-free inner boundary departs from a Wien spectrum at large $\

  6. Radio Frequency Energy Harvesting for Long Lifetime Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Han, Bo; Nielsen, Rasmus Hjorth; Prasad, Ramjee

    2014-01-01

    , harvesting energy from the radio frequency (RF) waves gives the lowest system design. Previous research on RF energy harvesting is based on the model that the radio energy is omnidirectional in the air. In this paper, a directional transmission/receiving model is proposed which can further overcome the path...... loss of the RF signals. On the node level, a virtual floating gate based CMOS biasing is used for the energy conversion circuit. With the proposed technique, the sensor node is able to harvest the energy from base station up to 30 meters......., in most of the cases, the sensor nodes are either powered by non-replaceable batteries, or there will be a considerable replacement cost. Thus a self-rechargeable sensor node design is necessary: the sensor node should be able to harvest energy from the environment. Among the existing techniques...

  7. Distributed multi-frequency image reconstruction for radio-interferometry

    CERN Document Server

    Deguignet, Jérémy; Mary, David; Ferrari, Chiara

    2016-01-01

    The advent of enhanced technologies in radio interferometry and the perspective of the SKA telescope bring new challenges in image reconstruction. One of these challenges is the spatio-spectral reconstruction of large (Terabytes) data cubes with high fidelity. This contribution proposes an alternative implementation of one such 3D prototype algorithm, MUFFIN (MUlti-Frequency image reconstruction For radio INterferometry), which combines spatial and spectral analysis priors. Using a recently proposed primal dual algorithm, this new version of MUFFIN allows a parallel implementation where computationally intensive steps are split by spectral channels. This parallelization allows to implement computationally demanding translation invariant wavelet transforms (IUWT), as opposed to the union of bases used previously. This alternative implementation is important as it opens the possibility of comparing these efficient dictionaries, and others, in spatio-spectral reconstruction. Numerical results show that the IUWT-...

  8. Goodness-of-fit based secure cooperative spectrum sensing for cognitive radio network.

    Science.gov (United States)

    Vu-Van, Hiep; Koo, Insoo

    2014-01-01

    Cognitive radio (CR) is a promising technology for improving usage of frequency band. Cognitive radio users (CUs) are allowed to use the bands without interference in operation of licensed users. Reliable sensing information about status of licensed band is a prerequirement for CR network. Cooperative spectrum sensing (CSS) is able to offer an improved sensing reliability compared to individual sensing. However, the sensing performance of CSS can be destroyed due to the appearance of some malicious users. In this paper, we propose a goodness-of-fit (GOF) based cooperative spectrum sensing scheme to detect the dissimilarity between sensing information of normal CUs and that of malicious users, and reject their harmful effect to CSS. The empirical CDF will be used in GOF test to determine the measured distance between distributions of observation sample set according to each hypothesis of licensed user signal. Further, the DS theory is used to combine results of multi-GOF tests. The simulation results demonstrate that the proposed scheme can protect the sensing process against the attack from malicious users.

  9. High-resolution radio study of SNR IC443 at low radio frequencies

    CERN Document Server

    Castelletti, G; Clarke, T; Kassim, N E

    2011-01-01

    We investigated in detail the morphology at low radio frequencies of the supernova remnant IC443 and accurately established its radio continuum spectral properties. We used the VLA in multiple configurations to produce high resolution radio images of IC443 at 74 and 330 MHz. The changes with position in the radio spectral index were correlated with data in near infrared from 2MASS, in gamma-rays from VERITAS, and with the molecular 12^CO line emission. The new image at 74 MHz has HPBW=35", rms=30 mJy/beam and at 330 MHz HPBW= 17" and rms=1.7 mJy/beam. The integrated flux densities for the whole SNR are S_74MHz=470+/-51 Jy and S_330MHz=248+/-15 Jy. For the pulsar wind nebula associated with the compact source CXOUJ061705.3+222127, we calculated S_330MHz=0.23+/-0.05 Jy, S_1420MHz=0.20+/-0.04 Jy, and alpha~0.0. Substantial variations are observed in spectral index between 74 and 330 MHz across IC443. The flattest spectral components (-0.25< alpha<-0.05) coincide with the brightest parts of the SNR along th...

  10. Radio Frequency Interference Detection for Passive Remote Sensing Using Eigenvalue Analysis

    Science.gov (United States)

    Schoenwald, Adam; Kim, Seung-Jun; Mohammed-Tano, Priscilla

    2017-01-01

    Radio frequency interference (RFI) can corrupt passive remote sensing measurements taken with microwave radiometers. With the increasingly utilized spectrum and the push for larger bandwidth radiometers, the likelihood of RFI contamination has grown significantly. In this work, an eigenvalue-based algorithm is developed to detect the presence of RFI and provide estimates of RFI-free radiation levels. Simulated tests show that the proposed detector outperforms conventional kurtosis-based RFI detectors in the low-to-medium interferece-to-noise-power-ratio (INR) regime under continuous wave (CW) and quadrature phase shift keying (QPSK) RFIs.

  11. Generating topological optical flux lattices for ultracold atoms by modulated Raman and radio-frequency couplings

    Science.gov (United States)

    Yu, Jinlong; Xu, Zhi-Fang; You, Li

    2017-01-01

    We propose a scheme to dynamically generate optical flux lattices with nontrivial band topology using amplitude-modulated Raman lasers and radio-frequency (rf) magnetic fields. By tuning the strength of Raman and rf fields, three distinct phases are realized at unit filling for a unit cell. Respectively, these three phases correspond to normal insulator, topological Chern insulator, and semimetal. Nearly nondispersive bands are found to appear in the topological phase, which promises opportunities for investigating strongly correlated quantum states within a simple cold-atom setup. The validity of our proposal is confirmed by comparing the Floquet quasienergies from the evolution operator with the spectrum of the effective Hamiltonian.

  12. Multi-frequency radio observations of BAL quasar 1045+352

    CERN Document Server

    Kunert-Bajraszewska, M; Kunert-Bajraszewska, Magdalena; Marecki, Andrzej

    2006-01-01

    Multi-frequency 1.7, 5 and 8.4-GHz VLBA observations of a radio-loud broad absorption line (BAL) quasar 1045+352 are presented. It is a young compact steep spectrum (CSS) object and its asymmetric, two-sided morphology on a scale of several hundred parsecs, extending in two different directions, may suggest intermittent activity. The young age and unusual morphology of 1045+352 are arguments in favour of an evolution scenario for BAL quasars, in which the BAL features appear at a very early stage of their evolution.

  13. Radio frequency feedback method for parallelized droplet microfluidics

    KAUST Repository

    Conchouso Gonzalez, David

    2016-12-19

    This paper reports on a radio frequency micro-strip T-resonator that is integrated to a parallel droplet microfluidic system. The T-resonator works as a feedback system to monitor uniform droplet production and to detect, in real-time, any malfunctions due to channel fouling or clogging. Emulsions at different W/O flow-rate ratios are generated in a microfluidic device containing 8 parallelized generators. These emulsions are then guided towards the RF sensor, which is then read using a Network Analyzer to obtain the frequency response of the system. The proposed T-resonator shows frequency shifts of 45MHz for only 5% change in the emulsion\\'s water in oil content. These shifts can then be used as a feedback system to trigger alarms and notify production and quality control engineers about problems in the droplet generation process.

  14. Flexible Frequency Discrimination Subsystems for Reconfigurable Radio Front Ends

    Directory of Open Access Journals (Sweden)

    Carey-Smith Bruce E

    2005-01-01

    Full Text Available The required flexibility of the software-defined radio front end may currently be met with better overall performance by employing tunable narrowband circuits rather than pursuing a truly wideband approach. A key component of narrowband transceivers is appropriate filtering to reduce spurious spectral content in the transmitter and limit out-of-band interference in the receiver. In this paper, recent advances in flexible, frequency-selective, circuit components applicable to reconfigurable SDR front ends are reviewed. The paper contains discussion regarding the filtering requirements in the SDR context and the use of intelligent, adaptive control to provide environment-aware frequency discrimination. Wide tuning-range frequency-selective circuit elements are surveyed including bandpass and bandstop filters and narrowband tunable antennas. The suitability of these elements to the mobile wireless SDR environment is discussed.

  15. Flexible Frequency Discrimination Subsystems for Reconfigurable Radio Front Ends

    Directory of Open Access Journals (Sweden)

    Carey-Smith Bruce E.

    2005-01-01

    Full Text Available The required flexibility of the software-defined radio front end may currently be met with better overall performance by employing tunable narrowband circuits rather than pursuing a truly wideband approach. A key component of narrowband transceivers is appropriate filtering to reduce spurious spectral content in the transmitter and limit out-of-band interference in the receiver. In this paper, recent advances in flexible, frequency-selective, circuit components applicable to reconfigurable SDR front ends are reviewed. The paper contains discussion regarding the filtering requirements in the SDR context and the use of intelligent, adaptive control to provide environment-aware frequency discrimination. Wide tuning-range frequency-selective circuit elements are surveyed including bandpass and bandstop filters and narrowband tunable antennas. The suitability of these elements to the mobile wireless SDR environment is discussed.

  16. Multifunctional radio-frequency generator for cold atom experiments

    Science.gov (United States)

    Wei, Chun-hua; Yan, Shu-hua

    2016-05-01

    We present a low cost radio-frequency (RF) generator suitable for experiments with cold atoms. The RF source achieves a sub-hertz frequency with tunable resolution from 0 MHz to 400 MHz and a maximum output power of 33 dBm. Based on a direct digital synthesizer (DDS) chip, we implement a ramping capability for frequency, amplitude and phase. The system can also operate as an arbitrary waveform generator. By measuring the stability in a duration of 600 s, we find the presented device performs comparably as Agilent33522A in terms of short-term stability. Due to its excellent performance, the RF generator has been already applied to cold atom trapping experiments.

  17. Dynamic Spectrum Access: regulations, standards and green radio policy considerations

    CSIR Research Space (South Africa)

    Mfupe, L

    2012-09-01

    Full Text Available -related requirements of electric utilities so that FCC can advise appropriately on federal smart grid policies and governmental departments on improving the energy-efficiency of their data centres [20]. Table 1 presents a SWOT analysis on green radio policies. IV... Table 1: A summary SWOT analysis of green radio policies. Method vs. Indicator Strengths Weaknesses Opportunities Threats Green radio compliance strategies ? Some regulators, telecommunications operators and standardization bodies around...

  18. Modal response of 4-rod type radio frequency quadrupole linac

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Avik; Mahapatra, Abhijit [Central Mechanical Engineering Research Institute (CMERI), M.G. Avenue, Durgapur 713209 (India); Mondal, Manas; Chakrabarti, Alok [Variable Energy Cyclotron Centre (VECC), Sector-1/AF, Bidhannagar, Kolkata 700064 (India)

    2009-10-15

    This paper deals with the analysis and experimental study of natural frequencies of vibration of a 4-rod type radio frequency quadrupole (RFQ) linear accelerator. The eigenvalue analysis of the structure has been done both analytically (multispan beam concept) as well as using blocked Lanczos eigenvalue finite element solver with an ability to extract the rigid body modes. This has been done in the mechanical design phase to find the level of agreement between the output of simplified analytical analysis results and the output of a commercial finite element method (FEM) solver, since a full scale RFQ structure is too complex to handle analytically. Experimental validation of the analysis results has been done on the physical 1.7 m RFQ at the installation site. The experimental data obtained were later analyzed and found to be in close agreement with the predicted frequencies in the lower frequency ranges. It gets more and more deviated in the higher frequency ranges. Also some frequencies were observed during experimentation, which were not found in the finite element analysis results. The source of those frequencies are to be further investigated as it may play a predominant role in the design high quality factor beam line cavities for higher operational efficiency.

  19. Intelligent Spectrum Handoff via Docitive Learning in Cognitive Radio Networks (CRNs)

    Science.gov (United States)

    2017-03-01

    Learning based Cooperative Sensing in Sognitive Radio Ad HocNetworks,” in 21st IEEE Intl. Symposium Personal Indoor and Mobile Radio Communications...INTELLIGENT SPECTRUM HANDOFF VIA DOCITIVE LEARNING IN COGNITIVE RADIO NETWORKS (CRNs) THE UNIVERSITY OF ALABAMA MARCH 2017 FINAL TECHNICAL REPORT...Government formulated or supplied the drawings, specifications, or other data does not license the holder or any other person or corporation; or

  20. Radio Frequency Compatibility of an RFID Tag on Glideslope Navigation Receivers

    Science.gov (United States)

    Nguyen, Truong X.; Mielnik, John J.

    2008-01-01

    A process is demonstrated to show compatibility between a radio frequency identification (RFID) tag and an aircraft glideslope (GS) radio receiver. The particular tag chosen was previously shown to have significant peak spurious emission levels that far exceeded the emission limits in the GS aeronautical band. The spurious emissions are emulated in the study by capturing the RFID fundamental transmission and playing back the signal in the GS band. The signal capturing and playback are achieved with a vector signal generator and a spectrum analyzer that can output the in-phase and quadrature components (IQ). The simulated interference signal is combined with a desired GS signal before being injected into a GS receiver s antenna port for interference threshold determination. Minimum desired propagation loss values to avoid interference are then computed and compared against actual propagation losses for several aircraft.

  1. Time frequency analysis of Jovian and Saturnian radio spectral patterns

    Science.gov (United States)

    Boudjada, Mohammed Y.; Galopeau, Patrick H. M.; Al-Haddad, Emad; Lammer, Helmut

    2016-04-01

    Prominent radio spectral patterns were observed by the Cassini Radio and Plasma Wave Science experiment (RPWS) principally at Jupiter and Saturn. The spectral shapes are displayed in the usual dynamic spectra showing the flux density versus the time and the frequency. Those patterns exhibit well-organized shapes in the time-frequency plane connected with the rotation of the planet. We consider in this analysis the auroral emissions which occurred in the frequency range between 10 kHz and approximately 3 MHz. It concerns the Jovian hectometric emission (HOM) and the Saturnian kilometric radiation (SKR). We show in the case of Jupiter's HOM that the spectral patterns are well-arranged arc structures with curvatures depending on the Jovian rotation. Regarding the SKR emission, the spectral shapes exhibit generally complex patterns, and only sometimes arc structures are observed. We emphasize the curve alterations from vertex-early to vertex-late arcs (and vice versa) and we study their dependences, or not, on the planetary rotations. We also discuss the common physical process at the origin of the HOM and SKR emissions, specifically the spectral patterns created by the interaction between planetary satellites (e.g. Io or Dione) and the Jovian and Saturnian magnetospheres.

  2. Daris, a low-frequency distributed aperture array for radio astronomy in space

    NARCIS (Netherlands)

    Boonstra, A.J.; Saks, N.; Bentum, Marinus Jan; van 't Klooster, K.; Falcke, H.

    2010-01-01

    DARIS (Distributed Aperture Array for Radio Astronomy in Space) is a radio astronomy space mission concept aimed at observing the low-frequency radio sky in the range 1-10 MHz. Because of the Earth's ionospheric disturbances and opaqueness, this frequency range can only be observed from space. The a

  3. Highly sensitive passive radio frequency identification based sensor systems.

    Science.gov (United States)

    Wissenwasser, J; Vellekoop, M; Heer, R

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments.

  4. Highly sensitive passive radio frequency identification based sensor systems

    Science.gov (United States)

    Wissenwasser, J.; Vellekoop, M.; Heer, R.

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments.

  5. Beam acceleration through proton radio frequency quadrupole accelerator in BARC

    Science.gov (United States)

    Bhagwat, P. V.; Krishnagopal, S.; Mathew, J. V.; Singh, S. K.; Jain, P.; Rao, S. V. L. S.; Pande, M.; Kumar, R.; Roychowdhury, P.; Kelwani, H.; Rama Rao, B. V.; Gupta, S. K.; Agarwal, A.; Kukreti, B. M.; Singh, P.

    2016-05-01

    A 3 MeV proton Radio Frequency Quadrupole (RFQ) accelerator has been designed at the Bhabha Atomic Research Centre, Mumbai, India, for the Low Energy High Intensity Proton Accelerator (LEHIPA) programme. The 352 MHz RFQ is built in 4 segments and in the first phase two segments of the LEHIPA RFQ were commissioned, accelerating a 50 keV, 1 mA pulsed proton beam from the ion source, to an energy of 1.24 MeV. The successful operation of the RFQ gave confidence in the physics understanding and technology development that have been achieved, and indicate that the road forward can now be traversed rather more quickly.

  6. Fast Adaptive Beamforming with Smart Antenna for Radio Frequency Repeater

    Directory of Open Access Journals (Sweden)

    Wang Chaoqun

    2016-01-01

    Full Text Available We present a fast adaptive beamforming null algorithm with smart antenna for Radio Frequency Repeater (RFR. The smart antenna system is realized by a Direction Of Arrival (DOA Estimator, whose output is used by an adaptive beamforming algorithm to shape a suitable radiation pattern of the equivalent antenna; so that the co-channel interference due to retransmitting antenna can be reduced. The proposed adaptive beamforming algorithm, which has been proved by formulaic analysis and simulation, has a lower computation complexity yet better performance.

  7. Radio Frequency Identification (RFID) in healthcare: a literature review.

    Science.gov (United States)

    Kolokathi, Aikaterini; Rallis, Panagiotis

    2013-01-01

    Creating and maintaining a safe and high-quality health care environment is of great importance for global community. New technologies and their applications can help us achieve this goal. Radio-Frequency Identification (RIFD) technology is considered one of those technologies and even today there are some interesting deployments in the health industry. As a result, this work aims to present the basic idea behind RFID solutions, problems that can be addressed with the adoption of RFID and the benefits of relative applications.

  8. RFID explained a primer on radio frequency identification technologies

    CERN Document Server

    Want, Roy

    2006-01-01

    This lecture provides an introduction to Radio Frequency Identification (RFID), a technology enabling automatic identification of objects at a distance without requiring line-of-sight. Electronic tagging can be divided into technologies that have a power source (active tags), and those that are powered by the tag interrogation signal (passive tags); the focus here is on passive tags. An overview of the principles of the technology divides passive tags into devices that use either near field or far field coupling to communicate with a tag reader. The strengths and weaknesses of the approaches a

  9. Applications of Radio Frequency Identification (RFID) in Mining Industries

    Science.gov (United States)

    Khairul Nizam Mahmad, Mohd; Z, Mohd Remy Rozainy M. A.; Baharun, Norlia

    2016-06-01

    RFID technology has recently become a dream of many companies or organizations because of its strategic potential in transforming mining operations. Now is the perfect time, for RFID technology arise as the next revolution in mining industries. This paper will review regarding the application of RFID in mining industries and access knowledge regarding RFID technology and overseen the opportunity of this technology to become an importance element in mining industries. The application of Radio-Frequency Identification (RFID) in mining industries includes to control of Personal Protective Equipment (PPE), control of personnel to access mining sites and RFID solutions for tracking explosives.

  10. Electromagnetic induction imaging with a radio-frequency atomic magnetometer

    CERN Document Server

    Deans, Cameron; Hussain, Sarah; Renzoni, Ferruccio

    2016-01-01

    We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

  11. Implantable radio frequency identification sensors: wireless power and communication.

    Science.gov (United States)

    Hutchens, Chriswell; Rennaker, Robert L; Venkataraman, Srinivasan; Ahmed, Rehan; Liao, Ran; Ibrahim, Tamer

    2011-01-01

    There are significant technical challenges in the development of a fully implantable wirelessly powered neural interface. Challenges include wireless transmission of sufficient power to the implanted device to ensure reliable operation for decades without replacement, minimizing tissue heating, and adequate reliable communications bandwidth. Overcoming these challenges is essential for the development of implantable closed loop system for the treatment of disorders ranging from epilepsy, incontinence, stroke and spinal cord injury. We discuss the development of the wireless power, communication and control for a Radio-Frequency Identification Sensor (RFIDS) system with targeted power range for a 700 mV, 30 to 40 uA load attained at -2 dBm.

  12. Hollow metal target magnetron sputter type radio frequency ion source

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, N., E-mail: mwada@mail.doshisha.ac.jp; Kasuya, T.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyoto 610–0321 (Japan); Tsubouchi, N. [Kansai Institute, Advanced Industrial Science and Technology, Osaka 563–8577 (Japan)

    2014-02-15

    A 70 mm diameter 70 mm long compact ion source equipped with a hollow sputtering target has been designed and tested. The hollow sputtering target serves as the radio frequency (RF) plasma excitation electrode at 13.56 MHz. A stable beam of Cu{sup +} has been extracted when Ar was used as the discharge support gas. In the extracted beam, Cu{sup +} had occupied more than 85% of the total ion current. Further increase in Cu{sup +} ions in the beam is anticipated by increasing the RF power and Ar pressure.

  13. Potentials for Radio Frequency Identification in AEC/FM

    Institute of Scientific and Technical Information of China (English)

    Karsten Menzel; CONG Zixiang; Luke Allan

    2008-01-01

    Radio frequency identification (RFID) technology has proved to be very effective in industries as di-verse as aircraft manufacturing to health and care. The construction industry has been slow to take up on RFID and this paper will discuss the merits of the technology in its potential for application within the con-struction sector. The paper reports about the prototypical implementation of RFID-based information man-agement in FM-scenarios. The prototypes were tested at University College Cork (UCC). The general appli-cability of RFID for decentralised information management could be demonstrated.

  14. INTEGRATING RADIO FREQUENCY IDENTIFICATION TECHNOLOGY IN ACADEMIC MANAGEMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    Zainab Rasheed Mirza

    2014-01-01

    Full Text Available The purpose of this study is building a web and windows based intelligent system using web technologies, biometric and Radio Frequency Identification technologies (RFID to strengthen an Academic Management System (AMS in a campus for monitoring and improving academic performance of teachers and students. A campus mobile phone application will allow guardians to monitor student’s movement history at campus, e-payments and food choices at canteen, class attendance, exam attendance and academic performance on daily basis. Mobile application for students will allow students to view their class schedules, teacher appointments, e-payment statement, warnings or announcements, locate their exam halls and search for classrooms.

  15. NQR Spectrometer with a Two Integrated Circuits Radio Frequency Head

    Science.gov (United States)

    Zikumaru, Yushi

    1990-04-01

    An NQR spectrometer has been constructed using two linear integrated circuits in its oscillator-detector. This is very simple and compact and works in range 3-65 MHz. The radio frequency voltage can be varied from 10 mVp-p to 15 V p-p by changing the supply-voltage of an integrated circuit μA 733. The utility of the spectrometer is demonstrated by recording 35Cl NQR spectra in p-C6H4Cl2 , NaClO3 , and KClO3 .

  16. Computer controls of the CERN PS radio-frequency system

    Energy Technology Data Exchange (ETDEWEB)

    Benincasa, G.P.; Garoby, R.

    1986-06-01

    The PS computer control project has recently been terminated with the integration of the radio-frequency system. While the general controls frame was used, special software and hardware solutions were also necessary to cope with the peculiarities of the RF system. After a brief description of both the RF process and the PS control system, this paper recalls the various operational requirements and real-time constraints and relates on the criteria and methods followed during the design phase. Some implementation is illustrated with emphasis on diagnostics and measurements.

  17. Computer controls of the CERN PS radio-frequency system

    Science.gov (United States)

    Benincasa, G. P.; Garoby, R.

    1986-06-01

    The PS computer control project has recently been terminated with the integration of the radio-frequency system. While the general controls frame was used, special software and hardware solutions were also necessary to cope with the peculiarities of the rf system. After a brief description of both the rf process and the PS control system, this paper recalls the various operational requirements and real-time constraints and relates on the criteria and methods followed during the design phase. Some implementation is illustrated with emphasis on diagnostics and measurements.

  18. Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

    Science.gov (United States)

    Foschini, L.; Berton, M.; Caccianiga, A.; Ciroi, S.; Cracco, V.; Peterson, B. M.; Angelakis, E.; Braito, V.; Fuhrmann, L.; Gallo, L.; Grupe, D.; Järvelä, E.; Kaufmann, S.; Komossa, S.; Kovalev, Y. Y.; Lähteenmäki, A.; Lisakov, M. M.; Lister, M. L.; Mathur, S.; Richards, J. L.; Romano, P.; Sievers, A.; Tagliaferri, G.; Tammi, J.; Tibolla, O.; Tornikoski, M.; Vercellone, S.; La Mura, G.; Maraschi, L.; Rafanelli, P.

    2015-03-01

    We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio frequencies to X-rays, and supplement these with information available from online catalogues and the literature in order to cover the full electromagnetic spectrum. This is the largest known multiwavelength survey for this type of source. We detected 90% of the sources in X-rays and found 17% at γ rays. Extreme variability at high energies was also found, down to timescales as short as hours. In some sources, dramatic spectral and flux changes suggest interplay between a relativistic jet and the accretion disk. The estimated masses of the central black holes are in the range ~106-8 M⊙, lower than those of blazars, while the accretion luminosities span a range from ~0.01 to ~0.49 times the Eddington limit, with an outlier at 0.003, similar to those of quasars. The distribution of the calculated jet power spans a range from ~1042.6 to ~1045.6 erg s-1, generally lower than quasars and BL Lac objects, but partially overlapping with the latter. Once normalised by the mass of the central black holes, the jet power of the three types of active galactic nuclei are consistent with each other, indicating that the jets are similar and the observational differences are due to scaling factors. Despite the observational differences, the central engine of RLNLS1s is apparently quite similar to that of blazars. The historical difficulties in finding radio-loud narrow-line Seyfert 1 galaxies might be due to their low power and to intermittent jetactivity. Tables 4-9 and Figs. 8-13 are available in electronic form at http://www.aanda.org

  19. High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

    Science.gov (United States)

    2016-07-20

    REPORT NO: NAWCADPAX/TIM-2016/49 HIGH - FREQUENCY AXIAL FATIGUE TEST PROCEEDURES FOR SPECTRUM LOADING by David T. Rusk, AIR...OF THE NAVY NAVAL AIR WARFARE CENTER AIRCRAFT DIVISION PATUXENT RIVER, MARYLAND NAWCADPAX/TIM-2016/49 20 July 2016 HIGH - FREQUENCY AXIAL...Technical Information Memorandum 3. DATES COVERED 4. TITLE AND SUBTITLE High - Frequency Axial Fatigue Test Procedures for Spectrum Loading

  20. Application of the Frequency Spectrum to Spectral Similarity Measures

    Directory of Open Access Journals (Sweden)

    Ke Wang

    2016-04-01

    Full Text Available Several frequency-based spectral similarity measures, derived from commonly-used ones, are developed for hyperspectral image classification based on the frequency domain. Since the frequency spectrum (magnitude spectrum of the original signature for each pixel from hyperspectral data can clearly reflect the spectral features of different types of land covers, we replace the original spectral signature with its frequency spectrum for calculating the existing spectral similarity measure. The frequency spectrum is symmetrical around the direct current (DC component; thus, we take one-half of the frequency spectrum from the DC component to the highest frequency component as the input signature. Furthermore, considering the fact that the low frequencies include most of the frequency energy, we can optimize the classification result by choosing the ratio of the frequency spectrum (from the DC component to the highest frequency component involved in the calculation. In our paper, the frequency-based measures based on the spectral gradient angle (SAM, spectral information divergence (SID, spectral correlation mapper (SCM, Euclidean distance (ED, normalized Euclidean distance (NED and SID × sin(SAM (SsS measures are called the F-SAM, F-SID, F-SCM, F-ED, F-NED and F-SsS, respectively. In the experiment, three commonly-used hyperspectral remote sensing images are employed as test data. The frequency-based measures proposed here are compared to the corresponding existing ones in terms of classification accuracy. The classification results by parameter optimization are also analyzed. The results show that, although not all frequency-based spectral similarity measures are better than the original ones, some frequency-based measures, such as the F-SsS and F-SID, exhibit a relatively better performance and have more robust applications than the other spectral similarity measures.

  1. The Cubesat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) Mission

    Science.gov (United States)

    Misra, S.; Johnson, J. T.; Ball, C.; Chen, C. C.; Smith, G.; McKelvey, C.; Andrews, M.; O'Brien, A.; Kocz, J.; Jarnot, R.; Brown, S. T.; Piepmeier, J. R.; Lucey, J.; Miles, L. R.; Bradley, D.; Mohammed, P.

    2016-12-01

    Passive microwave measurements made below 40GHz have experienced increased amounts of man-made radio frequency interference (RFI) over the past couple of decades. Such RFI has had a degenerative impact on various important geophysical retrievals such as soil-moisture, sea-surface salinity, atmospheric water vapor, precipitation etc. The commercial demand for spectrum allocation has increased over the past couple of years - infringing on frequencies traditionally reserved for scientific uses such as Earth observation at passive microwave frequencies. With the current trend in shared spectrum allocations, future microwave radiometers will have to co-exist with terrestrial RFI sources. The CubeSat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) mission is developing a 6U Cubesat system to demonstrate RFI detection and filtering technologies for future microwave radiometer remote sensing missions. CubeRRT will operate between 6-40GHz, and demonstrate on-board real-time RFI detection on Earth brightness temperatures tuned over 1GHz steps. The expected launch date for CubeRRT is early 2018. Digital subsystems for higher frequency microwave radiometry require a larger bandwidth, as well as more processing power and on-board operation capabilities for RFI filtering. Real-time and on-board RFI filtering technology development is critical for future missions to allow manageable downlink data volumes. The enabling CubeRRT technology is a digital FPGA-based spectrometer with a bandwidth of 1 GHz that is capable of implementing advanced RFI filtering algorithms that use the kurtosis and cross-frequency RFI detection methods in real-time on board the spacecraft. The CubeRRT payload consists of 3 subsystems: a wideband helical antenna, a tunable analog radiometer subsystem, and a digital backend. The following presentation will present an overview of the system and results from the latest integration and test.

  2. Radio-frequency ion deflector for mass separation

    Energy Technology Data Exchange (ETDEWEB)

    Schlösser, Magnus, E-mail: magnus.schloesser@googlemail.com; Rudnev, Vitaly; Ureña, Ángel González, E-mail: laseres@pluri.ucm.es [Unidad de Láseres y Haces Moleculares, Instituto Plurisdisciplinar, Universidad Complutense de Madrid, Madrid 28040 (Spain)

    2015-10-15

    Electrostatic cylindrical deflectors act as energy analyzer for ion beams. In this article, we present that by imposing of a radio-frequency modulation on the deflecting electric field, the ion transmission becomes mass dependent. By the choice of the appropriate frequency, amplitude, and phase, the deflector can be used as mass filter. The basic concept of the new instrument as well as simple mathematic relations are described. These calculations and further numerical simulations show that a mass sensitivity is achievable. Furthermore, we demonstrate the proof-of-principle in experimental measurements, compare the results to those of from a 1 m linear time-of-flight spectrometer, and comment on the mass resolution of the method. Finally, some potential applications are indicated.

  3. Radio-frequency-modulated Rydberg states in a vapor cell

    CERN Document Server

    Miller, Stephanie A; Raithel, Georg

    2016-01-01

    We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60$S_{1/2}$ and 58$D_{5/2}$ Rydberg states with 50~MHz and 100~MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitable for precision field measurements. A quantitative description of strong-field level modulation and mixing of $S$ and $D$ states with hydrogenic states is provided by Floquet theory. Additionally, we estimate the shielding of DC electric fields in the interior of the glass vapor cell.

  4. Multiplexed infrared photodetection using resonant radio-frequency circuits

    Energy Technology Data Exchange (ETDEWEB)

    Liu, R.; Lu, R.; Gong, S.; Wasserman, D. [Department of Electrical and Computer Engineering, University of Illinois Urbana Champaign, Urbana, Illinois 61801 (United States); Roberts, C. [Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854 (United States); Allen, J. W.; Allen, M. S. [Air Force Research Laboratory, Munitions Directorate, Eglin Air Force Base, Florida 32542 (United States); Wenner, B. R. [Air Force Research Laboratory, Sensors Directorate, Wright Patterson Air Force Base, Ohio 45433 (United States)

    2016-02-08

    We demonstrate a room-temperature semiconductor-based photodetector where readout is achieved using a resonant radio-frequency (RF) circuit consisting of a microstrip split-ring resonator coupled to a microstrip busline, fabricated on a semiconductor substrate. The RF resonant circuits are characterized at RF frequencies as function of resonator geometry, as well as for their response to incident IR radiation. The detectors are modeled analytically and using commercial simulation software, with good agreement to our experimental results. Though the detector sensitivity is weak, the detector architecture offers the potential for multiplexing arrays of detectors on a single read-out line, in addition to high speed response for either direct coupling of optical signals to RF circuitry, or alternatively, carrier dynamics characterization of semiconductor, or other, material systems.

  5. Antarctic Radio Frequency Albedo and Implications for Cosmic Ray Reconstruction

    CERN Document Server

    Besson, D Z; Sullivan, M; Allison, P; Barwick, S W; Baughman, B M; Beatty, J J; Belov, K; Bevan, S; Binns, W R; Chen, C; Chen, P; Clem, J M; Connolly, A; De Marco, D; Dowkontt, P F; DuVernois, M; Goldstein, D; Gorham, P W; Grashorn, E W; Hill, B; Hoover, S; Huang, M; Israel, M H; Javaid, A; Kowalski, J; Learned, J; Liewer, K M; Matsuno, S; Mercurio, B C; Miki, C; Mottram, M; Nam, J; Naudet, C J; Nichol, R J; Palladino, K; Romero-Wolf, A; Ruckman, L; Saltzberg, D; Seckel, D; Shang, R Y; Stockham, M; Varner, G S; Vieregg, A G; Wang, Y

    2013-01-01

    From an elevation of ~38 km, the balloon-borne ANtarctic Impulsive Transient Antenna (ANITA) is designed to detect the up-coming radio frequency (RF) signal resulting from a sub-surface neutrino-nucleon collision. Although no neutrinos have been discovered thus far, ANITA is nevertheless the only experiment to self-trigger on radio frequency emissions from cosmic-ray induced atmospheric air showers. In the majority of those cases, down-coming RF signals are observed via their reflection from the Antarctic ice sheet and back up to the ANITA interferometer. Estimating the energy scale of the incident cosmic rays therefore requires an estimate of the fractional power reflected at the air-ice interface. Similarly, inferring the energy of neutrinos interacting in-ice from observations of the upwards-directed signal refracting out to ANITA also requires consideration of signal coherence across the interface. By comparing the direct Solar RF signal intensity measured with ANITA to the surface-reflected Solar signal ...

  6. A new look at the integrated radio/microwave continuum spectrum of Galactic supernova remnant IC443

    CERN Document Server

    Onic, D; Leahy, D

    2016-01-01

    Recent observations of the microwave sky, by the space telescopes such as WMAP and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of presently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility that the slight bump in the integrated continuum of this remnant around 20 -- 70~GHz is genuine and that can be explained by the contribution of additional emission mechanism such as of spinning dust is emphasized. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while, at the same time preserves the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.

  7. A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant IC 443

    Science.gov (United States)

    Onić, D.; Urošević, D.; Leahy, D.

    2017-01-01

    Recent observations of the microwave sky, by space telescopes such as the Wilkinson Microwave Anisotropy Probe and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of currently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility is emphasized that the slight bump in the integrated continuum of this remnant around 20–70 GHz is genuine and that it can be explained by the contribution of an additional emission mechanism such as spinning dust. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while at the same time preserving the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.

  8. Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

    Science.gov (United States)

    Titov, O.; Pursimo, T.; Johnston, Helen M.; Stanford, Laura M.; Hunstead, Richard W.; Jauncey, David L.; Zenere, Katrina A.

    2017-04-01

    In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ˜160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

  9. Solar Corona and plasma effects on Radio Frequency waves

    Science.gov (United States)

    Nkono, C.; Rosenblatt, P.; Dehant, V. M.

    2009-12-01

    Solar corona (plasma) effects on radio signal waves for three different frequency bands S (2.3 GHz), X (8.4 GHz), and Ka (32 GHz), currently used to track probes in the solar system, have been computed using different models of the total electron content (TEC) along the propagation path between the Earth and Mars. The Earth-Mars-Sun configuration has been obtained from the planetary ephemerides DE421 (using SPICE kernels) for the period from September 2004 to September 2006. This configuration is expressed as a function of the Sun-Earth-Probe (SEP) angles (the probe being in close orbit to Mars). We used the TEC values provided by the different models proposed in the literature in order to estimate the TEC along the propagation path (STEC, for Slant TEC). From these model-dependent STEC estimates, the time delay on the wave propagation as well as the associated frequency shift with a 10 seconds sampling time have been obtained for each of the three frequency bands. For the X-band mostly used in radio science, we have obtained estimates differing by up to several orders of magnitude due to the different STEC values derived from different models of TEC. For example, if the propagation path passes near the Sun such that SEP angle is 1.55° the STEC is ranging from 4.6x1020 electron/m2 to 6.07x1016 electron/m2, which corresponds to a time delay range between 0.87 μs and 1.15x10-4 μs, respectively. For SEP angles between 2° and 8°, the range of the different time delay values reduces to 2.8x10-1 μs and becomes as small as 1.6x10-2 μs for SEP angles larger than 8° (1x10-2 μs is about the order of magnitude of the radioscience instrument precision). These results show that the correction of the solar corona effect on radio frequency waves can be reliably done on usual X-band tracking data of spacecraft for SEP angles >12°, but should be use with caution for lower SEP angles, especially lower than 2°.

  10. The very flat radio spectrum of 0735 plus 178 - A cosmic conspiracy

    Science.gov (United States)

    Cotton, W. D.; Wittels, J. J.; Shapiro, I. I.; Marcaide, J.; Owen, F. N.; Spangler, S. R.; Rius, A.; Angulo, C.; Clark, T. A.; Knight, C. A.

    1980-01-01

    Multifrequency interferometric and total flux density measurements of the radiation from 0735 plus 178 are discussed. It is shown that it is far more likely that the very flat radio spectrum of this source results from a superposition of incoherent synchrotron radiation from four distinct, homogeneous components, each with a peaked spectrum, than from radiation from a single inhomogeneous component.

  11. The Spectrum Sharing in Cognitive Radio Networks Based on Competitive Price Game

    Directory of Open Access Journals (Sweden)

    Y. B. Li

    2012-09-01

    Full Text Available The competitive price game model is used to analyze the spectrum sharing problem in the cognitive radio networks, and the spectrum sharing problem with the constraints of available spectrum resource from primary users is further discussed in this paper. The Rockafeller multiplier method is applied to deal with the constraints of available licensed spectrum resource, and the improved profits function is achieved, which can be used to measure the impact of shared spectrum price strategies on the system profit. However, in the competitive spectrum sharing problem of practical cognitive radio network, primary users have to determine price of the shared spectrum without the acknowledgement of the other primary user’s price strategies. Thus a fast gradient iterative calculation method of equilibrium price is proposed, only with acknowledgement of the price strategies of shared spectrum during last cycle. Through the adaptive iteration at the direction with largest gradient of improved profit function, the equilibrium price strategies can be achieved rapidly. It can also avoid the predefinition of adjustment factor according to the parameters of communication system in conventional linear iteration method. Simulation results show that the proposed competitive price spectrum sharing model can be applied in the cognitive radio networks with constraints of available licensed spectrum, and it has better convergence performance.

  12. Radio frequency electromagnetic field compliance assessment of multi-band and MIMO equipped radio base stations.

    Science.gov (United States)

    Thors, Björn; Thielens, Arno; Fridén, Jonas; Colombi, Davide; Törnevik, Christer; Vermeeren, Günter; Martens, Luc; Joseph, Wout

    2014-05-01

    In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances.

  13. Linear Optimization of Frequency Spectrum Assignments Across System

    Science.gov (United States)

    2016-03-01

    Instead of separate transmit and receive apertures for each of the multiple radar , communications, and electronic warfare systems, a few pairs of AMRF-C... OPTIMIZATION OF FREQUENCY SPECTRUM ASSIGNMENTS ACROSS SYSTEMS by Steven J. Fischbach March 2016 Thesis Advisor: Jeffrey Hyink Thesis Co-Advisor...March 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE LINEAR OPTIMIZATION OF FREQUENCY SPECTRUM ASSIGNMENTS ACROSS

  14. Radio-frequency energy harvesting for wearable sensors.

    Science.gov (United States)

    Borges, Luís M; Chávez-Santiago, Raul; Barroca, Norberto; Velez, Fernando José; Balasingham, Ilangko

    2015-02-01

    The use of wearable biomedical sensors for the continuous monitoring of physiological signals will facilitate the involvement of the patients in the prevention and management of chronic diseases. The fabrication of small biomedical sensors transmitting physiological data wirelessly is possible as a result of the tremendous advances in ultra-low power electronics and radio communications. However, the widespread adoption of these devices depends very much on their ability to operate for long periods of time without the need to frequently change, recharge or even use batteries. In this context, energy harvesting (EH) is the disruptive technology that can pave the road towards the massive utilisation of wireless wearable sensors for patient self-monitoring and daily healthcare. Radio-frequency (RF) transmissions from commercial telecommunication networks represent reliable ambient energy that can be harvested as they are ubiquitous in urban and suburban areas. The state-of-the-art in RF EH for wearable biomedical sensors specifically targeting the global system of mobile 900/1800 cellular and 700 MHz digital terrestrial television networks as ambient RF energy sources are showcased. Furthermore, guidelines for the choice of the number of stages for the RF energy harvester are presented, depending on the requirements from the embedded system to power supply, which is useful for other researchers that work in the same area. The present authors' recent advances towards the development of an efficient RF energy harvester and storing system are presented and thoroughly discussed too.

  15. Radio frequency identification enabled wireless sensing for intelligent food logistics.

    Science.gov (United States)

    Zou, Zhuo; Chen, Qiang; Chen, Qing; Uysal, Ismail; Zheng, Lirong

    2014-06-13

    Future technologies and applications for the Internet of Things (IoT) will evolve the process of the food supply chain and create added value of business. Radio frequency identifications (RFIDs) and wireless sensor networks (WSNs) have been considered as the key technological enablers. Intelligent tags, powered by autonomous energy, are attached on objects, networked by short-range wireless links, allowing the physical parameters such as temperatures and humidities as well as the location information to seamlessly integrate with the enterprise information system over the Internet. In this paper, challenges, considerations and design examples are reviewed from system, implementation and application perspectives, particularly with focus on intelligent packaging and logistics for the fresh food tracking and monitoring service. An IoT platform with a two-layer network architecture is introduced consisting of an asymmetric tag-reader link (RFID layer) and an ad-hoc link between readers (WSN layer), which are further connected to the Internet via cellular or Wi-Fi. Then, we provide insights into the enabling technology of RFID with sensing capabilities. Passive, semi-passive and active RFID solutions are discussed. In particular, we describe ultra-wideband radio RFID which has been considered as one of the most promising techniques for ultra-low-power and low-cost wireless sensing. Finally, an example is provided in the form of an application in fresh food tracking services and corresponding field testing results.

  16. The Radio Frequency Health Node Wireless Sensor System

    Science.gov (United States)

    Valencia, J. Emilio; Stanley, Priscilla C.; Mackey, Paul J.

    2009-01-01

    The Radio Frequency Health Node (RFHN) wireless sensor system differs from other wireless sensor systems in ways originally intended to enhance utility as an instrumentation system for a spacecraft. The RFHN can also be adapted to use in terrestrial applications in which there are requirements for operational flexibility and integrability into higher-level instrumentation and data acquisition systems. As shown in the figure, the heart of the system is the RFHN, which is a unit that passes commands and data between (1) one or more commercially available wireless sensor units (optionally, also including wired sensor units) and (2) command and data interfaces with a local control computer that may be part of the spacecraft or other engineering system in which the wireless sensor system is installed. In turn, the local control computer can be in radio or wire communication with a remote control computer that may be part of a higher-level system. The remote control computer, acting via the local control computer and the RFHN, cannot only monitor readout data from the sensor units but can also remotely configure (program or reprogram) the RFHN and the sensor units during operation. In a spacecraft application, the RFHN and the sensor units can also be configured more nearly directly, prior to launch, via a serial interface that includes an umbilical cable between the spacecraft and ground support equipment. In either case, the RFHN wireless sensor system has the flexibility to be configured, as required, with different numbers and types of sensors for different applications. The RFHN can be used to effect realtime transfer of data from, and commands to, the wireless sensor units. It can also store data for later retrieval by an external computer. The RFHN communicates with the wireless sensor units via a radio transceiver module. The modular design of the RFHN makes it possible to add radio transceiver modules as needed to accommodate additional sets of wireless sensor

  17. Novel radio-frequency ion trap with spherical geometry

    CERN Document Server

    Noshad, Houshyar

    2014-01-01

    Confinement of single ions in a novel radio-frequency (RF) quadrupole ion trap with spherical shape is investigated. An optimization of this spherical ion trap (SIT) is carried out in order to suppress its nonlinearity substantially by eliminating the electric octupole moment. Hence, a trapping potential and consequently an electric field very similar to the ideal quadrupole ion trap (QIT) are obtained. Afterwards, three stability regions for the optimized SIT are numerically computed. The regions coincide well with those reported in the literature for the ideal QIT. The reason is attributed to the zero electric octupole moment of our proposed trap. The SIT simple geometry and relative ease of fabrication along with its increased trapping volume compared to the conventional hyperbolic quadrupole ion trap, make it an appropriate choice for miniaturization.

  18. Biomedical Monitoring By A Novel Noncontact Radio Frequency Technology Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    The area of Space Health and Medicine is one of the NASA's Space Technology Grand Challenges. Space is an extreme environment which is not conducive to human life. The extraterrestrial environment can result in the deconditioning of various human physiological systems and thus require easy to use physiological monitoring technologies in order to better monitor space crews for appropriate health management and successful space missions and space operations. Furthermore, the Space Technology Roadmap's Technology Area Breakdown Structure calls for improvements in research to support human health and performance (Technology Area 06). To address these needs, this project investigated a potential noncontact and noninvasive radio frequency-based technique of monitoring central hemodynamic function in human research subjects in response to orthostatic stress.

  19. Radio-frequency dressed state potentials for neutral atoms

    CERN Document Server

    Hofferberth, S; Fischer, B; Verdu, J; Schmiedmayer, J

    2006-01-01

    Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronically excited states of an atom with light. Here we present an experimental investigation of the remarkable properties of potentials derived from radio-frequency (RF) coupling between electronic ground states. The coupling is magnetic and the vector character allows to design state dependent potential landscapes. On atom chips this enables robust coherent atom manipulation on much smaller spatial scales than possible with static fields alone. We find no additional heating or collisional loss up to densities approaching $10^{15}$ atoms / cm$^3$ compared to static magnetic traps. We demonstrate the creation of Bose-Einstein condensates in RF potentials and investigate the difference in the interference between two independe...

  20. High-frequency radio polarization measurements of WMAP point sources

    CERN Document Server

    Jackson, N; Battye, R A; Gabuzda, D; Taylor, A C

    2009-01-01

    We present polarization measurements at 8.4, 22, and 43 GHz made with the VLA of a complete sample of extragalactic sources stronger than 1 Jy in the 5-year WMAP catalogue and with declinations north of -34 degrees. The observations were motivated by the need to know the polarization properties of radio sources at frequencies of tens of GHz in order to subtract polarized foregrounds for future sensitive Cosmic Microwave Background (CMB) experiments. The total intensity and polarization measurements are generally consistent with comparable VLA calibration measurements for less-variable sources, and within a similar range to WMAP fluxes for unresolved sources. A further paper will present correlations between measured parameters and derive implications for CMB measurements.

  1. An evaluation of radio frequency exposure from therapeutic diathermy equipment.

    Science.gov (United States)

    Li, C Y; Feng, C K

    1999-10-01

    To assess the physiotherapist's exposure to radio frequency electromagnetic fields (RF) leaking from short wave diathermy equipment, we conducted on-site measurements of stray electric and magnetic fields (27.12 MHz) close to continuous wave (CW) short wave equipment. The results show that the operator's knees may have the highest exposure level for both electric field (E-field) and magnetic field (H-field) in the normal operating position, i.e., behind the device console. The whole-body E-field exposure normally does not exceed the 1992 IEEE recommended limit during a normal treatment session. On the other hand, the operator's whole-body exposure to H-field was barely below the recommended limit. Our data suggest little chance of immediate harmful effects of RF leakage from the diathermy. Nonetheless, physiotherapists should still be advised to remain at a distance of at least 20 cm from the electrodes and cables to avoid possible overexposure.

  2. Numerical model study of radio frequency vessel sealing thermodynamics

    Science.gov (United States)

    Pearce, John

    2015-03-01

    Several clinically successful clinical radio frequency vessel-sealing devices are currently available. The dominant thermodynamic principles at work involve tissue water vaporization processes. It is necessary to thermally denature vessel collagen, elastin and their adherent proteins to achieve a successful fusion. Collagens denature at middle temperatures, between about 60 and 90 C depending on heating time and rate. Elastin, and its adherent proteins, are more thermally robust, and require temperatures in excess of the boiling point of water at atmospheric pressure to thermally fuse. Rapid boiling at low apposition pressures leads to steam vacuole formation, brittle tissue remnants and frequently to substantial disruption in the vessel wall, particularly in high elastin-content arteries. High apposition pressures substantially increase the equilibrium boiling point of tissue water and are necessary to ensure a high probability of a successful seal. The FDM numerical models illustrate the beneficial effects of high apposition pressures.

  3. Indoor localization and beacon calibration using ultrasonic and radio frequency

    Science.gov (United States)

    Yoon, Jeong-Yong; Jung, Kyoo-Sick; Shin, Dong-Hun

    2005-12-01

    Using the ultrasonic and the radio frequency, a method for the robot localization and calibration was presented. The distance between the receiver and a beacon can be computed by using the difference between times of flight. The presented method uses the gradient of the maximum amplitude of the ultrasonic in order to measure the time of flight precisely. The measured three distances between the receiver and the beacon were used to compute the robot position by the direct inverse method and the iterated least square approximation method. This paper defines the calibration as the problem to find the location of 3 beacons and 3 robots, and presents 3 methods for it and found the 2B2R method as the best among them.

  4. Application of radio-frequency identification in perioperative care.

    Science.gov (United States)

    Ku, Hsueh-Ling; Wang, Pa-Chun; Su, Mu-Chun; Liu, Charles C H; Hwang, Wu-Yuin

    2011-08-01

    Every perioperative department could benefit from having an information system that facilitates managerial function and improves efficiency in the OR. The Patient Advancement Monitoring System-Surgical implemented in a hospital in Taipei, Taiwan, is one such a system that uses radio-frequency identification technology for tracking perioperative care of patients along workflow checkpoints. This web-based medical information system can facilitate care provided throughout perioperative services by providing instant patient information to staff members in cross-functional health care teams. Manpower is not wasted on duplicating data entry because the surgical progression is displayed in real time. Satisfaction with the system has been high for both nurses and administrators. Copyright © 2011 AORN, Inc. Published by Elsevier Inc. All rights reserved.

  5. Effective Control of Cold Collisions with Radio Frequency Fields

    CERN Document Server

    Ding, Yijue; Greene, Chris H

    2016-01-01

    We study $^{87}$Rb cold collisions in a static magnetic field and a single-color radio frequency (RF) field by employing the multi-channel quantum defect theory in combination with the Floquet method to solve the two-body time-dependent Schr\\"odinger equation. Our results show that RF fields can modify the two-body scattering length by a large scale through Feshbach resonances both in low and high static magnetic field regimes. Such RF induced Feshbach resonances can be applied to quenching experiments or controlling interactions in spinor condensates. Here, we also show that analogous to photo-association, RF fields can also associate cold atoms into molecules at a useful rate.

  6. Radio frequency heating of ceramic windows in fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J.D. Jr.

    1981-11-01

    Ceramic windows will be used as material barriers for radio frequency plasma heating in fusion reactors. This report examines the theory behind rf heating phenomena. Heating calculations are presented for various window materials, thicknesses, wavelengths, and power densities. The most pertinent material properties are loss tangent, thermal conductivity, dielectric constant, strength, and radiation resistance. Calculations indicate that among candidate materials, beryllium oxide offers the most promise because of its large thermal conductivity and relatively low loss tangent and dielectric constant. On the other hand, beryllia is susceptible to neutron damage, and this may adversely affect its electrical properties. Another promising candidate is sapphire, particularly at lower temperatures where the thermal conductivity is high. Fused silica suffers from low thermal conductivity and large positive temperature coefficient for loss tangent, but it may be useful under some conditions. In summary, calculations of heating can lead to elimination of some candidate materials and selection of others for further study.

  7. CERN Open Days 2013, Point 4: LHC Radio Frequency

    CERN Multimedia

    CERN Photolab

    2013-01-01

    Stand description: At Point 4 visitors will descend into the LHC tunnel to see the "engine" of the collider: the accelerating cavities where the circulating particles get a small kick of energy as they pass by 11,000 times each second. During your visit underground, you will see the superconducting magnets as well as instruments for observing the beams. You will also walk through the huge cavern containing the Radio Frequency power plants which provide the particle beams with energy. On surface no restricted access  Above ground, you will see the cryogenics installations which keep the accelerator at a just few degrees above absolute zero. Lots of fascinating information and exhibits about CERN's accelerators and experiments will be on display, with CERN engineers and physicists on hand all day to answer your questions.

  8. Fiducialization of Superconducting Radio Frequency Cryomodules at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    C. J. Curtis; J. Dahlberg; W. Oren; J. Preble; K. Tremblay

    2006-09-26

    During the early 1990's the Continuous Electron Beam Accelerator Facility (CEBAF), was under construction in Newport News, Virginia. The facility was to be the first of its kind in that it was to provide a continuous beam of electrons for experimental physics at energies of several GeV. One of the key elements of this unique machine was the 338 superconducting radio frequency (SRF) cavities built into 42 cryomodules and arranged in two linacs. These were linked by arcs of conventional magnets which allowed recirculation through the linacs up to five times, in order to achieve the design energy of 4GeV. Within each cryomodule the cavities were aligned and referenced to external fiducials allowing alignment on the design beampath. This paper describes the process developed to achieve this, how it evolved with improving instrumentation, and the results obtained. Suggestions for alternative methods which may prove useful for future projects are also discussed.

  9. Technologies for Low Frequency Radio Observations of the Cosmic Dawn

    Science.gov (United States)

    Jones, Dayton L.

    2014-01-01

    The Jet Propulsion Laboratory (JPL) is developing concepts and technologies for low frequency radio astronomy space missions aimed at observing highly redshifted neutral Hydrogen from the Dark Ages. This is the period of cosmic history between the recombination epoch when the microwave background radiation was produced and the re-ionization of the intergalactic medium by the first generation of stars (Cosmic Dawn). This period, at redshifts greater than about 20, is a critical epoch for the formation and evolution of large-scale structure in the universe. The 21-cm spectral line of Hydrogen provides the most promising method for directly studying the Dark Ages, but the corresponding frequencies at such large redshifts are only tens of MHz and thus require space-based observations to avoid terrestrial RFI and ionospheric absorption and refraction. This paper reports on the status of several low frequency technology development activities at JPL, including deployable bi-conical dipoles for a planned lunar-orbiting mission, and both rover-deployed and inflation-deployed long dipole antennas for use on the lunar surface.

  10. High Frequency Cut-off and Changing of Radio Emission Mechanism in Pulsars

    CERN Document Server

    Kontorovich, V M

    2012-01-01

    Pulsars are the fast rotating neutron stars with strong magnetic field emitting over a wide frequency range. In spite of the efforts during 40 years after the discovery of pulsars, the mechanism of their radio emission remains to be unknown so far. We propose a new approach to solving this problem. The object of our study is a sample of pulsars with a high-frequency break of the spectrum from Pushchino catalogue. A theoretical explanation of the observed dependence of the high-frequency break from the pulsar period is given. The dependence of the break position from the magnetic field is predicted. This explanation is based on a new mechanism for electron emission in the inner polar gap. Radiation occurs when electrons are accelerated in the electric field rising from zero at the star surface. Acceleration passes through a maximum and tends to zero when the electron velocity approaches the velocity of light. The all radiated power is allocated to the radio band. The averaging over the polar cap, with some nat...

  11. Design, development, and acceleration trials of radio-frequency quadrupole

    Science.gov (United States)

    Rao, S. V. L. S.; Jain, Piyush; Pande, Rajni; Roy, Shweta; Mathew, Jose V.; Kumar, Rajesh; Pande, Manjiri; Krishnagopal, S.; Gupta, S. K.; Singh, P.

    2014-04-01

    A deuteron radio frequency quadrupole (RFQ) accelerator has been designed, fabricated, and tested at BARC, which will be used for neutron generation. The RFQ operates at a frequency of 350 MHz and needs an inter-vane voltage of 44 kV to accelerate the deuteron beam to 400 keV within a length of 1.03 m. The error analysis shows that the offset of two opposite vanes in the same direction by 100 μm leads to a change in resonant frequency by 1.3 MHz and a significant change of fields in the quadrants (˜±40% with respect to average field). From the 3D analysis, we have observed that the unwanted dipole mode frequencies are very near to the quadrupole mode frequency which will make structure sensitive to the perturbations. In order to move the dipole modes away from the quadrupole modes, we have used the dipole stabilizer rods. The 5 wire transmission line theory was used to study the perturbative analysis of the RFQ and based on this a computer program has been written to tune the cavity to get required field distribution. Based on these studies, a 1.03 m long RFQ made of OFE copper has been fabricated and tested. Even though the RFQ was designed for deuteron (D+) beam, we tested it by accelerating both the proton (H+) and D+ beams. The RFQ was operated in pulsed mode and accelerated both H+ and D+ beams to designed values of 200 and 400 keV, respectively. The measured parameters are in good agreement with the designed values validating our simulations and fabrication processes. In this paper, simulations, RF measurements, and beam commissioning results are presented.

  12. ON THE FREQUENCY SPECTRUM OF TSUNAMI RADIATION

    Directory of Open Access Journals (Sweden)

    Frank C Lin

    2015-07-01

    Full Text Available We have measured the spectrum of the tsunami radiation at the following wavelengths: 0.73 μm, 10.8μm, 12.0μm, 6.8μm and 3.8 μm (or 13,698 cm-1, 925 cm-1, 833 cm-1, 1,470 cm-1 and 2,631 cm-1 in wave numbers. By comparing with infrared spectroscopic measurements of water, we are able to identify these transitions corroborating our hypothesis that the radiation originates from the transition of vibrational quantum energy levels of water molecules in aggregate. We have also repeated our previous study of the decay rate of tsunamis for a different tsunami. An estimate of the intensity of the tsunami radiation is made.

  13. Wireless Chalcogenide Nanoionic-Based Radio-Frequency Switch

    Science.gov (United States)

    Nessel, James; Miranda, Felix

    2013-01-01

    A new nonvolatile nanoionic switch is powered and controlled through wireless radio-frequency (RF) transmission. A thin layer of chalcogenide glass doped with a metal ion, such as silver, comprises the operational portion of the switch. For the switch to function, an oxidizable electrode is made positive (anode) with respect to an opposing electrode (cathode) when sufficient bias, typically on the order of a few tenths of a volt or more, is applied. This action causes the metal ions to flow toward the cathode through a coordinated hopping mechanism. At the cathode, a reduction reaction occurs to form a metal deposit. This metal deposit creates a conductive path that bridges the gap between electrodes to turn the switch on. Once this conductive path is formed, no further power is required to maintain it. To reverse this process, the metal deposit is made positive with respect to the original oxidizable electrode, causing the dissolution of the metal bridge thereby turning the switch off. Once the metal deposit has been completely dissolved, the process self-terminates. This switching process features the following attributes. It requires very little to change states (i.e., on and off). Furthermore, no power is required to maintain the states; hence, the state of the switch is nonvolatile. Because of these attributes the integration of a rectenna to provide the necessary power and control is unique to this embodiment. A rectenna, or rectifying antenna, generates DC power from an incident RF signal. The low voltages and power required for the nanoionic switch control are easily generated from this system and provide the switch with a novel capability to be operated and powered from an external wireless device. In one realization, an RF signal of a specific frequency can be used to set the switch into an off state, while another frequency can be used to set the switch to an on state. The wireless, miniaturized, and nomoving- part features of this switch make it

  14. Spectrum decision in cognitive radio networks: a survey

    CSIR Research Space (South Africa)

    Masonta, MT

    2012-11-01

    Full Text Available environment conditions, but also on the PU activities. The second step involves spectrum selection, whereby the most appropriate spectrum band is selected to satisfy SUs’ QoS requirements. Finally, the CR should be able to reconfigure its transmission...

  15. VHF spectrum monitoring using Meraka cognitive radio platform

    CSIR Research Space (South Africa)

    Aderonmu, AI

    2012-11-01

    Full Text Available to the enhancement of new techniques for better utilization of the RF spectrums. The questions asked are how much RF spectrum is available and can be used opportunistically and dynamically without interfering with licensed or primary users (PUs)? More so, how...

  16. Attack Prevention for Collaborative Spectrum Sensing in Cognitive Radio Networks

    CERN Document Server

    Duan, Lingjie; Huang, Jianwei; Shin, Kang G

    2011-01-01

    Collaborative spectrum sensing can significantly improve the detection performance of secondary unlicensed users (SUs). However, the performance of collaborative sensing is vulnerable to sensing data falsification attacks, where malicious SUs (attackers) submit manipulated sensing reports to mislead the fusion center's decision on spectrum occupancy. Moreover, attackers may not follow the fusion center's decision regarding their spectrum access. This paper considers a challenging attack scenario where multiple rational attackers overhear all honest SUs' sensing reports and cooperatively maximize attackers' aggregate spectrum utilization. We show that, without attack-prevention mechanisms, honest SUs are unable to transmit over the licensed spectrum, and they may further be penalized by the primary user for collisions due to attackers' aggressive transmissions. To prevent such attacks, we propose two novel attack-prevention mechanisms with direct and indirect punishments. The key idea is to identify collisions...

  17. The GMRT Radio Halo Survey and low frequency follow-up

    CERN Document Server

    Venturi, T; Cassano, R; Brunetti, G; Dallacasa, D; Macario, G; Setti, G; Bardelli, S; Athreya, R

    2009-01-01

    The GMRT Radio Halo Survey, carried out at 610 MHz to investigate the statistical properties of cluster radio halos in a complete cluster sample selected in the redshift interval z=0.2-0.4, has significantly improved our understanding of the origin of cluster radio halos and relics. Here we briefly summarize the most relevant results of our investigation. A low frequency follow-up is in progress with the GMRT at 325 MHz and 240 MHz on the diffuse sources and candidated found at 610 MHz. We briefly report some preliminary results on these low frequency observations. Cluster radio halos with different radio spectral properties have been unexpectedly found.

  18. Electron Temperatures in W51 Complex from High Resolution, Low Frequency Radio Observations

    Indian Academy of Sciences (India)

    P. K. Srivastava; A. Pramesh Rao

    2010-03-01

    W51 is a giant radio complex lying along the tangent to the Sagitarius arm at a distance of about 7 kpc from the Sun, with an extension of about 1° in the sky. It is divided into three components A, B, C where W51A and W51B consist of many compact HII regions while W51C is a supernova remnant. We have made continuum radio observations of these HII regions of the W51 complex at 240, 610, 1060 and 1400 MHz using GMRT with lower resolution (20'' × 15'') at the lowest frequency. The observed spectra of the prominent thermal subcomponents of W51 have been fitted to a free-free emission spectrum and their physical properties like electron temperatures and emission measures have been estimated. The electron temperatures from continuum spectra are found to be lower than the temperatures reported from radio recombination line (RRL) studies of these HII regions indicating the need for a filling factor even at this resolution. Also, the observed brightness at 240 MHz is found to be higher than expected from the best fits suggesting the need for a multicomponent model for the region.

  19. Primary user localisation and uplink resource allocation in orthogonal frequency division multiple access cognitive radio systems

    KAUST Repository

    Nam, Haewoon

    2015-05-21

    In cognitive radio networks, secondary users (SUs) can share spectrum with primary users (PUs) under the condition that no interference is caused to the PUs. To evaluate the interference imposed to the PUs, the cognitive systems discussed in the literature usually assume that the channel state information (CSI) of the link from a secondary transmitter to a primary receiver (interference link) is known at the secondary transmitter. However, this assumption may often be impractical in cognitive radio systems, since the PUs need to be oblivious to the presence of the SUs. The authors first discuss PU localisation and then introduce an uplink resource allocation algorithm for orthogonal frequency division multiple access-based cognitive radio systems, where relative location information between primary and SUs is used instead of CSI of the interference link to estimate the interference. Numerical and simulation results show that it is indeed effective to use location information as a part of resource allocation and thus a near-optimal capacity is achieved. © The Institution of Engineering and Technology 2015.

  20. Alternative Adaptive Filter Structures for Improved Radio Frequency Interference Cancellation in Radio Astronomy

    CERN Document Server

    Mitchell, D A; Sault, R J

    2010-01-01

    In radio astronomy, reference signals from auxiliary antennas that receive only the radio frequency interference (RFI) can be modified to model the RFI environment at the astronomy receivers. The RFI can then be canceled from the astronomy signal paths. However, astronomers typically only require signal statistics. If the RFI statistics are changing slowly, the cancellation can be applied to the signal correlations at a much lower rate than is required for standard adaptive filters. In this paper we describe five canceler setups; precorrelation and postcorrelation cancelers that use one or two reference signals in different ways. The theoretical residual RFI and added noise levels are examined and are demonstrated using microwave television RFI at the Australia Telescope Compact Array. The RFI is attenuated to below the system noise, a reduction of at least 20 dB. While dual-reference cancelers add more reference noise than single-reference cancelers, this noise is zero-mean and only adds to the system noise,...

  1. A Review on Spectrum Sensing for Cognitive Radio: Challenges and Solutions

    Directory of Open Access Journals (Sweden)

    Zeng Yonghong

    2010-01-01

    Full Text Available Cognitive radio is widely expected to be the next Big Bang in wireless communications. Spectrum sensing, that is, detecting the presence of the primary users in a licensed spectrum, is a fundamental problem for cognitive radio. As a result, spectrum sensing has reborn as a very active research area in recent years despite its long history. In this paper, spectrum sensing techniques from the optimal likelihood ratio test to energy detection, matched filtering detection, cyclostationary detection, eigenvalue-based sensing, joint space-time sensing, and robust sensing methods are reviewed. Cooperative spectrum sensing with multiple receivers is also discussed. Special attention is paid to sensing methods that need little prior information on the source signal and the propagation channel. Practical challenges such as noise power uncertainty are discussed and possible solutions are provided. Theoretical analysis on the test statistic distribution and threshold setting is also investigated.

  2. [EMD Time-Frequency Analysis of Raman Spectrum and NIR].

    Science.gov (United States)

    Zhao, Xiao-yu; Fang, Yi-ming; Tan, Feng; Tong, Liang; Zhai, Zhe

    2016-02-01

    This paper analyzes the Raman spectrum and Near Infrared Spectrum (NIR) with time-frequency method. The empirical mode decomposition spectrum becomes intrinsic mode functions, which the proportion calculation reveals the Raman spectral energy is uniform distributed in each component, while the NIR's low order intrinsic mode functions only undertakes fewer primary spectroscopic effective information. Both the real spectrum and numerical experiments show that the empirical mode decomposition (EMD) regard Raman spectrum as the amplitude-modulated signal, which possessed with high frequency adsorption property; and EMD regards NIR as the frequency-modulated signal, which could be preferably realized high frequency narrow-band demodulation during first-order intrinsic mode functions. The first-order intrinsic mode functions Hilbert transform reveals that during the period of empirical mode decomposes Raman spectrum, modal aliasing happened. Through further analysis of corn leaf's NIR in time-frequency domain, after EMD, the first and second orders components of low energy are cut off, and reconstruct spectral signal by using the remaining intrinsic mode functions, the root-mean-square error is 1.001 1, and the correlation coefficient is 0.981 3, both of these two indexes indicated higher accuracy in re-construction; the decomposition trend term indicates the absorbency is ascending along with the decreasing to wave length in the near-infrared light wave band; and the Hilbert transform of characteristic modal component displays, 657 cm⁻¹ is the specific frequency by the corn leaf stress spectrum, which could be regarded as characteristic frequency for identification.

  3. Low radio frequency signatures of ram pressure stripping in Virgo spiral NGC 4254

    CERN Document Server

    Kantharia, N G; Sirothia, S K

    2007-01-01

    We report the detection of extended low radio frequency continuum emission beyond the optical disk of the spiral galaxy NGC 4254 using the Giant Metrewave Radio Telescope. NGC 4254, which has an almost face-on orientation, is located in the outskirts of the Virgo cluster. Since such extended emission is uncommon in low inclination galaxies, we believe it is a signature of magnetised plasma pushed out of the disk by ram pressure of the intracluster medium as NGC 4254 falls into the Virgo cluster. The detailed spectral index distribution across NGC 4254 shows that the steepest spectrum alpha < -1 (S propto nu^{alpha}) arises in the gas beyond the optical disk. This lends support to the ram pressure scenario by indicating that the extended emission is not from the disk gas but from matter which has been stripped by ram pressure. The steeper spectrum of the extended emission is reminiscent of haloes in edge-on galaxies. The sharp fall in intensity and enhanced polarization in the south of the galaxy, in additi...

  4. Radio-Frequency (RF) Devices for Safeguards: Where We Are and Where We Need to Go

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Nathan C [ORNL; Younkin, James R [ORNL; Pickett, Chris A [ORNL; Whitaker, J Michael [ORNL

    2011-01-01

    Radio-Frequency (RF) devices have revolutionized many aspects of modern industrial processes. RF technology can enable wireless communication for tag identification, sensor communication, and asset tracking. Radio-frequency identification (RFID) is a technology that utilizes wireless communication to interrogate and identify an electronic tag attached to an item in order to identify the item. The technology can come in many forms: passive or active tags, low to ultra-wideband frequencies, small paper-thin tags to brick-sized units, and simple tags or highly integrated sensor packages. RF technology, and specifically RFID, has been applied widely in commercial markets for inventory, supply chain management, and asset tracking. Several recent studies have demonstrated the safeguards benefits of utilizing RFID versus conventional inventory tagging methods for tracking nuclear material. These studies have indicated that the RF requirements for safeguards functions are more stringent than the RF requirements for other inventory tracking and accounting applications. Additionally, other requirements must be addressed, including environmental and operating conditions, authentication, and tag location and attachment. Facility restrictions on radio spectrum, method of tag attachment, and sensitivity of the data collected impact the tag selection and system design. More important, the intended use of the system must be considered. The requirements for using RF to simply replace or supplement container identifiers such as bar codes that facilitate the inventory function will differ greatly from the requirements for deploying RF for unattended monitoring applications. Several studies have investigated these considerations to advance commercial RF devices for safeguards use, and a number of system concepts have been developed. This paper will provide an overview of past studies and current technologies, and will investigate the requirements, existing gaps, and several potential

  5. Low Frequency Radio-wave System for subsurface investigation

    Science.gov (United States)

    Soldovieri, Francesco; Gennarelli, Gianluca; Kudelya, Anatoliy; Denisov, Alexander

    2015-04-01

    Low frequency radio-wave methods (RWM) allow subsurface investigations in terms of lithological structure characterization, detection of filtration flows of ground water, anthropogenic and natural cavities. In this contribution, we present a RWM that exploits two coils working at frequencies of few MHz as transmitting and receiving antennas. The basic principle of this inductive method is as follows. The primary alternating electromagnetic field radiated by the transmitting coil induces eddy currents in the subsurface mainly due to the conductivity anomalies. These eddy currents generate a secondary (scattered) magnetic field which overlaps to the incident magnetic field and is detected by the receiving coil. Despite the simple operation of the system, the complexity of the electromagnetic scattering phenomenon at hand must be properly modeled to achieve adequate performance. Therefore, an advanced data processing technique, belonging to the class of the inverse scattering approaches, has been developed by the authors in a full 3D geometry. The proposed method allows to deal with data collected on a scanning surface under a dipole inductive profiling (DIP) modality, where the transmitting/receiving coils are moved simultaneously with fixed offset (multi-bistatic configuration). The hardware, called Dipole Inductive Radio-wave System (DIRS), is composed by an electronic unit and transmitting and receiving loop antennas radiating at frequencies of few MHz (2-4 MHz), which are installed on theodolite supports. The compactness of DIRS and its robustness to external electromagnetic interference offers the possibility to perform geophysical research up to the depth of some tens of meters and under several types of ground and water surfaces, vegetation, and weather conditions. The light weight and small size of system (the single antenna with support weights about 5 kg and has a diameter of 0.5m) allows two operators to perform geophysical research without disturbing the

  6. Microwave Sintering of Silver Nanoink for Radio Frequency Applications.

    Science.gov (United States)

    Kim, Kwang-Seok; Park, Bum-Geun; Jung, Kwang-Ho; Kim, Jong-Woong; Jeong, Myung Yung; Jung, Seung-Boo

    2015-03-01

    Microwave sintering is a promising method for low-temperature processes, as it provides advantages such as uniform, fast, and volumetric heating. In this study, we investigated the electrical characteristics of inkjet-printed silver (Ag) circuits sintered by microwaves. The microstructural evolutions of inkjet-printed Ag circuits sintered at various temperatures for different durations were observed with a field emission scanning electron microscope. The electrical properties of the inkjet-printed Ag circuits were analysed by electrical resistivity measurements and radio frequency properties including scattering-parameters in the frequency range of 20 MHz to 20 GHz. The experimental results show that the signal losses of the Ag circuits sintered by microwave heating were lower than those sintered by conventional heating as microwave heating led to granular films which were nearly fully sintered without pores on the surfaces. When the inkjet-printed Ag circuits were sintered by microwaves at 300 °C for 4 min, their electrical resistivity was 5.1 µΩ cm, which is 3.2 times larger than that of bulk Ag. Furthermore, microwave sintering at 150 °C for 4 min achieved much lower signal losses (1.1 dB at 20 GHz) than conventional sintering under the same conditions.

  7. Mechanical properties of niobium radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G., E-mail: gciovati@jlab.org [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Dhakal, P.; Matalevich, J.; Myneni, G. [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Schmidt, A.; Iversen, J.; Matheisen, A.; Singer, W. [Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607 Hamburg (Germany)

    2015-08-26

    Radio-frequency cavities made of bulk niobium are one of the components used in modern particle accelerators. The mechanical stability is an important aspect of cavity design, which typically relies on finite-element analysis simulations using material properties from tensile tests on sample. This contribution presents the results of strain and resonant frequency measurements as a function of a uniform pressure up to 620 kPa, applied to single-cell niobium cavities with different crystallographic structure, purity and treatments. In addition, burst tests of high-purity multi-cell cavities with different crystallographic structures have been conducted up to the tensile strength of the material. Finite-element analysis of the single-cell cavity geometry is in good agreement with the observed behavior in the elastic regime assuming a Young’s modulus value of 88.5 GPa and a Poisson’s ratio of 0.4, regardless of crystallographic structure, purity or treatment. However, the measured yield strength and tensile strength depend on crystallographic structure, material purity and treatment. In particular, the results from this study show that the mechanical properties of niobium cavities made from ingot material with large crystals are comparable to those of cavities made of fine-grain niobium.

  8. Ultra High-Speed Radio Frequency Switch Based on Photonics.

    Science.gov (United States)

    Ge, Jia; Fok, Mable P

    2015-11-26

    Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch that is capable of switching at tens of picoseconds speed, which is hundreds of times faster than any existing RF switch technologies. The high-speed switching property is achieved with the use of a rapidly tunable microwave photonic filter with tens of gigahertz frequency tuning speed, where the tuning mechanism is based on the ultra-fast electro-optics Pockels effect. The RF switch has a wide operation bandwidth of 12 GHz and can go up to 40 GHz, depending on the bandwidth of the modulator used in the scheme. The proposed RF switch can either work as an ON/OFF switch or a two-channel switch, tens of picoseconds switching speed is experimentally observed for both type of switches.

  9. Flat-Spectrum Radio Sources as Likely Counterparts of Unidentified INTEGRAL Sources (Research Note)

    Science.gov (United States)

    Molina, M.; Landi, R.; Bassani, L.; Malizia, A.; Stephen, J. B.; Bazzano, A.; Bird, A. J.; Gehrels, N.

    2012-01-01

    Many sources in the fourth INTEGRAL/IBIS catalogue are still unidentified since they lack an optical counterpart. An important tool that can help in identifying and classifying these sources is the cross-correlation with radio catalogues, which are very sensitive and positionally accurate. Moreover, the radio properties of a source, such as the spectrum or morphology, could provide further insight into its nature. In particular, flat-spectrum radio sources at high Galactic latitudes are likely to be AGN, possibly associated to a blazar or to the compact core of a radio galaxy. Here we present a small sample of 6 sources extracted from the fourth INTEGRAL/IBIS catalogue that are still unidentified or unclassified, but which are very likely associated with a bright, flat-spectrum radio object. To confirm the association and to study the source X-ray spectral parameters, we performed X-ray follow-up observations with Swift/XRT of all objects. We report in this note the overall results obtained from this search and discuss the nature of each individual INTEGRAL source. We find that 5 of the 6 radio associations are also detected in X-rays; furthermore, in 3 cases they are the only counterpart found. More specifically, IGR J06073-0024 is a flat-spectrum radio quasar at z = 1.08, IGR J14488-4008 is a newly discovered radio galaxy, while IGR J18129-0649 is an AGN of a still unknown type. The nature of two sources (IGR J07225-3810 and IGR J19386-4653) is less well defined, since in both cases we find another X-ray source in the INTEGRAL error circle; nevertheless, the flat-spectrum radio source, likely to be a radio loud AGN, remains a viable and, in fact, a more convincing association in both cases. Only for the last object (IGR J11544-7618) could we not find any convincing counterpart since the radio association is not an X-ray emitter, while the only X-ray source seen in the field is a G star and therefore unlikely to produce the persistent emission seen by INTEGRAL.

  10. Hybrid Accuracy-Time Trade-off Solution for Spectrum Sensing in Cognitive Radio Networks

    DEFF Research Database (Denmark)

    Ivanov, Antoni Stefkov; Mihovska, Albena Dimitrova; Poulkov, Vladimir

    2017-01-01

    is then compared with the one acquired using the statistical method. Finally, an optimal balance between the sensing time and accuracy is obtained for the current environmental conditions using the derived closed form expression. The algorithm is implemented using the USRP and GNU Radio. Through simulation results......The rise of the cognitive radio systems as a concept for future networks has seen a great amount of scientific effort in the recent years. Appropriately, much attention is given to how the vital function of spectrum sensing should be executed. The cognitive radio device is required to be able...

  11. Multiantenna spectrum sensing for cognitive radio: overcoming noise uncertainty

    OpenAIRE

    López Valcarce, Roberto; Vázquez Vilar, Gonzalo; Sala Álvarez, José

    2010-01-01

    Spectrum sensing is a key ingredient of the dynamic spectrum access paradigm, but it needs powerful detectors operating at SNRs well below the decodability levels of primary signals. Noise uncertainty poses a significant challenge to the development of such schemes, requiring some degree of diversity (spatial, temporal, or in distribution) for identifiability of the noise level. Multiantenna detectors exploit spatial independence of receiver thermal noise. We review this ...

  12. Nanoionics-Based Switches for Radio-Frequency Applications

    Science.gov (United States)

    Nessel, James; Lee, Richard

    2010-01-01

    Nanoionics-based devices have shown promise as alternatives to microelectromechanical systems (MEMS) and semiconductor diode devices for switching radio-frequency (RF) signals in diverse systems. Examples of systems that utilize RF switches include phase shifters for electronically steerable phased-array antennas, multiplexers, cellular telephones and other radio transceivers, and other portable electronic devices. Semiconductor diode switches can operate at low potentials (about 1 to 3 V) and high speeds (switching times of the order of nanoseconds) but are characterized by significant insertion loss, high DC power consumption, low isolation, and generation of third-order harmonics and intermodulation distortion (IMD). MEMS-based switches feature low insertion loss (of the order of 0.2 dB), low DC power consumption (picowatts), high isolation (>30 dB), and low IMD, but contain moving parts, are not highly reliable, and must be operated at high actuation potentials (20 to 60 V) generated and applied by use of complex circuitry. In addition, fabrication of MEMS is complex, involving many processing steps. Nanoionics-based switches offer the superior RF performance and low power consumption of MEMS switches, without need for the high potentials and complex circuitry necessary for operation of MEMS switches. At the same time, nanoionics-based switches offer the high switching speed of semiconductor devices. Also, like semiconductor devices, nanoionics-based switches can be fabricated relatively inexpensively by use of conventional integrated-circuit fabrication techniques. More over, nanoionics-based switches have simple planar structures that can easily be integrated into RF power-distribution circuits.

  13. Multi-frequency polarimetry of a complete sample of PACO radio sources

    CERN Document Server

    Galluzzi, V; Bonaldi, A; Casasola, V; Gregorini, L; Trombetti, T; Burigana, C; De Zotti, G; Ricci, R; Stevens, J; Ekers, R D; Bonavera, L; Alighieri, S di Serego; Liuzzo, E; Lopez-Caniego, M; Mignano, A; Paladino, R; Toffolatti, L; Tucci, M

    2016-01-01

    We present high sensitivity polarimetric observations in 6 bands covering the 5.5-38 GHz range of a complete sample of 53 compact extragalactic radio sources brighter than 200 mJy at 20 GHz. The observations, carried out with the Australia Telescope Compact Array (ATCA), achieved a 91% detection rate (at 5 sigma). Within this frequency range the spectra of about 95% of sources are well fitted by double power laws, both in total intensity and in polarisation, but the spectral shapes are generally different in the two cases. Most sources were classified as either steep- or peaked-spectrum but less than 50% have the same classification in total and in polarised intensity. No significant trends of the polarisation degree with flux density or with frequency were found. The mean variability index in total intensity of steep-spectrum sources increases with frequency for a 4-5 year lag, while no significant trend shows up for the other sources and for the 8 year lag. In polarisation, the variability index, that could...

  14. A Novel Algorithm for Cooperative Distributed Sequential Spectrum Sensing in Cognitive Radio

    CERN Document Server

    S, Jithin K

    2010-01-01

    This paper considers cooperative spectrum sensing in Cognitive Radios. In our previous work we have developed DualSPRT, a distributed algorithm for cooperative spectrum sensing using Sequential Probability Ratio Test (SPRT) at the Cognitive Radios as well as at the fusion center. This algorithm works well, but is not optimal. In this paper we propose an improved algorithm- SPRT-CSPRT, which is motivated from Cumulative Sum Procedures (CUSUM). We analyse it theoretically. We also modify this algorithm to handle uncertainties in SNR's and fading.

  15. Radio-frequency transparent demodulation for broadband hybrid wireless-optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Sambaraju, Rakesh; Alemany, Ruben

    2010-01-01

    A novel demodulation technique which is transparent to radio-frequency (RF) carrier frequency is presented and experimentally demonstrated for multigigabit wireless signals. The presented demodulation technique employs optical single-sideband filtering, coherent detection, and baseband digital si...

  16. Spectrum Measurement and Analysis of TV Band in Support of Cognitive Radio Operation in India

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Prasad, Ramjee

    2013-01-01

    have estimated the spectrum utilization of TV band in Pune, India. We have designed the measurement set up and methodology for the measurement campaign. Our spectrum occupancy analysis provides the realistic view on the spectrum opportunities in India for (i) spectrum refarming of TV band; (ii......) Cognitive Radio operation in TV band. Also we have stressed on the need of quantitative analysis of TVWSs availability and compatibility studies for protection of incumbent services for CR access of TVWSs in India. Also this paper reviews the state-of-the-art in standardization of cognitive access to TVWS....

  17. Compatibility of the Radio Frequency Mass Gauge with Composite Tanks

    Science.gov (United States)

    Zimmerli, Greg; Mueller, Carl

    2015-01-01

    The radio frequency mass gauge (RFMG) is a low-gravity propellant quantity gauge being developed at NASA for possible use in long-duration space missions utilizing cryogenic propellants. As part of the RFMG technology development process, we evaluated the compatibility of the RFMG with a graphite-epoxy composite material used to construct propellant tanks. The key material property that can affect compatibility with the RFMG is the electrical conductivity. Using samples of 8552IM7 graphite-epoxy composite, we characterized the resistivity and reflectivity over a range of frequencies. An RF impedance analyzer was used to characterize the out-of-plane electrical properties (along the sample thickness) in the frequency range 10 to 1800 MHZ. The resistivity value at 500 MHz was 4.8 ohm-cm. Microwave waveguide measurements of samples in the range 1.7 2.6 GHz, performed by inserting the samples into a WR-430 waveguide, showed reflectivity values above 98. Together, these results suggested that a tank constructed from graphite-epoxy composite would produce good quality electromagnetic tank modes, which is needed for the RFMG. This was verified by room-temperature measurements of the electromagnetic modes of a 2.4 m diameter tank constructed by Boeing from similar graphite-epoxy composite material. The quality factor Q of the tank electromagnetic modes, measured via RF reflection measurements from an antenna mounted in the tank, was typically in the range 400 Q 3000. The good quality modes observed in the tank indicate that the RFMG is compatible with graphite-epoxy tanks, and thus the RFMG could be used as a low-gravity propellant quantity gauge in such tanks filled with cryogenic propellants.

  18. Experimental characterization of radio frequency microthermal thruster performance

    Science.gov (United States)

    Williams, Shae E.

    Microsatellite (cold gas thrusters. Design constraints rule out much of traditional propulsion, requiring new and nonobvious technologies to advance the state of the art and enable longer and more flexible missions. The radio frequency microthermal thruster is shown to be worth thorough study for this application. A basic analytical model is constructed to look at expected performance, and the theory behind that model is explained. Calibration and the challenges in working with extremely low forces and displacements are also examined. The results of extensive testing on this thruster type are presented. Important trends are confirmed and validated, such as a linearity of specific impulse with power, and consistent nonlinearities with frequency and mass flow rate. Additionally, tests indicate a nonlinear relationship between applied frequency and thruster internal geometry that can more than triple the heating occurring in the thruster. Further tests focus on this relationship, and find more information about how these parameters couple are found to be primarily due to induced inefficiencies in stochastic heating and the inability of a vibrating voltage sheath to transfer energy into the flow. Additionally, first steps towards optimizing a design for performance are taken, such as analyzing the effect of adding a converging/diverging nozzle and finding an optimal length of inner electrode to be exposed to plasma. Overall, specific impulses of up to 85 seconds are found with argon as the propellant, doubling cold gas specific impulse, and an error on specific impulse is calculated to be less than 3% in either direction. These results after only slight efforts at design optimization indicate much more improvement is possible with this technology that would make an RF microthermal thruster viable as a commercial product.

  19. Low radio frequency observations and spectral modelling of the remnant of Supernova 1987A

    Science.gov (United States)

    Callingham, J. R.; Gaensler, B. M.; Zanardo, G.; Staveley-Smith, L.; Hancock, P. J.; Hurley-Walker, N.; Bell, M. E.; Dwarakanath, K. S.; Franzen, T. M. O.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A.; For, B.-Q.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2016-10-01

    We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing the lowest frequency observations of the source to date. This large lever arm in frequency space constrains the properties of the circumstellar medium created by the progenitor of SNR 1987A when it was in its red supergiant phase. As of late 2013, the radio spectrum of SNR 1987A between 72 MHz and 8.64 GHz does not show any deviation from a non-thermal power law with a spectral index of -0.74 ± 0.02. This spectral index is consistent with that derived at higher frequencies, beneath 100 GHz, and with a shock in its adiabatic phase. A spectral turnover due to free-free absorption by the circumstellar medium has to occur below 72 MHz, which places upper limits on the optical depth of ≤0.1 at a reference frequency of 72 MHz, emission measure of ≲13 000 cm-6 pc, and an electron density of ≲110 cm-3. This upper limit on the electron density is consistent with the detection of prompt radio emission and models of the X-ray emission from the supernova. The electron density upper limit implies that some hydrodynamic simulations derived a red supergiant mass-loss rate that is too high, or a wind velocity that is too low. The mass-loss rate of ˜5 × 10-6 M⊙ yr-1 and wind velocity of 10 km s-1 obtained from optical observations are consistent with our upper limits, predicting a current turnover frequency due to free-free absorption between 5 and 60 MHz.

  20. 76 FR 18652 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2011-04-05

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, NTIA updates the version of the Manual...

  1. 78 FR 52097 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2013-08-22

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, NTIA is releasing a new edition of the...

  2. 75 FR 54790 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2010-09-09

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, NTIA updates the version of the Manual...

  3. 75 FR 6818 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2010-02-11

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, the NTIA updates the version of the Manual...

  4. 77 FR 75567 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2012-12-21

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, NTIA updates the version of the Manual...

  5. 76 FR 56984 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Science.gov (United States)

    2011-09-15

    ... Manual of Regulations and Procedures for Federal Radio Frequency Management AGENCY: National... regulations, which relate to the public availability of the Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual). Specifically, NTIA updates the version of the Manual...

  6. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Science.gov (United States)

    2010-10-01

    ... Identification (RFID) using passive tags. 552.211-92 Section 552.211-92 Federal Acquisition Regulations System... Provisions and Clauses 552.211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed in 511.204(b)(11), insert the following clause: Radio Frequency Identification (RFID) Using Passive...

  7. 78 FR 19311 - Certain Radio Frequency Identification (“RFID”) Products And Components Thereof; Institution of...

    Science.gov (United States)

    2013-03-29

    ... COMMISSION Certain Radio Frequency Identification (``RFID'') Products And Components Thereof; Institution of... (``RFID'') products and components thereof by reason of infringement of U.S. Patent No. 7,081,819 (``the... sale within the United States after importation of certain radio frequency identification...

  8. Coordinated observations using the world largest low-frequency radio telescopes and space misiions

    Science.gov (United States)

    Konovalenko, A. A.; Zarka, Ph.; Kolyadin, V. L.; Zakharenko, V. V.; Stepkin, S. V.; Panchenko, M.; Lecacheux, A.; Rucker, H. O.; Fischer, G.; Ulyanov, O. M.; Melnik, V. N.; Litvinenko, G. V.; Sidorchuk, M. A.; Bubnov, I. N.; Vasilyeva, Ya. Yu.; Bojko, A. I.; Shaposhnikov, V.; Mann, G.; Kalinichenko, N. N.; Falkovich, I. S.; Koval, A. A.; Mylostna, K.; Pylaev, O. S.; Shepelev, V. A.; Reznik, A. P.

    2013-09-01

    The positive possibilities of astrophysical objects studies(including the Solar system investigations) using coordinated observations with the largest existing and coming low frequency radio telescopes are shown. The observations of the Sun, Jupiter, Saturn, ant others with UTR-2, URAN, NDA radio telescopes, and WIND, Cassini and STEREO space missions at frequencies lower than 40 MHz have been carried out.

  9. On the Spectrum Handoff for Cognitive Radio Ad Hoc Networks without Common Control Channel

    CERN Document Server

    Song, Yi

    2011-01-01

    Cognitive radio (CR) technology is a promising solution to enhance the spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. Since unlicensed users are temporary visitors to the licensed spectrum, they are required to vacate the spectrum when a licensed user reclaims it. Due to the randomness of the appearance of licensed users, disruptions to both licensed and unlicensed communications are often difficult to prevent. In this chapter, a proactive spectrum handoff framework for CR ad hoc networks is proposed to address these concerns. In the proposed framework, channel switching policies and a proactive spectrum handoff protocol are proposed to let unlicensed users vacate a channel before a licensed user utilizes it to avoid unwanted interference. Network coordination schemes for unlicensed users are also incorporated into the spectrum handoff protocol design to realize channel rendezvous. Moreover, a distributed channel selection scheme to eliminate collisions a...

  10. Deep 1.4 GHZ Follow Up of the Steep Spectrum Radio Halo in Abell 521

    CERN Document Server

    Dallacasa, D; Giacintucci, S; Cassano, R; Venturi, T; Macario, G; Kassim, N E; Lane, W; Setti, G

    2009-01-01

    In a recent paper we reported on the discovery of a radio halo with very steep spectrum in the merging galaxy cluster Abell 521 through observations with the Giant Metrewave Radio Telescope (GMRT). We showed that the steep spectrum of the halo is inconsistent with a secondary origin of the relativistic electrons and supports a turbulent acceleration scenario. At that time, due to the steep spectrum, the available observations at 1.4 GHz (archival NRAO - Very Large Array - VLA CnB-configuration data) were not adequate to accurately determine the flux density associated with the radio halo. In this paper we report the detection at 1.4 GHz of the radio halo in Abell 521 using deep VLA observations in the D-configuration. We use these new data to confirm the steep-spectrum of the object. We consider Abell 521 the prototype of a population of very-steep spectrum halos. This population is predicted assuming that turbulence plays an important role in the acceleration of relativistic particles in galaxy clusters, and...

  11. High energy emission from flat-spectrum radio sources with ˜ kpc-scale structure

    Science.gov (United States)

    Augusto, Pedro

    Active Galactic Nuclei emit a substantial portion of their bolometric luminosities in X-rays. For example, the knots in radio jets are prominent sources of synchrotron X-rays while the hotspots of the brightest FRIIs emit self-synchrotron or Inverse Compton radiation. Most high-energy studies on flat-spectrum radio sources have been conducted for blazars which are dominant at γ-rays.Augusto et al. (1998) have built a sample of 55 flat-spectrum radio sources dominated by structures (knots, hotspots, etc.) ˜0.1-2 kpc away from the nucleus. Seventeen (31%) of these are detected in X-rays (they tend to be the radio strongest) evenly splitting, morphologically, both at optical (radio) bands: nine QSO/BLLac (core-jets) on one-side; eight Galaxy/Sy2 (CSO/MSO/FRII) on the other. We have identified five confirmed compact/medium symmetric objects (CSO/MSOs) as X-ray emitters. A comparable type of source to CSO/MSOs is the physically similar (1-15 kpc) compact steep spectrum source (CSS), 28/129 (22%) of which are detected in X-rays, from a literature-selected sample (the percentage is smaller than for the 55-source sample due to a lower ). A 95% conf. level relation is found for CSSs: S_X ∝ (S4.85)0.6 and we found undistinguishable radio/X-ray properties for both the 55-source and CSS samples: clearly, their similar morphologies (e.g. knots in jets) stand up stronger than their radical radio spectrum differences.Only two sources among the 55 (4%) have γ-ray detections and they seem quite abnormal (in αxγ values, at least)-one of them is in a Sy2, not in a blazar.

  12. Cluster-based spectrum sensing for cognitive radios with imperfect channel to cluster-head

    KAUST Repository

    Ben Ghorbel, Mahdi

    2012-04-01

    Spectrum sensing is considered as the first and main step for cognitive radio systems to achieve an efficient use of spectrum. Cooperation and clustering among cognitive radio users are two techniques that can be employed with spectrum sensing in order to improve the sensing performance by reducing miss-detection and false alarm. In this paper, within the framework of a clustering-based cooperative spectrum sensing scheme, we study the effect of errors in transmitting the local decisions from the secondary users to the cluster heads (or the fusion center), while considering non-identical channel conditions between the secondary users. Closed-form expressions for the global probabilities of detection and false alarm at the cluster head are derived. © 2012 IEEE.

  13. Optimal Spectrum Access for Users in Multi-Channel Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Vivek Agrawal

    2013-09-01

    Full Text Available Cognitive Radio, a software defined radio, is an emerging technology which uses opportunistic spectrum access (OSA for the efficient utilization of the spectrum. Its main aim is to utilize the unused portions of the spectrum by allowing unlicensed users (secondary users to transmit data in absence of primary users. In this paper the assignment of multiple primary and secondary users in a multiple channel system is addressed with the sole aim of optimizing the total throughput. We have considered an optimal spectrum access (OSA algorithm for the allotment of both the primary and secondary users in a multiple channel system and compared the results with the well-known meta-heuristic techniques such as Simulated Annealing (SA and Tabu Search (TS. The results reveal that OSA algorithm is more efficient as compared to SA and TS as far as throughput optimization is considered.

  14. Turbulent Cosmic-Ray Reacceleration and the Curved Radio Spectrum of the Radio Relic in the Sausage Cluster

    CERN Document Server

    Fujita, Yutaka; Kimura, Shigeo S

    2016-01-01

    It has often been thought that the northern radio relic in the galaxy cluster CIZA J2242.8+5301 (the "Sausage" Cluster) is associated with cosmic-ray (CR) electrons that are accelerated at a shock through diffusive shock acceleration (DSA) mechanism. However, recent radio observations have shown that the radio spectrum is curved, which is inconsistent with the prediction of a simple DSA model. Moreover, the CR electron spectrum before being affected by radiative cooling seems to be too hard for the DSA. In this study, we show that these facts are natural consequences if the electrons are reaccelerated in turbulence in the downstream of the shock. In this model, the DSA is not the main mechanism to generate high-energy electrons. We find that the mean free path of the electrons should be much shorter than the Coulomb mean free path for efficient reacceleration. The scale of the turbulent eddies must be smaller than the width of the relic. We also predict hard X-ray spectra of inverse Compton scattering of phot...

  15. Turbulent cosmic ray reacceleration and the curved radio spectrum of the radio relic in the Sausage Cluster

    Science.gov (United States)

    Fujita, Yutaka; Akamatsu, Hiroki; Kimura, Shigeo S.

    2016-06-01

    It has often been thought that the northern radio relic in the galaxy cluster CIZA J2242.8+5301 (the "Sausage" Cluster) is associated with cosmic ray (CR) electrons that are accelerated at a shock through the diffusive shock acceleration (DSA) mechanism. However, recent radio observations have shown that the radio spectrum is curved, which is inconsistent with the prediction of a simple DSA model. Moreover, the CR electron spectrum before being affected by radiative cooling seems to be too hard for DSA. In this study, we show that these facts are natural consequences if the electrons are reaccelerated in turbulence downstream of the shock. In this model, DSA is not the main mechanism for generating high-energy electrons. We find that the mean free path of the electrons should be much shorter than the Coulomb mean free path for efficient reacceleration. The scale of the turbulent eddies must be smaller than the width of the relic. We also predict hard X-ray spectra of inverse Compton scattering of photons.

  16. Radio frequency nonionizing radiation in a community exposed to radio and television broadcasting.

    Science.gov (United States)

    Burch, James B; Clark, Maggie; Yost, Michael G; Fitzpatrick, Cole T E; Bachand, Annette M; Ramaprasad, Jaya; Reif, John S

    2006-02-01

    Exposure to radio frequency (RF) nonionizing radiation from telecommunications is pervasive in modern society. Elevated disease risks have been observed in some populations exposed to radio and television transmissions, although findings are inconsistent. This study quantified RF exposures among 280 residents living near the broadcasting transmitters for Denver, Colorado. RF power densities outside and inside each residence were obtained, and a global positioning system (GPS) identified geographic coordinates and elevations. A view-shed model within a geographic information system (GIS) characterized the average distance and percentage of transmitters visible from each residence. Data were collected at the beginning and end of a 2.5-day period, and some measurements were repeated 8-29 months later. RF levels logged at 1-min intervals for 2.5 days varied considerably among some homes and were quite similar among others. The greatest differences appeared among homes within 1 km of the transmitters. Overall, there were no differences in mean residential RF levels compared over 2.5 days. However, after a 1- to 2-year follow-up, only 25% of exterior and 38% of interior RF measurements were unchanged. Increasing proximity, elevation, and line-of-sight visibility were each associated with elevated RF exposures. At average distances from > 1-3 km, exterior RF measurements were 13-30 times greater among homes that had > 50% of the transmitters visible compared with homes with < or = 50% visibility at those distances. This study demonstrated that both spatial and temporal factors contribute to residential RF exposure and that GPS/GIS technologies can improve RF exposure assessment and reduce exposure misclassification.

  17. Resonant-frequency discharge in a multi-cell radio frequency cavity

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, S; Upadhyay, J; Mammosser, J; Nikolic, M; Vuskovic, L

    2014-11-07

    We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

  18. Resonant-frequency discharge in a multi-cell radio frequency cavity

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, S; Upadhyay, J; Mammosser, J; Nikolic, M; Vuskovic, L

    2014-11-07

    We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

  19. Full-Duplex Cooperative Sensing for Spectrum-Heterogeneous Cognitive Radio Networks.

    Science.gov (United States)

    Liu, Peng; Qi, Wangdong; Yuan, En; Wei, Li; Zhao, Yuexin

    2017-08-02

    In cognitive radio networks (CRNs), spectrum sensing is critical for guaranteeing that the opportunistic spectrum access by secondary users (SUs) will not interrupt legitimate primary users (PUs). The application of full-duplex radio to spectrum sensing enables SU to carry out sensing and transmission simultaneously, improving both spectrum awareness and CRN throughput. However, the issue of spectrum sensing with full-duplex radios deployed in heterogeneous environments, where SUs may observe different spectrum activities, has not been addressed. In this paper, we give a first look into this problem and develop a light-weight cooperative sensing framework called PaCoSIF, which involves only a pairwise SU transmitter (SU-Tx) and its receiver (SU-Rx) in cooperation. A dedicated control channel is not required for pairwise cooperative sensing with instantaneous feedback (PaCoSIF) because sensing results are collected and fused via the reverse channel provided by full-duplex radios. We present a detailed protocol description to illustrate how PaCoSIF works. However, it is a challenge to optimize the sensing performance of PaCoSIF since the two sensors suffer from spectrum heterogeneity and different kinds of interference. Our goal is to minimize the false alarm rate of PaCoSIF given the bound on the missed detection rate by adaptively adjusting the detection threshold of each sensor. We derive an expression for the optimal threshold using the Lagrange method and propose a fast binary-searching algorithm to solve it numerically. Simulations show that, with perfect signal-to-interference-and-noise-ratio (SINR) information, PaCoSIF could decrease the false alarm rate and boost CRN throughput significantly against conventional cooperative sensing when SUs are deployed in spectrum-heterogeneous environments. Finally, the impact of SINR error upon the performance of PaCoSIF is evaluated via extensive simulations.

  20. Time-Delay Estimation in Dispersed Spectrum Cognitive Radio Systems

    Directory of Open Access Journals (Sweden)

    Celebi Hasari

    2010-01-01

    Full Text Available Time-delay estimation is studied for cognitive radio systems, which facilitate opportunistic use of spectral resources. A two-step approach is proposed to obtain accurate time-delay estimates of signals that occupy multiple dispersed bands simultaneously, with significantly lower computational complexity than the optimal maximum likelihood (ML estimator. In the first step of the proposed approach, an ML estimator is used for each band of the signal in order to estimate the unknown parameters of the signal occupying that band. Then, in the second step, the estimates from the first step are combined in various ways in order to obtain the final time-delay estimate. The combining techniques that are used in the second step are called optimal combining, signal-to-noise ratio (SNR combining, selection combining, and equal combining. It is shown that the performance of the optimal combining technique gets very close to the Cramer-Rao lower bound at high SNRs. These combining techniques provide various mechanisms for diversity combining for time-delay estimation and extend the concept of diversity in communications systems to the time-delay estimation problem in cognitive radio systems. Simulation results are presented to evaluate the performance of the proposed estimators and to verify the theoretical analysis.

  1. Radio Frequency Identification (RFID) technology and patient safety.

    Science.gov (United States)

    Ajami, Sima; Rajabzadeh, Ahmad

    2013-09-01

    Radio frequency identification (RFID) systems have been successfully applied in areas of manufacturing, supply chain, agriculture, transportation, healthcare, and services to name a few. However, the different advantages and disadvantages expressed in various studies of the challenges facing the technology of the use of the RFID technology have been met with skepticism by managers of healthcare organizations. The aim of this study was to express and display the role of RFID technology in improving patient safety and increasing the impact of it in healthcare. This study was non-systematical review, which the literature search was conducted with the help of libraries, books, conference proceedings, PubMed databases and also search engines available at Google, Google scholar in which published between 2004 and 2013 during Febuary 2013. We employed the following keywords and their combinations; RFID, healthcare, patient safety, medical errors, and medication errors in the searching areas of title, keywords, abstract, and full text. The preliminary search resulted in 68 articles. After a careful analysis of the content of each paper, a total of 33 papers was selected based on their relevancy. We should integrate RFID with hospital information systems (HIS) and electronic health records (EHRs) and support it by clinical decision support systems (CDSS), it facilitates processes and reduce medical, medication and diagnosis errors.

  2. Radio-frequency plasma transducer for use in harsh environments.

    Science.gov (United States)

    May, Andrew; Andarawis, Emad

    2007-10-01

    We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer, eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0-5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate.

  3. Fast biodiesel production from beef tallow with radio frequency heating

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shaoyang; Wang, Yifen [Biosystems Engineering Department, Auburn University, 200 Tom E. Corley Building, Auburn, AL 36849-5417 (United States); Oh, Jun-Hyun [Department of Plant Science and Technology, Sangmyung University (Korea, Republic of); Herring, Josh L. [Department of Food and Animal Sciences, Alabama A and M University, Normal, AL 35762 (United States)

    2011-03-15

    Efficient biodiesel production from beef tallow was achieved with radio frequency (RF) heating. A conversion rate of 96.3 {+-} 0.5% was obtained with a NaOH concentration of 0.6% (based on tallow), an RF heating for 5 min, and a methanol/tallow molar ratio of 9:1. Response surface methodology was employed to evaluate the influence of NaOH dose, RF heating time, and methanol/tallow ratio. The alkaline concentration showed the largest positive impact on the conversion rate. Similar fast conversion from canola oil to biodiesel was achieved in our previous work, indicating that RF heating, as an accelerating technique for biodiesel production, had a large applying area. Viscosities of biodiesel products from beef tallow and canola oil were measured as 5.23 {+-} 0.01 and 4.86 {+-} 0.01 mm{sup 2} s{sup -1}, respectively, both meeting the specification in ASTM D6751 (1.9-6.0 mm{sup 2} s{sup -1}). (author)

  4. Radio frequency leakage current from unipolar laparoscopic electrocoagulators.

    Science.gov (United States)

    DiNovo, J A

    1983-09-01

    Radio frequency (RF) leakage current has been suspected of causing accidental tissue burns associated with laparoscopic electrocoagulation used for tubal sterilization. A study was done to determine the levels of capacitively coupled RF leakage current from six unipolar laparoscopes manufactured by five companies. Leakage current values ranging from less than 100 mA to over 550 mA were measured at electrosurgical unit power settings of up to 150 w into 1,000 ohms. These levels represent 24-62% of the total electrosurgical current generated by the electrosurgical units. Using a criterion for tissue injury of 100 mA/sq cm applied for ten seconds, leakage current levels exceeding 400 mA are capable of producing burns either at the abdominal wall or to internal organs that accidentally come into contact with the body of the laparoscope. One of the six devices tested had leakage current levels higher than 400 mA at power settings lower than 100 w. Capacitance measurements between the unipolar laparoscope body and the forceps ranged from 53 to 140 picofarads.

  5. Radio frequency plasma mediated dry functionalization of multiwall carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Leena G.; Mahapatra, Anirban S. [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Gomathi, N., E-mail: gomathi@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Joseph, K. [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Neogi, S. [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721301 (India); Nair, C.P. Reghunadan [Polymers and Special Chemicals Group, Vikram Sarabhai Space Centre, Trivandrum, Kerala 695022 (India)

    2015-06-15

    Highlights: • Plasma functionalization of MWCNT to obtain oxygen and nitrogen containing groups. • Functionalization and removal of amorphous carbon from MWCNT without affecting structural integrity. • Enhanced dispersion in water. • Plasma-CNT interaction mechanism. - Abstract: Surface modification of multiwall carbon nanotubes (MWCNT) was carried out by radio frequency (RF) plasma discharges of oxygen and nitrogen gases to improve their dispersibility. Various oxygen and nitrogen containing functional groups were incorporated as a result of plasma treatment and were confirmed through Fourier transform infrared spectroscopy (FTIR). The effect of plasma treatment on structural properties and morphology changes of MWCNTs was analyzed by Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The morphological studies indicate that untreated MWCNT exists as closely packed with highly entangled bundle. During the plasma treatment, MWCNT tubes get disentangled. XRD, Raman and TEM confirmed the absence of any surface damage during plasma treatment. Functionalized carbon nanotubes exhibit high zeta potential values indicating their good dispersibility in water. The method offers a direct and dry means for functionalization of MWCNT without affecting the structure of MWCNT.

  6. Radio Frequency Microelectromechanical Systems in Defence and Aerospace

    Directory of Open Access Journals (Sweden)

    D.V.K. Sastry

    2009-11-01

    Full Text Available For all onboard systems applications, it is important to have very low-loss characteristics and low power consumption coupled with size reduction. The controls and instrumentation in defence and aerospace continually calls for newer technologies and developments. One such technology showing remarkable potential over the years is radio frequency microelectromechanical systems (RF MEMS which have already made their presence felt prominently by offering replacement in radar and communication systems with high quality factors and precise tunability. The RF MEMS components have emerged as potential candidates for defence and aerospace applications. The core theme of this paper is to drive home the fact that the limitations faced by the current RF devices can be overcome by the flexibility and better device performance characteristics of RF MEMS components, which ultimately propagate the device level benefits to the final system to attain the unprecedented levels of performance.Defence Science Journal, 2009, 59(6, pp.568-567, DOI:http://dx.doi.org/10.14429/dsj.59.1561

  7. Report on GMI Special Study #15: Radio Frequency Interference

    Science.gov (United States)

    Draper, David W.

    2015-01-01

    This report contains the results of GMI special study #15. An analysis is conducted to identify sources of radio frequency interference (RFI) to the Global Precipitation Measurement (GPM) Microwave Imager (GMI). The RFI impacts the 10 GHz and 18 GHz channels at both polarities. The sources of RFI are identified for the following conditions: over the water (including major inland water bodies) in the earth view, and over land in the earth view, and in the cold sky view. A best effort is made to identify RFI sources in coastal regions, with noted degradation of flagging performance due to the highly variable earth scene over coastal regions. A database is developed of such sources, including latitude, longitude, country and city of earth emitters, and position in geosynchronous orbit for space emitters. A description of the recommended approach for identifying the sources and locations of RFI in the GMI channels is given in this paper. An algorithm to flag RFI contaminated pixels which can be incorporated into the GMI Level 1Base/1B algorithms is defined, which includes Matlab code to perform the necessary flagging of RFI. A Matlab version of the code is delivered with this distribution.

  8. Manufacture of Radio Frequency Micromachined Switches with Annealing

    Directory of Open Access Journals (Sweden)

    Cheng-Yang Lin

    2014-01-01

    Full Text Available The fabrication and characterization of a radio frequency (RF micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V.

  9. Manufacture of radio frequency micromachined switches with annealing.

    Science.gov (United States)

    Lin, Cheng-Yang; Dai, Ching-Liang

    2014-01-17

    The fabrication and characterization of a radio frequency (RF) micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW) lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS) process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM) software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V.

  10. Radio Frequency Identification (RFID technology and patient safety

    Directory of Open Access Journals (Sweden)

    Sima Ajami

    2013-01-01

    Full Text Available Background: Radio frequency identification (RFID systems have been successfully applied in areas of manufacturing, supply chain, agriculture, transportation, healthcare, and services to name a few. However, the different advantages and disadvantages expressed in various studies of the challenges facing the technology of the use of the RFID technology have been met with skepticism by managers of healthcare organizations. The aim of this study was to express and display the role of RFID technology in improving patient safety and increasing the impact of it in healthcare. Materials and Methods: This study was non-systematical review, which the literature search was conducted with the help of libraries, books, conference proceedings, PubMed databases and also search engines available at Google, Google scholar in which published between 2004 and 2013 during Febuary 2013. We employed the following keywords and their combinations; RFID, healthcare, patient safety, medical errors, and medication errors in the searching areas of title, keywords, abstract, and full text. Results: The preliminary search resulted in 68 articles. After a careful analysis of the content of each paper, a total of 33 papers was selected based on their relevancy. Conclusion: We should integrate RFID with hospital information systems (HIS and electronic health records (EHRs and support it by clinical decision support systems (CDSS, it facilitates processes and reduce medical, medication and diagnosis errors.

  11. Radio Frequency Identification (RFID) technology and patient safety

    Science.gov (United States)

    Ajami, Sima; Rajabzadeh, Ahmad

    2013-01-01

    Background: Radio frequency identification (RFID) systems have been successfully applied in areas of manufacturing, supply chain, agriculture, transportation, healthcare, and services to name a few. However, the different advantages and disadvantages expressed in various studies of the challenges facing the technology of the use of the RFID technology have been met with skepticism by managers of healthcare organizations. The aim of this study was to express and display the role of RFID technology in improving patient safety and increasing the impact of it in healthcare. Materials and Methods: This study was non-systematical review, which the literature search was conducted with the help of libraries, books, conference proceedings, PubMed databases and also search engines available at Google, Google scholar in which published between 2004 and 2013 during Febuary 2013. We employed the following keywords and their combinations; RFID, healthcare, patient safety, medical errors, and medication errors in the searching areas of title, keywords, abstract, and full text. Results: The preliminary search resulted in 68 articles. After a careful analysis of the content of each paper, a total of 33 papers was selected based on their relevancy. Conclusion: We should integrate RFID with hospital information systems (HIS) and electronic health records (EHRs) and support it by clinical decision support systems (CDSS), it facilitates processes and reduce medical, medication and diagnosis errors. PMID:24381626

  12. A Graphical Approach to Radio Frequency Quadrupole Design

    CERN Document Server

    Turemen, G; Yasatekin, B

    2014-01-01

    The design of a radio frequency quadrupole, an important section of all ion accelerators, and the calculation of its beam dynamics properties can be achieved using the existing computational tools. These programs, originally designed in 1980s, show effects of aging in their user interfaces and in their output. The authors believe there is room for improvement in both design techniques using a graphical approach and in the amount of analytical calculations before going into CPU burning finite element analysis techniques. Additionally an emphasis on the graphical method of controlling the evolution of the relevant parameters using the drag-to-change paradigm is bound to be beneficial to the designer. A computer code, named DEMIRCI, has been written in C++ to demonstrate these ideas. This tool has been used in the design of Turkish Atomic Energy Authority (TAEK)'s 1.5 MeV proton beamline at Saraykoy Nuclear Research and Training Center (SANAEM). DEMIRCI starts with a simple analytical model, calculates the RFQ b...

  13. Surface processing for bulk niobium superconducting radio frequency cavities

    Science.gov (United States)

    Kelly, M. P.; Reid, T.

    2017-04-01

    The majority of niobium cavities for superconducting particle accelerators continue to be fabricated from thin-walled (2–4 mm) polycrystalline niobium sheet and, as a final step, require material removal from the radio frequency (RF) surface in order to achieve performance needed for use as practical accelerator devices. More recently bulk niobium in the form of, single- or large-grain slices cut from an ingot has become a viable alternative for some cavity types. In both cases the so-called damaged layer must be chemically etched or electrochemically polished away. The methods for doing this date back at least four decades, however, vigorous empirical studies on real cavities and more fundamental studies on niobium samples at laboratories worldwide have led to seemingly modest improvements that, when taken together, constitute a substantial advance in the reproducibility for surface processing techniques and overall cavity performance. This article reviews the development of niobium cavity surface processing, and summarizes results of recent studies. We place some emphasis on practical details for real cavity processing systems which are difficult to find in the literature but are, nonetheless, crucial for achieving the good and reproducible cavity performance. New approaches for bulk niobium surface treatment which aim to reduce cost or increase performance, including alternate chemical recipes, barrel polishing and ‘nitrogen doping’ of the RF surface, continue to be pursued and are closely linked to the requirements for surface processing.

  14. Compact Superconducting Radio-frequency Accelerators and Innovative RF Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kephart, Robert [Fermilab; Chattopadhyay, Swaapan [Northern Illinois U.; Milton, Stephen [Colorado State U.

    2015-04-10

    We will present several new technical and design breakthroughs that enable the creation of a new class of compact linear electron accelerators for industrial purposes. Use of Superconducting Radio-Frequency (SRF) cavities allow accelerators less than 1.5 M in length to create electron beams beyond 10 MeV and with average beam powers measured in 10’s of KW. These machines can have the capability to vary the output energy dynamically to produce brehmstrahlung x-rays of varying spectral coverage for applications such as rapid scanning of moving cargo for security purposes. Such compact accelerators will also be cost effective for many existing and new industrial applications. Examples include radiation crosslinking of plastics and rubbers, creation of pure materials with surface properties radically altered from the bulk, modification of bulk or surface optical properties of materials, sterilization of medical instruments animal solid or liquid waste, and destruction of organic compounds in industrial waste water effluents. Small enough to be located on a mobile platform, such accelerators will enable new remediation methods for chemical and biological spills and/or in-situ crosslinking of materials. We will describe one current design under development at Fermilab including plans for prototype and value-engineering to reduce costs. We will also describe development of new nano-structured field-emitter arrays as sources of electrons, new methods for fabricating and cooling superconducting RF cavities, and a new novel RF power source based on magnetrons with full phase and amplitude control.

  15. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

    2009-11-11

    Ceralink Inc. developed FastFuse™, a rapid, new, energy saving process for lamination of glass and composites using radio frequency (RF) heating technology. The Inventions and Innovations program supported the technical and commercial research and development needed to elevate the innovation from bench scale to a self-supporting technology with significant potential for growth. The attached report provides an overview of the technical and commerical progress achieved for FastFuse™ during the course of the project. FastFuse™ has the potential to revolutionize the laminate manufacturing industries by replacing energy intensive, multi-step processes with an energy efficient, single-step process that allows higher throughput. FastFuse™ transmits RF energy directly into the interlayer to generate heat, eliminating the need to directly heat glass layers and the surrounding enclosures, such as autoclaves or vacuum systems. FastFuse™ offers lower start-up and energy costs (up to 90% or more reduction in energy costs), and faster cycles times (less than 5 minutes). FastFuse™ is compatible with EVA, TPU, and PVB interlayers, and has been demonstrated for glass, plastics, and multi-material structures such as photovoltaics and transparent armor.

  16. Accoustic Localization of Breakdown in Radio Frequency Accelerating Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Lane, Peter Gwin [IIT, Chicago

    2016-07-01

    Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.

  17. Split-aloha algorithm for radio frequency identification system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Anti-Collision algorithm is one of the most important components of radio frequency identification (RFID) technology, which possesses a key position in the performance of the whole system. ALOHA algorithm is one of the most popular methods to solve the collision problem because of its efficiency and practicability. The grouping method has been developed for enhancing the performance of conventional ALOHA when there are thousands of tags. However, the existing grouping method has limitations in applications due to its rigorous requirements for the estimation of the number of backlog tags or the admirable characteristics of the tags' ID number. Working on the improvement of the grouping methods, we proposed an algorithm named split-ALOHA with a novel grouping method that split tags as a binary tree. The novel grouping method makes it more practicable than the existing grouping methods due to the simplified requirements for tags. Simulations of the proposed algorithm show the superior performance of a linearly increasing of the number of consumed time slots while the number of tags increases. The algorithm performance analysis between split-ALOHA and ALOHA algorithms with other grouping methods has been implemented in a proper way.

  18. Evaluating the Readability of Radio Frequency Identification for Construction Materials

    Directory of Open Access Journals (Sweden)

    Younghan Jung

    2017-01-01

    Full Text Available Radio Frequency Identification (RFID, which was originally introduced to improve material handling and speed production as part of supply chain management, has become a globally accepted technology that is now applied on many construction sites to facilitate real-time information visibility and traceability. This paper describes a senior undergraduate project for a Construction Management (CM program that was specifically designed to give the students a greater insight into technical research in the CM area. The students were asked to determine whether it would be possible to utilize an RFID system capable of tracking tagged equipment, personnel and materials across an entire construction site. This project required them to set up an experimental program, execute a series of experiments, analyze the results and summarize them in a report. The readability test was performed using an active Ultra-High frequency (UHF, 433.92 MHz RFID system with various construction materials, including metal, concrete, wood, plastic, and aluminum. The readability distance distances are measured for each of the six scenarios. The distance at which a tag was readable with no obstructions was found to be an average of 133.9m based on three measurements, with a standard deviation of 3.9m. This result confirms the manufacturer’s claimed distance of 137.2m. The RFID tag embedded under 50.8mm of concrete was readable for an average distance of only 12.2m, the shortest readable distance of any of the scenarios tested. At the end of the semester, faculty advisors held an open discussion session to gather feedback and elicit the students’ reflections on their research experiences, revealing that the students’ overall impressions of their undergraduate research had positively affected their postgraduate education plans.

  19. TESTBED IMPLEMENTATION OF MULTI DIMENSIONAL SPECTRUM SENSING SCHEMES FOR COGNITIVE RADIO

    Directory of Open Access Journals (Sweden)

    Deepa N Reddy

    2016-06-01

    Full Text Available Cognitive Radio (CR is a promising technology to exploit the underutilized spectrum. Spectrum sensing is one of the most important components for the establishment of cognitive radio system. Spectrum sensing allows the secondary users (SUs to detect the presence of the primary users (PUs. The aim of this work is to create a CR environment to study the spectrum sensing methods using Universal software radio Peripheral (USRP boards. In this paper a novel method of estimation of spectrum opportunities in multiple dimensions especially the space and the angle dimensions are carried out on USRP boards. This paper typically provides the experimental results carried out in an indoor wireless environment. To enhance the sensing performance the space dimension is firstly studied using spatial diversity of the cooperative SUs. Secondly the receiver diversity is analyzed using multiple antennas to enhance the error performance of the wireless system. The spectrum usage is also determined in the angle dimension by investigating the direction of the dominant signals using MUSIC algorithm.

  20. Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes

    Energy Technology Data Exchange (ETDEWEB)

    Gui, B. [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Lawerence Livermore National Lab, Livermore, California 94550 (United States); Xu, X. Q. [Lawerence Livermore National Lab, Livermore, California 94550 (United States); Myra, J. R.; D' Ippolito, D. A. [Lodestar Research Corporation, Boulder, Colorado 80301 (United States)

    2014-11-15

    The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallel current near the sheath region is also suppressed locally due to the sheath boundary condition.

  1. Spectrum sharing in cognitive radio networks medium access control protocol based approach

    CERN Document Server

    Pandit, Shweta

    2017-01-01

    This book discusses the use of the spectrum sharing techniques in cognitive radio technology, in order to address the problem of spectrum scarcity for future wireless communications. The authors describe a cognitive radio medium access control (MAC) protocol, with which throughput maximization has been achieved. The discussion also includes use of this MAC protocol for imperfect sensing scenarios and its effect on the performance of cognitive radio systems. The authors also discuss how energy efficiency has been maximized in this system, by applying a simple algorithm for optimizing the transmit power of the cognitive user. The study about the channel fading in the cognitive user and licensed user and power adaption policy in this scenario under peak transmit power and interference power constraint is also present in this book.

  2. Distance Dependent Model for the Delay Power Spectrum of In-room Radio Channels

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Pedersen, Troels; Fleury, Bernard Henri;

    2013-01-01

    A model based on experimental observations of the delay power spectrum in closed rooms is proposed. The model includes the distance between the transmitter and the receiver as a parameter which makes it suitable for range based radio localization. The experimental observations motivate the propos...

  3. Machine Learning Aided Efficient and Robust Algorithms for Spectrum Knowledge Acquisition in Wideband Autonomous Cognitive Radios

    Science.gov (United States)

    2016-08-01

    WIDEBAND AUTONOMOUS COGNITIVE RADIOS Sudharman Jayaweera Department of Electrical and Computer Engineering University of New Mexico Albuquerque, NM...of Electrical and Computer Engineering 8. PERFORMING ORGANIZATION REPORT NUMBER University of New Mexico Albuquerque, NM 87131 9. SPONSORING...1, is the wideband spectrum scanning [1,8]. Hardware constraints limit the instantaneous sensing bandwidth of most state-of-the- art software

  4. The Population of KPC-Scale Flat-Spectrum Radio Sources

    Science.gov (United States)

    Augusto, Pedro; Wilkinson, Peter N.; Browne, Ian W. A.

    In this paper we present a subsample of 55 flat-spectrum radio sources dominated by (~ 100 mas) kpc-scale structure, selected from a parent sample of 1665 VLA sources. Most are core-jets and 23 are CSO/MSO candidates. Properties of the subsample are discussed.

  5. Opportunistic spectrum access in cognitive radio based on channel switching

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-01-01

    This paper investigates the performance of a cognitive radio transceiver that can monitor multiple channels and opportunistically use any one of them should it be available. In our work, we propose and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. Two switching strategies, namely the switch and examine and the switch and stay strategies, are proposed. For these proposed access schemes, we investigate their performance by deriving the analytical expression of the novel metric of the average access duration and the average waiting time and based on these two metrics a time average SU throughput formula is proposed to predict the performance of the secondary cognitive system. © 2012 ICST.

  6. Cooperative detection algorithm of spectrum holes in cognitive radio

    Institute of Scientific and Technical Information of China (English)

    SHI Lei; YE Zhun; ZHANG Zhong-zhao

    2009-01-01

    To improve the detection performance of sensing users for primary users in the cognitive radio, an optimal cooperative detection algorithm for many sensing users is proposed. In this paper, optimal decision thresholds of each sensing user are discussed. Theoretical analysis and simulation results indicate that the detection probability of optimal decision threshold rules is better than that of determined threshold rules when the false alarm of the fusion center is constant. The proposed optimal cooperative detection algorithm improves the detection performance of primary users as the attendees grow. The 2 dB gain of detection probabihty can be obtained when a new sensing user joins in, and there is a 17 dB improvement when the accumulation number increases from 1 to 50.

  7. A Secure Distributed Spectrum Sensing Scheme in Cognitive Radio

    Science.gov (United States)

    Nhan, Nguyen-Thanh; Koo, Insoo

    Distributed spectrum sensing provides an improvement for primary user detection but leads a new security threat into CR system. The spectrum sensing data falsification malicious users can decrease the cooperative sensing performance. In this paper, we propose a distributed scheme in which the presence and absence hypotheses distribution of primary signal is estimated based on past sensing received power data by robust statistics, and the data fusion are performed according to estimated parameters by Dempster-Shafer theory of evidence. Our scheme can achive a powerful capability of malicious user elimination due to the abnormality of the distribution of malicious users compared with that of other legitimate users. In addition, the performance of our data fusion scheme is enhanced by supplemented nodes’ reliability weight.

  8. Low Radio Frequency Observations and Spectral Modelling of the Remnant of Supernova 1987A

    CERN Document Server

    Callingham, J R; Zanardo, G; Staveley-Smith, L; Hancock, P J; Hurley-Walker, N; Bell, M E; Dwarakanath, K S; Franzen, T M O; Hindson, L; Johnston-Hollitt, M; Kapinska, A; For, B Q; Lenc, E; McKingley, B; Offringa, A R; Procopio, P; Wayth, R B; Wu, C; Zheng, Q

    2016-01-01

    We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing the lowest frequency observations of the source to date. This large lever arm in frequency space constrains the properties of the circumstellar medium created by the progenitor of SNR 1987A when it was in its red supergiant phase. As of late-2013, the radio spectrum of SNR 1987A between 72 MHz and 8.64 GHz does not show any deviation from a non-thermal power-law with a spectral index of $-0.74 \\pm 0.02$. This spectral index is consistent with that derived at higher frequencies, beneath 100 GHz, and with a shock in its adiabatic phase. A spectral turnover due to free-free absorption by the circumstellar medium has to occur below 72 MHz, which places upper limits on the optical depth of $\\leq$ 0.1 at a reference frequency of 72 MHz, emission measure of $\\lesssim$ 13,000 cm$^{-6}$ pc, and an electron density of $\\lesssim$ 110 cm$^{-3}$. This upper limit on the electron density is consistent...

  9. Wavelet-based Characterization of Small-scale Solar Emission Features at Low Radio Frequencies

    Science.gov (United States)

    Suresh, A.; Sharma, R.; Oberoi, D.; Das, S. B.; Pankratius, V.; Timar, B.; Lonsdale, C. J.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Emrich, D.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kratzenberg, E.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Ord, S. M.; Prabu, T.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.

    2017-07-01

    Low radio frequency solar observations using the Murchison Widefield Array have recently revealed the presence of numerous weak short-lived narrowband emission features, even during moderately quiet solar conditions. These nonthermal features occur at rates of many thousands per hour in the 30.72 MHz observing bandwidth, and hence necessarily require an automated approach for their detection and characterization. Here, we employ continuous wavelet transform using a mother Ricker wavelet for feature detection from the dynamic spectrum. We establish the efficacy of this approach and present the first statistically robust characterization of the properties of these features. In particular, we examine distributions of their peak flux densities, spectral spans, temporal spans, and peak frequencies. We can reliably detect features weaker than 1 SFU, making them, to the best of our knowledge, the weakest bursts reported in literature. The distribution of their peak flux densities follows a power law with an index of -2.23 in the 12-155 SFU range, implying that they can provide an energetically significant contribution to coronal and chromospheric heating. These features typically last for 1-2 s and possess bandwidths of about 4-5 MHz. Their occurrence rate remains fairly flat in the 140-210 MHz frequency range. At the time resolution of the data, they appear as stationary bursts, exhibiting no perceptible frequency drift. These features also appear to ride on a broadband background continuum, hinting at the likelihood of them being weak type-I bursts.

  10. Testing of Policy-Based Dynamic Spectrum Access Radios

    Science.gov (United States)

    2010-01-01

    WiFi , WiMax, etc.) and network size. 7) Network Join Time: Network join time characterizes the time for one slave node to join a previously formed DSA...may be achieved through built-in or commercially available GPS simulators, which also allow for the simulation of moving or varying locations...environment, with building obstructions, indoors and outdoors communications, and very dense RF spectrum utilization (due to RF interference or

  11. Energy detection for spectrum sensing in cognitive radio

    CERN Document Server

    Atapattu, Saman; Jiang, Hai

    2014-01-01

    This Springer Brief focuses on the current state-of-the-art research on spectrum sensing by using energy detection, a low-complexity and low-cost technique. It includes a comprehensive summary of recent research, fundamental theories, possible architectures, useful performance measurements of energy detection and applications of energy detection. Concise, practical chapters explore conventional energy detectors, alternative forms of energy detectors, performance measurements, diversity techniques and cooperative networks. The careful analysis enables reader to identify the most efficient techn

  12. Frequency-Comb Spectrum of Periodic-Patterned Signals

    Science.gov (United States)

    Steinmann, Johannes L.; Blomley, Edmund; Brosi, Miriam; Bründermann, Erik; Caselle, Michele; Hesler, Jeffrey L.; Hiller, Nicole; Kehrer, Benjamin; Mathis, Yves-Laurent; Nasse, Michael J.; Raasch, Juliane; Schedler, Manuel; Schönfeldt, Patrik; Schuh, Marcel; Schwarz, Markus; Siegel, Michael; Smale, Nigel; Weber, Marc; Müller, Anke-Susanne

    2016-10-01

    Using arbitrary periodic pulse patterns we show the enhancement of specific frequencies in a frequency comb. The envelope of a regular frequency comb originates from equally spaced, identical pulses and mimics the single pulse spectrum. We investigated spectra originating from the periodic emission of pulse trains with gaps and individual pulse heights, which are commonly observed, for example, at high-repetition-rate free electron lasers, high power lasers, and synchrotrons. The ANKA synchrotron light source was filled with defined patterns of short electron bunches generating coherent synchrotron radiation in the terahertz range. We resolved the intensities of the frequency comb around 0.258 THz using the heterodyne mixing spectroscopy with a resolution of down to 1 Hz and provide a comprehensive theoretical description. Adjusting the electron's revolution frequency, a gapless spectrum can be recorded, improving the resolution by up to 7 and 5 orders of magnitude compared to FTIR and recent heterodyne measurements, respectively. The results imply avenues to optimize and increase the signal-to-noise ratio of specific frequencies in the emitted synchrotron radiation spectrum to enable novel ultrahigh resolution spectroscopy and metrology applications from the terahertz to the x-ray region.

  13. Analytical Dielectric Spectrum Formula Based on Representative Frequencies

    Institute of Scientific and Technical Information of China (English)

    Bo Kong; Ke-xiang Fu; Min-hua Shan; Xiang-yuan Li

    2009-01-01

    According to experimental data available for the complex refractive index of particular di-electrics, a dielectric spectrum formula is proposed by the least square fitting technique combined with selected natural frequencies. From the dielectric spectrum formula, the spec-tra of optical and dielectric constants can be obtained in the whole frequency region. Three dielectrics, water, ethanol, and toluene, are taken as examples. In the region where the ex-perimental data are available, the spectra of the optical constants calculated by the formula are in good agreement with the real refractive spectrum obtained by Kramers-Kronig (K-K) transform and the experimental imaginary refractive spectrum. In the region where no ex-perimental data are available, the extrapolation of our formula can make predictions. The merits of the present treatment are that we are able to get the uniform spectrum formula, without splitting into different frequency sections, and the analytical form of the dielectric spectra will be useful in the theoretical description of solvation dynamics.

  14. Frequency spectrum analysis for spectrum stabilization in airborne gamma-ray spectrometer.

    Science.gov (United States)

    Zeng, Guoqiang; Tan, Chengjun; Ge, Liangquan; Zhang, Qingxian; Gu, Yi

    2014-02-01

    Abnormal multi-crystal spectral drifts often can be observed when power on the airborne gamma-ray spectrometer. Currently, these spectral drifts of each crystal are generally eliminated through manual adjustment, which is time-consuming and labor-ineffective. To realize this quick automatic spectrum stabilization of multi-crystal, a frequency spectrum analysis method for natural gamma-ray background spectrum is put forward in this paper to replace traditional spectrum stabilization method used characteristic peak. Based on the polynomial fitting of high harmonics in frequency spectrum and gamma-ray spectral drift, it calculates overall spectral drift of natural gamma-ray spectrum and adjusts the gain of spectrometer by this spectral drift value, thus completing quick spectrum stabilization in the power on stage of spectrometer. This method requires no manual intervention and can obtain the overall spectral drift value automatically under no time-domain pre-processing to the natural gamma-ray spectra. The spectral drift value calculated by this method has an absolute error less than five channels (1024 resolution) and a relative error smaller than 0.80%, which can satisfy the quick automatic spectrum stabilization requirement when power on the airborne gamma-ray spectrometer instead of manual operation.

  15. Spatial Identification of Passive Radio Frequency Identification Tags Using Software Defined Radios

    Science.gov (United States)

    2012-03-01

    of 56 MBytes per second [20]. All communications between the main board and GNU Radio on the host PC take place through this controller. More recent...Digital AGC and Data signal from the main board are both determined by the Python code generated by GNU Radio on the host PC. This local oscillator signal...running Ubuntu 10.10 and GNU Radio , a USRP1 SDR with a Flex 900 daughter card and two Alien 9611-CR antennas. The GNU Radio installation has been

  16. Potential radio frequency interference with the GPS L5 band for radio occultation measurements

    Directory of Open Access Journals (Sweden)

    A. M. Wolff

    2014-05-01

    Full Text Available New Radio Occultation (RO receivers are planned to utilize the newly implemented Global Positioning System (GPS L5 signal centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance Measuring Equipment (DME and Tactical Air Navigation (TACAN stations share the same frequency band as the GPS L5 signal. DME/TACAN signals have been identified to be a means of interference for any GPS L5 receiver. This study focuses on implementing a Systems Tools Kit (STK simulation to gain insight into the power received by a RO satellite in Low Earth Orbit (LEO from a DME/TACAN transmission. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME/TACAN station as well as a tool to predict the number of interfering DME/TACAN stations at any point in time. Taking a conservative approach, the signal power received was much greater than the typical power level received by a RO satellite from a GPS satellite transmission. This relatively high received power along with a high number of interfering DME/TACAN stations as an RO satellite passes over North America or Western Europe indicate that DME/TACAN interference may conflict with RO receivers.

  17. Variable low-frequency radio emission of the solar system and galactic objects

    Science.gov (United States)

    Konovalenko, Alexander; Kolyadin, Vladimir; Rucker, Helmut; Zakharenko, Vyacheslav; Zarka, Philippe; Griessmeier, Jean-M.; Denis, Loran; Melnik, Valentin; Litvinenko, Galina; Zaitsev, Valerij; Falkovich, Igor; Ulyanov, Oleg; Sidorchuk, Mikhail; Stepkin, Sergej; Stanislavskij, Alexander; Kalinichenko, Nikolaj; Boiko, Nastja; Vasiljiva, Iaroslavna; Mukha, Dmytro; Koval, Artem

    2013-04-01

    There are many physical processes and propagation effects for the producing the time variable radio emission just at the low frequencies (at the decameter wavelength). The study of this radio emission is the important part of the modern radio astronomy. Strong progress in the development of the radio telescopes, methods and instrumentation allowed to start the corresponding investigations at new quality and quantity levels. It related to the implementation of the world largest UTR-2 radio telescope (effective area is more than 100 000 sq.m) more high sensitive at frequencies less than 30 MHz. During last years many new observations were carried out with this radio telescope and many new effects have been detected for the Sun, planets, interplanetary medium, exoplanets as well as various kinds of the stars.

  18. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Salim, Shelly; Moh, Sangman

    2016-06-30

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  19. Spectrum sensing algorithm based on autocorrelation energy in cognitive radio networks

    Science.gov (United States)

    Ren, Shengwei; Zhang, Li; Zhang, Shibing

    2016-10-01

    Cognitive radio networks have wide applications in the smart home, personal communications and other wireless communication. Spectrum sensing is the main challenge in cognitive radios. This paper proposes a new spectrum sensing algorithm which is based on the autocorrelation energy of signal received. By taking the autocorrelation energy of the received signal as the statistics of spectrum sensing, the effect of the channel noise on the detection performance is reduced. Simulation results show that the algorithm is effective and performs well in low signal-to-noise ratio. Compared with the maximum generalized eigenvalue detection (MGED) algorithm, function of covariance matrix based detection (FMD) algorithm and autocorrelation-based detection (AD) algorithm, the proposed algorithm has 2 11 dB advantage.

  20. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Shelly Salim

    2016-06-01

    Full Text Available A cognitive radio sensor network (CRSN is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  1. Low-frequency measurements of the CMB spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, A.; Bensadoun, M.; Amici, G.D.; Levin, S.; Limon, M.; Smoot, G. (U. C. Berkeley, Berkeley, CA (USA) Lawrence Berkeley Laboratory, Berkeley, CA (USA) Space Sciences Laboratory, Berkeley, CA (USA)); Sironi, G. (Physics Department, University of Milano (Italy)); Bersanelli, M.; Bonelli, G. (IFCTR/CNR-Milano (Italy))

    1990-01-15

    As part of an extended program to characterize the spectrum of the cosmic microwave background (CMB) at low frequencies, we have performed multiple measurements from a high-altitude site in Calfornia. On average, these measurements suggests a CMB temperature slightly lower than measurements at higher frequencies. Atmospheric conditions and the encroachment of civilization are now significant limitations from our present observing site. In November 1989, we will make new measurements from the South Pole Amundsen-Scott Station at frequencies 0.82, 1.5, 2.5, 3.8, 7.5, and 90 GHz. We discuss recent measurements and indicate improvements possible from a polar observing site.

  2. Low-Frequency Measurements of the CMB Spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, A.; Bensadoun, M.; De Amici, Giovanni; Levin, S.; Limon,M.; Smoot, George F.; Sironi, G.; Bersanelli, M.; Bonelli, G.

    1989-10-01

    As part of an extended program to characterize the spectrum of the cosmic microwave background (CMB) at low frequencies, we have performed multiple measurements from a high-altitude site in California. On average, these measurements suggest a CMB temperature slightly lower than measurements at higher frequencies. Atmospheric conditions and the encroachment of civilization are now significant limitations from our present observing site. In November 1989, we will make new measurements from the South Pole Amundsen-Scott Station at frequencies 0.82, 1.5, 2.5, 3.8, 7.5, and 90 GHz. We discuss recent measurements and indicate improvements possible from a polar observing site.

  3. Collisionless expansion of pulsed radio frequency plasmas. I. Front formation

    Science.gov (United States)

    Schröder, T.; Grulke, O.; Klinger, T.; Boswell, R. W.; Charles, C.

    2016-01-01

    The dynamics during plasma expansion are studied with the use of a versatile particle-in-cell simulation with a variable neutral gas density profile. The simulation is tailored to a radio frequency plasma expansion experiment [Schröder et al., J. Phys. D: Appl. Phys. 47(5), 055207 (2014)]. The experiment has shown the existence of a propagating ion front. The ion front features a strong electric field and features a sharp plasma potential drop similar to a double layer. However, the presented results of a first principle simulation show that, in general, the ion front does not have to be entangled with an electric field. The propagating electric field reflects the downstream ions, which stream with velocities up to twice as high as that of the ion front propagation. The observed ion density peak forms due to the accumulation of the reflected ions. The simulation shows that the ion front formation strongly depends on the initial ion density profile and is subject to a wave-breaking phenomenon. Virtual diagnostics in the code allow for a direct comparison with experimental results. Using this technique, the plateau forming in the wake of the plasma front could be indirectly verified in the expansion experiment. Although the simulation considers profiles only in one spatial dimensional, its results are qualitatively in a very good agreement with the laboratory experiment. It can successfully reproduce findings obtained by independent numerical models and simulations. This indicates that the effects of magnetic field structures and tangential inhomogeneities are not essential for the general expansion dynamic. The presented simulation will be used for a detailed parameter study dealt with in Paper II [Schröder et al., Phys. Plasma 23, 013512 (2016)] of this series.

  4. Energy Saving Glass Lamination via Selective Radio-Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shulman, Holly S.; Allan, Shawn M.

    2009-11-11

    This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for

  5. FR II radio galaxies at low frequencies - II. Spectral ageing and source dynamics

    Science.gov (United States)

    Harwood, Jeremy J.; Hardcastle, Martin J.; Morganti, Raffaella; Croston, Judith H.; Brüggen, Marcus; Brunetti, Gianfranco; Röttgering, Huub J. A.; Shulevski, Aleksander; White, Glenn J.

    2017-07-01

    In this paper, the second in a series investigating Fanaroff-Riley type II (FR II) radio galaxies at low frequencies, we use LOw Frequency ARray (LOFAR) and Very Large Array (VLA) observations between 117 and 456 MHz, in addition to archival data, to determine the dynamics and energetics of two radio galaxies, 3C 452 and 3C 223, by fitting spectral ageing models on small spatial scales. We provide improved measurements for the physical extent of the two sources, including a previously unknown low surface brightness extension to the northern lobe of 3C 223, and revised energetics based on these values. We find spectral ages of 77.05^{+9.22}_{-8.74} and 84.96^{+15.02}_{-13.83} Myr for 3C 452 and 3C 223, respectively, suggesting a characteristic advance speed for the lobes of around 1 per cent of the speed of light. For 3C 452, we show that, even for a magnetic field strength not assumed to be in equipartition, a disparity of a factor of approximately 2 exists between the spectral age and that determined from a dynamical standpoint. We confirm that the injection index of both sources (as derived from the lobe emission) remains steeper than classically assumed values, even when considered on well-resolved scales at low frequencies. However, we find an unexpected sharp discontinuity between the spectrum of the hotspots and the surrounding lobe emission. We suggest that this discrepancy is a result of the absorption of hotspot emission and/or non-homogeneous and additional acceleration mechanisms; as such, hotspots should not be used in the determination of the underlying initial electron energy distribution.

  6. Radiation effects on communication performance of radio frequency identification tags.

    Science.gov (United States)

    Mori, Kazuyuki; Meng, Zhaowu; Kikuchi, Hirosumi; Kataoka, Yasuhide; Nakazato, Kazuhisa; Deji, Shizuhiko; Ito, Shigeki; Saze, Takuya; Hirota, Masahiro; Nishizawa, Kunihide

    2010-11-01

    Radioactive materials (sources) are managed by bookkeeping and stocktaking. The radiation protection section staffs should check the sources manually. Annual effective dose concerning stocktaking of them are estimated at some mSv concerning fingers. A radio frequency identification (RFID) tag's absorbed dose is estimated at some dozen Gy. RFID for stocktaking automatically was devised. Radiation effects on the communication performance of RFID tags were investigated by using response times and read ranges as indices. The RFID system was composed of a computer, a detector, and transponders (tag) consisting of an integrated circuit chip and an antenna. The tag is joined to the source for identification. The tags were irradiated at doses between 5 and 5,000 Gy by an x-ray irradiator. The response times and the read ranges were tracked from 40 to 23,200 min after irradiation. Relative read ranges fluctuated between 0.9 and 1.1 in the dose region less than 2,000 Gy, but fluctuated greatly in the dose region beyond 2,000 Gy. Malfunctioning tags appeared from 3,000 Gy, and all tags malfunctioned in the dose region over 4,500 Gy. The threshold dose leading to malfunction was determined to be 2,100 Gy. Time variation of relative read ranges was classified into four patterns. The pattern shifted from pattern 1 to 4 when the dose was increased. The relative read ranges lengthened in pattern 1. The relative read rages were approximately 1.0 in pattern 2. The read ranges tentatively shortened, then recovered in pattern 3. The tags malfunctioned in pattern 4. Once the tags malfunctioned, they never recovered their performance. Radiation enhances or deteriorates communication performance depending on dosage. Tags can spontaneously recover from radiation deterioration. The time variation of the read ranges can be illustrated by enhancement, deterioration, and recovery. The mechanism of four patterns is explained based on the variation of the frequency harmonization strength and

  7. Joint Spectrum Allocation and Scheduling in Multi-Radio Multi-Channel Cognitive Radio Wireless Networks

    Science.gov (United States)

    2010-04-01

    radios in node y. The time required to solve this problem can be significantly decreased if a greedy clique decomposition of the conflict graph is...performed. Specifically, a set of cliques © Qi, i = 1, 2, ...Q ª are found such that if yj ∈ χ (xk), then there is a clique Qi such that xk ∈ Qi and yj ∈ Qi...and trace files. The propagation simulator is based on ray -tracing and accounts for reflections off of the ground and off of buildings, transmission

  8. An in situ measurement of the radio-frequency attenuation in ice at Summit Station, Greenland

    CERN Document Server

    Avva, J; Miki, C; Saltzberg, D; Vieregg, A G

    2014-01-01

    We report an in situ measurement of the electric field attenuation length at radio frequencies for the bulk ice at Summit Station, Greenland, made by broadcasting radio-frequency signals vertically through the ice and measuring the relative power in the return ground bounce signal. We find the depth-averaged field attenuation length to be 947 +92/-85 meters at 75 MHz. While this measurement has clear radioglaciological applications, the radio clarity of the ice also has implications for the detection of ultra-high energy (UHE) astrophysical particles via their radio emission in dielectric media such as ice. The measured attenuation length at Summit Station is comparable to previously measured radio-frequency attenuation lengths at candidate particle detector sites around the world, and strengthens the case for Summit Station as the most promising northern site for UHE neutrino detection.

  9. Low Frequency Radio Emission from the 'Quiet' Sun

    Indian Academy of Sciences (India)

    R. Ramesh

    2000-09-01

    We present observations of the 'quiet' Sun close to the recent solar minimum (Cycle 22), with the Gauribidanur radioheliograph. Our main conclusion is that coronal streamers also influence the observed radio brightness temperature.

  10. Coalitional Games in Partition Form for Joint Spectrum Sensing and Access in Cognitive Radio Networks

    CERN Document Server

    Saad, Walid; Zheng, Rong; Hjørungnes, Are; Başar, Tamer; Poor, H Vincent

    2012-01-01

    Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing as well as the capacity achi...

  11. Performance of transmit-reference radio system in frequency-selective fading channels

    NARCIS (Netherlands)

    Wang, Jing; Haartsen, J.C.

    2005-01-01

    Noise-based Transmit-Reference (TR) radio system is a simple and practical candidate for ultra-wideband (UWB) communication applications. This paper evaluates the performance of the Transmit-Reference radio system in a frequency-selective fading channel by theoretical analysis and computer

  12. 47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.

    Science.gov (United States)

    2010-10-01

    ... person shall use, manufacture, sell or lease, offer for sale or lease (including advertising for sale or lease), or import, ship, or distribute for the purpose of selling or leasing, any external radio... separate product. (1) An external radio frequency power amplifier may be marketed for individual...

  13. Calculus, Radio Dials and the Straight-Line Frequency Variable Capacitor

    Science.gov (United States)

    Boyadzhiev, Khristo N.

    2010-01-01

    Most often radio dials of analogue radios are not uniformly graded; the frequencies are cramped on the left side or on the right side. This makes tuning more difficult. Why are dials made this way? We shall see here that simple calculus can help understand this problem and solve it. (Contains 7 figures.)

  14. Software architecture design for a dynamic spectrum allocation-enabled cognitive radio testbed

    DEFF Research Database (Denmark)

    Tonelli, Oscar; Berardinelli, Gilberto; Cattoni, Andrea Fabio

    2011-01-01

    The evolution of wireless communications is bringing into reality the dense deployment of femto and local area cells, which represents a challenging scenario for proving the effectiveness of Cognitive Radio (CR) frameworks. In particular the Dynamic Spectrum Allocation (DSA) paradigm aims...... at solving the resource allocation problem in a fully autonomous way. While in both CR and standardization lot of effort has been spent in developing efficient DSA algorithms, their research-oriented software radio implementation is still disregarded. In this paper, the design approach used......: preliminary results show a computational load compatible with nowadays Commercial-Off-The-Shelf computers....

  15. A Compact High Frequency Doppler Radio Scatterometer for Coastal Oceanography

    Science.gov (United States)

    Flament, P. J.; Harris, D.; Flament, M.; Fernandez, I. Q.; Hlivak, R.; Flores-vidal, X.; Marié, L.

    2016-12-01

    A low-power High Frequency Doppler Radar has been designed for large series production. The use of commercial-off-the-shelf components is maximized to minimize overall cost. Power consumption is reduced to 130W in full duty and 20W in stand-by under 20-36 V-DC, thus enabling solar/wind and/or fuel cell operation by default. For 8 channels, commercial components and sub-assemblies cost less than k20 excluding coaxial antenna cables, and less than four man-weeks of technician suffice for integration, testing and calibration, suggesting a final cost of about k36, based on production batches of 25 units. The instrument is integrated into passively-cooled 90x60x20 cm3 field-deployable enclosures, combining signal generation, transmitter, received, A/D converter and computer, alleviating the need for additional protection such as a container or building. It uses frequency-ramped continuous wave signals, and phased-array transmissions to decouple the direct path to the receivers. Five sub-assemblies are controlled by a Linux embedded computer: (i) direct digital synthesis of transmit and orthogonal local oscillator signals, derived from a low phase noise oven-controlled crystal; (ii) distributed power amplifiers totaling 5 W, integrated into λ/8 passive transmit antenna monopoles; (iii) λ/12 compact active receive antenna monopoles with embedded out-of-band rejection filters; (iv) analog receivers based on complex demodulation by double-balanced mixers, translating the HF spectrum to the audio band; (v) 24-bit analog-to-digital sigma-delta conversion at 12 kHz with 512x oversampling, followed by decimation to a final sampling frequency of 750 Hz. Except for the HF interference rejection filters, the electronics can operate between 3 and 50 MHz with no modification. At 13.5 MHz, 5 W transmit power, 15 min integration time, the high signal-to-noise ratio permits a typical range of 120 km for currents measurements with 8-antenna beam-forming. The University of Hawaii HFR

  16. Spectrum Handoffs Based on Preemptive Repeat Priority Queue in Cognitive Radio Networks.

    Science.gov (United States)

    Yang, Xiaolong; Tan, Xuezhi; Ye, Liang; Ma, Lin

    2016-07-20

    Cognitive radio can significantly improve the spectrum efficiency, and spectrum handoff is considered as an important functionality to guarantee the quality of service (QoS) of primary users (PUs) and the continuity of data transmission of secondary users (SUs). In this paper, we propose an analytical framework based on a preemptive repeat identical (PRI) M/G/1 queuing network model to characterize spectrum handoff behaviors with general service time distribution of both primary and secondary connections, multiple interruptions and transmission delay resulting from the appearance of primary connections. Then, we derive the close-expression of the extended data delivery and the system sojourn time in both staying and changing scenarios. In addition, based on analysis of spectrum handoff behaviors resulting from multiple interruptions caused by the appearance of the primary connections, we investigate the traffic-adaptive policy, by which the considered SU will optimally adjust its handoff spectrum policy. Moreover, we investigate the admissible region and provide the reference for designing the admission control rule for the arriving secondary connection requests. Finally, simulation results verify that our proposed analytical framework is reasonable and can provide the reference for executing the optimal spectrum handoff strategy and designing the admission control rule for the SU in cognitive radio networks.

  17. Achievable Outage Rates In Cognitive Radio Networks under Imperfect Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    N. Tafaghodi Khajavi

    2012-06-01

    Full Text Available In this paper, we aim at deriving the outage rates achieved by the primary user due spectrum sensing in a cognitive radio network, that we call sensing-induced primary outage rates. To reach this goal, in the first step, instead of classical spectrum sensing techniques that evaluate sensing performance only based on correct detection of the presence of the primary user’s signal, we propose a modified framework that also takes into account the correct detection of the absence of primary user’s signal for spectrum sensing performance evaluation. In a second step, we derive the information rates achieved by the coexistence of a primary and a cognitive network. In the last step, assuming slow fading sensing channels, we derive the sensing-induced primary outage rates, i.e., outage rates achieved by the primary network in the presence of a CR with imperfect spectrum sensing, characterized by a given miss-detection probability. Numerical results show that the proposed spectrum sensing outperforms conventional spectrum sensing techniques in terms of primary signal outage rates and total achievable throughputs, without any increase in the cognitive radio complexity.

  18. Spectrum Sensing and Primary User Localization in Cognitive Radio Networks via Sparsity

    Directory of Open Access Journals (Sweden)

    Lanchao Liu

    2016-01-01

    Full Text Available The theory of compressive sensing (CS has been employed to detect available spectrum resource in cognitive radio (CR networks recently. Capitalizing on the spectrum resource underutilization and spatial sparsity of primary user (PU locations, CS enables the identification of the unused spectrum bands and PU locations at a low sampling rate. Although CS has been studied in the cooperative spectrum sensing mechanism in which CR nodes work collaboratively to accomplish the spectrum sensing and PU localization task, many important issues remain unsettled. Does the designed compressive spectrum sensing mechanism satisfy the Restricted Isometry Property, which guarantees a successful recovery of the original sparse signal? Can the spectrum sensing results help the localization of PUs? What are the characteristics of localization errors? To answer those questions, we try to justify the applicability of the CS theory to the compressive spectrum sensing framework in this paper, and propose a design of PU localization utilizing the spectrum usage information. The localization error is analyzed by the Cramér-Rao lower bound, which can be exploited to improve the localization performance. Detail analysis and simulations are presented to support the claims and demonstrate the efficacy and efficiency of the proposed mechanism.

  19. Electromagnetic interference from radio frequency identification inducing potentially hazardous incidents in critical care medical equipment

    NARCIS (Netherlands)

    Togt, R. van der; Lieshout, E.J. van; Hensbroek, R.; Beinat, E.; Binnekade, J.M.; Bakker, P.J.M.

    2008-01-01

    Context: Health care applications of autoidentification technologies, such as radio frequency identification (RFID), have been proposed to improve patient safety and also the tracking and tracing of medical equipment. However, electromagnetic interference (EMI) by RFID on medical devices has never

  20. 78 FR 43916 - Certain Radio Frequency Identification (RFID) Products and Components Thereof; Commission...

    Science.gov (United States)

    2013-07-22

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Radio Frequency Identification (RFID) Products and Components Thereof; Commission... that termination of this investigation did not impose any undue burdens on the public health...

  1. Computer-aided design of digital radio devices with frequency representation of information

    OpenAIRE

    Kychak, Vasyl; Kychak, Volodymyr

    2012-01-01

    This paper presents a system of automated design of digital radio devices with frequency representation of information, which can significantly simplify the design process of digital devices with large number of input signals.

  2. A C-Band Radio Frequency Interference (RFI) Detection and Mitigation Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radio Frequency Interference (RFI) can render microwave radiometer measurements useless. We propose a method and an architecture that can be used to identify sources...

  3. An L-Band Radio Frequency Interference (RFI) Detection and Mitigation Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radio Frequency Interference (RFI) can render microwave radiometer measurements useless. We have proposed a method and an architecture that can be used to identify...

  4. Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Mastoridis, Themistoklis [Stanford Univ., CA (United States)

    2010-08-01

    The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC

  5. Lagrangian frequency spectrum as a diagnostic for magnetohydrodynamic turbulence dynamics.

    Science.gov (United States)

    Busse, Angela; Müller, Wolf-Christian; Gogoberidze, Grigol

    2010-12-01

    For the phenomenological description of magnetohydrodynamic turbulence competing models exist, e.g., Boldyrev [Phys. Rev. Lett. 96, 115002 (2006)] and Gogoberidze [Phys. Plasmas 14, 022304 (2007)], which predict the same Eulerian inertial-range scaling of the turbulent energy spectrum although they employ fundamentally different basic interaction mechanisms. A relation is found that links the Lagrangian frequency spectrum with the autocorrelation time scale of the turbulent fluctuations τ(ac) and the associated cascade time scale τ(cas). Thus, the Lagrangian energy spectrum can serve to identify weak (τ(ac) ≪ τ(cas)) and strong (τ(ac) ∼ τ(cas)) interaction mechanisms providing insight into the turbulent energy cascade. The new approach is illustrated by results from direct numerical simulations of two- and three-dimensional incompressible MHD turbulence.

  6. Low frequency solar radio astronomy at the Indian Institute of Astrophysics (IIA)

    Science.gov (United States)

    Ramesh, R.

    IIA is presently involved in the expansion of its existing radioheliograph operating in the frequency 120-40 MHz at the Gauribidanur radio observatory located about 80 km north of Bangalore. Once completed, the expanded array will have an angular resolution of ≈ 1' at a typical frequency of 100 MHz. This paper describes the development of solar radio astronomy activities at IIA since 1952 when the first observations were carried out.

  7. Ultra-Wideband Harmonic Radar for Locating Radio-Frequency Electronics

    Science.gov (United States)

    2015-03-01

    Ultra-Wideband Harmonic Radar for Locating Radio- Frequency Electronics by Gregory J Mazzaro, Kyle A Gallagher, Albert R Owens, Kelly D...Department of the Army position unless so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an...Research Laboratory Adelphi, MD 20783-1138 ARL-TR-7256 March 2015 Ultra-Wideband Harmonic Radar for Locating Radio- Frequency Electronics

  8. Radio-Frequency Field-Induced Quantum Interference Effects in Cold Atoms

    Institute of Scientific and Technical Information of China (English)

    龙全; 周蜀渝; 周善钰; 王育竹

    2001-01-01

    We propose constructing a quantum interference configuration for cold atoms in a magneto-optical trap by applying a radio frequency field, which coherently couples adjacent Zeeman sublevels, in combination with a repumping laser field. One effect of this interference is that a dip exists in the absorption of the repumping light when the radio frequency is scanned. Our prediction has been indirectly detected through the fluorescence of cold atoms in a preliminary experiment.

  9. Surface Planar Ion Chip for Linear Radio-Frequency Paul Traps

    Institute of Scientific and Technical Information of China (English)

    WAN Jin-Yin; QU Qiu-Zhi; ZHOU Zi-Chao; LI Xiao-Lin; WANG Yu-Zhu; LIU Liang

    2007-01-01

    We propose a surface planar ion chip which forms a linear radio frequency Paul ion trap. The electrodes reside in the two planes of a chip, and the trap axis is located above the chip surface. Its electric field and potential distribution are similar to the standard linear radio frequency Paul ion trap. This ion trap geometry may be greatly meaningful for quantum information processing.

  10. Relations between integrated and monochromatic luminosities of flat-spectrum radio quasars

    Institute of Scientific and Technical Information of China (English)

    Zhi-Fu Chen; Zhao-Yu Chen; Yi-Ping Qin; Min-Feng Gu; Lian-Zhong Lü; Cheng-Yue Su; You-Bing Li; Ye Chen

    2011-01-01

    We employ a sample of 362 flat-spectrum radio quasars (FSRQs) to calculate their integrated luminosities by integrating the spectral energy distribution (SED) constructed with multi-band (radio, IR, optical, UV and X-ray) data.We compare these luminosities with those estimated from monochromatic luminosities by multiplying them by the conventional bolometric correction factors.Our analysis shows that the integrated luminosities calculated from the SED are much larger than the bolometric luminosities estimated from monochromatic luminosities.Their departing behavior tightly correlates with radio luminosities.The relations between integrated and monochromatic luminosities are explored, which are regarded as empirical relations that might be more suitable to be applied to estimate integrated luminosities of FSRQs from their monochromatic luminosities.

  11. Spread spectrum communication system with chaotic frequency modulation

    Science.gov (United States)

    Volkovskii, A. R.; Tsimring, L. Sh.; Rulkov, N. F.; Langmore, I.

    2005-09-01

    A new spread spectrum communication system utilizing chaotic frequency modulation of sinusoidal signals is discussed. A single phase lock loop (PLL) system in the receiver is used both to synchronize the local chaotic oscillator and to recover the information signal. We study the dynamics of the synchronization process, stability of the PLL system, and evaluate the bit-error-rate performance of this chaos-based communication system.

  12. Radio frequency identification-enabled capabilities in a healthcare context: An exploratory study.

    Science.gov (United States)

    Hornyak, Rob; Lewis, Mark; Sankaranarayan, Balaji

    2016-09-01

    Increasingly, the adoption and use of radio frequency identification systems in hospital settings is gaining prominence. However, despite the transformative impact that radio frequency identification has in healthcare settings, few studies have examined how and why this change may occur. The purpose of this study is to systematically understand how radio frequency identification can transform work practices in an operational process that directly impacts cost and operational efficiency and indirectly contributes to impacting patient safety and quality of care. We leverage an interdisciplinary framework to explore the contextual characteristics that shape the assimilation of radio frequency identification in healthcare settings. By linking the use of radio frequency identification with specific contextual dimensions in healthcare settings, we provide a data-driven account of how and why radio frequency identification can be useful in inventory management in this setting. In doing so, we also contribute to recent work by information systems scholars who argue for a reconfiguration of conventional assumptions regarding the role of technology in contemporary organizations.

  13. Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data

    Energy Technology Data Exchange (ETDEWEB)

    Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC), Universitat Politècnica de València, C/ Paranimf 1, Gandia, 46730 Spain (Spain); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568, Colmar, 68008 France (France); André, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, Vilanova i la Geltrú, Barcelona, 08800 Spain (Spain); Anton, G. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, Erlangen, 91058 Germany (Germany); Aubert, J.-J.; Bertin, V.; Brunner, J.; Busto, J. [Aix Marseille Université, CNRS/IN2P3, CPPM UMR 7346, Marseille, 13288 France (France); Baret, B. [APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, rue Alice Domon et Léonie Duquet, Paris Cedex 13, F-75205 France (France); Barrios-Martí, J. [IFIC - Instituto de Física Corpuscular, Edificios Investigación de Paterna, CSIC - Universitat de València, Apdo de Correos 22085, Valencia, 46071 Spain (Spain); Basa, S. [LAM - Laboratoire d' Astrophysique de Marseille, Pôle de l' Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, Marseille Cedex 13, 13388 France (France); Biagi, S. [INFN - Sezione di Bologna, Viale Berti-Pichat 6/2, Bologna, 40127 Italy (Italy); Bogazzi, C.; Bormuth, R.; Bouwhuis, M.C.; Bruijn, R. [Nikhef, Science Park 105, Amsterdam, 1098XG The Netherlands (Netherlands); Capone, A. [INFN -Sezione di Roma, P.le Aldo Moro 2, Roma, 00185 Italy (Italy); Caramete, L., E-mail: antares.spokesperson@in2p3.fr [Institute for Space Sciences, Bucharest, Măgurele, R-77125 Romania (Romania); and others

    2014-11-01

    This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazar populations. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed Flat-Spectrum Radio Quasars. The magnification factor is estimated for each system assuming a singular isothermal profile for the lens. Based on data collected from 2007 to 2012 by the ANTARES neutrino telescope, the strongest constraint is obtained from the lensed quasar B0218+357, providing a limit on the total neutrino luminosity of this source of 1.08× 10{sup 46} erg s{sup -1}. This limit is about one order of magnitude lower than those previously obtained in the ANTARES standard point source searches with non-lensed Flat-Spectrum Radio Quasars.

  14. Target Channel Visiting Order Design Using Particle Swarm Optimization for Spectrum Handoff in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Shilian Zheng

    2014-08-01

    Full Text Available In a dynamic spectrum access network, when a primary user (licensed user reappears on the current channel, cognitive radios (CRs need to vacate the channel and reestablish a communications link on some other channel to avoid interference to primary users, resulting in spectrum handoff. This paper studies the problem of designing target channel visiting order for spectrum handoff to minimize expected spectrum handoff delay. A particle swarm optimization (PSO based algorithm is proposed to solve the problem. Simulation results show that the proposed algorithm performs far better than random target channel visiting scheme. The solutions obtained by PSO are very close to the optimal solution which further validates the effectiveness of the proposed method.

  15. ISO observations of a sample of Compact Steep Spectrum and GHz Peaked Spectrum Radio Galaxies

    CERN Document Server

    Fanti, C; Fanti, R; Baum, S A; O'Dea, C P; Bremer, M; Dallacasa, D; Falcke, H; De Graauw, T; Marecki, A; Miley, G K; Röttgering, H J A; Schilizzi, R T; Snellen, I; Spencer, R E; Stanghellini, C

    2000-01-01

    We present results from observations obtained with ISOPHOT, on board the ISO satellite, of a representative sample of seventeen CSS/GPS radio galaxies and of a control sample of sixteen extended radio galaxies spanning similar ranges in redshift (0.2 = 10^26 W/Hz). The observations have been performed at lambda = 60, 90, 174 and 200 microns. Seven of the CSS/GPS sources have detections >= 3 sigma at one or more wavelengths, one of which is detected at >= 5 sigma. By co-adding the data we have obtained average flux densities at the four wavelengths. We found no evidence that the FIR luminosities of the CSS/GPS sources are significantly different from those of the extended objects and therefore there is not any support for CSS/GPS sources being objects "frustrated" by an abnormally dense ambient medium. The two samples were then combined, providing FIR information on a new sample of radio galaxies at intermediate redshifts. We compare this information with what previously known from IRAS and discuss the average...

  16. Near-infrared imaging of the host galaxies of intermediate redshift steep spectrum radio quasars

    CERN Document Server

    Kotilainen, J K

    2000-01-01

    We present the results of near-infrared H-band (1.65 microns) imaging of 19 steep spectrum radio quasars (SSRQ) in the redshift range 0.5 < z < 1.0. This sample of SSRQs is matched with our previously studied complete sample of 20 flat spectrum radio quasars (FSRQ) with respect to redshift and optical and radio luminosity. We are able to clearly detect the host galaxy in 10 (53 %) SSRQs and marginally in 6 (32 %) others, while the host remains unresolved in 3 (16 %) SSRQs. The galaxies hosting the SSRQs are large (average bulge scale-length R(e) = 9.0+-1.7 kpc) and luminous (average M(H) = -27.2+-1.1). They are, therefore, about 2 mag more luminous than the typical galaxy luminosity L* (M*(H) = -25.0+-0.2), and about 1 mag more luminous than the brightest cluster galaxies (M(H) = -26.3+-0.3). The SSRQ hosts appear to have similar luminosity to those of the FSRQ hosts (M(H) = -27), and they fall between the luminosities of lower redshift (M(H) = -26) and higher redshift (M(H) = -29) radio-loud quasars. T...

  17. Hard X-Ray Spectrum from West Lobe of Radio Galaxy Fornax A Observed with Suzaku

    CERN Document Server

    Tashiro, Makoto S; Seta, Hiromi; Matsuta, Keiko; Yaji, Yuichi

    2009-01-01

    An observation of the West lobe of radio galaxy Fornax A (NGC 1316) with Suzaku is reported. Since Feigelson et al. (1995) and Kaneda et al. (1995) discovered the cosmic microwave background boosted inverse-Comptonized (IC) X-rays from the radio lobe, the magnetic field and electron energy density in the lobes have been estimated under the assumption that a single component of the relativistic electrons generates both the IC X-rays and the synchrotron radio emission. However, electrons generating the observed IC X-rays in the 1 -- 10 keV band do not possess sufficient energy to radiate the observed synchrotron radio emission under the estimated magnetic field of a few micro-G. On the basis of observations made with Suzaku, we show in the present paper that a 0.7 -- 20 keV spectrum is well described by a single power-law model with an energy index of 0.68 and a flux density of 0.12+/-0.01 nJy at 1 keV from the West lobe. The derived multiwavelength spectrum strongly suggests that a single electron energy distr...

  18. Frequency Correction for MIRO Chirp Transformation Spectroscopy Spectrum

    Science.gov (United States)

    Lee, Seungwon

    2012-01-01

    This software processes the flyby spectra of the Chirp Transform Spectrometer (CTS) of the Microwave Instrument for Rosetta Orbiter (MIRO). The tool corrects the effect of Doppler shift and local-oscillator (LO) frequency shift during the flyby mode of MIRO operations. The frequency correction for CTS flyby spectra is performed and is integrated with multiple spectra into a high signal-to-noise averaged spectrum at the rest-frame RF frequency. This innovation also generates the 8 molecular line spectra by dividing continuous 4,096-channel CTS spectra. The 8 line spectra can then be readily used for scientific investigations. A spectral line that is at its rest frequency in the frame of the Earth or an asteroid will be observed with a time-varying Doppler shift as seen by MIRO. The frequency shift is toward the higher RF frequencies on approach, and toward lower RF frequencies on departure. The magnitude of the shift depends on the flyby velocity. The result of time-varying Doppler shift is that of an observed spectral line will be seen to move from channel to channel in the CTS spectrometer. The direction (higher or lower frequency) in the spectrometer depends on the spectral line frequency under consideration. In order to analyze the flyby spectra, two steps are required. First, individual spectra must be corrected for the Doppler shift so that individual spectra can be superimposed at the same rest frequency for integration purposes. Second, a correction needs to be applied to the CTS spectra to account for the LO frequency shifts that are applied to asteroid mode.

  19. Reducing Spectrum Handoffs and Energy Switching Consumption of MADM-Based Decisions in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Rafael Aguilar-Gonzalez

    2016-01-01

    Full Text Available In a cognitive radio network (CRN, the number of spectrum handoffs increases energy consumption of cognitive (or secondary users due to the channel switching process. This might limit the operation of the CRN, especially in scenarios where secondary users terminals are battery-powered. Thus, reducing the number of times a cognitive user involved in a transmission switch to different spectrum holes is required to increase battery life-time. In this regard, available spectrum holes possess different attributes (e.g., bandwidth that can be exploited to satisfy specific secondary users requirements (i.e., connection profile for data transmission while saving energy. Here, three multiple attribute decision-making (MADM algorithms for the spectrum decision functionality are evaluated using real spectrum measurements of TV bands. This is performed by proposing six decision parameters, which are extracted from the spectrum data to characterize its suitability. Then, these are used as inputs of the MADM algorithms to select the most suitable spectrum hole for a cognitive user. Thus, an enhanced MADM-based decision process is proposed to reduce the number of handoffs considering energy consumption due to channel switching (ECCS. Results quantify savings from 30% to 90% in ECCS and spectrum handoffs reductions from 47% to 90%.

  20. Optimal Entropy-Based Cooperative Spectrum Sensing for Maritime Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Waleed Ejaz

    2013-11-01

    Full Text Available Maritime cognitive radio networks (MCRNs have recently been proposed for opportunistic utilization of the licensed band. Spectrum sensing is one of the key issues for the successful deployment of the MCRNs. The maritime environment is unique in terms of radio wave propagation over water, surface reflection and wave occlusions. In order to deal with the challenging maritime environment, we proposed an optimal entropy-based cooperative spectrum sensing. As the results of spectrum sensing are sensitive to the number of samples in an entropy-based local detection scheme, we first calculated the optimal number of samples. Next, a cooperative spectrum sensing scheme considering the conditions of the sea environment is proposed. Finally, the throughput optimization of the m-out-of-n rule is considered. Results revealed that although the existing schemes work well for the lower sea states, they fail to perform at higher sea states. Moreover, simulation results also indicated the robustness of the entropy-based scheme and the proposed cooperative spectrum sensing scheme at higher sea states in comparison with the traditional energy detector.

  1. On the scalability of cognitive radio: : Assessing the commercial viability of secondary spectrum access

    OpenAIRE

    Zander, Jens; Rasmussen, Lars K.; Sung, Ki Won; Maehoenen, Petri; Petrova, Marina; Jantti, Riku; Kronander, Jonas

    2013-01-01

    We report results from the recently finished QUASAR project, which has studied overall system aspects of cognitive radio technologies and has paid attention particularly to the economic viability of different use cases. We find that successful secondary sharing goes far beyond the detection of spectrum holes. Large-scale commercial success requires that secondary systems are scalable so that a large number of users can be served in an economically viable fashion. Our key finding is that secon...

  2. Introducing Smartness in Future Wireless Systems Spectrum Utilization: A Cognitive Radio Perspective

    DEFF Research Database (Denmark)

    Marchetti, Nicola; Rahman, Muhammad Imadur; Frederiksen, Flemming Bjerge

    2007-01-01

    Next generation wireless systems requirements in terms of data rate and spectrum efficiency can be fulfilled only if some smartness is put into the system and Cognitive Radio (CR) is the technical means to achieve that. A general overview of this technology will be given from hardware, lower layers...... and networking point of view. Some interesting issues to be investigated will be introduced as examples of the challenges and benefits related to CR....

  3. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    Science.gov (United States)

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  4. The broad-band radio spectrum of LSI+61303 in outburst

    CERN Document Server

    Zimmermann, L; Massi, M

    2015-01-01

    Aims: Our aim is to explore the broad-band radio continuum spectrum of LSI+61303 during its outbursts by employing the available set of secondary focus receivers of the Effelsberg 100 m telescope. Methods: The clear periodicity of the system LSI+61303 allowed observations to be scheduled covering the large radio outburst in March-April 2012. We observed LSI+61303 on 14 consecutive days at 2.6, 4.85, 8.35, 10.45, 14.3, 23, and 32 GHz with a cadence of about 12 hours followed by two additional observations several days later. Based on these observations we obtained a total of 24 quasi-simultaneous broad-band radio spectra. Results: During onset, the main flare shows an almost flat broad-band spectrum, most prominently seen on March 27, 2012, where - for the first time - a flat spectrum (alpha=0.00+/-0.07, S nu^alpha) is observed up to 32 GHz (9 mm wavelength). The flare decay phase shows superimposed 'sub-flares' with the spectral index oscillating between -0.4 and -0.1 in a quasi-regular fashion. Finally, the ...

  5. Cognitive Radio Engine Model Utilizing Soft Fusion Based Genetic Algorithm for Cooperative Spectrum Optimization

    Directory of Open Access Journals (Sweden)

    Kamal Hossain

    2013-04-01

    Full Text Available Cognitive radio (CR is to detect the presence of primary users (PUs reliably in order to reduce theinterference to licensed communications. Genetic algorithms (GAs are well suited for CR optimizationproblems to increase efficiency of bandwidth utilization by manipulating its unused portions of theapparent spectrum. In this paper, a binary genetic algorithm (BGA-based soft fusion (SF scheme forcooperative spectrum sensing in cognitive radio network is proposed to improve detection performance andbandwidth utilization. The BGA-based optimization method is implemented at the fusion centre of a linearSF scheme to optimize the weighting coefficients vector to maximize global probability of detectionperformance. Simulation results and analyses confirm that the proposed scheme meets real timerequirements of cognitive radio spectrum sensing and it outperforms conventional natural deflectioncoefficient- (NDC-, modified deflection coefficient- (MDC-, maximal ratio combining- (MRC- and equalgain combining- (EGC- based SDF schemes as well as the OR-rule based hard decision fusion (HDF. Thepropose BGA scheme also converges fast and achieves the optimum performance, which means that BGAbasedmethod is efficient and quite stable also.

  6. Radio Gaga? Intra-team communication of Australian Rules Football umpires - effect of radio communication on content, structure and frequency.

    Science.gov (United States)

    Neville, Timothy J; Salmon, Paul M; Read, Gemma J M

    2017-07-31

    Intra-team communication plays an important role in team effectiveness in various domains including sport. As such, it is a key consideration when introducing new tools within systems that utilise teams. The difference in intra-team communication of Australian Rules Football (AFL) umpiring teams was studied when umpiring with or without radio communications technology. A cross-sectional observational study was conducted to analyse the verbal communication of seven umpiring teams (20 participants) grouped according to their experience with radio communication. The results identified that radio communication technology increased the frequency and altered the structure of intra-team communication. Examination of the content of the intra-team communication identified impacts on the 'Big Five' teamwork behaviours and associated coordinating mechanisms. Analysis revealed that the communications utilised did not align with the closed-loop form of communication described in the Big Five model. Implications for teamwork models, coaching and training of AFL umpires are discussed. Practitioner Summary: Assessing the impact of technology on performance is of interest to ergonomics practitioners. The impact of radio communications on teamwork is explored in the highly dynamic domain of AFL umpiring. When given radio technology, intra-team communication increased which supported teamwork behaviours, such as backup behaviour and mutual performance monitoring.

  7. Radio Frequency Radiation of Millimeter Wave Length: An Evaluation of Potential Occupational Safety Issues Relating to Surface Heating

    Science.gov (United States)

    2016-06-14

    Radio frequency radiation of millimeter wave length: An evaluation of potential occupational safety issues. 5a. CONTRACT NUMBER 5b. GRANT NUMBER...Paper------------------------------- RADIO FREQUENCY RADIATION OF MILLIMETER WAVE LENGTH: POTENTIAL OCCUPATIONAL...cancer. Health Phys. 78(2):170-181; 2000 Key words: cancer; radiation , nonionizing; occupational safety; radiofrequency INTRODUCTION THE RADIO

  8. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  9. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  10. Endotoxin removal by radio frequency gas plasma (glow discharge)

    Science.gov (United States)

    Poon, Angela

    2011-12-01

    Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were

  11. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  12. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  13. The Radio-to-X-Ray Spectrum of GRB 970508 on 1997 May 21.0 UT

    Science.gov (United States)

    Galama, T. J.; Wijers, R. A. M. J.; Bremer, M.; Groot, P. J.; Strom, R. G.; Kouveliotou. C.; vanParadijs, J.

    1998-01-01

    We have reconstructed the spectrum of the afterglow of GRB 970508 on 1997 May 21.0 UT (12.1 days after the gamma-ray burst burst) on the basis of observations spanning, the X-ray-to-radio range. The low-frequency power-law index of the spectrum, alpha = 0.44 +/- 0.07 (F, proportional to nu(sup alpha)) is in agreement with the expected value alpha = 1/3 for optically thin synchrotron radiation. The 1.4 emission is self-absorbed. We infer constraints on the break frequencies nu(sub c) and nu(sub m) on 1997 May 21.0 UT from a spectral transition from F, approximately nu(sup -0.6) to F, approximately nu(sup -1.1) in the optical passband around 1.4 days. A model of an adiabatically expanding blast wave emitting synchrotrons radiation, in which a significant fraction of the electrons cool rapidly, provides a successful and consistent description of the afterglow observations over nine decades in frequency, ranging in time from trigger until several months later.

  14. Cooperative spectrum sensing schemes with the interference constraint in cognitive radio networks.

    Science.gov (United States)

    Do, Tri-Nhu; An, Beongku

    2014-05-05

    In this paper, we propose cooperative spectrum sensing schemes, called decode-and-forward cooperative spectrum sensing (DF-CSS) scheme and amplify-and-forward cooperative spectrum sensing (AF-CSS) scheme, in cognitive radio networks. The main goals and features of the proposed cooperative spectrum sensing schemes are as follows: first, we solve the problem of high demand for bandwidth in a soft decision scheme using in our proposed schemes. Furthermore, the impact of transmission power of relaying users which is determined by the interference constraint on sensing performance of cooperative spectrum sensing schemes is also investigated. Second, we analyze the sensing performance of our proposed cooperative spectrum sensing schemes in terms of detection probability and interference probability, respectively. We take into account the interference caused by secondary user (SU) to primary user (PU) in the case that the transmission power of the relaying users exceeds a predefined interference constraint assigned by the primary user. The simulation results show that in cooperative spectrum sensing schemes the total sensing performance depends not only on the interference tolerance level, but also on the relay protocols used. We also prove that high transmission power of relaying users increases the interference between the secondary networks and the primary network.

  15. Effect of dipole-quadrupole Robinson mode coupling upon the beam response to radio-frequency phase noise

    Directory of Open Access Journals (Sweden)

    R. A. Bosch

    2006-09-01

    Full Text Available In an electron storage ring, coupling between dipole and quadrupole Robinson oscillations modifies the spectrum of longitudinal beam oscillations driven by radio-frequency (rf generator phase noise. In addition to the main peak at the resonant frequency of the coupled dipole Robinson mode, another peak occurs at the resonant frequency of the coupled quadrupole mode. To describe these peaks analytically for a quadratic synchrotron potential, we include the dipole and quadrupole modes when calculating the beam response to generator noise. We thereby obtain the transfer function from generator-noise phase modulation to beam phase modulation with and without phase feedback. For Robinson-stable bunches confined in a synchrotron potential with a single minimum, the calculated transfer function agrees with measurements at the Aladdin 800-MeV electron storage ring. The transfer function is useful in evaluating phase feedback that suppresses Robinson oscillations in order to obtain quiet operation of an infrared beam line.

  16. Long range ultra-high frequency (UHF) radio frequency identification (RFID) antenna design

    Science.gov (United States)

    Reynolds, Nathan D.

    There is an ever-increasing demand for radio frequency identification (RFID) tags that are passive, long range, and mountable on multiple surfaces. Currently, RFID technology is utilized in numerous applications such as supply chain management, access control, and public transportation. With the combination of sensory systems in recent years, the applications of RFID technology have been extended beyond tracking and identifying. This extension includes applications such as environmental monitoring and healthcare applications. The available sensory systems usually operate in the medium or high frequency bands and have a low read range. However, the range limitations of these systems are being overcome by the development of RFID sensors focused on utilizing tags in the ultra-high frequency (UHF) band. Generally, RFID tags have to be mounted to the object that is being identified. Often the objects requiring identification are metallic. The inherent properties of metallic objects have substantial effects on nearby electromagnetic radiation; therefore, the operation of the tag antenna is affected when mounted on a metallic surface. This outlines one of the most challenging problems for RFID systems today: the optimization of tag antenna performance in a complex environment. In this research, a novel UHF RFID tag antenna, which has a low profile, long range, and is mountable on metallic surfaces, is designed analytically and simulated using a 3-D electromagnetic simulator, ANSYS HFSS. A microstrip patch antenna is selected as the antenna structure, as patch antennas are low profile and suitable for mounting on metallic surfaces. Matching and theoretical models of the microstrip patch antenna are investigated. Once matching and theory of a microstrip patch antenna is thoroughly understood, a unique design technique using electromagnetic band gap (EBG) structures is explored. This research shows that the utilization of an EBG structure in the patch antenna design yields

  17. A Spectrum Handoff Scheme for Optimal Network Selection in NEMO Based Cognitive Radio Vehicular Networks

    Directory of Open Access Journals (Sweden)

    Krishan Kumar

    2017-01-01

    Full Text Available When a mobile network changes its point of attachments in Cognitive Radio (CR vehicular networks, the Mobile Router (MR requires spectrum handoff. Network Mobility (NEMO in CR vehicular networks is concerned with the management of this movement. In future NEMO based CR vehicular networks deployment, multiple radio access networks may coexist in the overlapping areas having different characteristics in terms of multiple attributes. The CR vehicular node may have the capability to make call for two or more types of nonsafety services such as voice, video, and best effort simultaneously. Hence, it becomes difficult for MR to select optimal network for the spectrum handoff. This can be done by performing spectrum handoff using Multiple Attributes Decision Making (MADM methods which is the objective of the paper. The MADM methods such as grey relational analysis and cost based methods are used. The application of MADM methods provides wider and optimum choice among the available networks with quality of service. Numerical results reveal that the proposed scheme is effective for spectrum handoff decision for optimal network selection with reduced complexity in NEMO based CR vehicular networks.

  18. Flexible radio-frequency photonics: Optoelectronic frequency combs and integrated pulse shaping

    Science.gov (United States)

    Metcalf, Andrew J.

    Microwave photonics is a discipline which leverages optoelectronics to enhance the generation, transport, and processing of high-frequency electrical signals. At the heart of many emerging techniques is the optical frequency comb. A comb is a lightwave source whose spectrum is made up of discrete equally spaced spectral components that share a fixed phase relationship. These discrete coherent oscillators --known as comb lines-- collectively form a Fourier basis that describe a periodic optical waveform. Within the last two decades frequency-stabilized broadband combs produced from mode-locked lasers have led to revolutionary advancements in precision optical frequency synthesis and metrology. Meanwhile, Fourier-transform optical pulse shaping, which provides a means to control a comb's Fourier basis in both amplitude and phase, has emerged as an integral tool in optical communications, broadband waveform generation, and microwave photonic filtering. However, traditional comb and pulse shaping architectures are often plagued by complex and bulky setups, rendering robust and cost effective implementation outside of the laboratory a challenge. In addition, traditional comb sources based on short-pulse lasers do not possess qualities which are ideally suited for this new application regime. Motivated by the shortcomings in current architectures, and empowered by recent advancements in optoelectronic technology, this dissertation focuses on developing novel and robust schemes in optical frequency comb generation and line-by-line pulse shaping. Our results include: the invention and low-noise characterization of a broadband flat-top comb source; the realization of an optoelectronic-based time cloak; and finally, the development of an integrated pulse shaper, which we use in conjunction with our flat-top comb source to demonstrate a rapidly reconfigurable microwave photonic filter.

  19. The spectral variability of the GHZ-Peaked spectrum radio source PKS 1718-649 and a comparison of absorption models

    Energy Technology Data Exchange (ETDEWEB)

    Tingay, S. J.; Macquart, J.-P.; Wayth, R. B.; Trott, C. M.; Emrich, D. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia); Collier, J. D.; Wong, G. F. [University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 (Australia); Rees, G.; Stevens, J.; Carretti, E. [CSIRO Astronomy and Space Science (CASS), PO Box 76, Epping, NSW 1710 (Australia); Callingham, J. R.; Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics (SiFA), The University of Sydney, NSW 2006 (Australia); McKinley, B.; Briggs, F. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Bernardi, G. [Square Kilometre Array South Africa (SKA SA), Cape Town 7405 (South Africa); Bowman, J. D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Cappallo, R. J.; Corey, B. E. [MIT Haystack Observatory, Westford, MA 01886 (United States); Deshpande, A. A. [Raman Research Institute, Bangalore 560080 (India); Goeke, R., E-mail: s.tingay@curtin.edu.au [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2015-02-01

    Using the new wideband capabilities of the ATCA, we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over 3 epochs spanning approximately 21 months, reveal variability both above the spectral peak at ∼3 GHz and below the peak. The combination of the low- and high-frequency variability cannot be easily explained using a single absorption mechanism, such as free–free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free–free optical depth on our line of sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of active galactic nuclei is considered. We find that the cause of the peaked spectrum in PKS 1718-649 is most likely due to free–free absorption. In agreement with previous studies, we find that the spectrum at each epoch of observation is best fit by a free–free absorption model characterized by a power-law distribution of free–free absorbing clouds. This agreement is extended to frequencies below the 1 GHz lower limit of the ATCA by considering new observations with Parkes at 725 MHz and 199 MHz observations with the newly operational Murchison Widefield Array. These lower frequency observations argue against families of absorption models (both free–free and synchrotron self-absorption) that are based on simple homogenous structures.

  20. Distributed Spectrum Sharing for Video Streaming in Cognitive Radio Ad Hoc Networks

    Science.gov (United States)

    Ding, Lei; Pudlewski, Scott; Melodia, Tommaso; Batalama, Stella; Matyjas, John D.; Medley, Michael J.

    A distributed joint routing and spectrum sharing algorithm for video streaming applications over cognitive radio ad hoc networks is proposed in this article. The proposed cross-layer control scheme dynamically allocates routes, spectrum and power to maximize the network throughput under the constraints posed by delay-sensitive video applications. The algorithm evaluates the expected delay of competing flows in single-hop and two-hop networks considering the time-varying spectrum condition and occupancy, traffic characteristics, and the condition of queues at intermediate nodes. Simulation results show that the proposed algorithm significantly reduces the packet loss rate and improves the average peak signal-to-noise ratio (PSNR) of the received video streams.