Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

2011-01-01

The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

modeling the effect of bandwidth allocation on network performance

African Journals Online (AJOL)

Using MATLAB, simulations were then .... of the network resource. Network bandwidth design, simulation, and management ... encoder processes longer signal data blocks, which entails longer ... c is the modulated signal carrier. However, the ...

Effective information rates of single-carrier and multi-carrier modulation schemes for bandwidth constrained IM/DD systems

KAUST Repository

Mazahir, Sana

2017-07-31

Information-theoretic and signal processing aspects of some modulation schemes designed for intensity modulation/direct detection (IM/DD) optical wireless communication (OWC) systems are studied. Due to the constraints of IM/DD signals (non-negative real and baseband signals), the construction of these signals along with their time and frequency characteristics differ from their RF counterparts. This necessitates a careful study of such schemes under practical constraints. Three schemes are studied in this paper, namely, single carrier pulse amplitude modulation (SC-PAM), asymmetrically clipped optical OFDM (ACO-OFDM), and DC biased optical OFDM (DCO-OFDM). Our aim is to carry out a comparative study of these schemes in the presence of identical constraints on bandwidth and average optical power. The study reveals that the clipping operation required in ACO-OFDM significantly reduces its information rate, and as a result, it is outperformed by SC-PAM. Such a limitation does not apply to DCO-OFDM which has a higher information rate, even though part of the available optical power is expended in the non-information-bearing DC bias.

Re-use of Low Bandwidth Equipment for High Bit Rate Transmission Using Signal Slicing Technique

DEFF Research Database (Denmark)

Wagner, Christoph; Spolitis, S.; Vegas Olmos, Juan José

: Massive fiber-to-the-home network deployment requires never ending equipment upgrades operating at higher bandwidth. We show effective signal slicing method, which can reuse low bandwidth opto-electronical components for optical communications at higher bit rates.......: Massive fiber-to-the-home network deployment requires never ending equipment upgrades operating at higher bandwidth. We show effective signal slicing method, which can reuse low bandwidth opto-electronical components for optical communications at higher bit rates....

Bandwidths of micro-twisted-pair cables and fusion-spliced SIMM-GRIN fiber

International Nuclear Information System (INIS)

Gan, K.K.; Kagan, H.P.; Kass, R.D.; Smith, D.S.

2007-01-01

The SLHC is designed to increase the luminosity of the LHC by a factor of 10. In the present ATLAS pixel detector, electrical signals between the pixel modules and the optical modules (opto-boards) are transmitted in ∼1 m of micro-twisted-pair cables. The optical signals between the opto-boards and the off-detector optical modules are transmitted in fiber ribbons. Each fiber link consists of 8 m of rad-hard/low bandwidth SIMM fiber fusion spliced to 70 m of rad-tolerant/medium bandwidth GRIN fiber. We currently transmit optical signals at 80 Mb/s and expect to transmit signals at 1 Gb/s in the SLHC. For the SLHC optical link, we would like to take advantage of some of the design features of the present pixel optical links and the many years of R and D effort and production experience. If the present architecture can transmit signals at the higher speed required by the SLHC, the constraint of requiring no extra service space is automatically satisfied. We have measured the bandwidths of the transmission lines and our preliminary results indicate that the micro-twisted-pair cables can transmit signals up to ∼1 Gb/s and the fusion-spliced fiber ribbon can transmit signals up to ∼2 Gb/s

Multi-granularity Bandwidth Allocation for Large-Scale WDM/TDM PON

Science.gov (United States)

Gao, Ziyue; Gan, Chaoqin; Ni, Cuiping; Shi, Qiongling

2017-12-01

WDM (wavelength-division multiplexing)/TDM (time-division multiplexing) PON (passive optical network) is being viewed as a promising solution for delivering multiple services and applications, such as high-definition video, video conference and data traffic. Considering the real-time transmission, QoS (quality of services) requirements and differentiated services model, a multi-granularity dynamic bandwidth allocation (DBA) in both domains of wavelengths and time for large-scale hybrid WDM/TDM PON is proposed in this paper. The proposed scheme achieves load balance by using the bandwidth prediction. Based on the bandwidth prediction, the wavelength assignment can be realized fairly and effectively to satisfy the different demands of various classes. Specially, the allocation of residual bandwidth further augments the DBA and makes full use of bandwidth resources in the network. To further improve the network performance, two schemes named extending the cycle of one free wavelength (ECoFW) and large bandwidth shrinkage (LBS) are proposed, which can prevent transmission from interruption when the user employs more than one wavelength. The simulation results show the effectiveness of the proposed scheme.

Small signal modulation characteristics of red-emitting (λ = 610 nm) III-nitride nanowire array lasers on (001) silicon

KAUST Repository

Jahangir, Shafat; Frost, Thomas; Hazari, Arnab; Yan, Lifan; Stark, Ethan; LaMountain, Trevor; Millunchick, Joanna M.; Ooi, Boon S.; Bhattacharya, Pallab

2015-01-01

The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and α-parameter, and large differential gain (3.1 × 10-17 cm2).

Small signal modulation characteristics of red-emitting (λ = 610 nm) III-nitride nanowire array lasers on (001) silicon

KAUST Repository

Jahangir, Shafat

2015-02-16

The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and α-parameter, and large differential gain (3.1 × 10-17 cm2).

Load-induced modulation of signal transduction networks.

Science.gov (United States)

Jiang, Peng; Ventura, Alejandra C; Sontag, Eduardo D; Merajver, Sofia D; Ninfa, Alexander J; Del Vecchio, Domitilla

2011-10-11

Biological signal transduction networks are commonly viewed as circuits that pass along information--in the process amplifying signals, enhancing sensitivity, or performing other signal-processing tasks--to transcriptional and other components. Here, we report on a "reverse-causality" phenomenon, which we call load-induced modulation. Through a combination of analytical and experimental tools, we discovered that signaling was modulated, in a surprising way, by downstream targets that receive the signal and, in doing so, apply what in physics is called a load. Specifically, we found that non-intuitive changes in response dynamics occurred for a covalent modification cycle when load was present. Loading altered the response time of a system, depending on whether the activity of one of the enzymes was maximal and the other was operating at its minimal rate or whether both enzymes were operating at submaximal rates. These two conditions, which we call "limit regime" and "intermediate regime," were associated with increased or decreased response times, respectively. The bandwidth, the range of frequency in which the system can process information, decreased in the presence of load, suggesting that downstream targets participate in establishing a balance between noise-filtering capabilities and a circuit's ability to process high-frequency stimulation. Nodes in a signaling network are not independent relay devices, but rather are modulated by their downstream targets.

A High Density Low Cost Digital Signal Processing Module for Large Scale Radiation Detectors

International Nuclear Information System (INIS)

Tan, Hui; Hennig, Wolfgang; Walby, Mark D.; Breus, Dimitry; Harris, Jackson T.; Grudberg, Peter M.; Warburton, William K.

2013-06-01

A 32-channel digital spectrometer PIXIE-32 is being developed for nuclear physics or other radiation detection applications requiring digital signal processing with large number of channels at relatively low cost. A single PIXIE-32 provides spectrometry and waveform acquisition for 32 input signals per module whereas multiple modules can be combined into larger systems. It is based on the PCI Express standard which allows data transfer rates to the host computer of up to 800 MB/s. Each of the 32 channels in a PIXIE-32 module accepts signals directly from a detector preamplifier or photomultiplier. Digitally controlled offsets can be individually adjusted for each channel. Signals are digitized in 12-bit, 50 MHz multi-channel ADCs. Triggering, pile-up inspection and filtering of the data stream are performed in real time, and pulse heights and other event data are calculated on an event-by event basis. The hardware architecture, internal and external triggering features, and the spectrometry and waveform acquisition capability of the PIXIE- 32 as well as its capability to distribute clock and triggers among multiple modules, are presented. (authors)

Preamplifier design with wide bandwidth using InGaP/GaAs HBT for 10-Gbps photoreceiver module

International Nuclear Information System (INIS)

Hong, S. E.; Lim, J. M.; Kim, S. I.; Nam, E. S.

2004-01-01

We report a preamplifier with wide bandwidth using high-speed and reliable InGaP/GaAs HBT applicable for 10-Gbps photoreceiver modules. The three-stage preamplifier with a negative feedback resistor demonstrates an effective transimpedance gain of 43 dBΩ, a -3-dB bandwidth of 14 GHz corresponding to a very high transimpedance-bandwidth product of 2.52 THzΩ, and an output return loss of -18 dB up to -3-dB bandwidth. This compact circuit is fabricated with an area of 800 X 700 μm 2 . A photoreceiver module of surface-mountable package type, that is composed of preamplifier and photodiode of surface-illumination type, demonstrates an optical bandwidth of 7.5 GHz at λ = 1.55 μ m and a 45-psec rise/fall time for 10-Gbps. The module shows higher sensitivity for a 10-Gbps optical transmission system.

Modulator reliability and bandwidth improvement: replacing tetrodes with MOSFETs

International Nuclear Information System (INIS)

Donaldson, A.R.

1982-01-01

Three types of power MOS field effect transistors were studied with the intent of replacing a parallel pair of vacuum tube tetrodes in a linear modulator. The tetrodes have the shortest lifetimes of any other tubes in the system. The FETs offer definite performance advantages when compared to bipolar transistors and definite cost advantages when compared to vacuum tubes. Replacement of the tetrodes does however require careful consideration of voltage, current and to a lesser extent bandwidth capability in order to enhance overall modulator reliability without compromising present performance

Visible light communications modulation and signal processing

CERN Document Server

Wang, Zhaocheng; Huang, Wei; Xu, Zhengyuan

2018-01-01

This informative new book on state-of-the-art visible light communication (VLC) provides, for the first time, a systematical and advanced treatment of modulation and signal processing for VLC. Visible Light Communications: Modulation and Signal Processing offers a practical guide to designing VLC, linking academic research with commercial applications. In recent years, VLC has attracted attention from academia and industry since it has many advantages over the traditional radio frequency, including wide unregulated bandwidth, high security, and low cost. It is a promising complementary technique in 5G and beyond wireless communications, especially in indoor applications. However, lighting constraints have not been fully considered in the open literature when considering VLC system design, and its importance has been underestimated. That’s why this book—written by a team of experts with both academic research experience and industrial development experience in the field—is so welcome. To help readers u...

Bandwidth tunable amplifier for recording biopotential signals.

Science.gov (United States)

Hwang, Sungkil; Aninakwa, Kofi; Sonkusale, Sameer

2010-01-01

This paper presents a low noise, low power, bandwidth tunable amplifier for bio-potential signal recording applications. By employing depletion-mode pMOS transistor in diode configuration as a tunable sub pA current source to adjust the resistivity of MOS-Bipolar pseudo-resistor, the bandwidth is adjusted without any need for a separate band-pass filter stage. For high CMRR, PSRR and dynamic range, a fully differential structure is used in the design of the amplifier. The amplifier achieves a midband gain of 39.8dB with a tunable high-pass cutoff frequency ranging from 0.1Hz to 300Hz. The amplifier is fabricated in 0.18εm CMOS process and occupies 0.14mm(2) of chip area. A three electrode ECG measurement is performed using the proposed amplifier to show its feasibility for low power, compact wearable ECG monitoring application.

Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

Science.gov (United States)

Peled, Itay; Kaminsky, Ron; Kotler, Zvi

2015-06-01

In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.

GHz modulation enabled using large extinction ratio waveguide-modulator integrated with 404 nm GaN laser diode

KAUST Repository

Shen, Chao

2017-01-30

A 404-nm emitting InGaN-based laser diode with integrated-waveguide-modulator showing a large extinction ratio of 11.3 dB was demonstrated on semipolar (2021) plane GaN substrate. The device shows a low modulation voltage of −2.5 V and ∼ GHz −3 dB bandwidth, enabling 1.7 Gbps data transmission.

GHz modulation enabled using large extinction ratio waveguide-modulator integrated with 404 nm GaN laser diode

KAUST Repository

Shen, Chao; Lee, Changmin; Ng, Tien Khee; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.; Alyamani, Ahmed Y.; Eldesouki, Munir M.; Ooi, Boon S.

2017-01-01

A 404-nm emitting InGaN-based laser diode with integrated-waveguide-modulator showing a large extinction ratio of 11.3 dB was demonstrated on semipolar (2021) plane GaN substrate. The device shows a low modulation voltage of −2.5 V and ∼ GHz −3 dB bandwidth, enabling 1.7 Gbps data transmission.

Structured Low-Density Parity-Check Codes with Bandwidth Efficient Modulation

Science.gov (United States)

Cheng, Michael K.; Divsalar, Dariush; Duy, Stephanie

2009-01-01

In this work, we study the performance of structured Low-Density Parity-Check (LDPC) Codes together with bandwidth efficient modulations. We consider protograph-based LDPC codes that facilitate high-speed hardware implementations and have minimum distances that grow linearly with block sizes. We cover various higher- order modulations such as 8-PSK, 16-APSK, and 16-QAM. During demodulation, a demapper transforms the received in-phase and quadrature samples into reliability information that feeds the binary LDPC decoder. We will compare various low-complexity demappers and provide simulation results for assorted coded-modulation combinations on the additive white Gaussian noise and independent Rayleigh fading channels.

EMG-Torque Dynamics Change With Contraction Bandwidth.

Science.gov (United States)

Golkar, Mahsa A; Jalaleddini, Kian; Kearney, Robert E

2018-04-01

An accurate model for ElectroMyoGram (EMG)-torque dynamics has many uses. One of its applications which has gained high attention among researchers is its use, in estimating the muscle contraction level for the efficient control of prosthesis. In this paper, the dynamic relationship between the surface EMG and torque during isometric contractions at the human ankle was studied using system identification techniques. Subjects voluntarily modulated their ankle torque in dorsiflexion direction, by activating their tibialis anterior muscle, while tracking a pseudo-random binary sequence in a torque matching task. The effects of contraction bandwidth, described by torque spectrum, on EMG-torque dynamics were evaluated by varying the visual command switching time. Nonparametric impulse response functions (IRF) were estimated between the processed surface EMG and torque. It was demonstrated that: 1) at low contraction bandwidths, the identified IRFs had unphysiological anticipatory (i.e., non-causal) components, whose amplitude decreased as the contraction bandwidth increased. We hypothesized that this non-causal behavior arose, because the EMG input contained a component due to feedback from the output torque, i.e., it was recorded from within a closed-loop. Vision was not the feedback source since the non-causal behavior persisted when visual feedback was removed. Repeating the identification using a nonparametric closed-loop identification algorithm yielded causal IRFs at all bandwidths, supporting this hypothesis. 2) EMG-torque dynamics became faster and the bandwidth of system increased as contraction modulation rate increased. Thus, accurate prediction of torque from EMG signals must take into account the contraction bandwidth sensitivity of this system.

Challenges in Polybinary Modulation for Bandwidth Limited Optical Links

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Tafur Monroy, Idelfonso; Madsen, Peter

2016-01-01

effectively increase the available capacity. Advanced modulation formats however require digitalization of the signals and digital signal processing blocks to both generate and recover the data. There is therefore a trade-off in terms of efficiency gain vs complexity. Polybinary modulation, a generalized form...

Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

International Nuclear Information System (INIS)

Prosnitz, D.; Scharlemann, E.T.; Sheaffer, M.K.

1991-10-01

Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by π radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple arguments

Optical spectral reshaping for directly modulated 4-pulse amplitude modulation signals

DEFF Research Database (Denmark)

Ozolins, Oskars; Da Ros, Francesco; Cristofori, Valentina

2017-01-01

The tremendous traffic growth in intra/inter-datacenters requires low-cost high-speed integrated solutions [1]. To enable a significantly reduced footprint directly modulated lasers (DMLs) have been proposed instead of large external modulators. However, it is challenging to use DMLs due to their......The tremendous traffic growth in intra/inter-datacenters requires low-cost high-speed integrated solutions [1]. To enable a significantly reduced footprint directly modulated lasers (DMLs) have been proposed instead of large external modulators. However, it is challenging to use DMLs due...... (PAM) [3] signals. However, moving to 4-PAM,many of the impressive demonstrations reported so far rely heavily on off-line digital signal processing (DSP), which increases latency, power consumption and cost. In this talk, we report on (i) a detailed numerical analysis on the complex transfer function...... of the optical filter for optical spectral reshaping in case of pulse amplitude modulation and(ii) an experimental demonstration of real-time dispersion-uncompensated transmission of 10-GBd and 14-GBd 4-PAM signals up to 10- and 26-km SSMF. This is achieved by combining a commercial 10-Gb/s DML with optical...

Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

DEFF Research Database (Denmark)

Bach, L.; Kaiser, W.; Reithmaier, J.P.

2003-01-01

Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

International Nuclear Information System (INIS)

Ng, L C; Holzrichter, J F; Larson, P E

2001-01-01

Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation

Extended-bandwidth frequency sweeps of a distributed feedback laser using combined injection current and temperature modulation.

Science.gov (United States)

Hefferman, Gerald; Chen, Zhen; Wei, Tao

2017-07-01

This article details the generation of an extended-bandwidth frequency sweep using a single, communication grade distributed feedback (DFB) laser. The frequency sweep is generated using a two-step technique. In the first step, injection current modulation is employed as a means of varying the output frequency of a DFB laser over a bandwidth of 99.26 GHz. A digital optical phase lock loop is used to lock the frequency sweep speed during current modulation, resulting in a linear frequency chirp. In the second step, the temperature of the DFB laser is modulated, resulting in a shifted starting laser output frequency. A laser frequency chirp is again generated beginning at this shifted starting frequency, resulting in a frequency-shifted spectrum relative to the first recorded data. This process is then repeated across a range of starting temperatures, resulting in a series of partially overlapping, frequency-shifted spectra. These spectra are then aligned using cross-correlation and combined using averaging to form a single, broadband spectrum with a total bandwidth of 510.9 GHz. In order to investigate the utility of this technique, experimental testing was performed in which the approach was used as the swept-frequency source of a coherent optical frequency domain reflectometry system. This system was used to interrogate an optical fiber containing a 20 point, 1-mm pitch length fiber Bragg grating, corresponding to a period of 100 GHz. Using this technique, both the periodicity of the grating in the frequency domain and the individual reflector elements of the structure in the time domain were resolved, demonstrating the technique's potential as a method of extending the sweeping bandwidth of semiconductor lasers for frequency-based sensing applications.

Extended-bandwidth frequency sweeps of a distributed feedback laser using combined injection current and temperature modulation

Science.gov (United States)

Hefferman, Gerald; Chen, Zhen; Wei, Tao

2017-07-01

This article details the generation of an extended-bandwidth frequency sweep using a single, communication grade distributed feedback (DFB) laser. The frequency sweep is generated using a two-step technique. In the first step, injection current modulation is employed as a means of varying the output frequency of a DFB laser over a bandwidth of 99.26 GHz. A digital optical phase lock loop is used to lock the frequency sweep speed during current modulation, resulting in a linear frequency chirp. In the second step, the temperature of the DFB laser is modulated, resulting in a shifted starting laser output frequency. A laser frequency chirp is again generated beginning at this shifted starting frequency, resulting in a frequency-shifted spectrum relative to the first recorded data. This process is then repeated across a range of starting temperatures, resulting in a series of partially overlapping, frequency-shifted spectra. These spectra are then aligned using cross-correlation and combined using averaging to form a single, broadband spectrum with a total bandwidth of 510.9 GHz. In order to investigate the utility of this technique, experimental testing was performed in which the approach was used as the swept-frequency source of a coherent optical frequency domain reflectometry system. This system was used to interrogate an optical fiber containing a 20 point, 1-mm pitch length fiber Bragg grating, corresponding to a period of 100 GHz. Using this technique, both the periodicity of the grating in the frequency domain and the individual reflector elements of the structure in the time domain were resolved, demonstrating the technique's potential as a method of extending the sweeping bandwidth of semiconductor lasers for frequency-based sensing applications.

Small-signal modulation and differential gain of red-emitting (λ = 630 nm) InGaN/GaN quantum dot lasers

Energy Technology Data Exchange (ETDEWEB)

Frost, Thomas; Banerjee, Animesh; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2013-11-18

We report small-signal modulation bandwidth and differential gain measurements of a ridge waveguide In{sub 0.4}Ga{sub 0.6}N/GaN quantum dot laser grown by molecular beam epitaxy. The laser peak emission is at λ = 630 nm. The −3 dB bandwidth of an 800 μm long device was measured to be 2.4 GHz at 250 mA under pulsed biasing, demonstrating the possibility of high-speed operation of these devices. The differential gain was measured to be 5.3 × 10{sup −17} cm{sup 2}, and a gain compression factor of 2.87 × 10{sup −17} cm{sup 3} is also derived from the small-signal modulation response.

Optical signal processing techniques and applications of optical phase modulation in high-speed communication systems

Science.gov (United States)

Deng, Ning

In recent years, optical phase modulation has attracted much research attention in the field of fiber optic communications. Compared with the traditional optical intensity-modulated signal, one of the main merits of the optical phase-modulated signal is the better transmission performance. For optical phase modulation, in spite of the comprehensive study of its transmission performance, only a little research has been carried out in terms of its functions, applications and signal processing for future optical networks. These issues are systematically investigated in this thesis. The research findings suggest that optical phase modulation and its signal processing can greatly facilitate flexible network functions and high bandwidth which can be enjoyed by end users. In the thesis, the most important physical-layer technology, signal processing and multiplexing, are investigated with optical phase-modulated signals. Novel and advantageous signal processing and multiplexing approaches are proposed and studied. Experimental investigations are also reported and discussed in the thesis. Optical time-division multiplexing and demultiplexing. With the ever-increasing demand on communication bandwidth, optical time division multiplexing (OTDM) is an effective approach to upgrade the capacity of each wavelength channel in current optical systems. OTDM multiplexing can be simply realized, however, the demultiplexing requires relatively complicated signal processing and stringent timing control, and thus hinders its practicability. To tackle this problem, in this thesis a new OTDM scheme with hybrid DPSK and OOK signals is proposed. Experimental investigation shows this scheme can greatly enhance the demultiplexing timing misalignment and improve the demultiplexing performance, and thus make OTDM more practical and cost effective. All-optical signal processing. In current and future optical communication systems and networks, the data rate per wavelength has been approaching

Coarse-Grain Bandwidth Estimation Scheme for Large-Scale Network

Science.gov (United States)

Cheung, Kar-Ming; Jennings, Esther H.; Sergui, John S.

2013-01-01

A large-scale network that supports a large number of users can have an aggregate data rate of hundreds of Mbps at any time. High-fidelity simulation of a large-scale network might be too complicated and memory-intensive for typical commercial-off-the-shelf (COTS) tools. Unlike a large commercial wide-area-network (WAN) that shares diverse network resources among diverse users and has a complex topology that requires routing mechanism and flow control, the ground communication links of a space network operate under the assumption of a guaranteed dedicated bandwidth allocation between specific sparse endpoints in a star-like topology. This work solved the network design problem of estimating the bandwidths of a ground network architecture option that offer different service classes to meet the latency requirements of different user data types. In this work, a top-down analysis and simulation approach was created to size the bandwidths of a store-and-forward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. These techniques were used to estimate the WAN bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network. A new analytical approach, called the "leveling scheme," was developed to model the store-and-forward mechanism of the network data flow. The term "leveling" refers to the spreading of data across a longer time horizon without violating the corresponding latency requirement of the data type. Two versions of the leveling scheme were developed: 1. A straightforward version that simply spreads the data of each data type across the time horizon and doesn't take into account the interactions among data types within a pass, or between data types across overlapping passes at a network node, and is inherently sub-optimal. 2. Two-state Markov leveling scheme that takes into account the second order behavior of

Calculus of the Power Spectral Density of Ultra Wide Band Pulse Position Modulation Signals Coded with Totally Flipped Code

Directory of Open Access Journals (Sweden)

DURNEA, T. N.

2009-02-01

Full Text Available UWB-PPM systems were noted to have a power spectral density (p.s.d. consisting of a continuous portion and a line spectrum, which is composed of energy components placed at discrete frequencies. These components are the major source of interference to narrowband systems operating in the same frequency interval and deny harmless coexistence of UWB-PPM and narrowband systems. A new code denoted as Totally Flipped Code (TFC is applied to them in order to eliminate these discrete spectral components. The coded signal transports the information inside pulse position and will have the amplitude coded to generate a continuous p.s.d. We have designed the code and calculated the power spectral density of the coded signals. The power spectrum has no discrete components and its envelope is largely flat inside the bandwidth with a maximum at its center and a null at D.C. These characteristics make this code suited for implementation in the UWB systems based on PPM-type modulation as it assures a continuous spectrum and keeps PPM modulation performances.

Design and Analysis of Enhanced Modulation Response in Integrated Coupled Cavities DBR Lasers Using Photon-Photon Resonance

Directory of Open Access Journals (Sweden)

Paolo Bardella

2016-01-01

Full Text Available In the last few decades, various solutions have been proposed to increase the modulation bandwidth and, consequently, the transmission bit-rate of semiconductor lasers. In this manuscript, we discuss a design procedure for a recently proposed laser cavity realized with the monolithic integration of two distributed Bragg reflector (DBR lasers allowing one to extend the modulation bandwidth. Such an extension is obtained introducing in the dynamic response a photon-photon resonance (PPR at a frequency higher than the modulation bandwidth of the corresponding single-section laser. Design guidelines will be proposed, and dynamic small and large signal simulations results, calculated using a finite difference traveling wave (FDTW numerical simulator, will be discussed to confirm the design results. The effectiveness of the design procedure is verified in a structure with PPR frequency at 35 GHz allowing one to obtain an open eye diagram for a non-return-to-zero (NRZ digital signal up to 80 GHz . Furthermore, the investigation of the rich dynamics of this structure shows that with proper bias conditions, it is possible to obtain also a tunable self-pulsating signal in a frequency range related to the PPR design.

Self-aligned BCB planarization method for high-frequency signal injection in a VCSEL with an integrated modulator

Science.gov (United States)

Marigo-Lombart, Ludovic; Doucet, Jean-Baptiste; Lecestre, Aurélie; Reig, Benjamin; Rousset, Bernard; Thienpont, Hugo; Panajotov, Krassimir; Almuneau, Guilhem

2016-04-01

The huge increase of datacom capacities requires lasers sources with more and more bandwidth performances. Vertical-Cavity Surface-Emitting Lasers (VCSEL) in direct modulation is a good candidate, already widely used for short communication links such as in datacenters. Recently several different approaches have been proposed to further extend the direct modulation bandwidth of these devices, by improving the VCSEL structure, or by combining the VCSEL with another high speed element such as lateral slow light modulator or transistor/laser based structure (TVCSEL). We propose to increase the modulation bandwidth by vertically integrating a continuous-wave VCSEL with a high-speed electro-modulator. This vertical structure implies multiple electrodes with sufficiently good electrical separation between the different input electrical signals. This high frequency modulation requires both good electrical insulation between metal electrodes and an optimized design of the coplanar lines. BenzoCyclobutene (BCB) thanks to its low dielectric constant, low losses, low moisture absorption and good thermal stability, is often used as insulating layer. Also, BCB planarization offers the advantages of simpler and more reliable technological process flow in such integrated VCSEL/modulator structures with important reliefs. As described by Burdeaux et al. a degree of planarization (DOP) of about 95% can be achieved by simple spin coating whatever the device thickness. In most of the cases, the BCB planarization process requires an additional photolithography step in order to open an access to the mesa surface, thus involving a tight mask alignment and resulting in a degraded planarization. In this paper, we propose a self-aligned process with improved BCB planarization by combining a hot isostatic pressing derived from nanoimprint techniques with a dry plasma etching step.

Compact electro-absorption modulator integrated with vertical-cavity surface-emitting laser for highly efficient millimeter-wave modulation

International Nuclear Information System (INIS)

Dalir, Hamed; Ahmed, Moustafa; Bakry, Ahmed; Koyama, Fumio

2014-01-01

We demonstrate a compact electro-absorption slow-light modulator laterally-integrated with an 850 nm vertical-cavity surface-emitting laser (VCSEL), which enables highly efficient millimeter-wave modulation. We found a strong leaky travelling wave in the lateral direction between the two cavities via widening the waveguide width with a taper shape. The small signal response of the fabricated device shows a large enhancement of over 55 dB in the modulation amplitude at frequencies beyond 35 GHz; thanks to the photon-photon resonance. A large group index of over 150 in a Bragg reflector waveguide enables the resonance at millimeter wave frequencies for 25 μm long compact modulator. Based on the modeling, we expect a resonant modulation at a higher frequency of 70 GHz. The resonant modulation in a compact slow-light modulator plays a significant key role for high efficient narrow-band modulation in the millimeter wave range far beyond the intrinsic modulation bandwidth of VCSELs.

All-optical microwave signal processing based on optical phase modulation

Science.gov (United States)

Zeng, Fei

This thesis presents a theoretical and experimental study of optical phase modulation and its applications in all-optical microwave signal processing, which include all-optical microwave filtering, all-optical microwave mixing, optical code-division multiple-access (CDMA) coding, and ultrawideband (UWB) signal generation. All-optical microwave signal processing can be considered as the use of opto-electronic devices and systems to process microwave signals in the optical domain, which provides several significant advantages such as low loss, low dispersion, light weight, high time bandwidth products, and immunity to electromagnetic interference. In conventional approaches, the intensity of an optical carrier is modulated by a microwave signal based on direct modulation or external modulation. The intensity-modulated optical signal is then fed to a photonic circuit or system to achieve specific signal processing functionalities. The microwave signal being processed is usually obtained based on direct detection, i.e., an opto-electronic conversion by use of a photodiode. In this thesis, the research efforts are focused on the optical phase modulation and its applications in all-optical microwave signal processing. To avoid using coherent detection which is complicated and costly, simple and effective phase modulation to intensity modulation (PM-IM) conversion schemes are pursued. Based on a theoretical study of optical phase modulation, two approaches to achieving PM-IM conversions are proposed. In the first approach, the use of chromatic dispersion induced by a dispersive device to alter the phase relationships among the sidebands and the optical carrier of a phase-modulated optical signal to realize PM-IM conversion is investigated. In the second approach, instead of using a dispersive device, the PM-IM conversion is realized based on optical frequency discrimination implemented using an optical filter. We show that the proposed PM-IM conversion schemes can be

GHz-bandwidth upconversion detector using a unidirectional ring cavity to reduce multilongitudinal mode pump effects

DEFF Research Database (Denmark)

Meng, Lichun; Høgstedt, Lasse; Tidemand-Lichtenberg, Peter

2017-01-01

We demonstrate efficient upconversion of modulated infrared (IR) signals over a wide bandwidth (up to frequencies in excess of 1 GHz) via cavity-enhanced sum-frequency generation (SFG) in a periodically poled LiNbO3. Intensity modulated IR signal is produced by combining beams from two 1547 nm...... narrow-linewidth lasers in a fiber coupler while tuning their wavelength difference down to 10 pm or less. The SFG crystal is placed inside an Nd:YVO4 ring cavity that provides 1064 nm circulating pump powers of up to 150 W in unidirectional operation. Measured Fabry-Perot spectrum at 1064 nm confirms...... the enhanced spectral stability from multiple to single longitudinal mode pumping condition. We describe analytically and demonstrate experimentally the deleterious effects of using a multimode pump to the high-bandwidth RF spectrum of the 630 nm SFG output. Offering enhanced sensitivity without the need...

Moiré volume Bragg grating filter with tunable bandwidth.

Science.gov (United States)

Mokhov, Sergiy; Ott, Daniel; Divliansky, Ivan; Zeldovich, Boris; Glebov, Leonid

2014-08-25

We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longitudinal envelope profile will shift from a sine profile to a cosine profile across the face of the device. The transmission peak of the filter has a tunable bandwidth while remaining at a fixed resonant wavelength by a transversal shift of incidence position. Analytical expressions for the tunable bandwidth of such a filter are calculated and experimental data from a filter operating at 1064 nm with bandwidth range 30-90 pm is demonstrated.

Teleoperation over low bandwidth communication links

International Nuclear Information System (INIS)

Fryer, R.J.; Mair, G.M.; Clark, N.; Heng, J.

1996-01-01

Teleoperation is well established for many areas of hazardous environment working. Where such environments are well structured and contained, such as within a working plant, communications bandwidths need not be a constraining factor. However where the worksite is remote, large, poorly structured or damaged communications rapidly become a critical factor in the efficient deployment and use of teleoperation equipment. The paper justifies and describes means which we are exploring to reduce the required communications bandwidth for teleoperation whist retaining full functionality. Techniques involved include incorporation of local intelligence at the worksite, with bandwidth devoted to high-level up-link control signals and down-link feedback, and the use of highly compressed video feeding 'virtual reality type' HMDs to provide maximum system transparency for the operator. The work is drawing on previous experience with an 'anthropomorphic robot heat' for telepresence work, and proprietary algorithms capable of compressing full colour video to standard telephone modem data rates. (Author)

Half-cycle QAM modulation for VCSEL-based optical links

DEFF Research Database (Denmark)

Pham, Tien Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee

2012-01-01

Abstract (40-Word Limit): Novel spectrally efficient half-cycle QAM modulation is experimentally demonstrated. 10 Gbps 4-QAM signal in 7.5-GHz bandwidth was successfully transmitted over 20 km SMF using an un-cooled 1.5 µm VCSEL with no equalization applied.......Abstract (40-Word Limit): Novel spectrally efficient half-cycle QAM modulation is experimentally demonstrated. 10 Gbps 4-QAM signal in 7.5-GHz bandwidth was successfully transmitted over 20 km SMF using an un-cooled 1.5 µm VCSEL with no equalization applied....

Large signal simulation of photonic crystal Fano laser

DEFF Research Database (Denmark)

Zali, Aref Rasoulzadeh; Yu, Yi; Moravvej-Farshi, Mohammad Kazem

2017-01-01

be modulated at frequencies exceeding 1 THz which is much higher than its corresponding relaxation oscillation frequency. Large signal simulation of the Fano laser is also investigated based on pseudorandom bit sequence at 0.5 Tbit/s. It shows eye patterns are open at such high modulation frequency, verifying...

Decoding a combined amplitude modulated and frequency modulated signal

DEFF Research Database (Denmark)

2015-01-01

The present disclosure relates to a method for decoding a combined AM/FM encoded signal, comprising the steps of: combining said encoded optical signal with light from a local oscillator configured with a local oscillator frequency; converting the combined local oscillator and encoded optical...... signal into one or more electrical signals by means of at least one opto-electrical converter having a predefined frequency bandwidth, thereby providing an amplified and encoded electrical signal having one or more encoded signal current(s), where one type of states have a higher oscillation frequency...... than other type of states; rectifying the encoded signal current(s), thereby obtaining an encoded power spectrum, wherein said power spectrum has different states, such as "0"-states and "1"-states, with different power levels such that they can be discriminated, said local oscillator frequency...

The effects of noise-bandwidth, noise-fringe duration, and temporal signal location on the binaural masking-level difference.

Science.gov (United States)

Yasin, Ifat; Henning, G Bruce

2012-07-01

The effects of forward and backward noise fringes on binaural signal detectability were investigated. Masked thresholds for a 12-ms, 250-Hz, sinusoidal signal masked by Gaussian noise, centered at 250 Hz, with bandwidths from 3 to 201 Hz, were obtained in N(0)S(0) and N(0)S(π) configurations. The signal was (a) temporally centered in a 12-ms noise burst (no fringe), (b) presented at the start of a 600-ms noise burst (backward fringe), or (c) temporally centered in a 600-ms noise burst (forward-plus-backward fringe). For noise bandwidths between 3 and 75 Hz, detection in N(0)S(0) improved with the addition of a backward fringe, improving further with an additional forward fringe; there was little improvement in N(0)S(π). The binaural masking-level difference (BMLD) increased from 0 to 8 dB with a forward-plus-backward fringe as noise bandwidths increased to 100 Hz, increasing slightly to 10 dB at 201 Hz. This two-stage increase was less pronounced with a backward fringe. With no fringe, the BMLD was about 10-14 dB at all bandwidths. Performance appears to result from the interaction of across-time and across-frequency listening strategies and the possible effects of gain reduction and suppression, which combine in complex ways. Current binaural models are, as yet, unable to account fully for these effects.

Combined Source-Channel Coding of Images under Power and Bandwidth Constraints

Directory of Open Access Journals (Sweden)

Fossorier Marc

2007-01-01

Full Text Available This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope -ary phase shift key ( -PSK signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded -PSK signaling (with . Then, it is extended to include coded -PSK modulation using trellis coded modulation (TCM. An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded -PSK signaling performs 3.1 to 5.2 dB better than uncoded -PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.

Improved-Bandwidth Transimpedance Amplifier

Science.gov (United States)

Chapsky, Jacob

2009-01-01

The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

Performance evaluation of multilevel modulation formats using partial response for capacity upgrade in access network with limited electronic bandwidth

DEFF Research Database (Denmark)

Madsen, Peter; Suhr, Lau Frejstrup; Rodríguez Páez, Juan Sebastián

2016-01-01

We present a successful experimental evaluation of 4 level Pulse Amplitude Modulation (4-PAM) and Duobinary modulation. An experimental performance evaluation is presented for Duobinary 4 PAM and other modulation formats. All modulation formants used, may be considered to be implemented in future...... Passive Optical Network (PON) class access networks with limited electrical bandwidth. We compared NRZ, Duobinary, 4-PAM and Duobinary 4-PAM operating at 9 Gbaud over 20 km single mode fiber. The results provides an insight and guidelines on the utilization of these advanced modulation formats....

Automatic modulation recognition of communication signals

CERN Document Server

Azzouz, Elsayed Elsayed

1996-01-01

Automatic modulation recognition is a rapidly evolving area of signal analysis. In recent years, interest from the academic and military research institutes has focused around the research and development of modulation recognition algorithms. Any communication intelligence (COMINT) system comprises three main blocks: receiver front-end, modulation recogniser and output stage. Considerable work has been done in the area of receiver front-ends. The work at the output stage is concerned with information extraction, recording and exploitation and begins with signal demodulation, that requires accurate knowledge about the signal modulation type. There are, however, two main reasons for knowing the current modulation type of a signal; to preserve the signal information content and to decide upon the suitable counter action, such as jamming. Automatic Modulation Recognition of Communications Signals describes in depth this modulation recognition process. Drawing on several years of research, the authors provide a cr...

Pseudo-Random Modulation of a Laser Diode for Generating Ultrasonic Longitudinal Waves

Science.gov (United States)

Madaras, Eric I.; Anatasi, Robert F.

2004-01-01

Laser generated ultrasound systems have historically been more complicated and expensive than conventional piezoelectric based systems, and this fact has relegated the acceptance of laser based systems to niche applications for which piezoelectric based systems are less suitable. Lowering system costs, while improving throughput, increasing ultrasound signal levels, and improving signal-to-noise are goals which will help increase the general acceptance of laser based ultrasound. One current limitation with conventional laser generated ultrasound is a material s damage threshold limit. Increasing the optical power to generate more signal eventually damages the material being tested due to rapid, high heating. Generation limitations for laser based ultrasound suggests the use of pulse modulation techniques as an alternate generation method. Pulse modulation techniques can spread the laser energy over time or space, thus reducing laser power densities and minimizing damage. Previous experiments by various organizations using spatial or temporal pulse modulation have been shown to generate detectable surface, plate, and bulk ultrasonic waves with narrow frequency bandwidths . Using narrow frequency bandwidths improved signal detectability, but required the use of expensive and powerful lasers and opto-electronic systems. The use of a laser diode to generate ultrasound is attractive because of its low cost, small size, light weight, simple optics and modulation capability. The use of pulse compression techniques should allow certain types of laser diodes to produce usable ultrasonic signals. The method also does not need to be limited to narrow frequency bandwidths. The method demonstrated here uses a low power laser diode (approximately 150 mW) that is modulated by controlling the diode s drive current and the resulting signal is recovered by cross correlation. A potential application for this system which is briefly demonstrated is in detecting signals in thick

47 CFR 74.535 - Emission and bandwidth.

Science.gov (United States)

2010-10-01

... digital modulation in paragraph (a) of this section, the resolution bandwidth (BRES) of the measuring...), adjusted upward to the nearest greater resolution bandwidth available on the measuring equipment. In all... frequency energy outside the assigned channel. Upon notice by the FCC to the station licensee that...

Experimental study of coexistence of multi-band OFDM-UWB and OFDM-baseband signals in long-reach PONs using directly modulated lasers.

Science.gov (United States)

Morgado, José A P; Fonseca, Daniel; Cartaxo, Adolfo V T

2011-11-07

Transmission of coexisting Orthogonal Frequency Division Multiplexing (OFDM)-baseband (BB) and multi-band OFDM-ultra-wideband (UWB) signals along long-reach passive optical networks using directly modulated lasers (DML) is experimentally demonstrated.When optimized modulation indexes are used, bit error ratios not exceeding 5 × 10⁻⁴ can be achieved by all (OFDM-BB and three OFDM-UWB sub-bands) signals for a reach of 100 km of standard single-mode fiber (SSMF) and optical signal-to-noise ratios not lower than 25dB@0.1 nm. It is experimentally shown that, for the SSMF reach of 100km, the optimized performance of coexisting OFDM-BB and OFDM-UWB signals is mainly imposed by the combination of two effects: the SSMF dispersion-induced nonlinear distortion of the OFDM-UWB signals caused by the OFDM-BB and OFDM-UWB signals, and the further degradation of the OFDM-UWB signals with higher frequency, due to the reduced DML bandwidth.

Modulator-free quadrature amplitude modulation signal synthesis

Science.gov (United States)

Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O'Carroll, John; Phelan, Richard; Richardson, David J.; Slavík, Radan

2014-12-01

The ability to generate high-speed on-off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5 Gbit s-1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on-off-keyed 10 Gbit s-1 systems and is absolutely prohibitive for today’s (>)100 Gbit s-1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions.

Towards Bandwidth Scalable Transceiver Technology for Optical Metro-Access Networks

DEFF Research Database (Denmark)

Spolitis, Sandis; Bobrovs, Vjaceslavs; Wagner, Christoph

2015-01-01

sliceable transceiver for 1 Gbit/s non-return to zero (NRZ) signal sliced into two slices is presented. Digital signal processing (DSP) power consumption and latency values for proposed sliceable transceiver technique are also discussed. In this research post FEC with 7% overhead error free transmission has......Massive fiber-to-the-home network deployment is creating a challenge for telecommunications network operators: exponential increase of the power consumption at the central offices and a never ending quest for equipment upgrades operating at higher bandwidth. In this paper, we report on flexible...... signal slicing technique, which allows transmission of high-bandwidth signals via low bandwidth electrical and optoelectrical equipment. The presented signal slicing technique is highly scalable in terms of bandwidth which is determined by the number of slices used. In this paper performance of scalable...

Combined Source-Channel Coding of Images under Power and Bandwidth Constraints

Directory of Open Access Journals (Sweden)

Marc Fossorier

2007-01-01

Full Text Available This paper proposes a framework for combined source-channel coding for a power and bandwidth constrained noisy channel. The framework is applied to progressive image transmission using constant envelope M-ary phase shift key (M-PSK signaling over an additive white Gaussian noise channel. First, the framework is developed for uncoded M-PSK signaling (with M=2k. Then, it is extended to include coded M-PSK modulation using trellis coded modulation (TCM. An adaptive TCM system is also presented. Simulation results show that, depending on the constellation size, coded M-PSK signaling performs 3.1 to 5.2 dB better than uncoded M-PSK signaling. Finally, the performance of our combined source-channel coding scheme is investigated from the channel capacity point of view. Our framework is further extended to include powerful channel codes like turbo and low-density parity-check (LDPC codes. With these powerful codes, our proposed scheme performs about one dB away from the capacity-achieving SNR value of the QPSK channel.

Custom chipset and compact module design for a 75–110 GHz laboratory signal source

International Nuclear Information System (INIS)

Morgan, Matthew A; Boyd, Tod A; Castro, Jason J

2016-01-01

We report on the development and characterization of a compact, full-waveguide bandwidth (WR-10) signal source for general-purpose testing of mm-wave components. The monolithic microwave integrated circuit (MMIC) based multichip module is designed for compactness and ease-of-use, especially in size-constrained test sets such as a wafer probe station. It takes as input a cm-wave continuous-wave (CW) reference and provides a factor of three frequency multiplication as well as amplification, output power adjustment, and in situ output power monitoring. It utilizes a number of custom MMIC chips such as a Schottky-diode limiter and a broadband mm-wave detector, both designed explicitly for this module, as well as custom millimeter-wave multipliers and amplifiers reported in previous papers. (paper)

Novel secure and bandwidth efficient optical code division multiplexed system for future access networks

Science.gov (United States)

Singh, Simranjit

2016-12-01

In this paper, a spectrally coded optical code division multiple access (OCDMA) system using a hybrid modulation scheme has been investigated. The idea is to propose an effective approach for simultaneous improvement of the system capacity and security. Data formats, NRZ (non-return to zero), DQPSK (differential quadrature phase shift keying), and PoISk (polarisation shift keying) are used to get the orthogonal modulated signal. It is observed that the proposed hybrid modulation provides efficient utilisation of bandwidth, increases the data capacity and enhances the data confidentiality over existing OCDMA systems. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes.

Photonics-based real-time ultra-high-range-resolution radar with broadband signal generation and processing.

Science.gov (United States)

Zhang, Fangzheng; Guo, Qingshui; Pan, Shilong

2017-10-23

Real-time and high-resolution target detection is highly desirable in modern radar applications. Electronic techniques have encountered grave difficulties in the development of such radars, which strictly rely on a large instantaneous bandwidth. In this article, a photonics-based real-time high-range-resolution radar is proposed with optical generation and processing of broadband linear frequency modulation (LFM) signals. A broadband LFM signal is generated in the transmitter by photonic frequency quadrupling, and the received echo is de-chirped to a low frequency signal by photonic frequency mixing. The system can operate at a high frequency and a large bandwidth while enabling real-time processing by low-speed analog-to-digital conversion and digital signal processing. A conceptual radar is established. Real-time processing of an 8-GHz LFM signal is achieved with a sampling rate of 500 MSa/s. Accurate distance measurement is implemented with a maximum error of 4 mm within a range of ~3.5 meters. Detection of two targets is demonstrated with a range-resolution as high as 1.875 cm. We believe the proposed radar architecture is a reliable solution to overcome the limitations of current radar on operation bandwidth and processing speed, and it is hopefully to be used in future radars for real-time and high-resolution target detection and imaging.

Reduction of pattern effects in SOA-based all-optical switches by using cross-gain modulated holding signal

DEFF Research Database (Denmark)

Bischoff, Svend; Mørk, Jesper

2002-01-01

The effective carrier lifetime of SOAs is typically shortened by an intense Continuous Wave (CW) holding signal. However, the SOA gain is reduced by the holding signal resulting in smaller gain and refractive index changes induced by the data signal. Accordingly, an optimum exists for the CW...... and data signal power. Here, we demonstrate that the modulation bandwidth (amplitude jitter) is significantly improved (reduced) by replacing the CW holding beam with a signal, which is low-pass filtered and inverted with respect to the data signal. Such a holding beam can be generated by XGM WC in an SOA......, and reduces the fluctuations of the total energy injected into the interferometer within a bit-slot. Thus, we demonstrate a technique for reducing pattern effects in SOAs by employing a partially inverted holding beam. The method should be useful for increasing the data rates of all-optical switches....

Dynamic characteristics of two-state lasing quantum dot lasers under large signal modulation

International Nuclear Information System (INIS)

Lv, Zun-Ren; Ji, Hai-Ming; Luo, Shuai; Gao, Feng; Xu, Feng; Yang, Tao; Xiao, De-Hang

2015-01-01

Large signal modulation characteristics of the simultaneous ground-state (GS) and excited-state (ES) lasing quantum dot lasers are theoretically investigated. Relaxation oscillations of ‘0 → 1’ and ‘1 → 0’ in the GS lasing region (Region I), the transition region from GS lasing to two-state lasing (Region II) and the two-state lasing region (Region III) are compared and analyzed. It is found that the overshooting power and settling time in both Regions I and III decrease as the bias current increases. However, there exist abnormal behaviors of the overshooting power and settling time in Region II owing to the occurrence of ES lasing, which lead to fuzzy eye diagrams of the GS and ES lasing. Moreover, the ES lasing in Region III possesses much better eye diagrams because of its shorter settling time and smaller overshooting power over the GS lasing in Region I

System and Method for Generating a Frequency Modulated Linear Laser Waveform

Science.gov (United States)

Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

2017-01-01

A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

Analysis of mobile fronthaul bandwidth and wireless transmission performance in split-PHY processing architecture.

Science.gov (United States)

Miyamoto, Kenji; Kuwano, Shigeru; Terada, Jun; Otaka, Akihiro

2016-01-25

We analyze the mobile fronthaul (MFH) bandwidth and the wireless transmission performance in the split-PHY processing (SPP) architecture, which redefines the functional split of centralized/cloud RAN (C-RAN) while preserving high wireless coordinated multi-point (CoMP) transmission/reception performance. The SPP architecture splits the base stations (BS) functions between wireless channel coding/decoding and wireless modulation/demodulation, and employs its own CoMP joint transmission and reception schemes. Simulation results show that the SPP architecture reduces the MFH bandwidth by up to 97% from conventional C-RAN while matching the wireless bit error rate (BER) performance of conventional C-RAN in uplink joint reception with only 2-dB signal to noise ratio (SNR) penalty.

Time domain spectral phase encoding/DPSK data modulation using single phase modulator for OCDMA application.

Science.gov (United States)

Wang, Xu; Gao, Zhensen; Kataoka, Nobuyuki; Wada, Naoya

2010-05-10

A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BEROCDMA) and secure optical communication applications. (c) 2010 Optical Society of America.

Apparatus and method for increasing the bandwidth of a laser beam

Science.gov (United States)

Wilcox, Russell B.

1992-01-01

A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulated signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

Coarse-grain bandwidth estimation techniques for large-scale network

Science.gov (United States)

Cheung, Kar-Ming; Jennings, E.

In this paper, we describe a top-down analysis and simulation approach to size the bandwidths of a store-and-forward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. We use these techniques to estimate the wide area network (WAN) bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network.

Duobinary pulse shaping for frequency chirp enabled complex modulation.

Science.gov (United States)

Che, Di; Yuan, Feng; Khodakarami, Hamid; Shieh, William

2016-09-01

The frequency chirp of optical direct modulation (DM) used to be a performance barrier of optical transmission system, because it broadens the signal optical spectrum, which becomes more susceptible to chromatic dispersion induced inter-symbol interference (ISI). However, by considering the chirp as frequency modulation, the single DM simultaneously generates a 2-D signal containing the intensity and phase (namely, the time integral of frequency). This complex modulation concept significantly increases the optical signal to noise ratio (OSNR) sensitivity of DM systems. This Letter studies the duobinary pulse shaping (DB-PS) for chirp enabled DM and its impact on the optical bandwidth and system OSNR sensitivity. DB-PS relieves the bandwidth requirement, at the sacrifice of system OSNR sensitivity. As DB-PS induces a controlled ISI, the receiver requires one more tap for maximum likelihood sequence estimation (MLSE). We verify this modified MLSE with a 10-Gbaud duobinary PAM-4 transmission experiment.

Network Bandwidth Utilization Forecast Model on High Bandwidth Network

Energy Technology Data Exchange (ETDEWEB)

Yoo, Wucherl; Sim, Alex

2014-07-07

With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

Network bandwidth utilization forecast model on high bandwidth networks

Energy Technology Data Exchange (ETDEWEB)

Yoo, Wuchert (William) [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sim, Alex [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-03-30

With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2%. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

Practical continuous-variable quantum key distribution without finite sampling bandwidth effects.

Science.gov (United States)

Li, Huasheng; Wang, Chao; Huang, Peng; Huang, Duan; Wang, Tao; Zeng, Guihua

2016-09-05

In a practical continuous-variable quantum key distribution system, finite sampling bandwidth of the employed analog-to-digital converter at the receiver's side may lead to inaccurate results of pulse peak sampling. Then, errors in the parameters estimation resulted. Subsequently, the system performance decreases and security loopholes are exposed to eavesdroppers. In this paper, we propose a novel data acquisition scheme which consists of two parts, i.e., a dynamic delay adjusting module and a statistical power feedback-control algorithm. The proposed scheme may improve dramatically the data acquisition precision of pulse peak sampling and remove the finite sampling bandwidth effects. Moreover, the optimal peak sampling position of a pulse signal can be dynamically calibrated through monitoring the change of the statistical power of the sampled data in the proposed scheme. This helps to resist against some practical attacks, such as the well-known local oscillator calibration attack.

Full distortion induced by dispersion evaluation and optical bandwidth constraining of fiber Bragg grating demultiplexers over analogue SCM systems.

Science.gov (United States)

Martinez, Alfonso; Pastor, Daniel; Capmany, Jose

2002-12-30

We provide a full analysis of the distortion effects produced by the first and second order in-band dispersion of fiber Bragg grating based optical demultiplexers over analogue SCM (Sub Carrier Multiplexed) signals. Optical bandwidth utilization ranges for Dense WDM network are calculated considering different SCM system cases of frequency extension and modulation conditions.

Differential pulse amplitude modulation for multiple-input single-output OWVLC

Science.gov (United States)

Yang, S. H.; Kwon, D. H.; Kim, S. J.; Son, Y. H.; Han, S. K.

2015-01-01

White light-emitting diodes (LEDs) are widely used for lighting due to their energy efficiency, eco-friendly, and small size than previously light sources such as incandescent, fluorescent bulbs and so on. Optical wireless visible light communication (OWVLC) based on LED merges lighting and communications in applications such as indoor lighting, traffic signals, vehicles, and underwater communications because LED can be easily modulated. However, physical bandwidth of LED is limited about several MHz by slow time constant of the phosphor and characteristics of device. Therefore, using the simplest modulation format which is non-return-zero on-off-keying (NRZ-OOK), the data rate reaches only to dozens Mbit/s. Thus, to improve the transmission capacity, optical filtering and pre-, post-equalizer are adapted. Also, high-speed wireless connectivity is implemented using spectrally efficient modulation methods: orthogonal frequency division multiplexing (OFDM) or discrete multi-tone (DMT). However, these modulation methods need additional digital signal processing such as FFT and IFFT, thus complexity of transmitter and receiver is increasing. To reduce the complexity of transmitter and receiver, we proposed a novel modulation scheme which is named differential pulse amplitude modulation. The proposed modulation scheme transmits different NRZ-OOK signals with same amplitude and unit time delay using each LED chip, respectively. The `N' parallel signals from LEDs are overlapped and directly detected at optical receiver. Received signal is demodulated by power difference between unit time slots. The proposed scheme can overcome the bandwidth limitation of LEDs and data rate can be improved according to number of LEDs without complex digital signal processing.

Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.

Science.gov (United States)

Ferrari, Giorgio; Sampietro, Marco

2007-09-01

This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6 Hz to 1.4 MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems.

SiGe HBT cryogenic preamplification for higher bandwidth donor spin read-out

Science.gov (United States)

Curry, Matthew; Carr, Stephen; Ten-Eyck, Greg; Wendt, Joel; Pluym, Tammy; Lilly, Michael; Carroll, Malcolm

2014-03-01

Single-shot read-out of a donor spin can be performed using the response of a single-electron-transistor (SET). This technique can produce relatively large changes in current, on the order of 1 (nA), to distinguish between the spin states. Despite the relatively large signal, the read-out time resolution has been limited to approximately 100 (kHz) of bandwidth because of noise. Cryogenic pre-amplification has been shown to extend the response of certain detection circuits to shorter time resolution and thus higher bandwidth. We examine a SiGe HBT circuit configuration for cryogenic preamplification, which has potential advantages over commonly used HEMT configurations. Here we present 4 (K) measurements of a circuit consisting of a Silicon-SET inline with a Heterojunction-Bipolar-Transistor (HBT). We compare the measured bandwidth with and without the HBT inline and find that at higher frequencies the signal-to-noise-ratio (SNR) with the HBT inline exceeds the SNR without the HBT inline. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. The work was supported by the Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

A Versatile Multichannel Digital Signal Processing Module for Microcalorimeter Arrays

Science.gov (United States)

Tan, H.; Collins, J. W.; Walby, M.; Hennig, W.; Warburton, W. K.; Grudberg, P.

2012-06-01

Different techniques have been developed for reading out microcalorimeter sensor arrays: individual outputs for small arrays, and time-division or frequency-division or code-division multiplexing for large arrays. Typically, raw waveform data are first read out from the arrays using one of these techniques and then stored on computer hard drives for offline optimum filtering, leading not only to requirements for large storage space but also limitations on achievable count rate. Thus, a read-out module that is capable of processing microcalorimeter signals in real time will be highly desirable. We have developed multichannel digital signal processing electronics that are capable of on-board, real time processing of microcalorimeter sensor signals from multiplexed or individual pixel arrays. It is a 3U PXI module consisting of a standardized core processor board and a set of daughter boards. Each daughter board is designed to interface a specific type of microcalorimeter array to the core processor. The combination of the standardized core plus this set of easily designed and modified daughter boards results in a versatile data acquisition module that not only can easily expand to future detector systems, but is also low cost. In this paper, we first present the core processor/daughter board architecture, and then report the performance of an 8-channel daughter board, which digitizes individual pixel outputs at 1 MSPS with 16-bit precision. We will also introduce a time-division multiplexing type daughter board, which takes in time-division multiplexing signals through fiber-optic cables and then processes the digital signals to generate energy spectra in real time.

Computational expressions for signals in frequency-modulation spectroscopy.

Science.gov (United States)

Di Rosa, Michael D; Reiten, M T

2015-06-01

General expressions for the signals in frequency-modulation spectroscopy (FMS) appear in the literature but are often reduced to simple analytical equations following the assumption of a weak modulation index. This is little help to the experimentalist who wants to predict signals for modulation depths of the order of unity or greater, where strong FMS signals reside. Here, we develop general formulas for FMS signals in the case of an absorber with a Voigt line shape and then link these expressions to an example and existing numerical code for the line shape. The resulting computational recipe is easy to implement and exercised here to show where the larger FMS signals are found over the coordinates of modulation index and modulation frequency. One can also estimate from provided curves the in-phase FMS signal over a wide range of modulation parameters at either the Lorentzian-broadening or Doppler-broadening limit, or anywhere in between by interpolation.

Towards 400GBASE 4-lane Solution Using Direct Detection of MultiCAP Signal in 14 GHz Bandwidth per Lane

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Tianjian, Zuo; Jensen, Jesper Bevensee

2013-01-01

We report on an experimental demonstration of 102 Gbit/s transmission over a 15km single wavelength and polarization fiber link with 14GHz 3dB bandwidth. Novel multiband CAP signaling allows for a 4-lane 400GBASE long reach solution....

37 GHz Direct-Modulation Bandwidth of Multi-Section InGaAsP/InP DBR-Laser with weakly coupled active grating section

DEFF Research Database (Denmark)

Kaiser, W.; Bach, L.; Reithmaier, J. P.

2003-01-01

37 GHz direct-modulation bandwidth could be obtained by a multi-section design with an integrated weakly coupled DBR grating. The laser shows side mode suppression ratios of 45 dB and output powers exceeding 20 mW....

Modulation cues influence binaural masking-level difference in masking-pattern experiments.

Science.gov (United States)

Nitschmann, Marc; Verhey, Jesko L

2012-03-01

Binaural masking patterns show a steep decrease in the binaural masking-level difference (BMLD) when masker and signal have no frequency component in common. Experimental threshold data are presented together with model simulations for a diotic masker centered at 250 or 500 Hz and a bandwidth of 10 or 100 Hz masking a sinusoid interaurally in phase (S(0)) or in antiphase (S(π)). Simulations with a binaural model, including a modulation filterbank for the monaural analysis, indicate that a large portion of the decrease in the BMLD in remote-masking conditions may be due to an additional modulation cue available for monaural detection. © 2012 Acoustical Society of America

Coarse-Grain Bandwidth Estimation Techniques for Large-Scale Space Network

Science.gov (United States)

Cheung, Kar-Ming; Jennings, Esther

2013-01-01

In this paper, we describe a top-down analysis and simulation approach to size the bandwidths of a store-andforward network for a given network topology, a mission traffic scenario, and a set of data types with different latency requirements. We use these techniques to estimate the wide area network (WAN) bandwidths of the ground links for different architecture options of the proposed Integrated Space Communication and Navigation (SCaN) Network.

Lrp4: a novel modulator of extracellular signaling in craniofacial organogenesis

OpenAIRE

Ohazama, Atsushi; Porntaveetus, Thantrira; Ota, Masato S.; Herz, Joachim; Sharpe, Paul T.

2010-01-01

The low-density lipoprotein (LDL) receptor family is a large evolutionarily conserved group of transmembrane proteins. It has been shown that LDL receptor family members can also function as direct signal transducers or modulators for a broad range of cellular signalling pathways. We have identified a novel mode of signalling pathway integration/coordination that occurs outside cells during development that involves an LDL family member. Physical interaction between an extracellular protein (...

Large-signal characterization of DDR silicon IMPATTs operating in millimeter-wave and terahertz regime

International Nuclear Information System (INIS)

Acharyya, Aritra; Banerjee, J. P.; Chakraborty, Jit; Das, Kausik; Datta, Subir; De, Pritam; Banerjee, Suranjana

2013-01-01

The authors have carried out the large-signal characterization of silicon-based double-drift region (DDR) impact avalanche transit time (IMPATT) devices designed to operate up to 0.5 THz using a large-signal simulation method developed by the authors based on non-sinusoidal voltage excitation. The effect of band-to-band tunneling as well as parasitic series resistance on the large-signal properties of DDR Si IMPATTs have also been studied at different mm-wave and THz frequencies. Large-signal simulation results show that DDR Si IMPATT is capable of delivering peak RF power of 633.69 mW with 7.95% conversion efficiency at 94 GHz for 50% voltage modulation, whereas peak RF power output and efficiency fall to 81.08 mW and 2.01% respectively at 0.5 THz for same voltage modulation. The simulation results are compared with the experimental results and are found to be in close agreement. (semiconductor devices)

High-bandwidth memory interface

CERN Document Server

Kim, Chulwoo; Song, Junyoung

2014-01-01

This book provides an overview of recent advances in memory interface design at both the architecture and circuit levels. Coverage includes signal integrity and testing, TSV interface, high-speed serial interface including equalization, ODT, pre-emphasis, wide I/O interface including crosstalk, skew cancellation, and clock generation and distribution. Trends for further bandwidth enhancement are also covered.   • Enables readers with minimal background in memory design to understand the basics of high-bandwidth memory interface design; • Presents state-of-the-art techniques for memory interface design; • Covers memory interface design at both the circuit level and system architecture level.

Capacity upgrade in short-reach optical fibre networks: simultaneous 4-PAM 20 Gbps data and polarization-modulated PPS clock signal using a single VCSEL carrier

Science.gov (United States)

Isoe, G. M.; Wassin, S.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-11-01

In this work, a four-level pulse amplitude modulation (4-PAM) format with a polarization-modulated pulse per second (PPS) clock signal using a single vertical cavity surface emitting laser (VCSEL) carrier is for the first time experimentally demonstrated. We propose uncomplex alternative technique for increasing capacity and flexibility in short-reach optical communication links through multi-signal modulation onto a single VCSEL carrier. A 20 Gbps 4-PAM data signal is directly modulated onto a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm, therefore, doubling the network bit rate. Carrier spectral efficiency is further maximized by exploiting the inherent orthogonal polarization switching of the VCSEL carrier with changing bias in transmission of a PPS clock signal. We, therefore, simultaneously transmit a 20 Gbps 4-PAM data signal and a polarization-based PPS clock signal using a single VCSEL carrier. It is the first time a signal VCSEL carrier is reported to simultaneously transmit a directly modulated 20 Gbps 4-PAM data signal and a polarization-based PPS clock signal. We further demonstrate on the design of a software-defined digital signal processing (DSP)-assisted receiver as an alternative to costly receiver hardware. Experimental results show that a 3.21 km fibre transmission with simultaneous 20 Gbps 4-PAM data signal and polarization-based PPS clock signal introduced a penalty of 3.76 dB. The contribution of polarization-based PPS clock signal to this penalty was found out to be 0.41 dB. Simultaneous distribution of data and timing clock signals over shared network infrastructure significantly increases the aggregated data rate at different optical network units (ONUs), without costly investment.

High-speed data transfer with FPGAs and QSFP+ modules

International Nuclear Information System (INIS)

Ammendola, R; Salamon, A; Salina, G; Biagioni, A; Chiodi, G; Frezza, O; Lo Cicero, F; Lonardo, A; Lunadei, R; Paolucci, P S; Rossetti, D; Simula, F; Tosoratto, L; Vicini, P

2010-01-01

We present test results and characterization of a data transmission system based on a last generation FPGA and a commercial QSFP+ (Quad Small Form Pluggable +) module. QSFP+ standard defines a hot-pluggable transceiver available in copper or optical cable assemblies for an aggregated bandwidth of up to 40 Gbps. We implemented a complete testbench based on a commercial development card mounting an Altera Stratix IV FPGA with 24 serial transceivers at 8.5 Gbps, together with a custom mezzanine hosting three QSFP+ modules. We present test results and signal integrity measurements up to an aggregated bandwidth of 12 Gbps.

High-speed data transfer with FPGAs and QSFP+ modules

Energy Technology Data Exchange (ETDEWEB)

Ammendola, R; Salamon, A; Salina, G [INFN Sezione di Roma Tor Vergata, Via della Ricerca Scientifica, 1 - 00133 Roma (Italy); Biagioni, A; Chiodi, G; Frezza, O; Lo Cicero, F; Lonardo, A; Lunadei, R; Paolucci, P S; Rossetti, D; Simula, F; Tosoratto, L; Vicini, P [INFN Sezione di Roma, P.le Aldo Moro, 2 - 00185 Roma (Italy)

2010-12-15

We present test results and characterization of a data transmission system based on a last generation FPGA and a commercial QSFP+ (Quad Small Form Pluggable +) module. QSFP+ standard defines a hot-pluggable transceiver available in copper or optical cable assemblies for an aggregated bandwidth of up to 40 Gbps. We implemented a complete testbench based on a commercial development card mounting an Altera Stratix IV FPGA with 24 serial transceivers at 8.5 Gbps, together with a custom mezzanine hosting three QSFP+ modules. We present test results and signal integrity measurements up to an aggregated bandwidth of 12 Gbps.

Multi-band microwave photonic satellite repeater scheme employing intensity Mach-Zehnder modulators

Institute of Scientific and Technical Information of China (English)

Yin Jie; Dong Tao; Zhang Bin; Hao Yan; Cao Guixing; Cheng Zijing; Xu Kun; Zhou Yue; Dai Jian

2017-01-01

To solve the satellite repeater's flexible and wideband frequency conversion problem,we propose a novel microwave photonic repeater system,which can convert the upload signal's carrier to six different frequencies.The scheme employs one 20 GHz bandwidth dual-drive Mach-Zehnder modulator (MZM) and two 10 GHz bandwidth MZMs.The basic principle of this scheme is filtering out two optical sidebands after the optical carrier suppression (OCS) modulation and combining two sidebands modulated by the input radio frequency (RF) signal.This structure can realize simultaneous multi-band frequency conversion with only one frequency-fixed microwave source and prevent generating harmful interference sidebands by using two corresponding optical filters after optical modulation.In the simulation,one C-band signal of 6 GHz carrier can be successfully converted to 12 GHz (Ku-band),28 GHz,34 GHz,40 GHz,46 GHz (Ka-band) and 52 GHz (V-band),which can be an attractive method to realize multi-band microwave photonic satellite repeater.Alternatively,the scheme can be configured to generate multi-band local oscillators (LOs) for widely satellite onboard clock distribution when the input RF signal is replaced by the internal clock source.

Compression of surface myoelectric signals using MP3 encoding.

Science.gov (United States)

Chan, Adrian D C

2011-01-01

The potential of MP3 compression of surface myoelectric signals is explored in this paper. MP3 compression is a perceptual-based encoder scheme, used traditionally to compress audio signals. The ubiquity of MP3 compression (e.g., portable consumer electronics and internet applications) makes it an attractive option for remote monitoring and telemedicine applications. The effects of muscle site and contraction type are examined at different MP3 encoding bitrates. Results demonstrate that MP3 compression is sensitive to the myoelectric signal bandwidth, with larger signal distortion associated with myoelectric signals that have higher bandwidths. Compared to other myoelectric signal compression techniques reported previously (embedded zero-tree wavelet compression and adaptive differential pulse code modulation), MP3 compression demonstrates superior performance (i.e., lower percent residual differences for the same compression ratios).

Trade-off between bandwidth and efficiency in semipolar (20 2 ¯ 1 ¯) InGaN/GaN single- and multiple-quantum-well light-emitting diodes

Science.gov (United States)

Monavarian, M.; Rashidi, A.; Aragon, A. A.; Nami, M.; Oh, S. H.; DenBaars, S. P.; Feezell, D.

2018-05-01

InGaN/GaN light-emitting diodes (LEDs) with large modulation bandwidths are desirable for visible-light communication. Along with modulation speed, the consideration of the internal quantum efficiency (IQE) under operating conditions is also important. Here, we report the modulation characteristics of semipolar (20 2 ¯ 1 ¯ ) InGaN/GaN (LEDs) with single-quantum well (SQW) and multiple-quantum-well (MQW) active regions grown on free-standing semipolar GaN substrates with peak internal quantum efficiencies (IQEs) of 0.93 and 0.73, respectively. The MQW LEDs exhibit on average about 40-80% higher modulation bandwidth, reaching 1.5 GHz at 13 kA/cm2, but about 27% lower peak IQE than the SQW LEDs. We extract the differential carrier lifetimes (DLTs), RC parasitics, and carrier escape lifetimes and discuss their role in the bandwidth and IQE characteristics. A coulomb-enhanced capture process is shown to rapidly reduce the DLT of the MQW LED at high current densities. Auger recombination is also shown to play little role in increasing the speed of the LEDs. Finally, we investigate the trade-offs between the bandwidth and efficiency and introduce the bandwidth-IQE product as a potential figure of merit for optimizing speed and efficiency in InGaN/GaN LEDs.

Optimization of Integrated Electro-Absorption Modulated Laser Structures for 100 Gbit/s Ethernet Using Electromagnetic Simulation

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Kazmierski, Christophe; Jany, Christophe

2007-01-01

In this paper three options for very-high bit rate integrated electro-absorption modulated laser (EML) structures are investigated using electromagnetic simulation. A physics based distributed equivalent circuit model taking the slowwave propagation characteristics of the modulation signal...... into account is proposed for the electro-absorption modulator (EAM)electrode arrangement. This model makes it possible to apply an EM/circuit co-simulation approach to estimate the electrical to optical transmission bandwidth for the integrated EML. It is shown that a transmission bandwidth of 70 GHz seems...

Optimum filters for narrow-band frequency modulation.

Science.gov (United States)

Shelton, R. D.

1972-01-01

The results of a computer search for the optimum type of bandpass filter for low-index angle-modulated signals are reported. The bandpass filters are discussed in terms of their low-pass prototypes. Only filter functions with constant numerators are considered. The pole locations for the optimum filters of several cases are shown in a table. The results are fairly independent of modulation index and bandwidth.

Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

Science.gov (United States)

Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

2012-01-01

At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

Spectral Correlation of Multicarrier Modulated Signals and Its Application for Signal Detection

Directory of Open Access Journals (Sweden)

Zhang Haijian

2010-01-01

Full Text Available Spectral correlation theory for cyclostationary time-series signals has been studied for decades. Explicit formulas of spectral correlation function for various types of analog-modulated and digital-modulated signals are already derived. In this paper, we investigate and exploit the cyclostationarity characteristics for two kinds of multicarrier modulated (MCM signals: conventional OFDM and filter bank based multicarrier (FBMC signals. The spectral correlation characterization of MCM signal can be described by a special linear periodic time-variant (LPTV system. Using this LPTV description, we have derived the explicit theoretical formulas of nonconjugate and conjugate cyclic autocorrelation function (CAF and spectral correlation function (SCF for OFDM and FBMC signals. According to theoretical spectral analysis, Cyclostationary Signatures (CS are artificially embedded into MCM signal and a low-complexity signature detector is, therefore, presented for detecting MCM signal. Theoretical analysis and simulation results demonstrate the efficiency and robustness of this CS detector compared to traditionary energy detector.

Model-driven requirements engineering (MDRE) for real-time ultra-wide instantaneous bandwidth signal simulation

Science.gov (United States)

Chang, Daniel Y.; Rowe, Neil C.

2013-05-01

While conducting a cutting-edge research in a specific domain, we realize that (1) requirements clarity and correctness are crucial to our success [1], (2) hardware is hard to change, most work is in software requirements development, coding and testing [2], (3) requirements are constantly changing, so that configurability, reusability, scalability, adaptability, modularity and testability are important non-functional attributes [3], (4) cross-domain knowledge is necessary for complex systems [4], and (5) if our research is successful, the results could be applied to other domains with similar problems. In this paper, we propose to use model-driven requirements engineering (MDRE) to model and guide our requirements/development, since models are easy to understand, execute, and modify. The domain for our research is Electronic Warfare (EW) real-time ultra-wide instantaneous bandwidth (IBW1) signal simulation. The proposed four MDRE models are (1) Switch-and-Filter architecture, (2) multiple parallel data bit streams alignment, (3) post-ADC and pre-DAC bits re-mapping, and (4) Discrete Fourier Transform (DFT) filter bank. This research is unique since the instantaneous bandwidth we are dealing with is in gigahertz range instead of conventional megahertz.

Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

Science.gov (United States)

Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

2017-01-01

Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

The Role of MAPK Modules and ABA during Abiotic Stress Signaling

KAUST Repository

Zélicourt, Axel de

2016-05-01

To respond to abiotic stresses, plants have developed specific mechanisms that allow them to rapidly perceive and respond to environmental changes. The phytohormone abscisic acid (ABA) was shown to be a pivotal regulator of abiotic stress responses in plants, triggering major changes in plant physiology. The ABA core signaling pathway largely relies on the activation of SnRK2 kinases to mediate several rapid responses, including gene regulation, stomatal closure, and plant growth modulation. Mitogen-activated protein kinases (MAPKs) have also been implicated in ABA signaling, but an entire ABA-activated MAPK module was uncovered only recently. In this review, we discuss the evidence for a role of MAPK modules in the context of different plant ABA signaling pathways. Abiotic stresses impact average yield in agriculture by more than 50% globally.Since ABA is a key regulator of abiotic stress responses, an understanding of its functioning at the molecular level is essential for plant breeding. Although the ABA core signaling pathway has been unraveled, several downstream events are still unclear.MAPKs are involved in most plant developmental stages and in response to stresses. Several members of the MAPK family were shown to be directly or indirectly activated by the ABA core signaling pathway.Recent evidence shows that the complete MAP3K17/18-MKK3-MPK1/2/7/14 module is under the control of ABA, whose members are under the transcriptional and post-translational control of the ABA core signaling pathway. © 2016 Elsevier Ltd.

RECOVERY OF LARGE ANGULAR SCALE CMB POLARIZATION FOR INSTRUMENTS EMPLOYING VARIABLE-DELAY POLARIZATION MODULATORS

Energy Technology Data Exchange (ETDEWEB)

Miller, N. J.; Marriage, T. A.; Appel, J. W.; Bennett, C. L.; Eimer, J.; Essinger-Hileman, T.; Harrington, K.; Rostem, K.; Watts, D. J. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States); Chuss, D. T. [Department of Physics, Villanova University, 800 E Lancaster, Villanova, PA 19085 (United States); Wollack, E. J.; Fixsen, D. J.; Moseley, S. H.; Switzer, E. R., E-mail: Nathan.J.Miller@nasa.gov [Observational Cosmology Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2016-02-20

Variable-delay Polarization Modulators (VPMs) are currently being implemented in experiments designed to measure the polarization of the cosmic microwave background on large angular scales because of their capability for providing rapid, front-end polarization modulation and control over systematic errors. Despite the advantages provided by the VPM, it is important to identify and mitigate any time-varying effects that leak into the synchronously modulated component of the signal. In this paper, the effect of emission from a 300 K VPM on the system performance is considered and addressed. Though instrument design can greatly reduce the influence of modulated VPM emission, some residual modulated signal is expected. VPM emission is treated in the presence of rotational misalignments and temperature variation. Simulations of time-ordered data are used to evaluate the effect of these residual errors on the power spectrum. The analysis and modeling in this paper guides experimentalists on the critical aspects of observations using VPMs as front-end modulators. By implementing the characterizations and controls as described, front-end VPM modulation can be very powerful for mitigating 1/f noise in large angular scale polarimetric surveys. None of the systematic errors studied fundamentally limit the detection and characterization of B-modes on large scales for a tensor-to-scalar ratio of r = 0.01. Indeed, r < 0.01 is achievable with commensurately improved characterizations and controls.

A Robust 96.6-dB-SNDR 50-kHz-Bandwidth Switched-Capacitor Delta-Sigma Modulator for IR Imagers in Space Instrumentation.

Science.gov (United States)

Dei, Michele; Sutula, Stepan; Cisneros, Jose; Pun, Ernesto; Jansen, Richard Jan Engel; Terés, Lluís; Serra-Graells, Francisco

2017-06-02

Infrared imaging technology, used both to study deep-space bodies' radiation and environmental changes on Earth, experienced constant improvements in the last few years, pushing data converter designers to face new challenges in terms of speed, power consumption and robustness against extremely harsh operating conditions. This paper presents a 96.6-dB-SNDR (Signal-to-Noise-plus-Distortion Ratio) 50-kHz-bandwidth fourth-order single-bit switched-capacitor delta-sigma modulator for ADC operating at 1.8 V and consuming 7.9 mW fit for space instrumentation. The circuit features novel Class-AB single-stage switched variable-mirror amplifiers (SVMAs) enabling low-power operation, as well as low sensitivity to both process and temperature deviations for the whole modulator. The physical implementation resulted in a 1.8-mm 2 chip integrated in a standard 0.18-µm 1-poly-6-metal (1P6M) CMOS technology, and it reaches a 164.6-dB Schreier figure of merit from experimental SNDR measurements without making use of any clock bootstrapping,analogcalibration,nordigitalcompensationtechnique. Whencoupledtoa2048×2048 IR imager, the current design allows more than 50 frames per minute with a resolution of 16 effective number of bits (ENOB) while consuming less than 300 mW.

Bandwidth-narrowed Bragg gratings inscribed in double-cladding fiber by femtosecond laser.

Science.gov (United States)

Shi, Jiawei; Li, Yuhua; Liu, Shuhui; Wang, Haiyan; Liu, Ningliang; Lu, Peixiang

2011-01-31

Bragg gratings with the bandwidth(FWHM) narrowed up to 79 pm were inscribed in double-cladding fiber with femtosecond radiation and a phase mask followed by an annealing treatment. With the annealing temperature below a critical value, the bandwidth of Bragg gratings induced by Type I-IR and Type II-IR index change was narrowed without the reduction of reflectivity. The bandwidth narrowing is due to the profile transformation of the refractive index modulation caused by the annealing treatment. This mechanism was verified by comparing bandwidth narrowing processes of FBGs written with different power densities.

Method for Signal Processing of Electric Field Modulation Sensor in a Conductive Environment

Directory of Open Access Journals (Sweden)

O. I. Miseyk

2015-01-01

Full Text Available In investigating the large waters and deep oceans the most promising are modulation sensors for measuring electric field in a conducting environment in a very low frequency range in devices of autonomous or non-autonomous vertical sounding. When using sensors of this type it is necessary to solve the problem of enhancement and measurement of the modulated signal from the baseband noise.The work analyses hydrodynamic and electromagnetic noise at the input of transducer with "rotating" sensitive axis. By virtue of matching the measuring electrodes with the signal processing circuit a conclusion has been drawn that the proposed basic model of a transducer with "rotating” sensitive axis is the most efficient in terms of enhancement and measurement of modulated signal from the baseband noise. It has been shown that it is undesirable for transducers to have the rotation of electrodes resulting, in this case, in arising noise to be synchronously changed with transducer rotation frequency (modulation frequency. This will complicate the further signal-noise enhancement later in their processing.The paper justifies the choice of demodulation output signal, called synchronous demodulation using a low-pass filter with a cutoff frequency much lower than the carrier frequency to provide an output signal in the range of very low frequency and dc electric fields.The paper offers an original circuit to process the signals taken from the modulation sensor with "rotating" measurement base. This circuit has advantages over the earlier known circuits for measuring electric fields in a conducting (marine environment in the ultralow frequency range of these fields in terms of sensitivity and measuring accuracy of modulation sensors.

Si/SiC-based DD hetero-structure IMPATTs as MM-wave power-source: a generalized large-signal analysis

International Nuclear Information System (INIS)

Mukherjee, Moumita; Tripathy, P. R.; Pati, S. P.

2015-01-01

A full-scale, self-consistent, non-linear, large-signal model of double-drift hetero-structure IMPATT diode with general doping profile is derived. This newly developed model, for the first time, has been used to analyze the large-signal characteristics of hexagonal SiC-based double-drift IMPATT diode. Considering the fabrication feasibility, the authors have studied the large-signal characteristics of Si/SiC-based hetero-structure devices. Under small-voltage modulation (∼ 2%, i.e. small-signal conditions) results are in good agreement with calculations done using a linearised small-signal model. The large-signal values of the diode's negative conductance (5 × 10 6 S/m 2 ), susceptance (10.4 × 10 7 S/m 2 ), average breakdown voltage (207.6 V), and power generating efficiency (15%, RF power: 25.0 W at 94 GHz) are obtained as a function of oscillation amplitude (50% of DC breakdown voltage) for a fixed average current density. The large-signal calculations exhibit power and efficiency saturation for large-signal (> 50%) voltage modulation and thereafter decrease gradually with further increasing voltage-modulation. This generalized large-signal formulation is applicable for all types of IMPATT structures with distributed and narrow avalanche zones. The simulator is made more realistic by incorporating the space-charge effects, realistic field and temperature dependent material parameters in Si and SiC. The electric field snap-shots and the large-signal impedance and admittance of the diode with current excitation are expressed in closed loop form. This study will act as a guide for researchers to fabricate a high-power Si/SiC-based IMPATT for possible application in high-power MM-wave communication systems. (paper)

Wide modulation bandwidth terahertz detection in 130 nm CMOS technology

Science.gov (United States)

Nahar, Shamsun; Shafee, Marwah; Blin, Stéphane; Pénarier, Annick; Nouvel, Philippe; Coquillat, Dominique; Safwa, Amr M. E.; Knap, Wojciech; Hella, Mona M.

2016-11-01

Design, manufacturing and measurements results for silicon plasma wave transistors based wireless communication wideband receivers operating at 300 GHz carrier frequency are presented. We show the possibility of Si-CMOS based integrated circuits, in which by: (i) specific physics based plasma wave transistor design allowing impedance matching to the antenna and the amplifier, (ii) engineering the shape of the patch antenna through a stacked resonator approach and (iii) applying bandwidth enhancement strategies to the design of integrated broadband amplifier, we achieve an integrated circuit of the 300 GHz carrier frequency receiver for wireless wideband operation up to/over 10 GHz. This is, to the best of our knowledge, the first demonstration of low cost 130 nm Si-CMOS technology, plasma wave transistors based fast/wideband integrated receiver operating at 300 GHz atmospheric window. These results pave the way towards future large scale (cost effective) silicon technology based terahertz wireless communication receivers.

Use of modulated excitation signals in ultrasound. Part I: Basic concepts and expected benefits

DEFF Research Database (Denmark)

Misaridis, Thanassis; Jensen, Jørgen Arendt

2005-01-01

This paper, the first from a series of three papers on the application of coded excitation signals in medical ultrasound, discusses the basic principles and ultrasound-related problems of pulse compression. The concepts of signal modulation and matched filtering are given, and a simple model...... of attenuation relates the matched filter response with the ambiguity function, known from radar. Based on this analysis and the properties of the ambiguity function, the selection of coded waveforms suitable for ultrasound imaging is discussed. It is shown that linear frequency modulation (FM) signals have...... that in the case of linear FM signals, a SNR improvement of 12 to 18 dB can be expected for large imaging depths in attenuating media, without any depth-dependent filter compensation. In contrast, nonlinear FM modulation and binary codes are shown to give a SNR improvement of only 4 to 9 dB when processed...

Large conditional single-photon cross-phase modulation

Science.gov (United States)

Hosseini, Mahdi; Duan, Yiheng; Vuletić, Vladan

2016-01-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of π/6 (and up to π/3 by postselection on photons that remain in the system longer than average) between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. By upgrading to a state-of-the-art cavity, our system can reach a coherent phase shift of π at low loss, enabling deterministic and universal photonic quantum logic. PMID:27519798

Frequency bandwidth extension by use of multiple Zeeman field offsets for electron spin-echo EPR oxygen imaging of large objects

Science.gov (United States)

Seifi, Payam; Epel, Boris; Sundramoorthy, Subramanian V.; Mailer, Colin; Halpern, Howard J.

2011-01-01

Purpose: Electron spin-echo (ESE) oxygen imaging is a new and evolving electron paramagnetic resonance (EPR) imaging (EPRI) modality that is useful for physiological in vivo applications, such as EPR oxygen imaging (EPROI), with potential application to imaging of multicentimeter objects as large as human tumors. A present limitation on the size of the object to be imaged at a given resolution is the frequency bandwidth of the system, since the location is encoded as a frequency offset in ESE imaging. The authors’ aim in this study was to demonstrate the object size advantage of the multioffset bandwidth extension technique.Methods: The multiple-stepped Zeeman field offset (or simply multi-B) technique was used for imaging of an 8.5-cm-long phantom containing a narrow single line triaryl methyl compound (trityl) solution at the 250 MHz imaging frequency. The image is compared to a standard single-field ESE image of the same phantom.Results: For the phantom used in this study, transverse relaxation (T2e) electron spin-echo (ESE) images from multi-B acquisition are more uniform, contain less prominent artifacts, and have a better signal to noise ratio (SNR) compared to single-field T2e images.Conclusions: The multi-B method is suitable for imaging of samples whose physical size restricts the applicability of the conventional single-field ESE imaging technique. PMID:21815379

Controlling Laser Plasma Instabilities Using Temporal Bandwidth

Science.gov (United States)

Tsung, Frank; Weaver, J.; Lehmberg, R.

2016-10-01

We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temporal bandwidth under conditions relevant to current and future experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth (where the inverse bandwidth is comparable with the linear growth time), the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using beam smoothing techniques such as ISI). We will quantify these effects and investigate higher dimensional effects such as laser speckles. This work is supported by DOE and NRL.

Demonstration and comparison of tuned and detuned signal recycling in a large-scale gravitational wave detector

International Nuclear Information System (INIS)

Hild, S; Grote, H; Hewtison, M; Lueck, H; Smith, J R; Strain, K A; Willke, B; Danzmann, K

2007-01-01

The British/German gravitational wave detector GEO 600 located near Hannover in Germany is the first large-scale gravitational-wave detector using the advanced technique of signal recycling. Currently the instrument operates in detuned signal recycling mode. Several problems arise due to the fact that the signal recycling cavity changes amplitude and phase of all light fields (carrier and sidebands) present at the dark-port. In addition, in the case of detuned signal recycling this leads to unbalanced sideband fields at the detector output. The large amplitude modulation caused by this asymmetry does not carry any gravitational wave information, but might be the cause of saturation and nonlinearities on the main photodiode. We developed and demonstrated a new control method to realize tuned signal recycling operation in a large-scale gravitational wave detector. A detailed comparison of tuned and detuned signal recycling operation is given. The response function of the system (optical gain) was measured and compared, as was the size of amplitude modulation on the main photodiode. Some important noise couplings were measured and partly found to be strongly reduced in the case of tuned signal recycling operation

Sub-cycle QAM modulation for VCSEL-based optical fiber links

DEFF Research Database (Denmark)

Pham, Tien-Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee

2013-01-01

QAM modulation utilizing subcarrier frequency lower than the symbol rate is both theoretically and experimentally investigated. High spectral efficiency and concentration of power in low frequencies make sub-cycle QAM signals attractive for optical fiber links with direct modulated light sources....... Real-time generated 10-Gbps 4-level QAM signal in a 7.5-GHz bandwidth utilizing subcarrier frequency at a half symbol rate was successfully transmitted over 20-km SMF using an un-cooled 1.5-μm VCSEL. Only 2.5-dB fiber transmission power penalty was observed with no equalization applied....

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping

Institute of Scientific and Technical Information of China (English)

ZHANG Ai-ling; ZHANG Yue; SONG Hong-yun; YAO Yuan; PAN Hong-gang

2018-01-01

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated.Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme.In the experiment,non-return-to-zero (NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero (RZ) signal with bit rate of 13.51 Gbit/s are obtained.The maximum bit rate of modulation format signal is also analyzed.

QPSK Modulator with Continuous Phase and Fast Response Based on Phase-Locked Loop

Directory of Open Access Journals (Sweden)

L. Kirasamuthranon

2017-06-01

Full Text Available Among M-phase shift keying (M-PSK schemes, quadrature phase-shift keying (QPSK is used most often because of its efficient bandwidth consumption. However, in comparison with minimum-shift keying, which has continuous phase transitions, QPSK requires a higher bandwidth to transmit a signal. This article focuses on the phase transitions in QPSK signals, and a QPSK modulator based on a phase-locked loop (PLL is proposed. The PLL circuit in the proposed system differs from that of conventional PLL circuits because a three-input XOR gate and a summing circuit are used. With these additional components, the proposed PLL provides a continuous phase change in the QPSK signal. Consequently, the required bandwidth for transmitting the QPSK signal when using the proposed circuit is less than that for a conventional QPSK signal with a discontinuous phase. The analytical results for the proposed system in the time domain agree well with the experimental and simulation results of the circuit. Both the theoretical and experimental results thus confirm that the proposed technique can be realized in real-world applications.

A High Performance Delta-Sigma Modulator for Neurosensing.

Science.gov (United States)

Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md Kafiul; Yang, Zhi

2015-08-07

Recorded neural data are frequently corrupted by large amplitude artifacts that are triggered by a variety of sources, such as subject movements, organ motions, electromagnetic interferences and discharges at the electrode surface. To prevent the system from saturating and the electronics from malfunctioning due to these large artifacts, a wide dynamic range for data acquisition is demanded, which is quite challenging to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power. The modulator was fabricated in a 0.18-µm CMOS process. Powered by a 1.0-V supply, the chip can achieve an 85-dB peak signal-to-noise-and-distortion ratio (SNDR) and an 87-dB dynamic range when integrated over a 10-kHz bandwidth. The total power consumption of the modulator is 13 µW, which corresponds to a figure-of-merit (FOM) of 45 fJ/conversion step. These competitive circuit specifications make this design a good candidate for building high precision neurosensors.

Short Range Inter-Datacenter Transmission with Carrier Delivery and Remote Modulation for 112 Gb/s PM-QPSK Signals

DEFF Research Database (Denmark)

Echeverri, Santiago; Morales Vicente, Alvaro; Rodríguez Páez, Juan Sebastián

2017-01-01

The increasing demand for bandwidth in datacenter interconnect links is currently driving a transition towards four level pulse-amplitude modulation (PAM-4) as the de facto modulation format. Nevertheless, other schemes with even higher spectral efficiency will be required in the future given...

Design of Optical Pulse Position Modulation (PPM) Translating Receiver

Energy Technology Data Exchange (ETDEWEB)

Mendez, A J; Hernandez, V J; Gagliardi, R M; Bennett, C V

2009-06-19

M-ary pulse position modulation (M-ary PPM) signaling is a means of transmitting multiple bits per symbol in an intensity modulated/direct detection (IM/DD) system. PPM is used in applications with average power limitations. In optical communication systems, PPM becomes challenging to implement at gigabit rates and/or large M, since pulsed signaling requires higher electronic processing bandwidths than the fundamental transmission rate. they have thus been exploring techniques for PPM communications using optical processing. Previous work described a transmitter algorithm that directly translates a bit sequence of N digital bits to the optical pulse position m for any M = 2{sup N}. It has been considerably more difficult to define a similar receiver algorithm that translates the received optical pulse position directly back to a bit sequence with minimal electronic processing. Designs for specific Ms (e.g., 4-ary) have been shown and implemented, but are difficult to scale to larger M. In this work, they present for the first time a generalized PPM translating receiver that is applicable to all M and data rates.

Optimal filter bandwidth for pulse oximetry

Science.gov (United States)

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

Fast Faraday Cup With High Bandwidth

Science.gov (United States)

Deibele, Craig E [Knoxville, TN

2006-03-14

A circuit card stripline Fast Faraday cup quantitatively measures the picosecond time structure of a charged particle beam. The stripline configuration maintains signal integrity, and stitching of the stripline increases the bandwidth. A calibration procedure ensures the measurement of the absolute charge and time structure of the charged particle beam.

Bandwidth-limited control and ringdown suppression in high-Q resonators.

Science.gov (United States)

Borneman, Troy W; Cory, David G

2012-12-01

We describe how the transient behavior of a tuned and matched resonator circuit and a ringdown suppression pulse may be integrated into an optimal control theory (OCT) pulse-design algorithm to derive control sequences with limited ringdown that perform a desired quantum operation in the presence of resonator distortions of the ideal waveform. Inclusion of ringdown suppression in numerical pulse optimizations significantly reduces spectrometer deadtime when using high quality factor (high-Q) resonators, leading to increased signal-to-noise ratio (SNR) and sensitivity of inductive measurements. To demonstrate the method, we experimentally measure the free-induction decay of an inhomogeneously broadened solid-state free radical spin system at high Q. The measurement is enabled by using a numerically optimized bandwidth-limited OCT pulse, including ringdown suppression, robust to variations in static and microwave field strengths. We also discuss the applications of pulse design in high-Q resonators to universal control of anisotropic-hyperfine coupled electron-nuclear spin systems via electron-only modulation even when the bandwidth of the resonator is significantly smaller than the hyperfine coupling strength. These results demonstrate how limitations imposed by linear response theory may be vastly exceeded when using a sufficiently accurate system model to optimize pulses of high complexity. Copyright © 2012 Elsevier Inc. All rights reserved.

Sensitivity-Bandwidth Limit in a Multimode Optoelectromechanical Transducer

Science.gov (United States)

Moaddel Haghighi, I.; Malossi, N.; Natali, R.; Di Giuseppe, G.; Vitali, D.

2018-03-01

An optoelectromechanical system formed by a nanomembrane capacitively coupled to an L C resonator and to an optical interferometer has recently been employed for the highly sensitive optical readout of rf signals [T. Bagci et al., Nature (London) 507, 81 (2013), 10.1038/nature13029]. We propose and experimentally demonstrate how the bandwidth of such a transducer can be increased by controlling the interference between two electromechanical interaction pathways of a two-mode mechanical system. With a proof-of-principle device operating at room temperature, we achieve a sensitivity of 300 nV /√{Hz } over a bandwidth of 15 kHz in the presence of radio-frequency noise, and an optimal shot-noise-limited sensitivity of 10 nV /√{Hz } over a bandwidth of 5 kHz. We discuss strategies for improving the performance of the device, showing that, for the same given sensitivity, a mechanical multimode transducer can achieve a bandwidth significantly larger than that for a single-mode one.

PAM-4 signal delivery in one radio-over-fiber system

Science.gov (United States)

Wang, Hada; Zhou, Wen; Yu, Jianjun

2017-10-01

We propose and experimentally demonstrate four-level pulse-amplitude-modulation (PAM-4) signal delivery in a radio-over-fiber system for the first time. Over 8-Gbit/s PAM-4 signals have been transmitted over 20-km single-mode fiber-28 and 1-m wireless distance. The signal after transmission is detected directly by an envelope detector at the receiver side. The maximal bit rate could be increased if the bandpass amplifier and envelope detector have more bandwidth.

Neural Network-Based Receiver in Band-Limited Communication System with MPPSK Modulation

Directory of Open Access Journals (Sweden)

Wang Zixin

2018-01-01

Full Text Available As a type of the spectrally efficient modulation, the m-ary phase position shift keying (MPPSK has been considered to meet the increasing spectrum requirement in the future wireless system. To limit the signal bandwidth and cancel the out-band interference the band-pass filters are used, which introduce the waveform distortion and inter-symbol interference (ISI. Therefore, a single hidden-layer neural network (NN-based receiver is proposed to jointly equalize and demodulate the received signal. The impulse response of the system is static and the network parameters can be obtained after off-line training. The number of the hidden nodes is also determined through simulations. Simulation results show that the NN-based receiver works well in the communication system with different allocated bandwidths. By observing the modified confusion matrix, the false symbol decision is relevant to modulation index, waveform distortions and the ISI.

Audibility of modulation noise in stationary signals

NARCIS (Netherlands)

Neelen, J.J.M.

1970-01-01

Recordings of an acoustic signal on magnetic tape often show noise, which may be divided into two main classes: additive noise and multiplicative noise. A characteristic of the latter is that it is weak with weak signals and strong with strong signals. This modulation noise has been subjected to a

Note: Demodulation of spectral signal modulated by optical chopper with unstable modulation frequency.

Science.gov (United States)

Zhang, Shengzhao; Li, Gang; Wang, Jiexi; Wang, Donggen; Han, Ying; Cao, Hui; Lin, Ling; Diao, Chunhong

2017-10-01

When an optical chopper is used to modulate the light source, the rotating speed of the wheel may vary with time and subsequently cause jitter of the modulation frequency. The amplitude calculated from the modulated signal would be distorted when the frequency fluctuations occur. To precisely calculate the amplitude of the modulated light flux, we proposed a method to estimate the range of the frequency fluctuation in the measurement of the spectrum and then extract the amplitude based on the sum of power of the signal in the selected frequency range. Experiments were designed to test the feasibility of the proposed method and the results showed lower root means square error than the conventional way.

Phase ramping and modulation of reflectometer signals

International Nuclear Information System (INIS)

Conway, G.D.; Bartlett, D.V.; Stoff, P.E.

1999-01-01

The phase and amplitude signals of JET heterodyne reflectometers show varying levels of high frequency turbulence superimposed on a slow changing mean. The phase signal also shows multi-radian (> 1 fringe) variations with two quite different time scales (2-10 ms and sub-ms). In both cases the mean reflected power, together with turbulent phase and amplitude fluctuation levels, are modulated synchronously with the are modulated synchronously with the phase fringes. The slow fringes appear to result radial movement of the cutoff layer with the amplitude modulation possibly due to multiple reflection between plasma and wall. The fast fringes occur in intermittent bursts and appear to be phase runaway resulting from antenna misalignment. Using a 2-D physical optics simulation code it is possible to replicate the fast bursts of phase runaway from steady-state turbulence and misaligned antennas. This offers a possible alternative explanation for some of the observations of bursting turbulence seen in reflectometer signals. (authors)

A Signal Processing Module for the Analysis of Heart Sounds and Heart Murmurs

International Nuclear Information System (INIS)

Javed, Faizan; Venkatachalam, P A; H, Ahmad Fadzil M

2006-01-01

In this paper a Signal Processing Module (SPM) for the computer-aided analysis of heart sounds has been developed. The module reveals important information of cardiovascular disorders and can assist general physician to come up with more accurate and reliable diagnosis at early stages. It can overcome the deficiency of expert doctors in rural as well as urban clinics and hospitals. The module has five main blocks: Data Acquisition and Pre-processing, Segmentation, Feature Extraction, Murmur Detection and Murmur Classification. The heart sounds are first acquired using an electronic stethoscope which has the capability of transferring these signals to the near by workstation using wireless media. Then the signals are segmented into individual cycles as well as individual components using the spectral analysis of heart without using any reference signal like ECG. Then the features are extracted from the individual components using Spectrogram and are used as an input to a MLP (Multiple Layer Perceptron) Neural Network that is trained to detect the presence of heart murmurs. Once the murmur is detected they are classified into seven classes depending on their timing within the cardiac cycle using Smoothed Pseudo Wigner-Ville distribution. The module has been tested with real heart sounds from 40 patients and has proved to be quite efficient and robust while dealing with a large variety of pathological conditions

A Signal Processing Module for the Analysis of Heart Sounds and Heart Murmurs

Energy Technology Data Exchange (ETDEWEB)

Javed, Faizan; Venkatachalam, P A; H, Ahmad Fadzil M [Signal and Imaging Processing and Tele-Medicine Technology Research Group, Department of Electrical and Electronics Engineering, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia)

2006-04-01

In this paper a Signal Processing Module (SPM) for the computer-aided analysis of heart sounds has been developed. The module reveals important information of cardiovascular disorders and can assist general physician to come up with more accurate and reliable diagnosis at early stages. It can overcome the deficiency of expert doctors in rural as well as urban clinics and hospitals. The module has five main blocks: Data Acquisition and Pre-processing, Segmentation, Feature Extraction, Murmur Detection and Murmur Classification. The heart sounds are first acquired using an electronic stethoscope which has the capability of transferring these signals to the near by workstation using wireless media. Then the signals are segmented into individual cycles as well as individual components using the spectral analysis of heart without using any reference signal like ECG. Then the features are extracted from the individual components using Spectrogram and are used as an input to a MLP (Multiple Layer Perceptron) Neural Network that is trained to detect the presence of heart murmurs. Once the murmur is detected they are classified into seven classes depending on their timing within the cardiac cycle using Smoothed Pseudo Wigner-Ville distribution. The module has been tested with real heart sounds from 40 patients and has proved to be quite efficient and robust while dealing with a large variety of pathological conditions.

Wide-band analog frequency modulation of optic signals using indirect techniques

Science.gov (United States)

Fitzmartin, D. J.; Balboni, E. J.; Gels, R. G.

1991-01-01

The wideband frequency modulation (FM) of an optical carrier by a radio frequency (RF) or microwave signal can be accomplished independent of laser type when indirect modulation is employed. Indirect modulators exploit the integral relation of phase to frequency so that phase modulators can be used to impress frequency modulation on an optical carrier. The use of integrated optics phase modulators, which are highly linear, enables the generation of optical wideband FM signals with very low intermodulation distortion. This modulator can be used as part of an optical wideband FM link for RF and microwave signals. Experimental results from the test of an indirect frequency modulator for an optical carrier are discussed.

MITF Modulates Therapeutic Resistance through EGFR Signaling.

Science.gov (United States)

Ji, Zhenyu; Erin Chen, Yiyin; Kumar, Raj; Taylor, Michael; Jenny Njauw, Ching-Ni; Miao, Benchun; Frederick, Dennie T; Wargo, Jennifer A; Flaherty, Keith T; Jönsson, Göran; Tsao, Hensin

2015-07-01

Response to targeted therapies varies significantly despite shared oncogenic mutations. Nowhere is this more apparent than in BRAF (V600E)-mutated melanomas where initial drug response can be striking and yet relapse is commonplace. Resistance to BRAF inhibitors have been attributed to the activation of various receptor tyrosine kinases (RTKs), although the underlying mechanisms have been largely uncharacterized. Here, we found that EGFR-induced vemurafenib resistance is ligand dependent. We employed whole-genome expression analysis and discovered that vemurafenib resistance correlated with the loss of microphthalmia-associated transcription factor (MITF), along with its melanocyte lineage program, and with the activation of EGFR signaling. An inverse relationship between MITF, vemurafenib resistance, and EGFR was then observed in patient samples of recurrent melanoma and was conserved across melanoma cell lines and patients' tumor specimens. Functional studies revealed that MITF depletion activated EGFR signaling and consequently recapitulated the resistance phenotype. In contrast, forced expression of MITF in melanoma and colon cancer cells inhibited EGFR and conferred sensitivity to BRAF/MEK inhibitors. These findings indicate that an "autocrine drug resistance loop" is suppressed by melanocyte lineage signal(s), such as MITF. This resistance loop modulates drug response and could explain the unique sensitivity of melanomas to BRAF inhibition.

Limiter discriminator detection of M-ary FSK signals

Science.gov (United States)

Fonseka, John P.

1990-10-01

The performance of limiter discriminator detection of M-ary FSK signals is analyzed at arbitrary modulation indices. It is shown that the error rate performance of limiter discriminator detection can be significantly improved by increasing the modulation index above 1/M. The optimum modulation index that minimizes the overall error probability is determined for the cases M = 2, 4 and 8. The analysis is carried out for wideband and bandlimited channels with Gaussian and second-order Butterworth filters. It is shown that the optimum modulation index depends on the signal/noise ratio (SNR), in a wideband channel, and on both SNR and time-bandwidth product in a bandlimited channel. Finally, it is shown that the optimum sampling instance in presence of a nonzero phase IF filter can be approximately determined by using only the worst case symbol pattern.

VXI based multibunch detector and QPSK modulator for the PEP-II/ALS/DAΦNE longitudinal feedback system

International Nuclear Information System (INIS)

Young, A.; Fox, J.; Teytelman, D.

1997-04-01

The PEP-II/ALS/DAΦNE feedback systems are complex systems implemented using analog, digital and microwave circuits. The VXI hardware implementation for the Front-end and Back-end analog processing modules is presented. The Front-end module produces a baseband beam phase signal from pickups using a microwave tone burst generator. The Back-end VXI module generates an AM/QPSK modulated signal from a baseband correction signal computed in a digital signal processor. These components are implemented in VXI packages that allow a wide spectrum of system functions including a 120 MHz bandwidth rms detector, reference phase servo, woofer link to the RF control system, standard VXI status/control, and user defined registers. The details of the design and implementation of the VXI modules including performance characteristics are presented

Re-modulated technology of WDM-PON employing different DQPSK downstream signals

Science.gov (United States)

Gao, Chao; Xin, Xiang-jun; Yu, Chong-xiu

2012-11-01

This paper proposes a kind of modulation architecture for wavelength-division-multiplexing passive optical network (WDMPON) employing optical differential quadrature phase shift keying (DQPSK) downstream signals and two different modulation formats of re-modulated upstream signals. At the optical line terminal (OLT), 10 Gbit/s signal is modulated with DQPSK. At the optical network unit (ONU), part of the downstream signal is re-modulated with on-off keying (OOK) or inverse-return-to-zero (IRZ). Simulation results show the impact on the system employing NRZ, RZ and carrier-suppressed return-to-zero (CSRZ). The analyses also reflect that the architecture can restrain chromatic dispersion and channel crosstalk, which makes it the best architecture of access network in the future.

Signal modulation in cold-dark-matter detection

International Nuclear Information System (INIS)

Freese, K.; Frieman, J.; Gould, A.

1988-01-01

If weakly interacting massive particles (WIMP's) are the dark matter in the galactic halo, they may be detected in low-background ionization detectors now operating or with low-temperature devices under development. In detecting WIMP's of low mass or WIMP's with spin-dependent nuclear interactions (e.g., photinos), a principal technical difficulty appears to be achieving very low thresholds (approx. < keV) in large (∼ kg) detectors with low background noise. We present an analytic treatment of WIMP detection and show that the seasonal modulation of the signal can be used to detect WIMP's even at low-signal-to-background levels and thus without the necessity of going to very-low-energy thresholds. As a result, the prospects for detecting a variety of cold-dark-matter candidates may be closer at hand than previously thought. We discuss in detail the detector characteristics required for a number of WIMP candidates, and carefully work out expected event rates for several present and proposed detectors

Amplitude modulation detection with concurrent frequency modulation.

Science.gov (United States)

Nagaraj, Naveen K

2016-09-01

Human speech consists of concomitant temporal modulations in amplitude and frequency that are crucial for speech perception. In this study, amplitude modulation (AM) detection thresholds were measured for 550 and 5000 Hz carriers with and without concurrent frequency modulation (FM), at AM rates crucial for speech perception. Results indicate that adding 40 Hz FM interferes with AM detection, more so for 5000 Hz carrier and for frequency deviations exceeding the critical bandwidth of the carrier frequency. These findings suggest that future cochlear implant processors, encoding speech fine-structures may consider limiting the FM to narrow bandwidth and to low frequencies.

Optical modulation in silicon-vanadium dioxide photonic structures

Science.gov (United States)

Miller, Kevin J.; Hallman, Kent A.; Haglund, Richard F.; Weiss, Sharon M.

2017-08-01

All-optical modulators are likely to play an important role in future chip-scale information processing systems. In this work, through simulations, we investigate the potential of a recently reported vanadium dioxide (VO2) embedded silicon waveguide structure for ultrafast all-optical signal modulation. With a VO2 length of only 200 nm, finite-differencetime- domain simulations suggest broadband (200 nm) operation with a modulation greater than 12 dB and an insertion loss of less than 3 dB. Predicted performance metrics, including modulation speed, modulation depth, optical bandwidth, insertion loss, device footprint, and energy consumption of the proposed Si-VO2 all-optical modulator are benchmarked against those of current state-of-the-art all-optical modulators with in-plane optical excitation.

Analysis of blocking probability for OFDM-based variable bandwidth optical network

Science.gov (United States)

Gong, Lei; Zhang, Jie; Zhao, Yongli; Lin, Xuefeng; Wu, Yuyao; Gu, Wanyi

2011-12-01

Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique. For optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments, optical OFDM is much more flexible compared to traditional WDM systems, enabling elastic bandwidth transmissions, and optical networking is the future trend of development. In OFDM-based optical network the research of blocking rate has very important significance for network assessment. Current research for WDM network is basically based on a fixed bandwidth, in order to accommodate the future business and the fast-changing development of optical network, our study is based on variable bandwidth OFDM-based optical networks. We apply the mathematical analysis and theoretical derivation, based on the existing theory and algorithms, research blocking probability of the variable bandwidth of optical network, and then we will build a model for blocking probability.

Optoelectronic analogue signal transfer for LHC detectors, 1991

CERN Document Server

Dowell, John D; Homer, R J; Jovanovic, P; Kenyon, I; Staley, R; Webster, K; Da Via, C; Feyt, J; Nappey, P; Stefanini, G; Dwir, B; Reinhart, F K; Davies, J; Green, N; Stewart, W; Young, T; Hall, G; Akesson, T; Jarlskog, G; Kröll, S; Nickerson, R; Jaroslawski, S; CERN. Geneva. Detector Research and Development Committee

1991-01-01

We propose to study and develop opto-electronic analogue front-ends based on electro-optic intensity modulators. These devices translate the detector electrical analogue signals into optical signals which are then transferred via optical fibres to photodetector receivers at the remote readout. In comparison with conventional solutions based on copper cables, this technique offers the advantages of high speed, very low power dissipation and transmission losses, compactness and immunity to electromagnetic interference. The linearity and dynamic range that can be obtained are more than adequate for central tracking detectors, and the proposed devices have considerable radiation- hardness capabilities. The large bandwidth and short transit times offer possibilities for improved triggering schemes. The proposed R&D programme is aimed at producing multi-channel "demonstrator" units for evaluation both in laboratory and beam tests. This will allow the choice of the most effective technology. A detailed study wil...

X-(2) Modulator With 40-GHz Modulation Utilizing BaTiO3 Photonic Crystal Waveguides

DEFF Research Database (Denmark)

Girouard, Peter David; Chen, Pice; Jeong, Young Kyu

2017-01-01

Future telecommunication and data center networks as well as quantum optical communication systems will require optical modulators with wide bandwidths, large extinction, low operating voltage, and small size. We report the first quantitative demonstration of slow light enhancement of the electro......-optic (EO) coefficient in a.(2) ferroelectric waveguide at microwave modulation frequencies. This is demonstrated in a compact (1 mm) photonic crystal (PC) device with a voltage-length product (V pi . L) of 0.66 V-cm at 10 GHz and measured EO modulation out to 40 GHz. A local enhancement factor of 12...

An improved method to characterise the modulation of small-scale turbulent by large-scale structures

Science.gov (United States)

Agostini, Lionel; Leschziner, Michael; Gaitonde, Datta

2015-11-01

A key aspect of turbulent boundary layer dynamics is ``modulation,'' which refers to degree to which the intensity of coherent large-scale structures (LS) cause an amplification or attenuation of the intensity of the small-scale structures (SS) through large-scale-linkage. In order to identify the variation of the amplitude of the SS motion, the envelope of the fluctuations needs to be determined. Mathis et al. (2009) proposed to define this latter by low-pass filtering the modulus of the analytic signal built from the Hilbert transform of SS. The validity of this definition, as a basis for quantifying the modulated SS signal, is re-examined on the basis of DNS data for a channel flow. The analysis shows that the modulus of the analytic signal is very sensitive to the skewness of its PDF, which is dependent, in turn, on the sign of the LS fluctuation and thus of whether these fluctuations are associated with sweeps or ejections. The conclusion is that generating an envelope by use of a low-pass filtering step leads to an important loss of information associated with the effects of the local skewness of the PDF of the SS on the modulation process. An improved Hilbert-transform-based method is proposed to characterize the modulation of SS turbulence by LS structures

LFI 30 and 44 GHz receivers Back-End Modules

International Nuclear Information System (INIS)

Artal, E; Aja, B; Fuente, M L de la; Pascual, J P; Mediavilla, A; Martinez-Gonzalez, E; Pradell, L; Paco, P de; Bara, M; Blanco, E; GarcIa, E; Davis, R; Kettle, D; Roddis, N; Wilkinson, A; Bersanelli, M; Mennella, A; Tomasi, M; Butler, R C; Cuttaia, F

2009-01-01

The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency Instrument are broadband receivers (20% relative bandwidth) working at room temperature. The signals coming from the Front End Module are amplified, band pass filtered and finally converted to DC by a detector diode. Each receiver has two identical branches following the differential scheme of the Planck radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs P-HEMT devices, microstrip filters and Schottky diode detectors. Their manufacturing development has included elegant breadboard prototypes and finally qualification and flight model units. Electrical, mechanical and environmental tests were carried out for the characterization and verification of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules of Planck-LFI radiometers is given, with details of the tests done to determine their electrical and environmental performances. The electrical performances of the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth, equivalent noise temperature, 1/f noise and linearity are presented.

Performance analysis of an optical self-interference cancellation system with a directly modulated laser-based demonstration.

Science.gov (United States)

Yu, Yinghong; Zhang, Yunhao; Huang, Lin; Xiao, Shilin

2018-02-20

In this paper, two main performance indices of the optical self-interference cancellation (OSIC) system are theoretically analyzed: cancellation bandwidth and depth. Delay deviation is investigated to be the determining factor of cancellation bandwidth, based on which the bandwidth advantage of the OSIC system over electrical schemes is also proven theoretically. Cancellation depth in the narrowband is mostly influenced by attenuation and delay-adjusting deviation, while in the broadband case, the performance is mostly limited by frequency-dependent amplitude and phase mismatch. The cancellation performance analysis is suitable for most linear modulation-demodulation OSIC systems, including the directly modulated laser (DML)-based OSIC system verified experimentally in this paper. The cancellation model is well demonstrated by the agreement between experimental cancellation results and predicted performance. For over-the-air demonstration with the employment of antennas, broadband cancellation within 450 MHz bandwidth of 22 dB and 25 dB is achieved at 900 MHz and 2.4 GHz, respectively. In addition, orthogonal frequency division multiplexing signals are employed to show in-band full-duplex transmission with good performance by the DML-based OSIC system, with successful suppression of self-interference and recovery of the signal of interest.

Dual-Modulation, Dual-Wavelength, Optical Polarimetry System for Glucose Monitoring

Science.gov (United States)

2016-08-26

bandwidth transimpedance amplifier (CVI Melles Griot, Albuquerque, NM, USA) and fed into two lock-in amplifiers (Stanford Research Systems, Sunnyvale...were modulated using synchronous sinusoidal signals and linear amplifiers (carrier frequencies: 1 2=45 82c cf kHz f kHz， ). The sinusoidal signals...ferrite core was powered with an audio amplifier (Radio Shack, Fort Worth, TX, USA) connected in series with a 0.18 µF capacitor in order to achieve

Using Pulse Width Modulation for Wireless Transmission of Neural Signals in Multichannel Neural Recording Systems

Science.gov (United States)

Yin, Ming; Ghovanloo, Maysam

2013-01-01

We have used a well-known technique in wireless communication, pulse width modulation (PWM) of time division multiplexed (TDM) signals, within the architecture of a novel wireless integrated neural recording (WINeR) system. We have evaluated the performance of the PWM-based architecture and indicated its accuracy and potential sources of error through detailed theoretical analysis, simulations, and measurements on a setup consisting of a 15-channel WINeR prototype as the transmitter and two types of receivers; an Agilent 89600 vector signal analyzer and a custom wideband receiver, with 36 and 75 MHz of maximum bandwidth, respectively. Furthermore, we present simulation results from a realistic MATLAB-Simulink model of the entire WINeR system to observe the system behavior in response to changes in various parameters. We have concluded that the 15-ch WINeR prototype, which is fabricated in a 0.5-μm standard CMOS process and consumes 4.5 mW from ±1.5 V supplies, can acquire and wirelessly transmit up to 320 k-samples/s to a 75-MHz receiver with 8.4 bits of resolution, which is equivalent to a wireless data rate of ~ 2.26 Mb/s. PMID:19497823

Bandwidth scalable, coherent transmitter based on the parallel synthesis of multiple spectral slices using optical arbitrary waveform generation.

Science.gov (United States)

Geisler, David J; Fontaine, Nicolas K; Scott, Ryan P; He, Tingting; Paraschis, Loukas; Gerstel, Ori; Heritage, Jonathan P; Yoo, S J B

2011-04-25

We demonstrate an optical transmitter based on dynamic optical arbitrary waveform generation (OAWG) which is capable of creating high-bandwidth (THz) data waveforms in any modulation format using the parallel synthesis of multiple coherent spectral slices. As an initial demonstration, the transmitter uses only 5.5 GHz of electrical bandwidth and two 10-GHz-wide spectral slices to create 100-ns duration, 20-GHz optical waveforms in various modulation formats including differential phase-shift keying (DPSK), quaternary phase-shift keying (QPSK), and eight phase-shift keying (8PSK) with only changes in software. The experimentally generated waveforms showed clear eye openings and separated constellation points when measured using a real-time digital coherent receiver. Bit-error-rate (BER) performance analysis resulted in a BER < 9.8 × 10(-6) for DPSK and QPSK waveforms. Additionally, we experimentally demonstrate three-slice, 4-ns long waveforms that highlight the bandwidth scalable nature of the optical transmitter. The various generated waveforms show that the key transmitter properties (i.e., packet length, modulation format, data rate, and modulation filter shape) are software definable, and that the optical transmitter is capable of acting as a flexible bandwidth transmitter.

Visualization of frequency-modulated electric field based on photonic frequency tracking in asynchronous electro-optic measurement system

Science.gov (United States)

Hisatake, Shintaro; Yamaguchi, Koki; Uchida, Hirohisa; Tojyo, Makoto; Oikawa, Yoichi; Miyaji, Kunio; Nagatsuma, Tadao

2018-04-01

We propose a new asynchronous measurement system to visualize the amplitude and phase distribution of a frequency-modulated electromagnetic wave. The system consists of three parts: a nonpolarimetric electro-optic frequency down-conversion part, a phase-noise-canceling part, and a frequency-tracking part. The photonic local oscillator signal generated by electro-optic phase modulation is controlled to track the frequency of the radio frequency (RF) signal to significantly enhance the measurable RF bandwidth. We demonstrate amplitude and phase measurement of a quasi-millimeter-wave frequency-modulated continuous-wave signal (24 GHz ± 80 MHz with a 2.5 ms period) as a proof-of-concept experiment.

Analysis of small-signal intensity modulation of semiconductor ...

Indian Academy of Sciences (India)

Computer simulation of the model is applied to 1.55-µm ... Semiconductor laser; small-signal modulation; modulation response; gain suppression. ... originates from intraband relaxation processes of charge carriers that extend for times as ...

Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

Science.gov (United States)

Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

2011-03-01

We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

Superconducting bandpass delta-sigma modulator

International Nuclear Information System (INIS)

Bulzacchelli, J.F.; Lee, H.-S.; Misewich, J.A.; Ketchen, M.B.

1999-01-01

Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS. (author)

Barium Titanate Photonic Crystal Electro-Optic Modulators for Telecommunication and Data Network Applications

Science.gov (United States)

Girouard, Peter D.

The microwave, optical, and electro-optic properties of epitaxial barium titanate thin films grown on (100) MgO substrates and photonic crystal electro-optic modulators fabricated on these films were investigated to demonstrate the applicability of these devices for telecommunication and data networks. The electrical and electro-optical properties were characterized up to modulation frequencies of 50 GHz, and the optical properties of photonic crystal waveguides were determined for wavelengths spanning the optical C band between 1500 and 1580 nm. Microwave scattering parameters were measured on coplanar stripline devices with electrode gap spacings between 5 and 12 mum on barium titanate films with thicknesses between 230 and 680 nm. The microwave index and device characteristic impedance were obtained from the measurements. Larger (lower) microwave indices (impedances) were obtained for devices with narrower electrode gap spacings and on thicker films. Thinner film devices have both lower index mismatch between the co-propagating microwave and optical signals and lower impedance mismatch to a 50O system, resulting in a larger predicted electro-optical 3 dB bandwidth. This was experimentally verified with electro-optical frequency response measurements. These observations were applied to demonstrate a record high 28 GHz electro-optic bandwidth measured for a BaTiO3 conventional ridge waveguide modulator having 1mm long electrodes and 12 mum gap spacing on a 260nm thick film. The half-wave voltage and electro-optic coefficients of barium titanate modulators were measured for films having thicknesses between 260 and 500 nm. The half-wave voltage was directly measured at low frequencies using a polarizer-sample-compensator-analyzer setup by over-driving waveguide integrated modulators beyond their linear response regime. Effective in-device electro-optic coefficients were obtained from the measured half-wave voltages. The effective electro-optic coefficients were

PIC Simulation of Laser Plasma Interactions with Temporal Bandwidths

Science.gov (United States)

Tsung, Frank; Weaver, J.; Lehmberg, R.

2015-11-01

We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temperal bandwidths under conditions relevant to current and future shock ignition experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth, the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using smoothing techniques such as SSD or ISI). We will show that temporal bandwidth along play an important role in the control of LPI's in these lasers and discuss future directions. This work is conducted under the auspices of NRL.

Studying and comparing spectrum efficiency and error probability in GMSK and DBPSK modulation schemes

Directory of Open Access Journals (Sweden)

Juan Mario Torres Nova

2008-09-01

Full Text Available Gaussian minimum shift keying (GMSK and differential binary phase shift keying (DBPSK are two digital modulation schemes which are -frequently used in radio communication systems; however, there is interdependence in the use of its benefits (spectral efficiency, low bit error rate, low inter symbol interference, etc. Optimising one parameter creates problems for another; for example, the GMSK scheme succeeds in reducing bandwidth when introducing a Gaussian filter into an MSK (minimum shift ke-ying modulator in exchange for increasing inter-symbol interference in the system. The DBPSK scheme leads to lower error pro-bability, occupying more bandwidth; it likewise facilitates synchronous data transmission due to the receiver’s bit delay when re-covering a signal.

Deterministic reshaping of single-photon spectra using cross-phase modulation.

Science.gov (United States)

Matsuda, Nobuyuki

2016-03-01

The frequency conversion of light has proved to be a crucial technology for communication, spectroscopy, imaging, and signal processing. In the quantum regime, it also offers great potential for realizing quantum networks incorporating disparate physical systems and quantum-enhanced information processing over a large computational space. The frequency conversion of quantum light, such as single photons, has been extensively investigated for the last two decades using all-optical frequency mixing, with the ultimate goal of realizing lossless and noiseless conversion. I demonstrate another route to this target using frequency conversion induced by cross-phase modulation in a dispersion-managed photonic crystal fiber. Owing to the deterministic and all-optical nature of the process, the lossless and low-noise spectral reshaping of a single-photon wave packet in the telecommunication band has been readily achieved with a modulation bandwidth as large as 0.4 THz. I further demonstrate that the scheme is applicable to manipulations of a nonclassical frequency correlation, wave packet interference, and entanglement between two photons. This approach presents a new coherent frequency interface for photons for quantum information processing.

Receiver Signal to Noise Ratios for IPDA Lidars Using Sine-wave and Pulsed Laser Modulation and Direct Detections

Science.gov (United States)

Sun, Xiaoli; Abshire, James B.

2011-01-01

Integrated path differential absorption (IPDA) lidar can be used to remotely measure the column density of gases in the path to a scattering target [1]. The total column gas molecular density can be derived from the ratio of the laser echo signal power with the laser wavelength on the gas absorption line (on-line) to that off the line (off-line). 80th coherent detection and direct detection IPDA lidar have been used successfully in the past in horizontal path and airborne remote sensing measurements. However, for space based measurements, the signal propagation losses are often orders of magnitude higher and it is important to use the most efficient laser modulation and detection technique to minimize the average laser power and the electrical power from the spacecraft. This paper gives an analysis the receiver signal to noise ratio (SNR) of several laser modulation and detection techniques versus the average received laser power under similar operation environments. Coherent detection [2] can give the best receiver performance when the local oscillator laser is relatively strong and the heterodyne mixing losses are negligible. Coherent detection has a high signal gain and a very narrow bandwidth for the background light and detector dark noise. However, coherent detection must maintain a high degree of coherence between the local oscillator laser and the received signal in both temporal and spatial modes. This often results in a high system complexity and low overall measurement efficiency. For measurements through atmosphere the coherence diameter of the received signal also limits the useful size of the receiver telescope. Direct detection IPDA lidars are simpler to build and have fewer constraints on the transmitter and receiver components. They can use much larger size 'photon-bucket' type telescopes to reduce the demands on the laser transmitter. Here we consider the two most widely used direct detection IPDA lidar techniques. The first technique uses two CW

IMPROVING BANDWIDTH OF FLIPPED VOLTAGE FOLLOWER USING GATE-BODY DRIVEN TECHNIQUE

Directory of Open Access Journals (Sweden)

VANDANA NIRANJAN

2017-01-01

Full Text Available In this paper, a new approach to enhance the bandwidth of flipped voltage follower is explored. The proposed approach is based on gate-body driven technique. This technique boosts the transconductance in a MOS transistor as both gate and body/bulk terminals are tied together and used as signal input. This novel technique appears as a good solution to merge the advantages of gate-driven and bulk-driven techniques and suppress their disadvantages. The gate-body driven technique utilizes body effect to enable low voltage low power operation and improves the overall performance of flipped voltage follower, providing it with low output impedance, high input impedance and bandwidth extension ratio of 2.614. The most attractive feature is that bandwidth enhancement has been achieved without use of any passive component or extra circuitry. Simulations in PSpice environment for 180 nm CMOS technology verified the predicted theoretical results. The improved flipped voltage follower is particularly interesting for high frequency low noise signal processing applications.

Optical technologies for data communication in large parallel systems

International Nuclear Information System (INIS)

Ritter, M B; Vlasov, Y; Kash, J A; Benner, A

2011-01-01

Large, parallel systems have greatly aided scientific computation and data collection, but performance scaling now relies on chip and system-level parallelism. This has happened because power density limits have caused processor frequency growth to stagnate, driving the new multi-core architecture paradigm, which would seem to provide generations of performance increases as transistors scale. However, this paradigm will be constrained by electrical I/O bandwidth limits; first off the processor card, then off the processor module itself. We will present best-estimates of these limits, then show how optical technologies can help provide more bandwidth to allow continued system scaling. We will describe the current status of optical transceiver technology which is already being used to exceed off-board electrical bandwidth limits, then present work on silicon nanophotonic transceivers and 3D integration technologies which, taken together, promise to allow further increases in off-module and off-card bandwidth. Finally, we will show estimated limits of nanophotonic links and discuss breakthroughs that are needed for further progress, and will speculate on whether we will reach Exascale-class machine performance at affordable powers.

Optical technologies for data communication in large parallel systems

Energy Technology Data Exchange (ETDEWEB)

Ritter, M B; Vlasov, Y; Kash, J A [IBM T.J. Watson Research Center, Yorktown Heights, NY (United States); Benner, A, E-mail: mritter@us.ibm.com [IBM Poughkeepsie, Poughkeepsie, NY (United States)

2011-01-15

Large, parallel systems have greatly aided scientific computation and data collection, but performance scaling now relies on chip and system-level parallelism. This has happened because power density limits have caused processor frequency growth to stagnate, driving the new multi-core architecture paradigm, which would seem to provide generations of performance increases as transistors scale. However, this paradigm will be constrained by electrical I/O bandwidth limits; first off the processor card, then off the processor module itself. We will present best-estimates of these limits, then show how optical technologies can help provide more bandwidth to allow continued system scaling. We will describe the current status of optical transceiver technology which is already being used to exceed off-board electrical bandwidth limits, then present work on silicon nanophotonic transceivers and 3D integration technologies which, taken together, promise to allow further increases in off-module and off-card bandwidth. Finally, we will show estimated limits of nanophotonic links and discuss breakthroughs that are needed for further progress, and will speculate on whether we will reach Exascale-class machine performance at affordable powers.

A Hybrid OFDM-TDM Architecture with Decentralized Dynamic Bandwidth Allocation for PONs

Directory of Open Access Journals (Sweden)

Taner Cevik

2013-01-01

Full Text Available One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT which is the only competent authority, each optical network unit (ONU runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand.

A Hybrid OFDM-TDM Architecture with Decentralized Dynamic Bandwidth Allocation for PONs

Science.gov (United States)

Cevik, Taner

2013-01-01

One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand. PMID:24194684

Radio over fiber transceiver employing phase modulation of an optical broadband source.

Science.gov (United States)

Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

2010-10-11

This paper proposes a low-cost RoF transceiver for multichannel SCM/WDM signal distribution suitable for future broadband access networks. The transceiver is based on the phase modulation of an optical broadband source centered at third transmission window. Prior to phase modulation the optical broadband source output signal is launched into a Mach-Zehnder interferometer structure, as key device enabling radio signals propagation over the optical link. Furthermore, an optical CWDM is employed to create a multichannel scenario by performing the spectral slicing of the modulated optical signal into a number of channels each one conveying the information from the central office to different base stations. The operation range is up to 20 GHz with a modulation bandwidth around of 500 MHz. Experimental results of the transmission of SCM QPSK and 64-QAM data through 20 Km of SMF exhibit good EVM results in the operative range determined by the phase-to-intensity conversion process. The proposed approach shows a great suitability for WDM networks based on RoF signal transport and also represents a cost-effective solution for passive optical networks.

Single-lane 180  Gbit/s PAM-4 signal transmission over 2  km SSMF for short-reach applications.

Science.gov (United States)

Zhang, Qiang; Stojanovic, Nebojsa; Prodaniuc, Cristian; Xie, Changsong; Koenigsmann, Michael; Laskowski, Piotr

2016-10-01

We experimentally demonstrate the generation and transmission of a single-lane 180  Gbit/s (90 GBaud) four-level pulse-amplitude modulation (PAM-4) signal in an intensity-modulation direct-detection system with a 7.5 GHz 3 dB bandwidth. The generated signal is transmitted over a 2 km standard single-mode fiber with, to the best of our knowledge, the highest reported net data rate in the C-band: 150  Gbit/s. A net data rate of 168  Gbit/s is also reachable with 1 km reach. The PAM-4 and duobinary (DB) PAM-4 modulation schemes are compared; the obtained results show that DB-PAM-4 significantly outperforms PAM-4 in the considered strong bandwidth-constrained system. Both a feed-forward equalizer and a maximum-likelihood sequence estimator are investigated for data recovery.

New challenges in signal processing in astrophysics: the SKA case

International Nuclear Information System (INIS)

Faulkner, Andrew; Zarb-Adami, Kristian; De Vaate, Jan Geralt Bij

2015-01-01

Signal processing and communications are driving the latest generation of radio telescopes with major developments taking place for use on the Square Kilometre Array, SKA, the next generation low frequency radio telescope. The data rates and processing performance that can be achieved with currently available components means that concepts from the earlier days of radio astronomy, phased arrays, can be used at higher frequencies, larger bandwidths and higher numbers of beams. Indeed it has been argued that the use of dishes as a mechanical beamformer only gained strong acceptance to mitigate the processing load from phased array technology. The balance is changing and benefits in both performance and cost can be realised. In this paper we will mostly consider the signal processing implementation and control for very large phased arrays consisting of hundreds of thousands of antennas or even millions of antennas. They can use current technology for the initial deployments. These systems are very large extending to hundreds of racks with thousands of signal processing modules that link through high-speed, but commercially available data networking devices. There are major challenges to accurately calibrate the arrays, mitigate power consumption and make the system maintainable

Optical modulation techniques for analog signal processing and CMOS compatible electro-optic modulation

Science.gov (United States)

Gill, Douglas M.; Rasras, Mahmoud; Tu, Kun-Yii; Chen, Young-Kai; White, Alice E.; Patel, Sanjay S.; Carothers, Daniel; Pomerene, Andrew; Kamocsai, Robert; Beattie, James; Kopa, Anthony; Apsel, Alyssa; Beals, Mark; Mitchel, Jurgen; Liu, Jifeng; Kimerling, Lionel C.

2008-02-01

Integrating electronic and photonic functions onto a single silicon-based chip using techniques compatible with mass-production CMOS electronics will enable new design paradigms for existing system architectures and open new opportunities for electro-optic applications with the potential to dramatically change the management, cost, footprint, weight, and power consumption of today's communication systems. While broadband analog system applications represent a smaller volume market than that for digital data transmission, there are significant deployments of analog electro-optic systems for commercial and military applications. Broadband linear modulation is a critical building block in optical analog signal processing and also could have significant applications in digital communication systems. Recently, broadband electro-optic modulators on a silicon platform have been demonstrated based on the plasma dispersion effect. The use of the plasma dispersion effect within a CMOS compatible waveguide creates new challenges and opportunities for analog signal processing since the index and propagation loss change within the waveguide during modulation. We will review the current status of silicon-based electrooptic modulators and also linearization techniques for optical modulation.

Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

Science.gov (United States)

Djordjevic, Ivan B

2011-07-18

In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

Ultra-high bandwidth quantum secured data transmission

Science.gov (United States)

Dynes, James F.; Tam, Winci W.-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

2016-10-01

Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

KNN BASED CLASSIFICATION OF DIGITAL MODULATED SIGNALS

Directory of Open Access Journals (Sweden)

Sajjad Ahmed Ghauri

2016-11-01

Full Text Available Demodulation process without the knowledge of modulation scheme requires Automatic Modulation Classification (AMC. When receiver has limited information about received signal then AMC become essential process. AMC finds important place in the field many civil and military fields such as modern electronic warfare, interfering source recognition, frequency management, link adaptation etc. In this paper we explore the use of K-nearest neighbor (KNN for modulation classification with different distance measurement methods. Five modulation schemes are used for classification purpose which is Binary Phase Shift Keying (BPSK, Quadrature Phase Shift Keying (QPSK, Quadrature Amplitude Modulation (QAM, 16-QAM and 64-QAM. Higher order cummulants (HOC are used as an input feature set to the classifier. Simulation results shows that proposed classification method provides better results for the considered modulation formats.

Harbor porpoise clicks do not have conditionally minimum time bandwidth product

DEFF Research Database (Denmark)

Beedholm, Kristian

2008-01-01

The hypothesis that odontocete clicks have minimal time frequency product given their delay and center frequency values is tested by using an in-phase averaged porpoise click compared with a pure tone weighted with the same envelope. These signals have the same delay and the same center frequency...... values but the time bandwidth product of the artificial click is only 0.76 that of the original. Therefore signals with the same parameters exist that have a lower time bandwidth product. The observation that porpoise clicks are in fact minimum phase is confirmed for porpoise clicks and this property...... is argued to be incompatible with optimal reception, if auditory filters are also minimum phase....

BANDWIDTH AND EFFICIENT ENCODING SCHEME COMBINING TCM-UGM TO STBC

OpenAIRE

ABDELMOUNAIM MOULAY LAKHDAR; MOHAMMED BELADGHAM; ABDESSELAM BASSOU,; MOHAMED BENAISSA

2011-01-01

In this paper, a bandwidth efficient encoding scheme is proposed. It combines the modified version of trellis coded-modulation (called trellis coded-modulation with Ungerboeck-Gray mapping, TCM-UGM) to space-time block code (STBC). The performance of this encoding scheme is investigated over memoryless Rayleigh fading (MRF) channel for throughput 2 bits/s/Hz. The simulation result, using 2/3 rate 16-state TCM-UGM encoder, two transmit antennas and two receive antennas, shows clearly that the ...

Multi-channel logical circuit module used for high-speed, low amplitude signals processing and QDC gate signals generation

International Nuclear Information System (INIS)

Su Hong; Li Xiaogang; Zhu Haidong; Ma Xiaoli; Yin Weiwei; Li Zhuyu; Jin Genming; Wu Heyu

2001-01-01

A new kind of logical circuit will be introduced in brief. There are 16 independent channels in the module. The module receives low amplitude signals(≥40 mV), and processes them to amplify, shape, delay, sum and etc. After the processing each channel produces 2 pairs of ECL logical signal to feed the gate of QDC as the gate signal of QDC. The module consists of high-speed preamplifier unit, high-speed discriminate unit, delaying and shaping unit, summing unit and trigger display unit. The module is developed for 64 CH. 12 BIT Multi-event QDC. The impedance of QDC is 110 Ω. Each gate signal of QDC requires a pair of differential ECL level, Min. Gate width 30 ns and Max. Gate width 1 μs. It has showed that the outputs of logical circuit module satisfy the QDC requirements in experiment. The module can be used on data acquisition system to acquire thousands of data at high-speed ,high-density and multi-parameter, in heavy particle nuclear physics experiment. It also can be used to discriminate multi-coincidence events

Robust 9-QAM digital recovery for spectrum shaped coherent QPSK signal

DEFF Research Database (Denmark)

Huang, Bo; Zhang, Junwen; Yu, Jianjun

2013-01-01

division multiplexing (NWDM). The final equalized signal is detected by maximum likelihood sequence decision (MLSD) for data bit-error-ratio (BER) measurement. Optical signal-to-noise ratio (OSNR) tolerance is improved by 0.5 dB at a BER of 1x10-3 compared to constant modulus algorithm (CMA) plus post......We propose 9-ary quadrature amplitude modulation (9-QAM) data recovery for polarization multiplexing-quadrature phase shift keying (PM-QPSK) signal in presence of strong filtering to approach Nyquist bandwidth. The decision-directed least radius distance (DD-LRD) algorithm for blind equalization...

High bandwidth concurrent processing on commodity platforms

CERN Document Server

Boosten, M; Van der Stok, P D V

1999-01-01

The I/O bandwidth and real-time processing power required for high- energy physics experiments is increasing rapidly over time. The current requirements can only be met by using large-scale concurrent processing. We are investigating the use of a large PC cluster interconnected by Fast and Gigabit Ethernet to meet the performance requirements of the ATLAS second level trigger. This architecture is attractive because of its performance and competitive pricing. A major problem is obtaining frequent high-bandwidth I/O without sacrificing the CPU's processing power. We present a tight integration of a user-level scheduler and a zero-copy communication layer. This system closely approaches the performance of the underlying hardware in terms of both CPU power and I/O capacity. (0 refs).

Phase ramping and modulation of reflectometer signals

International Nuclear Information System (INIS)

Conway, G.; Bartlett, D.; Stott, P.

1999-06-01

The phase and amplitude signals of JET heterodyne reflectometers show varying levels of high frequency turbulence superimposed on a slow changing mean. The phase signal also shows multi-radian (>1 fringe) variations with two quite different time scales (2-10ms and sub-ms). In both cases the mean reflected power, together with turbulent phase and amplitude fluctuation levels, are modulated synchronously with the phase fringes. The slow fringes appear to result from radial movement of the cutoff layer with the amplitude modulation possibly due to multiple reflection between plasma and wall. The fast fringes occur in intermittent bursts and appear to be phase runaway resulting from antenna misalignment. Using a 2D physical optics simulation code it is possible to replicate the fast bursts of phase runaway from steady-state turbulence and misaligned antennas. This offers a possible alternative explanation for some of the observations of bursting turbulence seen in reflectometer signals. (author)

Analysis of interference of QPSK and QDPSK modulation signals by mathematical

Science.gov (United States)

Li, Dairuo; Xu, Kai

2017-03-01

In today's society, with the rapid development and extensive application of the information technology of the network central station and the integrated information system technology, information plays an important role in the military communication, mastering the information right to the competition Important role, how to protect one's own security, smooth access to and transmission of information, and to maximize the elimination of interference has become an important issue at home and abroad. QPSK modulation and its improved QPSK modulation as the mainstream signal modulation, the most widely used. In this paper, the principle of QPSK and QDPSK modulation and demodulation are introduced in this paper. Then, how to interfere with QPSK modulation signal is analyzed, and the interference of QPSK modulation signal is simulated by Matlab scripting program, which can be used in the next step. And to study the next step of anti-jamming measures provided the basis and preparatory work.

Signal processing and general purpose data acquisition system for on-line tomographic measurements

Science.gov (United States)

Murari, A.; Martin, P.; Hemming, O.; Manduchi, G.; Marrelli, L.; Taliercio, C.; Hoffmann, A.

1997-01-01

New analog signal conditioning electronics and data acquisition systems have been developed for the soft x-ray and bolometric tomography diagnostic in the reverse field pinch experiment (RFX). For the soft x-ray detectors the analog signal processing includes a fully differential current to voltage conversion, with up to a 200 kHz bandwidth. For the bolometers, a 50 kHz carrier frequency amplifier allows a maximum bandwidth of 10 kHz. In both cases the analog signals are digitized with a 1 MHz sampling rate close to the diagnostic and are transmitted via a transparent asynchronous xmitter/receiver interface (TAXI) link to purpose built Versa Module Europa (VME) modules which perform data acquisition. A software library has been developed for data preprocessing and tomographic reconstruction. It has been written in C language and is self-contained, i.e., no additional mathematical library is required. The package is therefore platform-free: in particular it can perform online analysis in a real-time application, such as continuous display and feedback, and is portable for long duration fusion or other physical experiments. Due to the modular organization of the library, new preprocessing and analysis modules can be easily integrated in the environment. This software is implemented in RFX over three different platforms: open VMS, digital Unix, and VME 68040 CPU.

Performance Study of optical Modulator based on electrooptic effect

International Nuclear Information System (INIS)

Palodiya, V; Raghuwanshi, S K

2016-01-01

In this paper, we have studied and derive performance parameter of highly integrated Lithium Niobate optical modulator. This is a chirp free modulator having low switching voltage and large bandwidth. For an external modulator in which travelling-wave electrodes length L imposed the modulating switching voltage, the product of V_π and L is fixed for a given electro optic material Lithium Niobate. We investigate to achieve a low V_π by both magnitude of the electro-optic coefficient for a wide variety of electro-optic materials. A Sellmeier equation for the extraordinary index of congruent lithium niobate is derived. For phase-matching, predictions are accmate for temperature between room temperature 250°C and wavelength ranging from 0.4 to 5µm. The Sellmeier equations predict more accmately refractive indices at long wavelengths. Theoretical result is confirmed by simulated results. We have analysed the various parameters such as switching voltage, device performance index, time constant, transmittance, cut-off frequency, 3-dB bandwidth, power absorption coefficient and transmission bit rate of Lithium Niobate optical Modulator based on electro -optic effect. (paper)

Probiotic Modulation of Innate Cell Pathogen Sensing and Signaling Events

Directory of Open Access Journals (Sweden)

Amy Llewellyn

2017-10-01

Full Text Available There is a growing body of evidence documenting probiotic bacteria to have a beneficial effect to the host through their ability to modulate the mucosal immune system. Many probiotic bacteria can be considered to act as either immune activators or immune suppressors, which have appreciable influence on homeostasis, inflammatory- and suppressive-immunopathology. What is becoming apparent is the ability of these probiotics to modulate innate immune responses via direct or indirect effects on the signaling pathways that drive these activatory or suppressive/tolerogenic mechanisms. This review will focus on the immunomodulatory role of probiotics on signaling pathways in innate immune cells: from positive to negative regulation associated with innate immune cells driving gut mucosal functionality. Research investigations have shown probiotics to modulate innate functionality in many ways including, receptor antagonism, receptor expression, binding to and expression of adaptor proteins, expression of negative regulatory signal molecules, induction of micro-RNAs, endotoxin tolerisation and finally, the secretion of immunomodulatory proteins, lipids and metabolites. The detailed understanding of the immunomodulatory signaling effects of probiotic strains will facilitate strain-specific selective manipulation of innate cell signal mechanisms in the modulation of mucosal adjuvanticity, immune deviation and tolerisation in both healthy subjects and patients with inflammatory and suppressive pathology.

Probiotic Modulation of Innate Cell Pathogen Sensing and Signaling Events

Science.gov (United States)

Llewellyn, Amy; Foey, Andrew

2017-01-01

There is a growing body of evidence documenting probiotic bacteria to have a beneficial effect to the host through their ability to modulate the mucosal immune system. Many probiotic bacteria can be considered to act as either immune activators or immune suppressors, which have appreciable influence on homeostasis, inflammatory- and suppressive-immunopathology. What is becoming apparent is the ability of these probiotics to modulate innate immune responses via direct or indirect effects on the signaling pathways that drive these activatory or suppressive/tolerogenic mechanisms. This review will focus on the immunomodulatory role of probiotics on signaling pathways in innate immune cells: from positive to negative regulation associated with innate immune cells driving gut mucosal functionality. Research investigations have shown probiotics to modulate innate functionality in many ways including, receptor antagonism, receptor expression, binding to and expression of adaptor proteins, expression of negative regulatory signal molecules, induction of micro-RNAs, endotoxin tolerisation and finally, the secretion of immunomodulatory proteins, lipids and metabolites. The detailed understanding of the immunomodulatory signaling effects of probiotic strains will facilitate strain-specific selective manipulation of innate cell signal mechanisms in the modulation of mucosal adjuvanticity, immune deviation and tolerisation in both healthy subjects and patients with inflammatory and suppressive pathology. PMID:29065562

Inhibitory neurons modulate spontaneous signaling in cultured cortical neurons: density-dependent regulation of excitatory neuronal signaling

International Nuclear Information System (INIS)

Serra, Michael; Guaraldi, Mary; Shea, Thomas B

2010-01-01

Cortical neuronal activity depends on a balance between excitatory and inhibitory influences. Culturing of neurons on multi-electrode arrays (MEAs) has provided insight into the development and maintenance of neuronal networks. Herein, we seeded MEAs with murine embryonic cortical/hippocampal neurons at different densities ( 1000 cells mm −2 ) and monitored resultant spontaneous signaling. Sparsely seeded cultures displayed a large number of bipolar, rapid, high-amplitude individual signals with no apparent temporal regularity. By contrast, densely seeded cultures instead displayed clusters of signals at regular intervals. These patterns were observed even within thinner and thicker areas of the same culture. GABAergic neurons (25% of total neurons in our cultures) mediated the differential signal patterns observed above, since addition of the inhibitory antagonist bicuculline to dense cultures and hippocampal slice cultures induced the signal pattern characteristic of sparse cultures. Sparsely seeded cultures likely lacked sufficient inhibitory neurons to modulate excitatory activity. Differential seeding of MEAs can provide a unique model for analyses of pertubation in the interaction between excitatory and inhibitory function during aging and neuropathological conditions where dysregulation of GABAergic neurons is a significant component

Hierarchical feedback modules and reaction hubs in cell signaling networks.

Science.gov (United States)

Xu, Jianfeng; Lan, Yueheng

2015-01-01

Despite much effort, identification of modular structures and study of their organizing and functional roles remain a formidable challenge in molecular systems biology, which, however, is essential in reaching a systematic understanding of large-scale cell regulation networks and hence gaining capacity of exerting effective interference to cell activity. Combining graph theoretic methods with available dynamics information, we successfully retrieved multiple feedback modules of three important signaling networks. These feedbacks are structurally arranged in a hierarchical way and dynamically produce layered temporal profiles of output signals. We found that global and local feedbacks act in very different ways and on distinct features of the information flow conveyed by signal transduction but work highly coordinately to implement specific biological functions. The redundancy embodied with multiple signal-relaying channels and feedback controls bestow great robustness and the reaction hubs seated at junctions of different paths announce their paramount importance through exquisite parameter management. The current investigation reveals intriguing general features of the organization of cell signaling networks and their relevance to biological function, which may find interesting applications in analysis, design and control of bio-networks.

Hierarchical feedback modules and reaction hubs in cell signaling networks.

Directory of Open Access Journals (Sweden)

Jianfeng Xu

Full Text Available Despite much effort, identification of modular structures and study of their organizing and functional roles remain a formidable challenge in molecular systems biology, which, however, is essential in reaching a systematic understanding of large-scale cell regulation networks and hence gaining capacity of exerting effective interference to cell activity. Combining graph theoretic methods with available dynamics information, we successfully retrieved multiple feedback modules of three important signaling networks. These feedbacks are structurally arranged in a hierarchical way and dynamically produce layered temporal profiles of output signals. We found that global and local feedbacks act in very different ways and on distinct features of the information flow conveyed by signal transduction but work highly coordinately to implement specific biological functions. The redundancy embodied with multiple signal-relaying channels and feedback controls bestow great robustness and the reaction hubs seated at junctions of different paths announce their paramount importance through exquisite parameter management. The current investigation reveals intriguing general features of the organization of cell signaling networks and their relevance to biological function, which may find interesting applications in analysis, design and control of bio-networks.

Hierarchical Feedback Modules and Reaction Hubs in Cell Signaling Networks

Science.gov (United States)

Xu, Jianfeng; Lan, Yueheng

2015-01-01

Despite much effort, identification of modular structures and study of their organizing and functional roles remain a formidable challenge in molecular systems biology, which, however, is essential in reaching a systematic understanding of large-scale cell regulation networks and hence gaining capacity of exerting effective interference to cell activity. Combining graph theoretic methods with available dynamics information, we successfully retrieved multiple feedback modules of three important signaling networks. These feedbacks are structurally arranged in a hierarchical way and dynamically produce layered temporal profiles of output signals. We found that global and local feedbacks act in very different ways and on distinct features of the information flow conveyed by signal transduction but work highly coordinately to implement specific biological functions. The redundancy embodied with multiple signal-relaying channels and feedback controls bestow great robustness and the reaction hubs seated at junctions of different paths announce their paramount importance through exquisite parameter management. The current investigation reveals intriguing general features of the organization of cell signaling networks and their relevance to biological function, which may find interesting applications in analysis, design and control of bio-networks. PMID:25951347

Linearity optimizations of analog ring resonator modulators through bias voltage adjustments

Science.gov (United States)

Hosseinzadeh, Arash; Middlebrook, Christopher T.

2018-03-01

The linearity of ring resonator modulator (RRM) in microwave photonic links is studied in terms of instantaneous bandwidth, fabrication tolerances, and operational bandwidth. A proposed bias voltage adjustment method is shown to maximize spur-free dynamic range (SFDR) at instantaneous bandwidths required by microwave photonic link (MPL) applications while also mitigating RRM fabrication tolerances effects. The proposed bias voltage adjustment method shows RRM SFDR improvement of ∼5.8 dB versus common Mach-Zehnder modulators at 500 MHz instantaneous bandwidth. Analyzing operational bandwidth effects on SFDR shows RRMs can be promising electro-optic modulators for MPL applications which require high operational frequencies while in a limited bandwidth such as radio-over-fiber 60 GHz wireless network access.

New hybrid reverse differential pulse position width modulation scheme for wireless optical communication

Science.gov (United States)

Liao, Renbo; Liu, Hongzhan; Qiao, Yaojun

2014-05-01

In order to improve the power efficiency and reduce the packet error rate of reverse differential pulse position modulation (RDPPM) for wireless optical communication (WOC), a hybrid reverse differential pulse position width modulation (RDPPWM) scheme is proposed, based on RDPPM and reverse pulse width modulation. Subsequently, the symbol structure of RDPPWM is briefly analyzed, and its performance is compared with that of other modulation schemes in terms of average transmitted power, bandwidth requirement, and packet error rate over ideal additive white Gaussian noise (AWGN) channels. Based on the given model, the simulation results show that the proposed modulation scheme has the advantages of improving the power efficiency and reducing the bandwidth requirement. Moreover, in terms of error probability performance, RDPPWM can achieve a much lower packet error rate than that of RDPPM. For example, at the same received signal power of -28 dBm, the packet error rate of RDPPWM can decrease to 2.6×10-12, while that of RDPPM is 2.2×10. Furthermore, RDPPWM does not need symbol synchronization at the receiving end. These considerations make RDPPWM a favorable candidate to select as the modulation scheme in the WOC systems.

Computational speech segregation based on an auditory-inspired modulation analysis

DEFF Research Database (Denmark)

May, Tobias; Dau, Torsten

2014-01-01

A monaural speech segregation system is presented that estimates the ideal binary mask from noisy speech based on the supervised learning of amplitude modulation spectrogram (AMS) features. Instead of using linearly scaled modulation filters with constant absolute bandwidth, an auditory- inspired...... about speech activity present in neighboring time-frequency units. In order to evaluate the generalization performance of the system to unseen acoustic conditions, the speech segregation system is trained with a limited set of low signal-to-noise ratio (SNR) conditions, but tested over a wide range...

Modulated convection at high frequencies and large modulation amplitudes

International Nuclear Information System (INIS)

Swift, J.B.; Hohenberg, P.C.

1987-01-01

Modulated Rayleigh-Benard convection is analyzed for high frequencies and large modulation amplitudes. The linear theory of Gershuni and Zhukhovitskii is generalized to the nonlinear domain, and a subcritical bifurcation to convection is found in agreement with the experiments of Niemela and Donnelly. The crossover between the high-frequency (''Stokes layer'') regime and the low-frequency regime studied previously is analyzed

Ring resonator-based on-chip modulation transformer for high-performance phase-modulated microwave photonic links.

Science.gov (United States)

Zhuang, Leimeng; Taddei, Caterina; Hoekman, Marcel; Leinse, Arne; Heideman, René; van Dijk, Paulus; Roeloffzen, Chris

2013-11-04

In this paper, we propose and experimentally demonstrate a novel wideband on-chip photonic modulation transformer for phase-modulated microwave photonic links. The proposed device is able to transform phase-modulated optical signals into intensity-modulated versions (or vice versa) with nearly zero conversion of laser phase noise to intensity noise. It is constructed using waveguide-based ring resonators, which features simple architecture, stable operation, and easy reconfigurability. Beyond the stand-alone functionality, the proposed device can also be integrated with other functional building blocks of photonic integrated circuits (PICs) to create on-chip complex microwave photonic signal processors. As an application example, a PIC consisting of two such modulation transformers and a notch filter has been designed and realized in TriPleX(TM) waveguide technology. The realized device uses a 2 × 2 splitting circuit and 3 ring resonators with a free spectral range of 25 GHz, which are all equipped with continuous tuning elements. The device can perform phase-to-intensity modulation transform and carrier suppression simultaneously, which enables high-performance phase-modulated microwave photonics links (PM-MPLs). Associated with the bias-free and low-complexity advantages of the phase modulators, a single-fiber-span PM-MPL with a RF bandwidth of 12 GHz (3 dB-suppression band 6 to 18 GHz) has been demonstrated comprising the proposed PIC, where the achieved spurious-free dynamic range performance is comparable to that of Class-AB MPLs using low-biased Mach-Zehnder modulators.

Comparison of WDM/Pulse-Position-Modulation (WDM/PPM) with Code/Pulse-Position-Swapping (C/PPS) Based on Wavelength/Time Codes

Energy Technology Data Exchange (ETDEWEB)

Mendez, A J; Hernandez, V J; Gagliardi, R M; Bennett, C V

2009-06-19

Pulse position modulation (PPM) signaling is favored in intensity modulated/direct detection (IM/DD) systems that have average power limitations. Combining PPM with WDM over a fiber link (WDM/PPM) enables multiple accessing and increases the link's throughput. Electronic bandwidth and synchronization advantages are further gained by mapping the time slots of PPM onto a code space, or code/pulse-position-swapping (C/PPS). The property of multiple bits per symbol typical of PPM can be combined with multiple accessing by using wavelength/time [W/T] codes in C/PPS. This paper compares the performance of WDM/PPM and C/PPS for equal wavelengths and bandwidth.

Frequency tracking and variable bandwidth for line noise filtering without a reference.

Science.gov (United States)

Kelly, John W; Collinger, Jennifer L; Degenhart, Alan D; Siewiorek, Daniel P; Smailagic, Asim; Wang, Wei

2011-01-01

This paper presents a method for filtering line noise using an adaptive noise canceling (ANC) technique. This method effectively eliminates the sinusoidal contamination while achieving a narrower bandwidth than typical notch filters and without relying on the availability of a noise reference signal as ANC methods normally do. A sinusoidal reference is instead digitally generated and the filter efficiently tracks the power line frequency, which drifts around a known value. The filter's learning rate is also automatically adjusted to achieve faster and more accurate convergence and to control the filter's bandwidth. In this paper the focus of the discussion and the data will be electrocorticographic (ECoG) neural signals, but the presented technique is applicable to other recordings.

Design of an ultra low power third order continuous time current mode ΣΔ modulator for WLAN applications.

Science.gov (United States)

Behzadi, Kobra; Baghelani, Masoud

2014-05-01

This paper presents a third order continuous time current mode ΣΔ modulator for WLAN 802.11b standard applications. The proposed circuit utilized feedback architecture with scaled and optimized DAC coefficients. At circuit level, we propose a modified cascade current mirror integrator with reduced input impedance which results in more bandwidth and linearity and hence improves the dynamic range. Also, a very fast and precise novel dynamic latch based current comparator is introduced with low power consumption. This ultra fast comparator facilitates increasing the sampling rate toward GHz frequencies. The modulator exhibits dynamic range of more than 60 dB for 20 MHz signal bandwidth and OSR of 10 while consuming only 914 μW from 1.8 V power supply. The FoM of the modulator is calculated from two different methods, and excellent performance is achieved for proposed modulator.

Optical integrated circuit of a 40-channel electrooptical LiNbO/sub 3/ modulator for data-processing devices

Energy Technology Data Exchange (ETDEWEB)

Bukreev, I.N.; Venediktov, V.V.; Gorbatovskii, M.V.; Demina, T.P.; Kashintsev, M.A.

1988-06-01

An optical integrated circuit for a 40-channel electrooptical phase modulator has been developed. The channel waveguides are prepared through Ti thermal diffusion into a Y-cut LiNbO/sub 3/ substrate. The half-wave voltage for each channel is 1.6 V at a modulating frequency bandwidth of 0-290 MHz. Results are presented from an experiment concerning the use of the modulator as an input device for the optical processing of radio signals.

Dual-signal heterodyne lock-in amplification with lasers

NARCIS (Netherlands)

Witteman, W.J.

2006-01-01

High-sensitivity heterodyne detection with lasers applied to radar and satellite communication is seriously hampered by the large electronic bandwidth due to Doppler shift and frequency instability. These drawbacks can be circumvented by dual-signal heterodyne detection. The system consists of

Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats.

Science.gov (United States)

Li, Borui; Feng, Zhenhua; Tang, Ming; Xu, Zhilin; Fu, Songnian; Wu, Qiong; Deng, Lei; Tong, Weijun; Liu, Shuang; Shum, Perry Ping

2015-05-04

Towards the next generation optical access network supporting large capacity data transmission to enormous number of users covering a wider area, we proposed a hybrid wavelength-space division multiplexing (WSDM) optical access network architecture utilizing multicore fibers with advanced modulation formats. As a proof of concept, we experimentally demonstrated a WSDM optical access network with duplex transmission using our developed and fabricated multicore (7-core) fibers with 58.7km distance. As a cost-effective modulation scheme for access network, the optical OFDM-QPSK signal has been intensity modulated on the downstream transmission in the optical line terminal (OLT) and it was directly detected in the optical network unit (ONU) after MCF transmission. 10 wavelengths with 25GHz channel spacing from an optical comb generator are employed and each wavelength is loaded with 5Gb/s OFDM-QPSK signal. After amplification, power splitting, and fan-in multiplexer, 10-wavelength downstream signal was injected into six outer layer cores simultaneously and the aggregation downstream capacity reaches 300 Gb/s. -16 dBm sensitivity has been achieved for 3.8 × 10-3 bit error ratio (BER) with 7% Forward Error Correction (FEC) limit for all wavelengths in every core. Upstream signal from ONU side has also been generated and the bidirectional transmission in the same core causes negligible performance degradation to the downstream signal. As a universal platform for wired/wireless data access, our proposed architecture provides additional dimension for high speed mobile signal transmission and we hence demonstrated an upstream delivery of 20Gb/s per wavelength with QPSK modulation formats using the inner core of MCF emulating a mobile backhaul service. The IQ modulated data was coherently detected in the OLT side. -19 dBm sensitivity has been achieved under the FEC limit and more than 18 dB power budget is guaranteed.

Method for calibration-free scanned-wavelength modulation spectroscopy for gas sensing

Science.gov (United States)

Hanson, Ronald K.; Jeffries, Jay B.; Sun, Kai; Sur, Ritobrata; Chao, Xing

2018-04-10

A method of calibration-free scanned-wavelength modulation spectroscopy (WMS) absorption sensing is provided by obtaining absorption lineshape measurements of a gas sample on a sensor using 1f-normalized WMS-2f where an injection current to an injection current-tunable diode laser (TDL) is modulated at a frequency f, where a wavelength modulation and an intensity modulation of the TDL are simultaneously generated, extracting using a numerical lock-in program and a low-pass filter appropriate band-width WMS-nf (n=1, 2, . . . ) signals, where the WMS-nf signals are harmonics of the f, determining a physical property of the gas sample according to ratios of the WMS-nf signals, determining the zero-absorption background using scanned-wavelength WMS, and determining non-absorption losses using at least two of the harmonics, where a need for a non-absorption baseline measurement is removed from measurements in environments where collision broadening has blended transition linewidths, where calibration free WMS measurements without knowledge of the transition linewidth is enabled.

Detecting modulated signals in modulated noise: (II) neural thresholds in the songbird forebrain.

Science.gov (United States)

Bee, Mark A; Buschermöhle, Michael; Klump, Georg M

2007-10-01

Sounds in the real world fluctuate in amplitude. The vertebrate auditory system exploits patterns of amplitude fluctuations to improve signal detection in noise. One experimental paradigm demonstrating these general effects has been used in psychophysical studies of 'comodulation detection difference' (CDD). The CDD effect refers to the fact that thresholds for detecting a modulated, narrowband noise signal are lower when the envelopes of flanking bands of modulated noise are comodulated with each other, but fluctuate independently of the signal compared with conditions in which the envelopes of the signal and flanking bands are all comodulated. Here, we report results from a study of the neural correlates of CDD in European starlings (Sturnus vulgaris). We manipulated: (i) the envelope correlations between a narrowband noise signal and a masker comprised of six flanking bands of noise; (ii) the signal onset delay relative to masker onset; (iii) signal duration; and (iv) masker spectrum level. Masked detection thresholds were determined from neural responses using signal detection theory. Across conditions, the magnitude of neural CDD ranged between 2 and 8 dB, which is similar to that reported in a companion psychophysical study of starlings [U. Langemann & G.M. Klump (2007) Eur. J. Neurosci., 26, 1969-1978]. We found little evidence to suggest that neural CDD resulted from the across-channel processing of auditory grouping cues related to common envelope fluctuations and synchronous onsets between the signal and flanking bands. We discuss a within-channel model of peripheral processing that explains many of our results.

Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Lund-Hansen, Toke

2012-01-01

This paper reports a comprehensive study of pump- to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT...... cut-off frequency in typical single-pump FOPAs is around 100–200 GHz. The possibilities to shift this frequency based on dispersion and nonlinearities involved in the parametric gain are discussed. The severe IMT to the signal at low modulation frequencies can be suppressed by more than 50...

Geometric phase modulation for stellar interferometry

International Nuclear Information System (INIS)

Roy, M.; Boschung, B.; Tango, W.J.; Davis, J.

2002-01-01

Full text: In a long baseline optical interferometer, the fringe visibility is normally measured by modulation of the optical path difference between the two arms of the instruments. To obtain accurate measurements, the spectral bandwidth must be narrow, limiting the sensitivity of the technique. The application of geometric phase modulation technique to stellar interferometry has been proposed by Tango and Davis. Modulation of the geometric phase has the potential for improving the sensitivity of optical interferometers, and specially the Sydney University Stellar Interferometer (SUSI), by allowing broad band modulation of the light signals. This is because a modulator that changes the geometric phase of the signal is, in principle, achromatic. Another advantage of using such a phase modulator is that it can be placed in the common path traversed by the two orthogonally polarized beams emerging from the beam combiner in a stellar interferometer. Thus the optical components of the modulator do not have to be interferometric quality and could be relatively easily introduced into SUSI. We have investigated the proposed application in a laboratory-based experiment using a Mach-Zehnder interferometer with white-light source. This can be seen as a small model of an amplitude stellar interferometer where the light source takes the place of the distant star and two corner mirrors replaces the entrance pupils of the stellar interferometer

Dipolar modulation of Large-Scale Structure

Science.gov (United States)

Yoon, Mijin

For the last two decades, we have seen a drastic development of modern cosmology based on various observations such as the cosmic microwave background (CMB), type Ia supernovae, and baryonic acoustic oscillations (BAO). These observational evidences have led us to a great deal of consensus on the cosmological model so-called LambdaCDM and tight constraints on cosmological parameters consisting the model. On the other hand, the advancement in cosmology relies on the cosmological principle: the universe is isotropic and homogeneous on large scales. Testing these fundamental assumptions is crucial and will soon become possible given the planned observations ahead. Dipolar modulation is the largest angular anisotropy of the sky, which is quantified by its direction and amplitude. We measured a huge dipolar modulation in CMB, which mainly originated from our solar system's motion relative to CMB rest frame. However, we have not yet acquired consistent measurements of dipolar modulations in large-scale structure (LSS), as they require large sky coverage and a number of well-identified objects. In this thesis, we explore measurement of dipolar modulation in number counts of LSS objects as a test of statistical isotropy. This thesis is based on two papers that were published in peer-reviewed journals. In Chapter 2 [Yoon et al., 2014], we measured a dipolar modulation in number counts of WISE matched with 2MASS sources. In Chapter 3 [Yoon & Huterer, 2015], we investigated requirements for detection of kinematic dipole in future surveys.

Efficient Bandwidth Management for Ethernet Passive Optical Networks

KAUST Repository

Elrasad, Amr Elsayed M.

2016-05-15

The increasing bandwidth demands in access networks motivates network operators, networking devices manufacturers, and standardization institutions to search for new approaches for access networks. These approaches should support higher bandwidth, longer distance between end user and network operator, and less energy consumption. Ethernet Passive Optical Network (EPON) is a favorable choice for broadband access networks. EPONs support transmission rates up to 10 Gbps. EPONs also support distance between end users and central office up to 20 Km. Moreover, optical networks have the least energy consumption among all types of networks. In this dissertation, we focus on reducing delay and saving energy in EPONs. Reducing delay is essential for delay-sensitive traffic, while minimizing energy consumption is an environmental necessity and also reduces the network operating costs. We identify five challenges, namely excess bandwidth allocation, frame delineation, congestion resolution, large round trip time delay in long-reach EPONs (LR-EPONs), and energy saving. We provide a Dynamic Bandwidth Allocation (DBA) approach for each challenge. We also propose a novel scheme that combines the features of the proposed approaches in one highly performing scheme. Our approach is to design novel DBA protocols that can further reduce the delay and be simultaneously simple and fair. We also present a dynamic bandwidth allocation scheme for Green EPONs taking into consideration maximizing energy saving under target delay constraints. Regarding excess bandwidth allocation, we develop an effective DBA scheme called Delayed Excess Scheduling (DES). DES achieves significant delay and jitter reduction and is more suitable for industrial deployment due to its simplicity. Utilizing DES in hybrid TDM/WDM EPONs (TWDM-EPONs) is also investigated. We also study eliminating the wasted bandwidth due to frame delineation. We develop an interactive DBA scheme, Efficient Grant Sizing Interleaved

SCIENTIFIC VERIFICATION OF FARADAY ROTATION MODULATORS: DETECTION OF DIFFUSE POLARIZED GALACTIC EMISSION

Energy Technology Data Exchange (ETDEWEB)

Moyerman, S.; Bierman, E.; Kaufman, J.; Keating, B. G. [Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92037 (United States); Ade, P. A. R. [Department of Physics and Astronomy, University of Wales, Cardiff CF24 3YB (United Kingdom); Aiken, R.; Hristov, V. V.; Jones, W. C.; Mason, P. V. [Department of Physics, California Institute of Technology, Pasadena, CA 91125 (United States); Barkats, D. [Joint ALMA Observatory, ESO, Santiago (Chile); Bischoff, C.; Kovac, J. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bock, J. J.; Dowell, C. D. [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Chiang, H. C. [Department of Physics, Princeton University, Princeton, NJ 08544 (United States); Duband, L. [SBT, Commissariat a l' Energie Atomique (apostrophe), F-38054 Grenoble (France); Hivon, E. F. [Insititut d' Astrophysique de Paris, F-75014 Paris (France); Holzapfel, W. L. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720 (United States); Kuo, C. L. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Palo Alto, CA 94305 (United States); Leitch, E. M., E-mail: smoyerma@ucsd.edu [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); and others

2013-03-01

The design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described. Faraday Rotation Modulators (FRMs) are solid-state polarization switches that are capable of modulation up to 10 kHz. Six FRMs were utilized during the 2006 observing season in the Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment; three FRMs were used at each of BICEP's 100 and 150 GHz frequency bands. The technology was verified through high signal-to-noise detection of Galactic polarization using two of the six FRMs during four observing runs in 2006. The features exhibit strong agreement with BICEP's measurements of the Galaxy using non-FRM pixels and with the Galactic polarization models. This marks the first detection of high signal-to-noise mm-wave celestial polarization using fast, active optical modulation. The performance of the FRMs during periods when they were not modulated was also analyzed and compared to results from BICEP's 43 pixels without FRMs.

Scientific Verification of Faraday Rotation Modulators: Detection of Diffuse Polarized Galactic Emission

Science.gov (United States)

Moyerman, S.; Bierman, E.; Ade, P. A. R.; Aiken, R.; Barkats, D.; Bischoff, C.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.;

Intracellular signal modulation by nanomaterials.

Science.gov (United States)

Hussain, Salik; Garantziotis, Stavros; Rodrigues-Lima, Fernando; Dupret, Jean-Marie; Baeza-Squiban, Armelle; Boland, Sonja

2014-01-01

A thorough understanding of the interactions of nanomaterials with biological systems and the resulting activation of signal transduction pathways is essential for the development of safe and consumer friendly nanotechnology. Here we present an overview of signaling pathways induced by nanomaterial exposures and describe the possible correlation of their physicochemical characteristics with biological outcomes. In addition to the hierarchical oxidative stress model and a review of the intrinsic and cell-mediated mechanisms of reactive oxygen species (ROS) generating capacities of nanomaterials, we also discuss other oxidative stress dependent and independent cellular signaling pathways. Induction of the inflammasome, calcium signaling, and endoplasmic reticulum stress are reviewed. Furthermore, the uptake mechanisms can be of crucial importance for the cytotoxicity of nanomaterials and membrane-dependent signaling pathways have also been shown to be responsible for cellular effects of nanomaterials. Epigenetic regulation by nanomaterials, effects of nanoparticle-protein interactions on cell signaling pathways, and the induction of various cell death modalities by nanomaterials are described. We describe the common trigger mechanisms shared by various nanomaterials to induce cell death pathways and describe the interplay of different modalities in orchestrating the final outcome after nanomaterial exposures. A better understanding of signal modulations induced by nanomaterials is not only essential for the synthesis and design of safer nanomaterials but will also help to discover potential nanomedical applications of these materials. Several biomedical applications based on the different signaling pathways induced by nanomaterials are already proposed and will certainly gain a great deal of attraction in the near future.

Optical interconnect technologies for high-bandwidth ICT systems

Science.gov (United States)

Chujo, Norio; Takai, Toshiaki; Mizushima, Akiko; Arimoto, Hideo; Matsuoka, Yasunobu; Yamashita, Hiroki; Matsushima, Naoki

2016-03-01

The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

Gigascale Silicon Photonic Transmitters Integrating HBT-based Carrier-injection Electroabsorption Modulator Structures

Science.gov (United States)

Fu, Enjin

Demand for more bandwidth is rapidly increasing, which is driven by data intensive applications such as high-definition (HD) video streaming, cloud storage, and terascale computing applications. Next-generation high-performance computing systems require power efficient chip-to-chip and intra-chip interconnect yielding densities on the order of 1Tbps/cm2. The performance requirements of such system are the driving force behind the development of silicon integrated optical interconnect, providing a cost-effective solution for fully integrated optical interconnect systems on a single substrate. Compared to conventional electrical interconnect, optical interconnects have several advantages, including frequency independent insertion loss resulting in ultra wide bandwidth and link latency reduction. For high-speed optical transmitter modules, the optical modulator is a key component of the optical I/O channel. This thesis presents a silicon integrated optical transmitter module design based on a novel silicon HBT-based carrier injection electroabsorption modulator (EAM), which has the merits of wide optical bandwidth, high speed, low power, low drive voltage, small footprint, and high modulation efficiency. The structure, mechanism, and fabrication of the modulator structure will be discussed which is followed by the electrical modeling of the post-processed modulator device. The design and realization of a 10Gbps monolithic optical transmitter module integrating the driver circuit architecture and the HBT-based EAM device in a 130nm BiCMOS process is discussed. For high power efficiency, a 6Gbps ultra-low power driver IC implemented in a 130nm BiCMOS process is presented. The driver IC incorporates an integrated 27-1 pseudo-random bit sequence (PRBS) generator for reliable high-speed testing, and a driver circuit featuring digitally-tuned pre-emphasis signal strength. With outstanding drive capability, the driver module can be applied to a wide range of carrier

Fibre Bragg grating based accelerometer with extended bandwidth

International Nuclear Information System (INIS)

Basumallick, Nandini; Biswas, Palas; Dasgupta, Kamal; Bandyopadhyay, Somnath; Chakraborty, Rajib; Chakraborty, Sushanta

2016-01-01

We have shown experimentally that the operable bandwidth of a fibre Bragg grating (FBG) based accelerometer can be extended significantly, without compromising its sensitivity, using a post-signal processing technique which involves frequency domain weighting. It has been demonstrated that using the above technique acceleration can be correctly interpreted even when the operating frequency encroaches on the region where the frequency response of the sensor is non-uniform. Two different excitation signals, which we often encounter in structural health monitoring applications, e.g. (i) a signal composed of multi-frequency components and (ii) a sinusoidal excitation with a frequency sweep, have been considered in our experiment. The results obtained have been compared with a piezo accelerometer. (paper)

Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

Science.gov (United States)

Vilnrotter, Victor A.; Hoppe, D.

2011-01-01

The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

Extracting a shape function for a signal with intra-wave frequency modulation.

Science.gov (United States)

Hou, Thomas Y; Shi, Zuoqiang

2016-04-13

In this paper, we develop an effective and robust adaptive time-frequency analysis method for signals with intra-wave frequency modulation. To handle this kind of signals effectively, we generalize our data-driven time-frequency analysis by using a shape function to describe the intra-wave frequency modulation. The idea of using a shape function in time-frequency analysis was first proposed by Wu (Wu 2013 Appl. Comput. Harmon. Anal. 35, 181-199. (doi:10.1016/j.acha.2012.08.008)). A shape function could be any smooth 2π-periodic function. Based on this model, we propose to solve an optimization problem to extract the shape function. By exploring the fact that the shape function is a periodic function with respect to its phase function, we can identify certain low-rank structure of the signal. This low-rank structure enables us to extract the shape function from the signal. Once the shape function is obtained, the instantaneous frequency with intra-wave modulation can be recovered from the shape function. We demonstrate the robustness and efficiency of our method by applying it to several synthetic and real signals. One important observation is that this approach is very stable to noise perturbation. By using the shape function approach, we can capture the intra-wave frequency modulation very well even for noise-polluted signals. In comparison, existing methods such as empirical mode decomposition/ensemble empirical mode decomposition seem to have difficulty in capturing the intra-wave modulation when the signal is polluted by noise. © 2016 The Author(s).

Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

Energy Technology Data Exchange (ETDEWEB)

Li, Hai-ming; Liu, Shao-bin, E-mail: lsb@nuaa.edu.cn; Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun [Key Laboratory of Radar Imaging and Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Shen-yun [Research Center of Applied Electromagnetics, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2015-03-16

In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

Spectrum Control through Discrete Frequency Diffraction in the Presence of Photonic Gauge Potentials

Science.gov (United States)

Qin, Chengzhi; Zhou, Feng; Peng, Yugui; Sounas, Dimitrios; Zhu, Xuefeng; Wang, Bing; Dong, Jianji; Zhang, Xinliang; Alù; , Andrea; Lu, Peixiang

2018-03-01

By using optical phase modulators in a fiber-optical circuit, we theoretically and experimentally demonstrate large control over the spectrum of an impinging signal, which may evolve analogously to discrete diffraction in spatial waveguide arrays. The modulation phase acts as a photonic gauge potential in the frequency dimension, realizing efficient control of the central frequency and bandwidth of frequency combs. We experimentally achieve a 50 GHz frequency shift and threefold bandwidth expansion of an impinging comb, as well as the frequency analogue of various refraction phenomena, including negative refraction and perfect focusing in the frequency domain, both for discrete and continuous incident spectra. Our study paves a promising way towards versatile frequency management for optical communications and signal processing using time modulation schemes.

Signal enhancement by spectral equalization of high frequency broadband signals transmitted through optical fibers

International Nuclear Information System (INIS)

Lyons, P.B.; Ogle, J.W.; Holzman, M.A.

1980-01-01

A new technique is discussed for enhancing the bandwidth and intensity of high frequency (> 1 GHz) analog, spectrally broad (40 nm) signals transmitted through one kilometer of optical fiber. The existing method for bandwidth enhancement of such a signal uses a very narrow (approx. 1 nm) filter between the fiber and detector to limit bandwidth degradation due to material dispersion. Using this method, most of the available optical intensity is rejected and lost. This new technique replaces the narrow-band filter with a spectral equalizer device which uses a reflection grating to disperse the input signal spectrum and direct it onto a linear array of fibers

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

Science.gov (United States)

Downey, Joseph; Downey, James; Reinhart, Richard C.; Evans, Michael Alan; Mortensen, Dale John

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 248-phase shift keying (PSK) and 1632- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 bsHz) modulation combined with various LDPC encoding rates to maximize throughput. With a symbol rate of 200 Mbaud, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results, compensation

Modulation Classification of Satellite Communication Signals Using Cumulants and Neural Networks

Science.gov (United States)

Smith, Aaron; Evans, Michael; Downey, Joseph

2017-01-01

National Aeronautics and Space Administration (NASA)'s future communication architecture is evaluating cognitive technologies and increased system intelligence. These technologies are expected to reduce the operational complexity of the network, increase science data return, and reduce interference to self and others. In order to increase situational awareness, signal classification algorithms could be applied to identify users and distinguish sources of interference. A significant amount of previous work has been done in the area of automatic signal classification for military and commercial applications. As a preliminary step, we seek to develop a system with the ability to discern signals typically encountered in satellite communication. Proposed is an automatic modulation classifier which utilizes higher order statistics (cumulants) and an estimate of the signal-to-noise ratio. These features are extracted from baseband symbols and then processed by a neural network for classification. The modulation types considered are phase-shift keying (PSK), amplitude and phase-shift keying (APSK),and quadrature amplitude modulation (QAM). Physical layer properties specific to the Digital Video Broadcasting - Satellite- Second Generation (DVB-S2) standard, such as pilots and variable ring ratios, are also considered. This paper will provide simulation results of a candidate modulation classifier, and performance will be evaluated over a range of signal-to-noise ratios, frequency offsets, and nonlinear amplifier distortions.

High speed gain coupled DFB laser diode integrated with MQW electroabsorption modulator

International Nuclear Information System (INIS)

Kim, Myung Gyoo; Lee, Seung Won; Park, Seong Su; Oh, Dae Kon; Lee, Hee Tae; Kim, Hong man; Pyun, Kwang Eui

1998-01-01

We have demonstrated stable modulation characteristics of the gain coupled distributed feedback(GC-DFB) laser diode integrated with butt-coupled InGaAsP/InGaAsP strain compensated MQW(multiple-Quantum-well) modulator for high speed optical transmission. For this purpose, we have adopted the InGaAsP/InGaAsP strain compensated MQW structure for the EA modulator and n-doped InGaAs absorptive grating for DFB laser. The typical threshold current and slope efficiency were about 15 mA and 0.1 mW/mA, respectively. The extinction ratio of fabricated integrated device was about 15 dB at -2 V, and the small signal bandwidth was shown to be around 17GHz. We also found that the α parameter becomes negative at below a -0.6 V bias voltage. We transmitted 10 Gbps NRZ electrical signal over 90 km of standard single mode optical fiber (SMF). A clearly opened eye diagram was observed in the modulated output

High speed gain coupled DFB laser diode integrated with MQW electroabsorption modulator

CERN Document Server

Kim, M G; Park, S S; Oh, D K; Lee, H T; Kim, H M; Pyun, K E

1998-01-01

We have demonstrated stable modulation characteristics of the gain coupled distributed feedback(GC-DFB) laser diode integrated with butt-coupled InGaAsP/InGaAsP strain compensated MQW(multiple-Quantum-well) modulator for high speed optical transmission. For this purpose, we have adopted the InGaAsP/InGaAsP strain compensated MQW structure for the EA modulator and n-doped InGaAs absorptive grating for DFB laser. The typical threshold current and slope efficiency were about 15 mA and 0.1 mW/mA, respectively. The extinction ratio of fabricated integrated device was about 15 dB at -2 V, and the small signal bandwidth was shown to be around 17GHz. We also found that the alpha parameter becomes negative at below a -0.6 V bias voltage. We transmitted 10 Gbps NRZ electrical signal over 90 km of standard single mode optical fiber (SMF). A clearly opened eye diagram was observed in the modulated output.

Searching for the annual modulation of dark matter signal with the GENIUS-TF experiment

International Nuclear Information System (INIS)

Tomei, C.; Dietz, A.; Krivosheina, I.; Klapdor-Kleingrothaus, H.V.

2003-01-01

The annual modulation of the recoil spectrum observed in an underground detector is well known as the main signature of a possible WIMP signal. The GENIUS-TF experiment, under construction in the Gran Sasso National Laboratory, can search for the annual modulation of the Dark Matter signal using 40 kg of naked-Ge detectors in liquid nitrogen. Starting from a set of data simulated under the hypothesis of modulation and using different methods, we show the potential of GENIUS-TF for extracting the modulated signal and the expected WIMP mass and WIMP cross-section

Large Signal Model of a Four-quadrant AC to DC Converter for Accelerator Magnets

CERN Document Server

De la Calle, R; Rinaldi, L; Völker, F V

2001-01-01

This paper presents the large signal model of a four-quadrant AC to DC converter, which is expected to be used in the area of particle accelerators. The system’s first stage is composed of a three-phase boost PWM (Pulse Width Modulated) rectifier with DSP (Digital Signal Processing) based power factor correction (PFC) and output voltage regulation. The second stage is a full-bridge PWM inverter that allows fast four-quadrant operation. The structure is fully reversible, and an additional resistance (brake chopper) is not needed to dissipate the energy when the beam deflection magnet acts as generator.

A conserved PHD finger protein and endogenous RNAi modulate insulin signaling in Caenorhabditis elegans.

Science.gov (United States)

Mansisidor, Andres R; Cecere, Germano; Hoersch, Sebastian; Jensen, Morten B; Kawli, Trupti; Kennedy, Lisa M; Chavez, Violeta; Tan, Man-Wah; Lieb, Jason D; Grishok, Alla

2011-09-01

Insulin signaling has a profound effect on longevity and the oxidative stress resistance of animals. Inhibition of insulin signaling results in the activation of DAF-16/FOXO and SKN-1/Nrf transcription factors and increased animal fitness. By studying the biological functions of the endogenous RNA interference factor RDE-4 and conserved PHD zinc finger protein ZFP-1 (AF10), which regulate overlapping sets of genes in Caenorhabditis elegans, we identified an important role for these factors in the negative modulation of transcription of the insulin/PI3 signaling-dependent kinase PDK-1. Consistently, increased expression of pdk-1 in zfp-1 and rde-4 mutants contributed to their reduced lifespan and sensitivity to oxidative stress and pathogens due to the reduction in the expression of DAF-16 and SKN-1 targets. We found that the function of ZFP-1 in modulating pdk-1 transcription was important for the extended lifespan of the age-1(hx546) reduction-of-function PI3 kinase mutant, since the lifespan of the age-1; zfp-1 double mutant strain was significantly shorter compared to age-1(hx546). We further demonstrate that overexpression of ZFP-1 caused an increased resistance to oxidative stress in a DAF-16-dependent manner. Our findings suggest that epigenetic regulation of key upstream signaling components in signal transduction pathways through chromatin and RNAi may have a large impact on the outcome of signaling and expression of numerous downstream genes.

±25ppm repeatable measurement of trapezoidal pulses with 5MHz bandwidth

CERN Document Server

AUTHOR|(SzGeCERN)712364; Arpaia, Pasquale; Cerqueira Bastos, Miguel; Martino, Michele

2015-01-01

High-quality measurements of pulses are nowadays widely used in fields such as radars, pulsed lasers, electromagnetic pulse generators, and particle accelerators. Whilst literature is mainly focused on fast systems for nanosecond regime with relaxed metrological requirements, in this paper, the high-performance measurement of slower pulses in microsecond regime is faced. In particular, the experimental proof demonstration for a 15 MS/s,_25 ppm repeatable acquisition system to characterize the flat-top of 3 ms rise-time trapezoidal pulses is given. The system exploits a 5MHz bandwidth circuit for analogue signal processing based on the concept of flat-top removal. The requirements, as well as the conceptual and physical designs are illustrated. Simulation results aimed at assessing the circuit performance are also presented. Finally, an experimental case study on the characterization of a pulsed power supply for the klystrons modulators of the Compact Linear Collider (CLIC) under study at CERN is reported. In ...

Dual-tone optical vector millimeter wave signal generated by frequency-nonupling the radio frequency 16-star quadrature-amplitude-modulation signal

Science.gov (United States)

Wu, Tonggen; Ma, Jianxin

2017-12-01

This paper proposes an original scheme to generate the photonic dual-tone optical millimeter wave (MMW) carrying the 16-star quadrature-amplitude-modulation (QAM) signal via an optical phase modulator (PM) and an interleaver with adaptive photonic frequency-nonupling without phase precoding. To enable the generated optical vector MMW signal to resist the power fading effect caused by the fiber chromatic dispersion, the modulated -5th- and +4th-order sidebands are selected from the output of the PM, which is driven by the precoding 16-star QAM signal. The modulation index of the PM is optimized to gain the maximum opto-electrical conversion efficiency. A radio over fiber link is built by simulation, and the simulated constellations and the bit error rate graph demonstrate that the frequency-nonupling 16-star QAM MMW signal has good transmission performance. The simulation results agree well with our theoretical results.

Removal of eye blink artifacts in wireless EEG sensor networks using reduced-bandwidth canonical correlation analysis.

Science.gov (United States)

Somers, Ben; Bertrand, Alexander

2016-12-01

Chronic, 24/7 EEG monitoring requires the use of highly miniaturized EEG modules, which only measure a few EEG channels over a small area. For improved spatial coverage, a wireless EEG sensor network (WESN) can be deployed, consisting of multiple EEG modules, which interact through short-distance wireless communication. In this paper, we aim to remove eye blink artifacts in each EEG channel of a WESN by optimally exploiting the correlation between EEG signals from different modules, under stringent communication bandwidth constraints. We apply a distributed canonical correlation analysis (CCA-)based algorithm, in which each module only transmits an optimal linear combination of its local EEG channels to the other modules. The method is validated on both synthetic and real EEG data sets, with emulated wireless transmissions. While strongly reducing the amount of data that is shared between nodes, we demonstrate that the algorithm achieves the same eye blink artifact removal performance as the equivalent centralized CCA algorithm, which is at least as good as other state-of-the-art multi-channel algorithms that require a transmission of all channels. Due to their potential for extreme miniaturization, WESNs are viewed as an enabling technology for chronic EEG monitoring. However, multi-channel analysis is hampered in WESNs due to the high energy cost for wireless communication. This paper shows that multi-channel eye blink artifact removal is possible with a significantly reduced wireless communication between EEG modules.

D1 dopamine receptor signaling is modulated by the R7 RGS protein EAT-16 and the R7 binding protein RSBP-1 in Caenoerhabditis elegans motor neurons.

Directory of Open Access Journals (Sweden)

Khursheed A Wani

Full Text Available Dopamine signaling modulates voluntary movement and reward-driven behaviors by acting through G protein-coupled receptors in striatal neurons, and defects in dopamine signaling underlie Parkinson's disease and drug addiction. Despite the importance of understanding how dopamine modifies the activity of striatal neurons to control basal ganglia output, the molecular mechanisms that control dopamine signaling remain largely unclear. Dopamine signaling also controls locomotion behavior in Caenorhabditis elegans. To better understand how dopamine acts in the brain we performed a large-scale dsRNA interference screen in C. elegans for genes required for endogenous dopamine signaling and identified six genes (eat-16, rsbp-1, unc-43, flp-1, grk-1, and cat-1 required for dopamine-mediated behavior. We then used a combination of mutant analysis and cell-specific transgenic rescue experiments to investigate the functional interaction between the proteins encoded by two of these genes, eat-16 and rsbp-1, within single cell types and to examine their role in the modulation of dopamine receptor signaling. We found that EAT-16 and RSBP-1 act together to modulate dopamine signaling and that while they are coexpressed with both D1-like and D2-like dopamine receptors, they do not modulate D2 receptor signaling. Instead, EAT-16 and RSBP-1 act together to selectively inhibit D1 dopamine receptor signaling in cholinergic motor neurons to modulate locomotion behavior.

Dynamic wave field synthesis: enabling the generation of field distributions with a large space-bandwidth product.

Science.gov (United States)

Kamau, Edwin N; Heine, Julian; Falldorf, Claas; Bergmann, Ralf B

2015-11-02

We present a novel approach for the design and fabrication of multiplexed computer generated volume holograms (CGVH) which allow for a dynamic synthesis of arbitrary wave field distributions. To achieve this goal, we developed a hybrid system that consists of a CGVH as a static element and an electronically addressed spatial light modulator as the dynamic element. We thereby derived a new model for describing the scattering process within the inhomogeneous dielectric material of the hologram. This model is based on the linearization of the scattering process within the Rytov approximation and incorporates physical constraints that account for voxel based laser-lithography using micro-fabrication of the holograms in a nonlinear optical material. In this article we demonstrate that this system basically facilitates a high angular Bragg selectivity on the order of 1°. Additionally, it allows for a qualitatively low cross-talk dynamic synthesis of predefined wave fields with a much larger space-bandwidth product (SBWP ≥ 8.7 × 10(6)) as compared to the current state of the art in computer generated holography.

Cell Size and Growth Rate Are Modulated by TORC2-Dependent Signals.

Science.gov (United States)

Lucena, Rafael; Alcaide-Gavilán, Maria; Schubert, Katherine; He, Maybo; Domnauer, Matthew G; Marquer, Catherine; Klose, Christian; Surma, Michal A; Kellogg, Douglas R

2018-01-22

The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2A Rts1 ) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network. Copyright © 2017 Elsevier Ltd. All rights reserved.

Signal Constellations for Multilevel Coded Modulation with Sparse Graph Codes

NARCIS (Netherlands)

Cronie, H.S.

2005-01-01

A method to combine error-correction coding and spectral efficient modulation for transmission over channels with Gaussian noise is presented. The method of modulation leads to a signal constellation in which the constellation symbols have a nonuniform distribution. This gives a so-called shape gain

Signal recognition and parameter estimation of BPSK-LFM combined modulation

Science.gov (United States)

Long, Chao; Zhang, Lin; Liu, Yu

2015-07-01

Intra-pulse analysis plays an important role in electronic warfare. Intra-pulse feature abstraction focuses on primary parameters such as instantaneous frequency, modulation, and symbol rate. In this paper, automatic modulation recognition and feature extraction for combined BPSK-LFM modulation signals based on decision theoretic approach is studied. The simulation results show good recognition effect and high estimation precision, and the system is easy to be realized.

Plant MAPK cascades: Just rapid signaling modules?

KAUST Repository

Boudsocq, Marie

2015-08-27

© 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

Coding of amplitude-modulated signals in the cochlear nucleus of a grass frog

Science.gov (United States)

Bibikov, N. G.

2002-07-01

To study the mechanisms that govern the coding of temporal features of complex sound signals, responses of single neurons located in the dorsal nucleus of the medulla oblongata (the cochlear nucleus) of a curarized grass frog ( Rana temporaria) to pure tone bursts and amplitude modulated tone bursts with a modulation frequency of 20 Hz and modulation depths of 10 and 80% were recorded. The carrier frequency was equal to the characteristic frequency of a neuron, the average signal level was 20 30 dB above the threshold, and the signal duration was equal to ten full modulation periods. Of the 133 neurons studied, 129 neurons responded to 80% modulated tone bursts by discharges that were phase-locked with the envelope waveform. At this modulation depth, the best phase locking was observed for neurons with the phasic type of response to tone bursts. For tonic neurons with low characteristic frequencies, along with the reproduction of the modulation, phase locking with the carrier frequency of the signal was observed. At 10% amplitude modulation, phasic neurons usually responded to only the onset of a tone burst. Almost all tonic units showed a tendency to reproduce the envelope, although the efficiency of the reproduction was low, and for half of these neurons, it was below the reliability limit. Some neurons exhibited a more efficient reproduction of the weak modulation. For almost half of the neurons, a reliable improvement was observed in the phase locking of the response during the tone burst presentation (from the first to the tenth modulation period). The cooperative histogram of a set of neurons responding to 10% modulated tone bursts within narrow ranges of frequencies and intensities retains the information on the dynamics of the envelope variation. The data are compared with the results obtained from the study of the responses to similar signals in the acoustic midbrain center of the same object and also with the psychophysical effect of a differential

Improving the signal-to-noise ratio in ultrasound-modulated optical tomography by a lock-in amplifier

Science.gov (United States)

Zhu, Lili; Wu, Jingping; Lin, Guimin; Hu, Liangjun; Li, Hui

2016-10-01

With high spatial resolution of ultrasonic location and high sensitivity of optical detection, ultrasound-modulated optical tomography (UOT) is a promising noninvasive biological tissue imaging technology. In biological tissue, the ultrasound-modulated light signals are very weak and are overwhelmed by the strong unmodulated light signals. It is a difficulty and key to efficiently pick out the weak modulated light from strong unmodulated light in UOT. Under the effect of an ultrasonic field, the scattering light intensity presents a periodic variation as the ultrasonic frequency changes. So the modulated light signals would be escape from the high unmodulated light signals, when the modulated light signals and the ultrasonic signal are processed cross correlation operation by a lock-in amplifier and without a chopper. Experimental results indicated that the signal-to-noise ratio of UOT is significantly improved by a lock-in amplifier, and the higher the repetition frequency of pulsed ultrasonic wave, the better the signal-to-noise ratio of UOT.

DMPD: Modulation of Toll-interleukin 1 receptor mediated signaling. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 15662540 Modulation of Toll-interleukin 1 receptor mediated signaling. Li X, Qin J.... J Mol Med. 2005 Apr;83(4):258-66. Epub 2005 Jan 21. (.png) (.svg) (.html) (.csml) Show Modulation of Toll-i...nterleukin 1 receptor mediated signaling. PubmedID 15662540 Title Modulation of Toll-interleukin 1 receptor

Gear wear monitoring by modulation signal bispectrum based on motor current signal analysis

Science.gov (United States)

Zhang, Ruiliang; Gu, Fengshou; Mansaf, Haram; Wang, Tie; Ball, Andrew D.

2017-09-01

Gears are important mechanical components for power transmissions. Tooth wear is one of the most common failure modes, which can present throughout a gear's lifetime. It is significant to accurately monitor gear wear progression in order to take timely predictive maintenances. Motor current signature analysis (MCSA) is an effective and non-intrusive approach which is able to monitor faults from both electrical and mechanical systems. However, little research has been reported in monitoring the gear wear and estimating its severity based on MCSA. This paper presents a novel gear wear monitoring method through a modulation signal bispectrum based motor current signal analysis (MSB-MCSA). For a steady gear transmission, it is inevitable to exist load and speed oscillations due to various errors including wears. These oscillations can induce small modulations in the current signals of the driving motor. MSB is particularly effective in characterising such small modulation signals. Based on these understandings, the monitoring process was implemented based on the current signals from a run-to-failure test of an industrial two stages helical gearbox under a moderate accelerated fatigue process. At the initial operation of the test, MSB analysis results showed that the peak values at the bifrequencies of gear rotations and the power supply can be effective monitoring features for identifying faulty gears and wear severity as they exhibit agreeable changes with gear loads. A monotonically increasing trend established by these features allows a clear indication of the gear wear progression. The dismantle inspection at 477 h of operation, made when one of the monitored features is about 123% higher than its baseline, has found that there are severe scuffing wear marks on a number of tooth surfaces on the driving gear, showing that the gear endures a gradual wear process during its long test operation. Therefore, it is affirmed that the MSB-MSCA approach proposed is reliable

Optimization of Quantum-Dot Molecular Beam Epitaxy for Broad Spectral Bandwidth Devices

KAUST Repository

Majid, Mohammed Abdul

2012-12-01

The optimization of the key growth parameters for broad spectral bandwidth devices based on quantum dots is reported. A combination of atomic force microscopy, photoluminescence of test samples, and optoelectronic characterization of superluminescent diodes (SLDs) is used to optimize the growth conditions to obtain high-quality devices with large spectral bandwidth, radiative efficiency (due to a reduced defective-dot density), and thus output power. The defective-dot density is highlighted as being responsible for the degradation of device performance. An SLD device with 160 nm of bandwidth centered at 1230 nm is demonstrated.

Optimization of Quantum-Dot Molecular Beam Epitaxy for Broad Spectral Bandwidth Devices

KAUST Repository

Majid, Mohammed Abdul; Hugues, M.; Vézian, S.; Childs, D. T. D.; Hogg, R. A.

2012-01-01

The optimization of the key growth parameters for broad spectral bandwidth devices based on quantum dots is reported. A combination of atomic force microscopy, photoluminescence of test samples, and optoelectronic characterization of superluminescent diodes (SLDs) is used to optimize the growth conditions to obtain high-quality devices with large spectral bandwidth, radiative efficiency (due to a reduced defective-dot density), and thus output power. The defective-dot density is highlighted as being responsible for the degradation of device performance. An SLD device with 160 nm of bandwidth centered at 1230 nm is demonstrated.

Strain-gage signal-conditioning system for use in the LCP

International Nuclear Information System (INIS)

Ellis, J.F.; Walstrom, P.L.

1979-01-01

A strain-gage signal-conditioning system, providing wide-band noise rejection and isolation from high voltages that occur during emergency coil discharges, has been developed and tested. The multichannel system combines double-shielded transformers, neutralizing networks, and bandpass filters (with commercial 3-kHz carrier amplifier modules to isolate the strain gages to 5000 V) eliminate thermoelectric effects, and provide a signal bandwidth of 200 Hz. Common-mode interference occurs primarily as a result of beat-note effects between the carrier and the superimposed noise at frequencies near the odd harmonics of the carrier. The common-mode rejection of the test circuit was measured to be 120 dB for noise at 2750 and 3250 Hz, 135 dB at 3 kHz, and 135 dB and better at the odd harmonics of 9 kHz and above. The system has been successfully used in strain measurements on the toroidal field coils of the ISX-B tokamak and will be used in the Large Coil Test Facility to monitor strains in the energized coil conductors

Bandwidth Extension of Telephone Speech Aided by Data Embedding

Directory of Open Access Journals (Sweden)

Sagi Ariel

2007-01-01

Full Text Available A system for bandwidth extension of telephone speech, aided by data embedding, is presented. The proposed system uses the transmitted analog narrowband speech signal as a carrier of the side information needed to carry out the bandwidth extension. The upper band of the wideband speech is reconstructed at the receiving end from two components: a synthetic wideband excitation signal, generated from the narrowband telephone speech and a wideband spectral envelope, parametrically represented and transmitted as embedded data in the telephone speech. We propose a novel data embedding scheme, in which the scalar Costa scheme is combined with an auditory masking model allowing high rate transparent embedding, while maintaining a low bit error rate. The signal is transformed to the frequency domain via the discrete Hartley transform (DHT and is partitioned into subbands. Data is embedded in an adaptively chosen subset of subbands by modifying the DHT coefficients. In our simulations, high quality wideband speech was obtained from speech transmitted over a telephone line (characterized by spectral magnitude distortion, dispersion, and noise, in which side information data is transparently embedded at the rate of 600 information bits/second and with a bit error rate of approximately . In a listening test, the reconstructed wideband speech was preferred (at different degrees over conventional telephone speech in of the test utterances.

Bandwidth Extension of Telephone Speech Aided by Data Embedding

Directory of Open Access Journals (Sweden)

David Malah

2007-01-01

Full Text Available A system for bandwidth extension of telephone speech, aided by data embedding, is presented. The proposed system uses the transmitted analog narrowband speech signal as a carrier of the side information needed to carry out the bandwidth extension. The upper band of the wideband speech is reconstructed at the receiving end from two components: a synthetic wideband excitation signal, generated from the narrowband telephone speech and a wideband spectral envelope, parametrically represented and transmitted as embedded data in the telephone speech. We propose a novel data embedding scheme, in which the scalar Costa scheme is combined with an auditory masking model allowing high rate transparent embedding, while maintaining a low bit error rate. The signal is transformed to the frequency domain via the discrete Hartley transform (DHT and is partitioned into subbands. Data is embedded in an adaptively chosen subset of subbands by modifying the DHT coefficients. In our simulations, high quality wideband speech was obtained from speech transmitted over a telephone line (characterized by spectral magnitude distortion, dispersion, and noise, in which side information data is transparently embedded at the rate of 600 information bits/second and with a bit error rate of approximately 3⋅10−4. In a listening test, the reconstructed wideband speech was preferred (at different degrees over conventional telephone speech in 92.5% of the test utterances.

Frequency modulator. Transmission of meteorological signals in LVC

International Nuclear Information System (INIS)

Rivero G, P.T.; Ramirez S, R.; Gonzalez M, J.L.; Rojas N, P.; Celis del Angel, L.

2007-01-01

The development of the frequency modulator and demodulator circuit for transmission of meteorological signals by means of fiber optics of the meteorology station to the nuclear reactor unit 1 in the Laguna Verde Central in Veracruz is described. (Author)

A polarization independent electromagnetically induced transparency-like metamaterial with large group delay and delay-bandwidth product

Science.gov (United States)

Bagci, Fulya; Akaoglu, Baris

2018-05-01

In this study, a classical analogue of electromagnetically induced transparency (EIT) that is completely independent of the polarization direction of the incident waves is numerically and experimentally demonstrated. The unit cell of the employed planar symmetric metamaterial structure consists of one square ring resonator and four split ring resonators (SRRs). Two different designs are implemented in order to achieve a narrow-band and wide-band EIT-like response. In the unit cell design, a square ring resonator is shown to serve as a bright resonator, whereas the SRRs behave as a quasi-dark resonator, for the narrow-band (0.55 GHz full-width at half-maximum bandwidth around 5 GHz) and wide-band (1.35 GHz full-width at half-maximum bandwidth around 5.7 GHz) EIT-like metamaterials. The observed EIT-like transmission phenomenon is theoretically explained by a coupled-oscillator model. Within the transmission window, steep changes of the phase result in high group delays and the delay-bandwidth products reach 0.45 for the wide-band EIT-like metamaterial. Furthermore, it has been demonstrated that the bandwidth and group delay of the EIT-like band can be controlled by changing the incidence angle of electromagnetic waves. These features enable the proposed metamaterials to achieve potential applications in filtering, switching, data storing, and sensing.

Mode-locked ytterbium fiber lasers using a large modulation depth carbon nanotube saturable absorber without an additional spectral filter

International Nuclear Information System (INIS)

Pan, Y Z; Miao, J G; Liu, W J; Huang, X J; Wang, Y B

2014-01-01

We demonstrate an all-normal-dispersion ytterbium (Yb)-doped fiber laser mode-locked by a higher modulation depth carbon nanotube saturable absorber (CNT-SA) based on an evanescent field interaction scheme. The laser cavity consists of pure normal dispersion fibers without dispersion compensation and an additional spectral filter. It is exhibited that the higher modulation depth CNT-SA could contribute to stabilize the mode-locking operation within a limited range of pump power and generate the highly chirped pulses with a high-energy level in the cavity with large normal dispersion and strong nonlinearity. Stable mode-locked pulses with a maximal energy of 29 nJ with a 5.59 MHz repetition rate at the operating wavelength around 1085 nm have been obtained. The maximal time-bandwidth product is 262.4. The temporal and spectral characteristics of pulses versus pump power are demonstrated. The experimental results suggest that the CNT-SA provides a sufficient nonlinear loss to compensate high nonlinearity and catch up the gain at a different pump power and thus leads to the stable mode locking. (letter)

Coherence bandwidth characterization in an urban microcell at 62.4 GHz

DEFF Research Database (Denmark)

Sánchez, M. G.; Hammoudeh, A. M.; Grindrod, E.

2000-01-01

Results of experiments made at 62.4 GHz in an urban mobile radio environment to characterize the coherence bandwidth are presented. The correlation coefficients between signal envelopes separated in frequency are measured and expressed as functions of distance from the base station. Due to the hi...

Deep neural network-based bandwidth enhancement of photoacoustic data.

Science.gov (United States)

Gutta, Sreedevi; Kadimesetty, Venkata Suryanarayana; Kalva, Sandeep Kumar; Pramanik, Manojit; Ganapathy, Sriram; Yalavarthy, Phaneendra K

2017-11-01

Photoacoustic (PA) signals collected at the boundary of tissue are always band-limited. A deep neural network was proposed to enhance the bandwidth (BW) of the detected PA signal, thereby improving the quantitative accuracy of the reconstructed PA images. A least square-based deconvolution method that utilizes the Tikhonov regularization framework was used for comparison with the proposed network. The proposed method was evaluated using both numerical and experimental data. The results indicate that the proposed method was capable of enhancing the BW of the detected PA signal, which inturn improves the contrast recovery and quality of reconstructed PA images without adding any significant computational burden. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Bandwidth broadening of a graphene-based circular polarization converter by phase compensation.

Science.gov (United States)

Gao, Xi; Yang, Wanli; Cao, Weiping; Chen, Ming; Jiang, Yannan; Yu, Xinhua; Li, Haiou

2017-10-02

We present a broadband tunable circular polarization converter composed of a single graphene sheet patterned with butterfly-shaped holes, a dielectric spacer, and a 7-layer graphene ground plane. It can convert a linearly polarized wave into a circularly polarized wave in reflection mode. The polarization converter can be dynamically tuned by varying the Fermi energy of the single graphene sheet. Furthermore, the 7-layer graphene acting as a ground plane can modulate the phase of its reflected wave by controlling the Femi energy, which provides constructive interference condition at the surface of the single graphene sheet in a broad bandwidth and therefore significantly broadens the tunable bandwidth of the proposed polarization converter.

Design and Analysis of Delayed Chip Slope Modulation in Optical Wireless Communication

KAUST Repository

Park, Kihong

2015-08-23

In this letter, we propose a novel slope-based binary modulation called delayed chip slope modulation (DCSM) and develop a chip-based hard-decision receiver to demodulate the resulting signal, detect the chip sequence, and decode the input bit sequence. Shorter duration of chips than bit duration are used to represent the change of state in an amplitude level according to consecutive bit information and to exploit the trade-off between bandwidth and power efficiency. We analyze the power spectral density and error rate performance of the proposed DCSM. We show from numerical results that the DCSM scheme can exploit spectrum density more efficiently than the reference schemes while providing an error rate performance comparable to conventional modulation schemes.

Design and Analysis of Delayed Chip Slope Modulation in Optical Wireless Communication

KAUST Repository

Park, Kihong; Alouini, Mohamed-Slim

2015-01-01

In this letter, we propose a novel slope-based binary modulation called delayed chip slope modulation (DCSM) and develop a chip-based hard-decision receiver to demodulate the resulting signal, detect the chip sequence, and decode the input bit sequence. Shorter duration of chips than bit duration are used to represent the change of state in an amplitude level according to consecutive bit information and to exploit the trade-off between bandwidth and power efficiency. We analyze the power spectral density and error rate performance of the proposed DCSM. We show from numerical results that the DCSM scheme can exploit spectrum density more efficiently than the reference schemes while providing an error rate performance comparable to conventional modulation schemes.

Detection and processing of phase modulated optical signals at 40 Gbit/s and beyond

DEFF Research Database (Denmark)

Geng, Yan

the amplitude regeneration capability based on FWM in a highly nonlinear fiber (HNLF). The first reported experimental demonstration of amplitude equalization of 40 Gbit/s RZ-DPSK signals using a 500 m long HNLF is presented. Using four possible phase levels to carry the information, DQPSK allows generation......This thesis addresses demodulation in direct detection systems and signal processing of high speed phase modulated signals in future all-optical wavelength division multiplexing (WDM) communication systems where differential phase shift keying (DPSK) or differential quadrature phase shift keying...... (DQPSK) are used to transport information. All-optical network functionalities -such as optical labeling, wavelength conversion and signal regeneration- are experimentally investigated. Direct detection of phase modulated signals requires phase-to-intensity modulation conversion in a demodulator...

Modulated Hermite series expansions and the time-bandwidth product

NARCIS (Netherlands)

Brinker, den A.C.; Sarroukh, B.E.

2000-01-01

The harmonically modulated Hermite series constitute an orthonormal basis in the Hilbert space of square-integrable functions. This basis comprises three free parameters, namely a translation, a modulation, and a scale factor. In practical situations, we are interested in series expansions that are

Applications of Microwave Photonics in Radio Astronomy and Space Communication

Science.gov (United States)

D'Addario, Larry R.; Shillue, William P.

2006-01-01

An overview of narrow band vs wide band signals is given. Topics discussed included signal transmission, reference distribution and photonic antenna metrology. Examples of VLA, ALMA, ATA and DSN arrays are given. . Arrays of small antennas have become more cost-effective than large antennas for achieving large total aperture or gain, both for astronomy and for communication. It is concluded that emerging applications involving arrays of many antennas require low-cost optical communication of both wide bandwidth and narrow bandwidth; development of round-trip correction schemes enables timing precision; and free-space laser beams with microwave modulation allow structural metrology with approx 100 micrometer precision over distances of 200 meters.

Optimal field splitting for large intensity-modulated fields

International Nuclear Information System (INIS)

Kamath, Srijit; Sahni, Sartaj; Ranka, Sanjay; Li, Jonathan; Palta, Jatinder

2004-01-01

The multileaf travel range limitations on some linear accelerators require the splitting of a large intensity-modulated field into two or more adjacent abutting intensity-modulated subfields. The abutting subfields are then delivered as separate treatment fields. This workaround not only increases the treatment delivery time but it also increases the total monitor units (MU) delivered to the patient for a given prescribed dose. It is imperative that the cumulative intensity map of the subfields is exactly the same as the intensity map of the large field generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. In this work, we describe field splitting algorithms that split a large intensity-modulated field into two or more intensity-modulated subfields with and without feathering, with optimal MU efficiency while satisfying the hardware constraints. Compared to a field splitting technique (without feathering) used in a commercial planning system, our field splitting algorithm (without feathering) shows a decrease in total MU of up to 26% on clinical cases and up to 63% on synthetic cases

An open-loop system design for deep space signal processing applications

Science.gov (United States)

Tang, Jifei; Xia, Lanhua; Mahapatra, Rabi

2018-06-01

A novel open-loop system design with high performance is proposed for space positioning and navigation signal processing. Divided by functions, the system has four modules, bandwidth selectable data recorder, narrowband signal analyzer, time-delay difference of arrival estimator and ANFIS supplement processor. A hardware-software co-design approach is made to accelerate computing capability and improve system efficiency. Embedded with the proposed signal processing algorithms, the designed system is capable of handling tasks with high accuracy over long period of continuous measurements. The experiment results show the Doppler frequency tracking root mean square error during 3 h observation is 0.0128 Hz, while the TDOA residue analysis in correlation power spectrum is 0.1166 rad.

All-optical wavelength conversion and signal regeneration using an electroabsorption modulator

DEFF Research Database (Denmark)

Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

2000-01-01

All-optical wavelength conversion and signal regeneration based on cross-absorption modulation in an InGaAsP quantum well electroabsorption modulator (EAM) is studied at different bit rates. We present theoretical results showing wavelength conversion efficiency in agreement with existing...

Stochastic resonance in a single-mode laser driven by frequency modulated signal and coloured noises

Institute of Scientific and Technical Information of China (English)

Jin Guo-Xiang; Zhang Liang-Ying; Cao Li

2009-01-01

By adding frequency modulated signals to the intensity equation of gain-noise model of the single-mode laser driven by two coloured noises which are correlated, this paper uses the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity. The results show that the SNR appears typical stochastic resonance with the variation of intensity of the pump noise and quantum noise. As the amplitude of a modulated signal has effects on the SNR, it shows suppression, monotone increasing, stochastic resonance, and multiple stochastic resonance with the variation of the frequency of a carrier signal and modulated signal.

Recent progress in self-assembled quantum-dot optical devices for optical telecommunication: temperature-insensitive 10 Gb s-1 directly modulated lasers and 40 Gb s-1 signal-regenerative amplifiers

International Nuclear Information System (INIS)

Sugawara, M; Hatori, N; Ishida, M; Ebe, H; Arakawa, Y; Akiyama, T; Otsubo, K; Yamamoto, T; Nakata, Y

2005-01-01

This paper presents recent progress in the field of semiconductor lasers and optical amplifiers with InAs-based self-assembled quantum dots in the active region for optical telecommunication. Based on our design in terms of the maximum bandwidth for high-speed modulation and p-type doping in quantum dots for high temperature stability, we realized temperature-insensitive 10 Gb s -1 laser diodes on a GaAs substrate at 1.3 μm. The output waveform at 10 Gb s -1 maintained a clear eye opening, average output power and extinction ratio without current adjustments from 20 deg. C to 70 deg. C. We developed ultrawide-band high-power amplifiers in the 1.5 μm wavelength region on an InP substrate. The amplifier showed ultrafast gain response under gain saturation, and enabled signal regeneration at 40 Gb s -1 by suppressing the '1'-level noise due to the beating between the signal and amplified spontaneous emission. We present our amplifier module with polarization diversity to enable a stable polarization-insensitive performance, and also, discuss prospects for polarization-insensitive quantum dots by the close stacking technique

Utilization of multi-band OFDM modulation to increase traffic rate of phosphor-LED wireless VLC.

Science.gov (United States)

Yeh, Chien-Hung; Chen, Hsing-Yu; Chow, Chi-Wai; Liu, Yen-Liang

2015-01-26

To increase the traffic rate in phosphor-LED visible light communication (VLC), a multi-band orthogonal frequency division multiplexed (OFDM) modulation is first proposed and demonstrated. In the measurement, we do not utilize optical blue filter to increase modulation bandwidth of phosphor-LED in the VLC system. In this proposed scheme, different bands of OFDM signals are applied to different LED chips in a LED lamp, this can avoid the power fading and nonlinearity issue by applying the same OFDM signal to all the LED chips in a LED lamp. Here, the maximum increase percentages of traffic rates are 41.1%, 17.8% and 17.8% under received illuminations of 200, 500 and 1000 Lux, respectively, when the proposed three-band OFDM modulation is used in the VLC system. In addition, the analysis and verification by experiments are also performed.

Optical-wireless-optical full link for polarization multiplexing quadrature amplitude/phase modulation signal transmission.

Science.gov (United States)

Li, Xinying; Yu, Jianjun; Chi, Nan; Zhang, Junwen

2013-11-15

We propose and experimentally demonstrate an optical wireless integration system at the Q-band, in which up to 40 Gb/s polarization multiplexing multilevel quadrature amplitude/phase modulation (PM-QAM) signal can be first transmitted over 20 km single-mode fiber-28 (SMF-28), then delivered over a 2 m 2 × 2 multiple-input multiple-output wireless link, and finally transmitted over another 20 km SMF-28. The PM-QAM modulated wireless millimeter-wave (mm-wave) signal at 40 GHz is generated based on the remote heterodyning technique, and demodulated by the radio-frequency transparent photonic technique based on homodyne coherent detection and baseband digital signal processing. The classic constant modulus algorithm equalization is used at the receiver to realize polarization demultiplexing of the PM-QAM signal. For the first time, to the best of our knowledge, we realize the conversion of the PM-QAM modulated wireless mm-wave signal to the optical signal as well as 20 km fiber transmission of the converted optical signal.

Modulation, resolution and signal processing in radar, sonar and related systems

CERN Document Server

Benjamin, R; Costrell, L

1966-01-01

Electronics and Instrumentation, Volume 35: Modulation, Resolution and Signal Processing in Radar, Sonar and Related Systems presents the practical limitations and potentialities of advanced modulation systems. This book discusses the concepts and techniques in the radar context, but they are equally essential to sonar and to a wide range of signaling and data-processing applications, including seismology, radio astronomy, and band-spread communications.Organized into 15 chapters, this volume begins with an overview of the principal developments sought in pulse radar. This text then provides a

Managing high-bandwidth real-time data storage

Energy Technology Data Exchange (ETDEWEB)

Bigelow, David D. [Los Alamos National Laboratory; Brandt, Scott A [Los Alamos National Laboratory; Bent, John M [Los Alamos National Laboratory; Chen, Hsing-Bung [Los Alamos National Laboratory

2009-09-23

There exist certain systems which generate real-time data at high bandwidth, but do not necessarily require the long-term retention of that data in normal conditions. In some cases, the data may not actually be useful, and in others, there may be too much data to permanently retain in long-term storage whether it is useful or not. However, certain portions of the data may be identified as being vitally important from time to time, and must therefore be retained for further analysis or permanent storage without interrupting the ongoing collection of new data. We have developed a system, Mahanaxar, intended to address this problem. It provides quality of service guarantees for incoming real-time data streams and simultaneous access to already-recorded data on a best-effort basis utilizing any spare bandwidth. It has built in mechanisms for reliability and indexing, can scale upwards to meet increasing bandwidth requirements, and handles both small and large data elements equally well. We will show that a prototype version of this system provides better performance than a flat file (traditional filesystem) based version, particularly with regard to quality of service guarantees and hard real-time requirements.

Distortions caused by the signal processing in analog AM modulators

International Nuclear Information System (INIS)

Njau, E.C.

1988-08-01

Complete analytical expressions for distortions caused by signal processing in analog AM modulators are developed. The salient features in these expressions are shown to be consistent with displays of actual spectra of AM signals. Finally suggestions are given on how the distortions may be practically minimized. (author). 6 refs, 3 figs

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

Science.gov (United States)

Downey, Joseph A.; Downey, James M.; Reinhart, Richard C.; Evans, Michael A.; Mortensen, Dale J.

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 2/4/8-phase shift keying (PSK) and 16/32- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 b/s/Hz) modulation combined with various LDPC encoding rates to maximize through- put. With a symbol rate of 200 M-band, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results

Estimating individual listeners’ auditory-filter bandwidth in simultaneous and non-simultaneous masking

DEFF Research Database (Denmark)

Buchholz, Jörg; Caminade, Sabine; Strelcyk, Olaf

2010-01-01

Frequency selectivity in the human auditory system is often measured using simultaneous masking of tones presented in notched noise. Based on such masking data, the equivalent rectangular bandwidth (ERB) of the auditory filters can be derived by applying the power spectrum model of masking....... Considering bandwidth estimates from previous studies based on forward masking, only average data across a number of subjects have been considered. The present study is concerned with bandwidth estimates in simultaneous and forward masking in individual normal-hearing subjects. In order to investigate...... the reliability of the individual estimates, a statistical resampling method is applied. It is demonstrated that a rather large set of experimental data is required to reliably estimate auditory filter bandwidth, particularly in the case of simultaneous masking. The poor overall reliability of the filter...

Wideband excitation in nonlinear vibro-acoustic modulation for damage detection

Science.gov (United States)

Klepka, A.; Adamczyk, M.; Pieczonka, L.; Staszewski, W. J.

2016-04-01

The paper discusses the use of wideband excitation in nonlinear vibro-acoustic modulation technique (VAM) used for damage detection. In its original form, two mono-harmonic signals (low and high frequency) are used for excitation. The low frequency excitation is typically selected based on a modal analysis test and high frequency excitation is selected arbitrarily in the ultrasonic frequency range. This paper presents a different approach with use of wideband excitation signals. The proposed approach gives the possibility to simplify the testing procedure by omitting the modal test used to determine the value of low frequency excitation. Simultaneous use of wideband excitation for high frequency solves the ambiguity related to the selection of the frequency of acoustic wave. Broadband excitation signals require, however, more elaborate signal processing methods to determine the intensity of modulation for a given bandwidth. The paper discusses the proposed approach and the related signal processing procedure. Experimental validation of the proposed technique is performed on a laminated composite plate with a barely visible impact damage that was generated in an impact test. Piezoceramic actuators are used for vibration excitation and a scanning laser vibrometer is used for noncontact data acquisition.

Large scale statistical inference of signaling pathways from RNAi and microarray data

Directory of Open Access Journals (Sweden)

Poustka Annemarie

2007-10-01

Full Text Available Abstract Background The advent of RNA interference techniques enables the selective silencing of biologically interesting genes in an efficient way. In combination with DNA microarray technology this enables researchers to gain insights into signaling pathways by observing downstream effects of individual knock-downs on gene expression. These secondary effects can be used to computationally reverse engineer features of the upstream signaling pathway. Results In this paper we address this challenging problem by extending previous work by Markowetz et al., who proposed a statistical framework to score networks hypotheses in a Bayesian manner. Our extensions go in three directions: First, we introduce a way to omit the data discretization step needed in the original framework via a calculation based on p-values instead. Second, we show how prior assumptions on the network structure can be incorporated into the scoring scheme using regularization techniques. Third and most important, we propose methods to scale up the original approach, which is limited to around 5 genes, to large scale networks. Conclusion Comparisons of these methods on artificial data are conducted. Our proposed module network is employed to infer the signaling network between 13 genes in the ER-α pathway in human MCF-7 breast cancer cells. Using a bootstrapping approach this reconstruction can be found with good statistical stability. The code for the module network inference method is available in the latest version of the R-package nem, which can be obtained from the Bioconductor homepage.

High-fidelity polarization storage in a gigahertz bandwidth quantum memory

International Nuclear Information System (INIS)

England, D G; Michelberger, P S; Champion, T F M; Reim, K F; Lee, K C; Sprague, M R; Jin, X-M; Langford, N K; Kolthammer, W S; Nunn, J; Walmsley, I A

2012-01-01

We demonstrate a dual-rail optical Raman memory inside a polarization interferometer; this enables us to store polarization-encoded information at GHz bandwidths in a room-temperature atomic ensemble. By performing full process tomography on the system, we measure up to 97 ± 1% process fidelity for the storage and retrieval process. At longer storage times, the process fidelity remains high, despite a loss of efficiency. The fidelity is 86 ± 4% for 1.5 μs storage time, which is 5000 times the pulse duration. Hence, high fidelity is combined with a large time-bandwidth product. This high performance, with an experimentally simple setup, demonstrates the suitability of the Raman memory for integration into large-scale quantum networks. (paper)

Jumping the energetics queue: Modulation of pulsar signals by extraterrestrial civilizations

Science.gov (United States)

Chennamangalam, Jayanth; Siemion, Andrew P. V.; Lorimer, D. R.; Werthimer, Dan

2015-01-01

It has been speculated that technological civilizations evolve along an energy consumption scale first formulated by Kardashev, ranging from human-like civilizations that consume energy at a rate of ∼1019 erg s-1 to hypothetical highly advanced civilizations that can consume ∼1044 erg s-1. Since the transmission power of a beacon a civilization can build depends on the energy it possesses, to make it bright enough to be seen across the Galaxy would require high technological advancement. In this paper, we discuss the possibility of a civilization using naturally-occurring radio transmitters - specifically, radio pulsars - to overcome the Kardashev limit of their developmental stage and transmit super-Kardashev power. This is achieved by the use of a modulator situated around a pulsar, that modulates the pulsar signal, encoding information onto its natural emission. We discuss a simple modulation model using pulse nulling and considerations for detecting such a signal. We find that a pulsar with a nulling modulator will exhibit an excess of thermal emission peaking in the ultraviolet during its null phases, revealing the existence of a modulator.

Modulation of EEG Theta Band Signal Complexity by Music Therapy

Science.gov (United States)

Bhattacharya, Joydeep; Lee, Eun-Jeong

The primary goal of this study was to investigate the impact of monochord (MC) sounds, a type of archaic sounds used in music therapy, on the neural complexity of EEG signals obtained from patients undergoing chemotherapy. The secondary goal was to compare the EEG signal complexity values for monochords with those for progressive muscle relaxation (PMR), an alternative therapy for relaxation. Forty cancer patients were randomly allocated to one of the two relaxation groups, MC and PMR, over a period of six months; continuous EEG signals were recorded during the first and last sessions. EEG signals were analyzed by applying signal mode complexity, a measure of complexity of neuronal oscillations. Across sessions, both groups showed a modulation of complexity of beta-2 band (20-29Hz) at midfrontal regions, but only MC group showed a modulation of complexity of theta band (3.5-7.5Hz) at posterior regions. Therefore, the neuronal complexity patterns showed different changes in EEG frequency band specific complexity resulting in two different types of interventions. Moreover, the different neural responses to listening to monochords and PMR were observed after regular relaxation interventions over a short time span.

System and method of modulating electrical signals using photoconductive wide bandgap semiconductors as variable resistors

Science.gov (United States)

Harris, John Richardson; Caporaso, George J; Sampayan, Stephen E

2013-10-22

A system and method for producing modulated electrical signals. The system uses a variable resistor having a photoconductive wide bandgap semiconductor material construction whose conduction response to changes in amplitude of incident radiation is substantially linear throughout a non-saturation region to enable operation in non-avalanche mode. The system also includes a modulated radiation source, such as a modulated laser, for producing amplitude-modulated radiation with which to direct upon the variable resistor and modulate its conduction response. A voltage source and an output port, are both operably connected to the variable resistor so that an electrical signal may be produced at the output port by way of the variable resistor, either generated by activation of the variable resistor or propagating through the variable resistor. In this manner, the electrical signal is modulated by the variable resistor so as to have a waveform substantially similar to the amplitude-modulated radiation.

Demonstration of the frequency modulation of optical signals with a high frequency deviation parameter

International Nuclear Information System (INIS)

Shamray, A V; Kozlov, A S; Il'ichev, I V; Petrov, M P

2008-01-01

A new type of an integrated optical modulator for the frequency coding of optical signals is developed and fabricated. The modulator operation is based on the original technology of the electric control of a Bragg grating. The frequency modulation of an optical signal with the frequency deviation of 25 GHz is demonstrated experimentally. The modular was used to transfer the ASCII code through an optical fibre. (optical communication)

ICE-Based Custom Full-Mesh Network for the CHIME High Bandwidth Radio Astronomy Correlator

Science.gov (United States)

Bandura, K.; Cliche, J. F.; Dobbs, M. A.; Gilbert, A. J.; Ittah, D.; Mena Parra, J.; Smecher, G.

2016-03-01

New generation radio interferometers encode signals from thousands of antenna feeds across large bandwidth. Channelizing and correlating this data requires networking capabilities that can handle unprecedented data rates with reasonable cost. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) correlator processes 8-bits from N=2,048 digitizer inputs across 400MHz of bandwidth. Measured in N2× bandwidth, it is the largest radio correlator that is currently commissioning. Its digital back-end must exchange and reorganize the 6.6terabit/s produced by its 128 digitizing and channelizing nodes, and feed it to the 256 graphics processing unit (GPU) node spatial correlator in a way that each node obtains data from all digitizer inputs but across a small fraction of the bandwidth (i.e. ‘corner-turn’). In order to maximize performance and reliability of the corner-turn system while minimizing cost, a custom networking solution has been implemented. The system makes use of Field Programmable Gate Array (FPGA) transceivers to implement direct, passive copper, full-mesh, high speed serial connections between sixteen circuit boards in a crate, to exchange data between crates, and to offload the data to a cluster of 256 GPU nodes using standard 10Gbit/s Ethernet links. The GPU nodes complete the corner-turn by combining data from all crates and then computing visibilities. Eye diagrams and frame error counters confirm error-free operation of the corner-turn network in both the currently operating CHIME Pathfinder telescope (a prototype for the full CHIME telescope) and a representative fraction of the full CHIME hardware providing an end-to-end system validation. An analysis of an equivalent corner-turn system built with Ethernet switches instead of custom passive data links is provided.

Combination of fat saturation and variable bandwidth imaging to increase signal-to-noise ratio and decrease motion artifacts for body MR imaging at high field

International Nuclear Information System (INIS)

Chew, W.M.

1989-01-01

The signal-to-noise ratio (SNR) of the MR imaging examination is a critical component of the quality of the image. Standard methods to increase SNR include signal averaging with multiple excitations, at the expense of imaging time (which on T2-weighted images could be quite significant), or increasing pixel volume by manipulation of field of view, matrix size, and/or section thickness, all at the expense of resolution. Another available method to increase SNR is to reduce the bandwidth of the receiver, which increases SNR by the square root of the amount of the reduction. The penalty imposed on high-field-strength MR examinations of the body is an unacceptable increase in chemical shift artifact. However, presaturating the fat resonance eliminates the chemical shift artifact. Thus, a combination of imaging techniques, fat suppression, and decreased bandwidth imaging can produce images free of chemical shift artifact with increased SNR and no penalty in resolution or imaging time. Early studies also show a reduction in motion artifact when fat saturation is used. This paper reports MR imaging performed with a 1.5-T Signa imager. With this technique, T2-weighted images (2,500/20/80 [repetition time msec/echo time msec/inversion time msec]) illustrating the increase in SNR and T1-weighted images (600/20) demonstrating a decrease in motion artifact are shown

Genetic variation in glia-neuron signalling modulates ageing rate.

Science.gov (United States)

Yin, Jiang-An; Gao, Ge; Liu, Xi-Juan; Hao, Zi-Qian; Li, Kai; Kang, Xin-Lei; Li, Hong; Shan, Yuan-Hong; Hu, Wen-Li; Li, Hai-Peng; Cai, Shi-Qing

2017-11-08

The rate of behavioural decline in the ageing population is remarkably variable among individuals. Despite the considerable interest in studying natural variation in ageing rate to identify factors that control healthy ageing, no such factor has yet been found. Here we report a genetic basis for variation in ageing rates in Caenorhabditis elegans. We find that C. elegans isolates show diverse lifespan and age-related declines in virility, pharyngeal pumping, and locomotion. DNA polymorphisms in a novel peptide-coding gene, named regulatory-gene-for-behavioural-ageing-1 (rgba-1), and the neuropeptide receptor gene npr-28 influence the rate of age-related decline of worm mating behaviour; these two genes might have been subjected to recent selective sweeps. Glia-derived RGBA-1 activates NPR-28 signalling, which acts in serotonergic and dopaminergic neurons to accelerate behavioural deterioration. This signalling involves the SIR-2.1-dependent activation of the mitochondrial unfolded protein response, a pathway that modulates ageing. Thus, natural variation in neuropeptide-mediated glia-neuron signalling modulates the rate of ageing in C. elegans.

Energy-efficient routing, modulation and spectrum allocation in elastic optical networks

Science.gov (United States)

Tan, Yanxia; Gu, Rentao; Ji, Yuefeng

2017-07-01

With tremendous growth in bandwidth demand, energy consumption problem in elastic optical networks (EONs) becomes a hot topic with wide concern. The sliceable bandwidth-variable transponder in EON, which can transmit/receive multiple optical flows, was recently proposed to improve a transponder's flexibility and save energy. In this paper, energy-efficient routing, modulation and spectrum allocation (EE-RMSA) in EONs with sliceable bandwidth-variable transponder is studied. To decrease the energy consumption, we develop a Mixed Integer Linear Programming (MILP) model with corresponding EE-RMSA algorithm for EONs. The MILP model jointly considers the modulation format and optical grooming in the process of routing and spectrum allocation with the objective of minimizing the energy consumption. With the help of genetic operators, the EE-RMSA algorithm iteratively optimizes the feasible routing path, modulation format and spectrum resources solutions by explore the whole search space. In order to save energy, the optical-layer grooming strategy is designed to transmit the lightpath requests. Finally, simulation results verify that the proposed scheme is able to reduce the energy consumption of the network while maintaining the blocking probability (BP) performance compare with the existing First-Fit-KSP algorithm, Iterative Flipping algorithm and EAMGSP algorithm especially in large network topology. Our results also demonstrate that the proposed EE-RMSA algorithm achieves almost the same performance as MILP on an 8-node network.

Hybrid Online Labs: Making Remote Laboratories Usable Under Unfavorable Bandwidth Conditions

OpenAIRE

Kayode Peter Ayodele; Lawrence O. Kehinde; Olusola A. Komolafe

2012-01-01

One of few limitations of remote laboratory technology is the fact that access and usability of such laboratories depend largely on the existence of favorable bandwidth conditions between the remote user and the system under test. This dependence is regrettable because some of the institutions likely to find remote laboratories attractive are also those most likely to have severe bandwidth limitations. Also, a typical remote laboratory will be completely unusable to remote students in the eve...

Orphan nuclear receptor TLX regulates astrogenesis by modulating BMP signaling

Directory of Open Access Journals (Sweden)

Song eQin

2014-04-01

Full Text Available Neural stem cells (NSCs are self-renewing multipotent progenitors that generate both neurons and glia. The precise control of NSC behavior is fundamental to the architecture and function of the central nervous system. We previously demonstrated that the orphan nuclear receptor TLX is required for postnatal NSC activation and neurogenesis in the neurogenic niche. Here, we show that TLX modulates BMP-SMAD signaling to control the timing of postnatal astrogenesis. Genes involved in the BMP signaling pathway, such as Bmp4, Hes1, and Id3, are upregulated in postnatal brains lacking Tlx. Chromatin immunoprecipitation and electrophoretic mobility shift assays reveal that TLX can directly bind the enhancer region of Bmp4. In accordance with elevated BMP signaling, the downstream effectors SMAD1/5/8 are activated by phosphorylation in Tlx mutant mice. Consequently, Tlx mutant brains exhibit an early appearance and increased number of astrocytes with marker expression of glial fibrillary acidic protein (GFAP and S100B. Taken together, these results suggest that TLX tightly controls postnatal astrogenesis through the modulation of BMP-SMAD signaling pathway activity.

Orphan nuclear receptor TLX regulates astrogenesis by modulating BMP signaling.

Science.gov (United States)

Qin, Song; Niu, Wenze; Iqbal, Nida; Smith, Derek K; Zhang, Chun-Li

2014-01-01

Neural stem cells (NSCs) are self-renewing multipotent progenitors that generate both neurons and glia. The precise control of NSC behavior is fundamental to the architecture and function of the central nervous system. We previously demonstrated that the orphan nuclear receptor TLX is required for postnatal NSC activation and neurogenesis in the neurogenic niche. Here, we show that TLX modulates bone morphogenetic protein (BMP)-SMAD signaling to control the timing of postnatal astrogenesis. Genes involved in the BMP signaling pathway, such as Bmp4, Hes1, and Id3, are upregulated in postnatal brains lacking Tlx. Chromatin immunoprecipitation and electrophoretic mobility shift assays reveal that TLX can directly bind the enhancer region of Bmp4. In accordance with elevated BMP signaling, the downstream effectors SMAD1/5/8 are activated by phosphorylation in Tlx mutant mice. Consequently, Tlx mutant brains exhibit an early appearance and increased number of astrocytes with marker expression of glial fibrillary acidic protein (GFAP) and S100B. Taken together, these results suggest that TLX tightly controls postnatal astrogenesis through the modulation of BMP-SMAD signaling pathway activity.

Protein conservation and variation suggest mechanisms of cell type-specific modulation of signaling pathways.

Directory of Open Access Journals (Sweden)

Martin H Schaefer

2014-06-01

Full Text Available Many proteins and signaling pathways are present in most cell types and tissues and yet perform specialized functions. To elucidate mechanisms by which these ubiquitous pathways are modulated, we overlaid information about cross-cell line protein abundance and variability, and evolutionary conservation onto functional pathway components and topological layers in the pathway hierarchy. We found that the input (receptors and the output (transcription factors layers evolve more rapidly than proteins in the intermediary transmission layer. In contrast, protein expression variability decreases from the input to the output layer. We observed that the differences in protein variability between the input and transmission layer can be attributed to both the network position and the tendency of variable proteins to physically interact with constitutively expressed proteins. Differences in protein expression variability and conservation are also accompanied by the tendency of conserved and constitutively expressed proteins to acquire somatic mutations, while germline mutations tend to occur in cell type-specific proteins. Thus, conserved core proteins in the transmission layer could perform a fundamental role in most cell types and are therefore less tolerant to germline mutations. In summary, we propose that the core signal transmission machinery is largely modulated by a variable input layer through physical protein interactions. We hypothesize that the bow-tie organization of cellular signaling on the level of protein abundance variability contributes to the specificity of the signal response in different cell types.

Maximum Bandwidth Enhancement of Current Mirror using Series-Resistor and Dynamic Body Bias Technique

Directory of Open Access Journals (Sweden)

V. Niranjan

2014-09-01

Full Text Available This paper introduces a new approach for enhancing the bandwidth of a low voltage CMOS current mirror. The proposed approach is based on utilizing body effect in a MOS transistor by connecting its gate and bulk terminals together for signal input. This results in boosting the effective transconductance of MOS transistor along with reduction of the threshold voltage. The proposed approach does not affect the DC gain of the current mirror. We demonstrate that the proposed approach features compatibility with widely used series-resistor technique for enhancing the current mirror bandwidth and both techniques have been employed simultaneously for maximum bandwidth enhancement. An important consequence of using both techniques simultaneously is the reduction of the series-resistor value for achieving the same bandwidth. This reduction in value is very attractive because a smaller resistor results in smaller chip area and less noise. PSpice simulation results using 180 nm CMOS technology from TSMC are included to prove the unique results. The proposed current mirror operates at 1Volt consuming only 102 µW and maximum bandwidth extension ratio of 1.85 has been obtained using the proposed approach. Simulation results are in good agreement with analytical predictions.

Multichannel photonic Hilbert transformers based on complex modulated integrated Bragg gratings.

Science.gov (United States)

Cheng, Rui; Chrostowski, Lukas

2018-03-01

Multichannel photonic Hilbert transformers (MPHTs) are reported. The devices are based on single compact spiral integrated Bragg gratings on silicon with coupling coefficients precisely modulated by the phase of each grating period. MPHTs with up to nine wavelength channels and a single-channel bandwidth of up to ∼625  GHz are achieved. The potential of the devices for multichannel single-sideband signal generation is suggested. The work offers a new possibility of utilizing wavelength as an extra degree of freedom in designing radio-frequency photonic signal processors. Such multichannel processors are expected to possess improved capacities and a potential to greatly benefit current widespread wavelength division multiplexed systems.

Resolving the range ambiguity in OFDR using digital signal processing

International Nuclear Information System (INIS)

Riesen, Nicolas; Lam, Timothy T-Y; Chow, Jong H

2014-01-01

A digitally range-gated variant of optical frequency domain reflectometry is demonstrated which overcomes the beat note ambiguity when sensing beyond a single frequency sweep. The range-gating is achieved using a spread spectrum technique involving time-stamping of the optical signal using high-frequency pseudorandom phase modulation. The reflections from different sections of fiber can then be isolated in the time domain by digitally inverting the phase modulation using appropriately-delayed copies of the pseudorandom noise code. Since the technique overcomes the range ambiguity in OFDR, it permits high sweep repetition rates without sacrificing range, thus allowing for high-bandwidth sensing over long lengths of fiber. This is demonstrated for the case of quasi-distributed sensing. (paper)

Statistical Modeling of Large-Scale Signal Path Loss in Underwater Acoustic Networks

Directory of Open Access Journals (Sweden)

Manuel Perez Malumbres

2013-02-01

Full Text Available In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation, we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc., an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc..

A Doherty Power Amplifier with Large Back-Off Power Range Using Integrated Enhancing Reactance

Directory of Open Access Journals (Sweden)

Wa Kong

2018-01-01

Full Text Available A symmetric Doherty power amplifier (DPA based on integrated enhancing reactance (IER was proposed for large back-off applications. The IER was generated using the peaking amplifier with the help of a desired impedance transformation in the low-power region to enhance the back-off efficiency of the carrier amplifier. To convert the impedances properly, both in the low-power region and at saturation, a two-impedance matching method was employed to design the output matching networks. For verification, a symmetric DPA with large back-off power range over 2.2–2.5 GHz was designed and fabricated. Measurement results show that the designed DPA has the 9 dB back-off efficiency of higher than 45%, while the saturated output power is higher than 44 dBm over the whole operation bandwidth. When driven by a 20 MHz LTE signal, the DPA can achieve good average efficiency of around 50% with adjacent channel leakage ratio of about –50 dBc after linearization over the frequency band of interest. The linearity improvement of the DPA for multistandard wireless communication system was also verified with a dual-band modulated signal.

Simultaneous generation of 40, 80 and 120 GHz optical millimeter-wave from one Mach-Zehnder modulator and demonstration of millimeter-wave transmission and down-conversion

Science.gov (United States)

Zhou, Wen; Qin, Chaoyi

2017-09-01

We demonstrate multi-frequency QPSK millimeter-wave (mm-wave) vector signal generation enabled by MZM-based optical carrier suppression (OCS) modulation and in-phase/quadrature (I/Q) modulation. We numerically simulate the generation of 40-, 80- and 120-GHz vector signal. Here, the three different signals carry the same QPSK modulation information. We also experimentally realize 11Gbaud/s QPSK vector signal transmission over 20 km fiber, and the generation of the vector signals at 40-GHz, 80-GHz and 120-GHz. The experimental results show that the bit-error-rate (BER) for all the three different signals can reach the forward-error-correction (FEC) threshold of 3.8×10-3. The advantage of the proposed system is that provide high-speed, high-bandwidth and high-capacity seamless access of TDM and wireless network. These features indicate the important application prospect in wireless access networks for WiMax, Wi-Fi and 5G/LTE.

Automatic Modulation Classification of LFM and Polyphase-coded Radar Signals

Directory of Open Access Journals (Sweden)

S. B. S. Hanbali

2017-12-01

Full Text Available There are several techniques for detecting and classifying low probability of intercept radar signals such as Wigner distribution, Choi-Williams distribution and time-frequency rate distribution, but these distributions require high SNR. To overcome this problem, we propose a new technique for detecting and classifying linear frequency modulation signal and polyphase coded signals using optimum fractional Fourier transform at low SNR. The theoretical analysis and simulation experiments demonstrate the validity and efficiency of the proposed method.

Ionospheric Coherence Bandwidth Measurements in the Lower VHF Frequency Range

Science.gov (United States)

Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

2015-12-01

The United States Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 820 - 1100 MHz. In this paper, we present simultaneous ionospheric coherence bandwidth and S4 scintillation index measurements in the 32 - 44 MHz frequency range collected during the ESCINT equatorial scintillation experiment. 40-MHz continuous wave (CW) and 32 - 44 MHz swept frequency signals were transmitted simultaneously to the RFProp receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in three separate campaigns during the 2014 and 2015 equinoxes. Results show coherence bandwidths as small as ~ 1 kHz for strong scintillation (S4 > 0.7) and indicate a high degree of ionospheric variability and irregularity on 10-m spatial scales. Spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities are also observed and are dominant at low elevation angles. The results are compared to previous measurements and available scaling laws.

Curcumin mediates anticancer effects by modulating multiple cell signaling pathways.

Science.gov (United States)

Kunnumakkara, Ajaikumar B; Bordoloi, Devivasha; Harsha, Choudhary; Banik, Kishore; Gupta, Subash C; Aggarwal, Bharat B

2017-08-01

Curcumin, a component of a spice native to India, was first isolated in 1815 by Vogel and Pelletier from the rhizomes of Curcuma longa (turmeric) and, subsequently, the chemical structure of curcumin as diferuloylmethane was reported by Milobedzka et al. [(1910) 43., 2163-2170]. Since then, this polyphenol has been shown to exhibit antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, and antifungal activities. The current review primarily focuses on the anticancer potential of curcumin through the modulation of multiple cell signaling pathways. Curcumin modulates diverse transcription factors, inflammatory cytokines, enzymes, kinases, growth factors, receptors, and various other proteins with an affinity ranging from the pM to the mM range. Furthermore, curcumin effectively regulates tumor cell growth via modulation of numerous cell signaling pathways and potentiates the effect of chemotherapeutic agents and radiation against cancer. Curcumin can interact with most of the targets that are modulated by FDA-approved drugs for cancer therapy. The focus of this review is to discuss the molecular basis for the anticancer activities of curcumin based on preclinical and clinical findings. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency

Science.gov (United States)

Liu, Yang; Li, Shu-qing; Feng, Zhong-ying; Liu, Xiao-fei; Gao, Jin-yue

2016-12-01

To obtain the weak signal light detection from the high background noise, we present a theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency. In a three-level Λ -type atomic system in the rubidium D1 line, the bandwidth of the EIT atomic filter is narrowed to ~6.5 \\text{MHz} . And the single peak transmission of the filter can be up to 86% . Moreover, the transmission wavelength can be tuned by changing the coupling light frequency. This theoretical scheme can also be applied to other alkali atomic systems.

Signal modulation as a mechanism for handicap disposal

Science.gov (United States)

Gavassa, Sat; Silva, Ana C.; Gonzalez, Emmanuel; Stoddard, Philip K.

2012-01-01

Signal honesty may be compromised when heightened competition provides incentive for signal exaggeration. Some degree of honesty might be maintained by intrinsic handicap costs on signalling or through imposition of extrinsic costs, such as social punishment of low quality cheaters. Thus, theory predicts a delicate balance between signal enhancement and signal reliability that varies with degree of social competition, handicap cost, and social cost. We investigated whether male sexual signals of the electric fish Brachyhypopomus gauderio would become less reliable predictors of body length when competition provides incentives for males to boost electric signal amplitude. As expected, social competition under natural field conditions and in controlled lab experiments drove males to enhance their signals. However, signal enhancement improved the reliability of the information conveyed by the signal, as revealed in the tightening of the relationship between signal amplitude and body length. Signal augmentation in male B. gauderio was independent of body length, and thus appeared not to be curtailed through punishment of low quality (small) individuals. Rather, all individuals boosted their signals under high competition, but those whose signals were farthest from the predicted value under low competition boosted signal amplitude the most. By elimination, intrinsic handicap cost of signal production, rather than extrinsic social cost, appears to be the basis for the unexpected reinforcement of electric signal honesty under social competition. Signal modulation may provide its greatest advantage to the signaller as a mechanism for handicap disposal under low competition rather than as a mechanism for exaggeration of quality under high competition. PMID:22665940

Raman scheme for adjustable-bandwidth quantum memory

International Nuclear Information System (INIS)

Le Goueet, J.-L.; Berman, P. R.

2009-01-01

We propose a scenario of quantum memory for light based on Raman scattering. The storage medium is a vapor and the different spectral components of the input pulse are stored in different atomic velocity classes. One uses appropriate pulses to reverse the resulting Doppler phase shift and to regenerate the input pulse, without distortion, in the backward direction. The different stages of the protocol are detailed and the recovery efficiency is calculated in the semiclassical picture. Since the memory bandwidth is determined by the Raman transition Doppler width, it can be adjusted by changing the angle between the input pulse wave vector and the control beams. The optical depth also depends on the beam angle. As a consequence the available optical depth can be optimized depending on the needed bandwidth. The predicted recovery efficiency is close to 100% for large optical depth.

The effect of extending high-frequency bandwidth on the acceptable noise level (ANL) of hearing-impaired listeners.

Science.gov (United States)

Johnson, Earl; Ricketts, Todd; Hornsby, Benjamin

2009-01-01

This study examined the effects of extending high-frequency bandwidth, for both a speech signal and a background noise, on the acceptable signal-to-noise ratio (SNR) of listeners with mild sensorineural hearing loss through utilization of the Acceptable Noise Level (ANL) procedure. In addition to extending high-frequency bandwidth, the effects of reverberation time and background noise type and shape were also examined. The study results showed a significant increase in the mean ANL (i.e. participants requested a better SNR for an acceptable listening situation) when high-frequency bandwidth was extended from 3 to 9 kHz and from 6 to 9 kHz. No change in the ANL of study participants was observed as a result of isolated modification to reverberation time or background noise stimulus. An interaction effect, however, of reverberation time and background noise stimulus was demonstrated. These findings may have implications for future design of hearing aid memory programs for listening to speech in the presence of broadband background noise.

A Study on the Bandwidth Characteristics of Pleated Pneumatic Artificial Muscles

Directory of Open Access Journals (Sweden)

Rino Versluys

2009-01-01

Full Text Available Pleated pneumatic artificial muscles have interesting properties that can be of considerable significance in robotics and automation. With a view to the potential use of pleated pneumatic artificial muscles as actuators for a fatigue test bench (high forces and small displacements, the bandwidth characteristics of a muscle-valve system were investigated. Bandwidth is commonly used for linear systems, as the Bode plot is independent of the amplitude of the input signal. However, due to the non-linear behaviour of pleated pneumatic artificial muscles, the system's gain becomes dependent on the amplitude of the input sine wave. As a result, only one Bode plot is insufficient to clearly describe or identify a non-linear system. In this study, the bandwidth of a muscle-valve system was assessed from two perspectives: a varying amplitude and a varying offset of the input sine wave. A brief introduction to pneumatic artificial muscles is given. The concept of pleated pneumatic artificial muscles is explained. Furthermore, the different test methods and experimental results are presented.

Coco is a dual activity modulator of TGFβ signaling

Science.gov (United States)

Deglincerti, Alessia; Haremaki, Tomomi; Warmflash, Aryeh; Sorre, Benoit; Brivanlou, Ali H.

2015-01-01

The TGFβ signaling pathway is a crucial regulator of developmental processes and disease. The activity of TGFβ ligands is modulated by various families of soluble inhibitors that interfere with the interactions between ligands and receptors. In an unbiased, genome-wide RNAi screen to identify genes involved in ligand-dependent signaling, we unexpectedly identified the BMP/Activin/Nodal inhibitor Coco as an enhancer of TGFβ1 signaling. Coco synergizes with TGFβ1 in both cell culture and Xenopus explants. Molecularly, Coco binds to TGFβ1 and enhances TGFβ1 binding to its receptor Alk5. Thus, Coco acts as both an inhibitor and an enhancer of signaling depending on the ligand it binds. This finding raises the need for a global reconsideration of the molecular mechanisms regulating TGFβ signaling. PMID:26116664

Signal-Characteristic analysis with respect to backing material of PVDF-based high-frequency ultrasound for photoacoustic microscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, Jun Su; Chang, Jin Ho [Dept. of Electronic Engineering, Sogang University, Seoul (Korea, Republic of)

2015-04-15

Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.

Universality and Realistic Extensions to the Semi-Analytic Simulation Principle in GNSS Signal Processing

Directory of Open Access Journals (Sweden)

O. Jakubov

2012-06-01

Full Text Available Semi-analytic simulation principle in GNSS signal processing bypasses the bit-true operations at high sampling frequency. Instead, signals at the output branches of the integrate&dump blocks are successfully modeled, thus making extensive Monte Carlo simulations feasible. Methods for simulations of code and carrier tracking loops with BPSK, BOC signals have been introduced in the literature. Matlab toolboxes were designed and published. In this paper, we further extend the applicability of the approach. Firstly, we describe any GNSS signal as a special instance of linear multi-dimensional modulation. Thereby, we state universal framework for classification of differently modulated signals. Using such description, we derive the semi-analytic models generally. Secondly, we extend the model for realistic scenarios including delay in the feed back, slowly fading multipath effects, finite bandwidth, phase noise, and a combination of these. Finally, a discussion on connection of this semi-analytic model and position-velocity-time estimator is delivered, as well as comparison of theoretical and simulated characteristics, produced by a prototype simulator developed at CTU in Prague.

Transmission Property of Directly Modulated Signals Enhanced by a Micro-ring Resonator

DEFF Research Database (Denmark)

An, Yi; Lorences Riesgo, Abel; Seoane, Jorge

2012-01-01

A silicon micro-ring resonator is used to enhance the modulation speed of a 10-Gbit/s directly modulated laser to 40 Gbit/s. The generated signal is transmitted error free over 4.5 km SSMF. Dispersion tolerance is also studied....

A HIGH BANDWIDTH BIPOLAR POWER SUPPLY FOR THE FAST CORRECTORS IN THE APS UPGRADE*

Energy Technology Data Exchange (ETDEWEB)

Wang, Ju; Sprau, Gary

2017-06-25

The APS Upgrade of a multi-bend achromat (MBA) storage ring requires a fast bipolar power supply for the fast correction magnets. The key performance requirement of the power supply includes a small-signal bandwidth of 10 kHz for the output current. This requirement presents a challenge to the design because of the high inductance of the magnet load and a limited input DC voltage. A prototype DC/DC power supply utilizing a MOSFET H-bridge circuit with a 500 kHz PWM has been developed and tested successfully. The prototype achieved a 10-kHz bandwidth with less than 3-dB attenuation for a signal 0.5% of the maximum operating current of 15 amperes. This paper presents the design of the power circuit, the PWM method, the control loop, and the test results.

Flexible power and bandwidth allocation in mobile satellites

Science.gov (United States)

Keyes, L. A.

The introduction of L-band mobile communication services by spot beam satellites creates a payload design challenge due to uncertainty in the location and size of the new market to be served. A combination of payload technologies that allow a flexible allocation of power and bandwidth to any portion of the coverage area is described. Power flexibility is achieved by a novel combination of a low-level beam-forming network and a matrix power module which ensures equal sharing of power among individual amplifiers. This eliminates the loss of efficiency and increased mass when an amplifier associated with a beam must be over-designed to meet uncertainties in power distribution between beams. Flexibility in allocation of bandwidth to beams is achieved by intermediate frequency subdivision of the L-band service categories defined by ITU. These spectral subdivisions are assigned to beams by an IF interconnect matrix having beam ports and filter ports as inputs and outputs, respectively. Two such filter switch matrices are required, one for the inbound L-band to feeder link transponder, and one for the outbound feeder link to L-band transponder.

Signal coupling and signal integrity in multi-strip resistive plate chambers used for timing applications

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Diaz, Diego, E-mail: D.Gonzalez-Diaz@gsi.de [GSI Helmholtzcenter for Heavy Ion Research, Darmstadt (Germany); Technical University, Darmstadt (Germany); Department of Engineering Physics, Tsinghua University, Beijing (China); Chen Huangshan; Wang Yi [Technical University, Darmstadt (Germany)

2011-08-21

We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range f=0.1-3.5GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100 ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 m scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to their inherent unbalance between capacitive and inductive coupling. A practical way to restore this symmetry has been introduced (hereafter 'electrostatic compensation'), allowing for a cross-talk suppression factor up to x12 and a rise-time reduction by 200 ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1 GHz for propagation along 2 m in typical float glass-based RPCs. It is further shown that 'electrostatic compensation' can be achieved for an arbitrary number of strips as long as the nature of the coupling is 'short-range', that is an almost exact assumption for typical strip-line RPCs. This work extends the bandwidth of previous studies by a factor ofx20.

Bandwidth-on-demand motion control

NARCIS (Netherlands)

Van Loon, S.J.L.M.; Hunnekens, B.G.B.; Simon, A.S.; van de Wouw, N.; Heemels, W.P.M.H.

2018-01-01

In this brief, we introduce a 'bandwidth-on-demand' variable-gain control (VGC) strategy that allows for a varying bandwidth of the feedback controller. The proposed VGC can achieve improved performance given time-varying, reference-dependent performance requirements compared with linear

A Novel Sigma-Delta Modulator with Fractional-Order Digital Loop Integrator

Directory of Open Access Journals (Sweden)

Chi Xu

2017-01-01

Full Text Available This paper proposes using a fractional-order digital loop integrator to improve the robust stability of Sigma-Delta modulator, thus extending the integer-order Sigma-Delta modulator to a non-integer-order (fractional-order one in the Sigma-Delta ADC design field. The proposed fractional-order Sigma-Delta modulator has reasonable noise characteristics, dynamic range, and bandwidth; moreover the signal-to-noise ratio (SNR is improved remarkably. In particular, a 2nd-order digital loop integrator and a digital PIλDμ controller are combined to work as the fractional-order digital loop integrator, which is realized using FPGA; this will reduce the ASIC analog circuit layout design and chip testing difficulties. The parameters of the proposed fractional-order Sigma-Delta modulator are tuned by using swarm intelligent algorithm, which offers opportunity to simplify the process of tuning parameters and further improve the noise performance. Simulation results are given and they demonstrate the efficiency of the proposed fractional-order Sigma-Delta modulator.

A microRNA-mediated regulatory loop modulates NOTCH and MYC oncogenic signals in B- and T-cell malignancies.

Science.gov (United States)

Ortega, M; Bhatnagar, H; Lin, A-P; Wang, L; Aster, J C; Sill, H; Aguiar, R C T

2015-04-01

Growing evidence suggests that microRNAs (miRNAs) facilitate the cross-talk between transcriptional modules and signal transduction pathways. MYC and NOTCH1 contribute to the pathogenesis of lymphoid malignancies. NOTCH induces MYC, connecting two signaling programs that enhance oncogenicity. Here we show that this relationship is bidirectional and that MYC, via a miRNA intermediary, modulates NOTCH. MicroRNA-30a (miR-30a), a member of a family of miRNAs that are transcriptionally suppressed by MYC, directly binds to and inhibits NOTCH1 and NOTCH2 expression. Using a murine model and genetically modified human cell lines, we confirmed that miR-30a influences NOTCH expression in a MYC-dependent fashion. In turn, through genetic modulation, we demonstrated that intracellular NOTCH1 and NOTCH2, by inducing MYC, suppressed miR-30a. Conversely, pharmacological inhibition of NOTCH decreased MYC expression and ultimately de-repressed miR-30a. Examination of genetic models of gain and loss of miR-30a in diffuse large B-cell lymphoma (DLBCL) and T-acute lymphoblastic leukemia (T-ALL) cells suggested a tumor-suppressive role for this miRNA. Finally, the activity of the miR-30a-NOTCH-MYC loop was validated in primary DLBCL and T-ALL samples. These data define the presence of a miRNA-mediated regulatory circuitry that may modulate the oncogenic signals originating from NOTCH and MYC.

First large DEPFET pixel modules for the Belle II Pixel Detector

Energy Technology Data Exchange (ETDEWEB)

Mueller, Felix; Avella, Paola; Kiesling, Christian; Koffmane, Christian; Moser, Hans-Guenther; Valentan, Manfred [Max-Planck-Institut fuer Physik, Muenchen (Germany); Andricek, Ladislav; Richter, Rainer [Halbleiterlabor der Max-Planck-Gesellschaft, Muenchen (Germany); Collaboration: Belle II-Collaboration

2016-07-01

DEPFET pixel detectors offer excellent signal to noise ratio, resolution and low power consumption with a low material budget. They will be used at Belle II and are a candidate for an ILC vertex detector. The pixels are integrated in a monolithic piece of silicon which also acts as PCB providing the signal and control routings for the ASICs on top. The first prototype DEPFET sensor modules for Belle II have been produced. The modules have 192000 pixels and are equipped with SMD components and three different kinds of ASICs to control and readout the pixels. The entire readout chain has to be studied; the metal layer interconnectivity and routings need to be verified. The modules are fully characterized, and the operation voltages and control sequences of the ASICs are investigated. An overview of the DEPFET concept and first characterization results is presented.

Low modulation index RF signal detection for a passive UHF RFID transponder

International Nuclear Information System (INIS)

Liu Zhongqi; Zhang Chun; Li Yongming; Wang Zhihua

2009-01-01

In a typical RFID system the reader transmits modulated RF power to provide both data and energy for the passive transponder. Low modulation index RF energy is preferable for an adequate tag power supply and increase in communication range but gives rise to difficulties for near-field conventional demodulation. Therefore, a novel ASK demodulator for minimum 20% modulation index RF signal detection over a range of 23 dB is presented. Thanks to the proposed innovative divisional linear conversion from the power into voltage signal, the detection sensitivity is ensured over a wide power range with low power consumption of 8.6 μW. The chip is implemented in UMC 0.18 μm mix-mode CMOS technology, and the chip area is 0.06 mm 2 .

Functional Redundancy Between Canonical Endocannabinoid Signaling Systems in the Modulation of Anxiety.

Science.gov (United States)

Bedse, Gaurav; Hartley, Nolan D; Neale, Emily; Gaulden, Andrew D; Patrick, Toni A; Kingsley, Philip J; Uddin, Md Jashim; Plath, Niels; Marnett, Lawrence J; Patel, Sachin

2017-10-01

Increasing the available repertoire of effective treatments for mood and anxiety disorders represents a critical unmet need. Pharmacological augmentation of endogenous cannabinoid (eCB) signaling has been suggested to represent a novel approach to the treatment of anxiety disorders; however, the functional interactions between two canonical eCB pathways mediated via anandamide (N-arachidonylethanolamine [AEA]) and 2-arachidonoylglycerol (2-AG) in the regulation of anxiety are not well understood. We utilized pharmacological augmentation and depletion combined with behavioral and electrophysiological approaches to probe the role of 2-AG signaling in the modulation of stress-induced anxiety and the functional redundancy between AEA and 2-AG signaling in the modulation of anxiety-like behaviors in mice. Selective 2-AG augmentation reduced anxiety in the light/dark box assay and prevented stress-induced increases in anxiety associated with limbic AEA deficiency. In contrast, acute 2-AG depletion increased anxiety-like behaviors, which was normalized by selective pharmacological augmentation of AEA signaling and via direct cannabinoid receptor 1 stimulation with Δ 9 -tetrahydrocannabinol. Electrophysiological studies revealed 2-AG modulation of amygdala glutamatergic transmission as a key synaptic correlate of the anxiolytic effects of 2-AG augmentation. Although AEA and 2-AG likely subserve distinct physiological roles, a pharmacological and functional redundancy between these canonical eCB signaling pathways exists in the modulation of anxiety-like behaviors. These data support development of eCB-based treatment approaches for mood and anxiety disorders and suggest a potentially wider therapeutic overlap between AEA and 2-AG augmentation approaches than was previously appreciated. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Self oscillating PWM modulators, a topological comparison

DEFF Research Database (Denmark)

Poulsen, Søren; Andersen, Michael Andreas E.

2004-01-01

or fs/ð range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal...... to fs which makes this type of modulators an excellent choice for a wide range of applications. Self oscillating PWM modulators can be made in a number of ways, either as voltage or current mode modulators, and the self oscillating behavior can be achieved either by using hysteresis control...... or by shaping the open loop function of the modulator so its gain and phase response causes a closed loop natural oscillation. The two main types of self oscillating modulators have many similarities, but differences in dynamic performance and linearity are present. The work presented is related to the author...

Glass Industry Bandwidth Analysis

Energy Technology Data Exchange (ETDEWEB)

Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States)

2006-07-01

This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

Industrial Glass Bandwidth Analysis

Energy Technology Data Exchange (ETDEWEB)

Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States); Servaites, James [Gas Technology Inst., Des Plaines, IL (United States); Wolf, Warren [Gas Technology Inst., Des Plaines, IL (United States)

2007-08-01

This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

Modulation of learning and memory by cytokines: signaling mechanisms and long term consequences.

Science.gov (United States)

Donzis, Elissa J; Tronson, Natalie C

2014-11-01

This review describes the role of cytokines and their downstream signaling cascades on the modulation of learning and memory. Immune proteins are required for many key neural processes and dysregulation of these functions by systemic inflammation can result in impairments of memory that persist long after the resolution of inflammation. Recent research has demonstrated that manipulations of individual cytokines can modulate learning, memory, and synaptic plasticity. The many conflicting findings, however, have prevented a clear understanding of the precise role of cytokines in memory. Given the complexity of inflammatory signaling, understanding its modulatory role requires a shift in focus from single cytokines to a network of cytokine interactions and elucidation of the cytokine-dependent intracellular signaling cascades. Finally, we propose that whereas signal transduction and transcription may mediate short-term modulation of memory, long-lasting cellular and molecular mechanisms such as epigenetic modifications and altered neurogenesis may be required for the long lasting impact of inflammation on memory and cognition. Copyright © 2014 Elsevier Inc. All rights reserved.

Amplitude and phase modulation with waveguide optics

International Nuclear Information System (INIS)

Burkhart, S.C.; Wilcox, R.B.; Browning, D.; Penko, F.A.

1996-01-01

We have developed amplitude and phase modulation systems for glass lasers using integrated electro-optic modulators and solid state high-speed electronics. The present and future generation of lasers for Inertial Confinement Fusion require laser beams with complex temporal and phase shaping to compensate for laser gain saturation, mitigate parametric processes such as transverse stimulated Brillouin scattering in optics, and to provide specialized drive to the fusion targets. These functions can be performed using bulk optoelectronic modulators, however using high-speed electronics to drive low voltage integrated optical modulators has many practical advantages. In particular, we utilize microwave GaAs transistors to perform precision, 250 ps resolution temporal shaping. Optical bandwidth is generated using a microwave oscillator at 3 GHz amplified by a solid state amplifier. This drives an integrated electrooptic modulator to achieve laser bandwidths exceeding 30 GHz

Optimal Bandwidth Selection for Kernel Density Functionals Estimation

Directory of Open Access Journals (Sweden)

Su Chen

2015-01-01

Full Text Available The choice of bandwidth is crucial to the kernel density estimation (KDE and kernel based regression. Various bandwidth selection methods for KDE and local least square regression have been developed in the past decade. It has been known that scale and location parameters are proportional to density functionals ∫γ(xf2(xdx with appropriate choice of γ(x and furthermore equality of scale and location tests can be transformed to comparisons of the density functionals among populations. ∫γ(xf2(xdx can be estimated nonparametrically via kernel density functionals estimation (KDFE. However, the optimal bandwidth selection for KDFE of ∫γ(xf2(xdx has not been examined. We propose a method to select the optimal bandwidth for the KDFE. The idea underlying this method is to search for the optimal bandwidth by minimizing the mean square error (MSE of the KDFE. Two main practical bandwidth selection techniques for the KDFE of ∫γ(xf2(xdx are provided: Normal scale bandwidth selection (namely, “Rule of Thumb” and direct plug-in bandwidth selection. Simulation studies display that our proposed bandwidth selection methods are superior to existing density estimation bandwidth selection methods in estimating density functionals.

10 CFR 431.224 - Uniform test method for the measurement of energy consumption for traffic signal modules and...

Science.gov (United States)

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Uniform test method for the measurement of energy consumption for traffic signal modules and pedestrian modules. 431.224 Section 431.224 Energy DEPARTMENT OF... measurement of energy consumption for traffic signal modules and pedestrian modules. (a) Scope. This section...

Fringe proteins modulate Notch-ligand cis and trans interactions to specify signaling states.

Science.gov (United States)

LeBon, Lauren; Lee, Tom V; Sprinzak, David; Jafar-Nejad, Hamed; Elowitz, Michael B

2014-09-25

The Notch signaling pathway consists of multiple types of receptors and ligands, whose interactions can be tuned by Fringe glycosyltransferases. A major challenge is to determine how these components control the specificity and directionality of Notch signaling in developmental contexts. Here, we analyzed same-cell (cis) Notch-ligand interactions for Notch1, Dll1, and Jag1, and their dependence on Fringe protein expression in mammalian cells. We found that Dll1 and Jag1 can cis-inhibit Notch1, and Fringe proteins modulate these interactions in a way that parallels their effects on trans interactions. Fringe similarly modulated Notch-ligand cis interactions during Drosophila development. Based on these and previously identified interactions, we show how the design of the Notch signaling pathway leads to a restricted repertoire of signaling states that promote heterotypic signaling between distinct cell types, providing insight into the design principles of the Notch signaling system, and the specific developmental process of Drosophila dorsal-ventral boundary formation.

Exploit the Bandwidth Capacities of the Perfluorinated Graded Index Polymer Optical Fiber for Multi-Services Distribution

Directory of Open Access Journals (Sweden)

Paul Alain Rolland

2011-06-01

Full Text Available The study reported here deals with the exploitation of perfluorinated graded index polymer optical fiber bandwidth to add further services in a home/office network. The fiber properties are exhibited in order to check if perfluorinated graded index plastic optical fiber (PFGI-POF is suitable to support a multiplexing transmission. According to the high bandwidth length of plastic fibers, both at 850 nm and 1,300 nm, the extension of the classical baseband existing network is proposed to achieve a dual concept, allowing the indoor coverage of wireless signals transmitted using the Radio over Fiber technology. The simultaneous transmission of a 10 GbE signal and a wireless signal is done respectively at 850 nm and 1,300 nm on a single plastic fiber using wavelength division multiplexing commercially available devices. The penalties have been evaluated both in digital (Bit Error Rate measurement and radiofrequency (Error Vector Magnitude measurement domains.

Low modulation index RF signal detection for a passive UHF RFID transponder

Energy Technology Data Exchange (ETDEWEB)

Liu Zhongqi [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China); Zhang Chun; Li Yongming; Wang Zhihua, E-mail: liu-zq04@mails.tsinghua.edu.c [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

2009-09-15

In a typical RFID system the reader transmits modulated RF power to provide both data and energy for the passive transponder. Low modulation index RF energy is preferable for an adequate tag power supply and increase in communication range but gives rise to difficulties for near-field conventional demodulation. Therefore, a novel ASK demodulator for minimum 20% modulation index RF signal detection over a range of 23 dB is presented. Thanks to the proposed innovative divisional linear conversion from the power into voltage signal, the detection sensitivity is ensured over a wide power range with low power consumption of 8.6 {mu}W. The chip is implemented in UMC 0.18 {mu}m mix-mode CMOS technology, and the chip area is 0.06 mm{sup 2}.

Intensity position modulation for free-space laser communication system

Science.gov (United States)

Jangjoo, Alireza; Faghihi, F.

2004-12-01

In this research a novel modulation technique for free-space laser communication system called Intensity Position Modulation (IPM) is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of linear part on the reverse biased pn photodiode produced alternating currents which contain the information. Here, no characteristic property of the beam as intensity or frequency is changed and only the beam position moves laterally. We demonstrated that in this method no bandwidth is required, so it is possible to reduce the background radiation noise by narrowband filtering of the carrier. The fidelity of the analog voice communication system which is made upon the IPM is satisfactory and we are able to transmit the audio signals up to 1Km.

Targeting CB2-GPR55 Receptor Heteromers Modulates Cancer Cell Signaling*

Science.gov (United States)

Moreno, Estefanía; Andradas, Clara; Medrano, Mireia; Caffarel, María M.; Pérez-Gómez, Eduardo; Blasco-Benito, Sandra; Gómez-Cañas, María; Pazos, M. Ruth; Irving, Andrew J.; Lluís, Carme; Canela, Enric I.; Fernández-Ruiz, Javier; Guzmán, Manuel; McCormick, Peter J.; Sánchez, Cristina

2014-01-01

The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. Because a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells. Here we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo. These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology. PMID:24942731

Banded all-optical OFDM super-channels with low-bandwidth receivers.

Science.gov (United States)

Song, Binhuang; Zhu, Chen; Corcoran, Bill; Zhuang, Leimeng; Lowery, Arthur James

2016-08-08

We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%.

Pressure modulation algorithm to separate cerebral hemodynamic signals from extracerebral artifacts.

Science.gov (United States)

Baker, Wesley B; Parthasarathy, Ashwin B; Ko, Tiffany S; Busch, David R; Abramson, Kenneth; Tzeng, Shih-Yu; Mesquita, Rickson C; Durduran, Turgut; Greenberg, Joel H; Kung, David K; Yodh, Arjun G

2015-07-01

We introduce and validate a pressure measurement paradigm that reduces extracerebral contamination from superficial tissues in optical monitoring of cerebral blood flow with diffuse correlation spectroscopy (DCS). The scheme determines subject-specific contributions of extracerebral and cerebral tissues to the DCS signal by utilizing probe pressure modulation to induce variations in extracerebral blood flow. For analysis, the head is modeled as a two-layer medium and is probed with long and short source-detector separations. Then a combination of pressure modulation and a modified Beer-Lambert law for flow enables experimenters to linearly relate differential DCS signals to cerebral and extracerebral blood flow variation without a priori anatomical information. We demonstrate the algorithm's ability to isolate cerebral blood flow during a finger-tapping task and during graded scalp ischemia in healthy adults. Finally, we adapt the pressure modulation algorithm to ameliorate extracerebral contamination in monitoring of cerebral blood oxygenation and blood volume by near-infrared spectroscopy.

Research on a Micro-Nano Si/SiGe/Si Double Heterojunction Electro-Optic Modulation Structure

Directory of Open Access Journals (Sweden)

Song Feng

2018-01-01

Full Text Available The electro-optic modulator is a very important device in silicon photonics, which is responsible for the conversion of optical signals and electrical signals. For the electro-optic modulator, the carrier density of waveguide region is one of the key parameters. The traditional method of increasing carrier density is to increase the external modulation voltage, but this way will increase the modulation loss and also is not conducive to photonics integration. This paper presents a micro-nano Si/SiGe/Si double heterojunction electro-optic modulation structure. Based on the band theory of single heterojunction, the barrier heights are quantitatively calculated, and the carrier concentrations of heterojunction barrier are analyzed. The band and carrier injection characteristics of the double heterostructure structure are simulated, respectively, and the correctness of the theoretical analysis is demonstrated. The micro-nano Si/SiGe/Si double heterojunction electro-optic modulation is designed and tested, and comparison of testing results between the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation and the micro-nano Silicon-On-Insulator (SOI micro-ring electro-optic modulation, Free Spectrum Range, 3 dB Bandwidth, Q value, extinction ratio, and other parameters of the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation are better than others, and the modulation voltage and the modulation loss are lower.

Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

DEFF Research Database (Denmark)

Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko

2012-01-01

. Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared...... LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber. However, achieving ultra low NA for single-mode (SM) guidance is challenging, and thus different design strategies must be applied to filter out higher order modes (HOMs). The novel...... distributed modal filtering (DMF) design presented here enables SM guidance, and previous results have shown a SM mode field diameter of 60 μm operating in a 20 nm SM bandwidth. The DMF rod fiber has high index ring-shaped inclusions acting as resonators enabling SM guidance through modal filtering of HOMs...

High-bandwidth scanned-wavelength-modulation spectroscopy sensors for temperature and H2O in a rotating detonation engine

International Nuclear Information System (INIS)

Goldenstein, Christopher S; Almodóvar, Christopher A; Jeffries, Jay B; Hanson, Ronald K; Brophy, Christopher M

2014-01-01

The design and use of two-color tunable diode laser (TDL) absorption sensors for measurements of temperature and H 2 O in a rotating detonation engine (RDE) are presented. Both sensors used first-harmonic-normalized scanned-wavelength-modulation spectroscopy with second-harmonic detection (scanned-WMS-2f/1f) to account for non-absorbing transmission losses and emission encountered in the harsh combustion environment. One sensor used two near-infrared (NIR) TDLs near 1391.7 nm and 1469.3 nm that were modulated at 225 kHz and 285 kHz, respectively, and sinusoidally scanned across the peak of their respective H 2 O absorption transitions to provide a measurement rate of 50 kHz and a detection limit in the RDE of 0.2% H 2 O by mole. The other sensor used two mid-infrared (MIR) TDLs near 2551 nm and 2482 nm that were modulated at 90 kHz and 112 kHz, respectively, and sinusoidally scanned across the peak of their respective H 2 O transitions to provide a measurement rate of 10 kHz and a detection limit in the RDE of 0.02% H 2 O by mole. Four H 2 O absorption transitions with different lower-state energies were used to assess the homogeneity of temperature in the measurement plane. Experimentally derived spectroscopic parameters that enable temperature and H 2 O sensing to within 1.5–3.5% of known values are reported. The sensor design enabling the high-bandwidth scanned-WMS-2f/1f measurements is presented. The two sensors were deployed across two orthogonal and coplanar lines-of-sight (LOS) located in the throat of a converging-diverging nozzle at the RDE combustor exit. Measurements in the non-premixed H 2 -fueled RDE indicate that the temperature and H 2 O oscillate at the detonation frequency (≈3.25 kHz) and that production of H 2 O is a weak function of global equivalence ratio. (paper)

High-bandwidth scanned-wavelength-modulation spectroscopy sensors for temperature and H2O in a rotating detonation engine

Science.gov (United States)

Goldenstein, Christopher S.; Almodóvar, Christopher A.; Jeffries, Jay B.; Hanson, Ronald K.; Brophy, Christopher M.

2014-10-01

The design and use of two-color tunable diode laser (TDL) absorption sensors for measurements of temperature and H2O in a rotating detonation engine (RDE) are presented. Both sensors used first-harmonic-normalized scanned-wavelength-modulation spectroscopy with second-harmonic detection (scanned-WMS-2f/1f) to account for non-absorbing transmission losses and emission encountered in the harsh combustion environment. One sensor used two near-infrared (NIR) TDLs near 1391.7 nm and 1469.3 nm that were modulated at 225 kHz and 285 kHz, respectively, and sinusoidally scanned across the peak of their respective H2O absorption transitions to provide a measurement rate of 50 kHz and a detection limit in the RDE of 0.2% H2O by mole. The other sensor used two mid-infrared (MIR) TDLs near 2551 nm and 2482 nm that were modulated at 90 kHz and 112 kHz, respectively, and sinusoidally scanned across the peak of their respective H2O transitions to provide a measurement rate of 10 kHz and a detection limit in the RDE of 0.02% H2O by mole. Four H2O absorption transitions with different lower-state energies were used to assess the homogeneity of temperature in the measurement plane. Experimentally derived spectroscopic parameters that enable temperature and H2O sensing to within 1.5-3.5% of known values are reported. The sensor design enabling the high-bandwidth scanned-WMS-2f/1f measurements is presented. The two sensors were deployed across two orthogonal and coplanar lines-of-sight (LOS) located in the throat of a converging-diverging nozzle at the RDE combustor exit. Measurements in the non-premixed H2-fueled RDE indicate that the temperature and H2O oscillate at the detonation frequency (≈3.25 kHz) and that production of H2O is a weak function of global equivalence ratio.

The Bandwidths of a Matrix. A Survey of Algorithms

Directory of Open Access Journals (Sweden)

Mafteiu-Scai Liviu Octavian

2014-12-01

Full Text Available The bandwidth, average bandwidth, envelope, profile and antibandwidth of the matrices have been the subjects of study for at least 45 years. These problems have generated considerable interest over the years because of them practical relevance in areas like: solving the system of equations, finite element methods, circuit design, hypertext layout, chemical kinetics, numerical geophysics etc. In this paper a brief description of these problems are made in terms of their definitions, followed by a comparative study of them, using both approaches: matrix geometry and graph theory. Time evolution of the corresponding algorithms as well as a short description of them are made. The work also contains concrete real applications for which a large part of presented algorithms were developed.

Improving the Bandwidth Selection in Kernel Equating

Science.gov (United States)

Andersson, Björn; von Davier, Alina A.

2014-01-01

We investigate the current bandwidth selection methods in kernel equating and propose a method based on Silverman's rule of thumb for selecting the bandwidth parameters. In kernel equating, the bandwidth parameters have previously been obtained by minimizing a penalty function. This minimization process has been criticized by practitioners…

The statistical bandwidth of Butterworth filters

Science.gov (United States)

Davy, J. L.; Dunn, I. P.

1987-06-01

The precision of standard architectural acoustic measurements is a function of the statistical bandwidth of the band pass filters used in the measurements. The International and United States Standards on octave and fractional octave-band filters which specify the band pass filters used in architectural acoustics measurements give the effective bandwidth, but unfortunately not the statistical bandwidth of the filters. Both these Standards are currently being revised and both revisions require the use of Butterworth filter characteristics. In this paper it is shown theoretically that the ratio of statistical bandwidth to effective bandwidth for an nth order Butterworth band pass filter is {2n}/{(2n-1)}. This is verified experimentally for third-octave third-order Butterworth band pass filters. It is also shown experimentally that this formula is approximately correct for some non-Butterworth third-octave third-order band pass filters. Because of the importance of Butterworth filters in the revised Standards, the theory of Butterworth filters is reviewed and the formulae for Butterworth filters given in both revised Standards are derived.

Large-area Fabry-Perot modulator based on electro-optic polymers

DEFF Research Database (Denmark)

Benter, Nils; Bertram, Ralph Peter; Soergel, Elisabeth

2006-01-01

We present a large-area electro-optic Fabry-Perot modulator utilizing a photoaddressable bis-azo polymer placed between two dielectric mirrors with an open aperture of 2 cm. A modulation efficientcy of 1% at an effective modulation voltage of 20 V for a wavelength of 1.55 mymeter is demonstrated...

A 1-V 60-μW 85-dB dynamic range continuous-time third-order sigma-delta modulator

International Nuclear Information System (INIS)

Li Yuanwen; Qi Da; Dong Yifeng; Xu Jun; Ren Junyan

2009-01-01

A 1-V third order one-bit continuous-time (CT) EA modulator is presented. Designed in the SMIC mixed-signal 0.13-μm CMOS process, the modulator utilizes active RC integrators to implement the loop filter. An efficient circuit design methodology for the CT ΣΔ modulator is proposed and verified. Low power dissipation is achieved through the use of two-stage class A/AB amplifiers. The presented modulator achieves 81.4-dB SNDR and 85-dB dynamic range in a 20-kHz bandwidth with an over sampling ratio of 128. The total power consumption of the modulator is only 60 μW from a 1-V power supply and the prototype occupies an active area of 0.12 mm 2 . (semiconductor integrated circuits)

Astrophysics-independent bounds on the annual modulation of dark matter signals.

Science.gov (United States)

Herrero-Garcia, Juan; Schwetz, Thomas; Zupan, Jure

2012-10-05

We show how constraints on the time integrated event rate from a given dark matter (DM) direct detection experiment can be used to bound the amplitude of the annual modulation signal in another experiment. The method requires only mild assumptions about the properties of the local DM distribution: that it is temporally stable on the scale of months and spatially homogeneous on the ecliptic. We apply the method to the annual modulation signal in DAMA/LIBRA, which we compare to the bounds derived from XENON10, XENON100, cryogenic DM search, and SIMPLE data. Assuming a DM mass of 10 GeV, we show that under the above assumptions about the DM halo, a DM interpretation of the DAMA/LIBRA signal is excluded for several classes of models: at 6.3σ (4.6σ) for elastic isospin conserving (violating) spin-independent interactions, and at 4.9σ for elastic spin-dependent interactions on protons.

Two-level modulation scheme to reduce latency for optical mobile fronthaul networks.

Science.gov (United States)

Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung; Chang, Gee-Kung

2016-10-31

A system using optical two-level orthogonal-frequency-division-multiplexing (OFDM) - amplitude-shift-keying (ASK) modulation is proposed and demonstrated to reduce the processing latency for the optical mobile fronthaul networks. At the proposed remote-radio-head (RRH), the high data rate OFDM signal does not need to be processed, but is directly launched into a high speed photodiode (HSPD) and subsequently emitted by an antenna. Only a low bandwidth PD is needed to recover the low data rate ASK control signal. Hence, it is simple and provides low-latency. Furthermore, transporting the proposed system over the already deployed optical-distribution-networks (ODNs) of passive-optical-networks (PONs) is also demonstrated with 256 ODN split-ratios.

Orientation masking and cross-orientation suppression (XOS): implications for estimates of filter bandwidth.

Science.gov (United States)

Meese, Tim S; Holmes, David J

2010-10-01

Most contemporary models of spatial vision include a cross-oriented route to suppression (masking from a broadly tuned inhibitory pool), which is most potent at low spatial and high temporal frequencies (T. S. Meese & D. J. Holmes, 2007). The influence of this pathway can elevate orientation-masking functions without exciting the target mechanism, and because early psychophysical estimates of filter bandwidth did not accommodate this, it is likely that they have been overestimated for this corner of stimulus space. Here we show that a transient 40% contrast mask causes substantial binocular threshold elevation for a transient vertical target, and this declines from a mask orientation of 0° to about 40° (indicating tuning), and then more gently to 90°, where it remains at a factor of ∼4. We also confirm that cross-orientation masking is diminished or abolished at high spatial frequencies and for sustained temporal modulation. We fitted a simple model of pedestal masking and cross-orientation suppression (XOS) to our data and those of G. C. Phillips and H. R. Wilson (1984) and found the dependency of orientation bandwidth on spatial frequency to be much less than previously supposed. An extension of our linear spatial pooling model of contrast gain control and dilution masking (T. S. Meese & R. J. Summers, 2007) is also shown to be consistent with our results using filter bandwidths of ±20°. Both models include tightly and broadly tuned components of divisive suppression. More generally, because XOS and/or dilution masking can affect the shape of orientation-masking curves, we caution that variations in bandwidth estimates might reflect variations in processes that have nothing to do with filter bandwidth.

Terahertz bandwidth all-optical Hilbert transformers based on long-period gratings.

Science.gov (United States)

Ashrafi, Reza; Azaña, José

2012-07-01

A novel, all-optical design for implementing terahertz (THz) bandwidth real-time Hilbert transformers is proposed and numerically demonstrated. An all-optical Hilbert transformer can be implemented using a uniform-period long-period grating (LPG) with a properly designed amplitude-only grating apodization profile, incorporating a single π-phase shift in the middle of the grating length. The designed LPG-based Hilbert transformers can be practically implemented using either fiber-optic or integrated-waveguide technologies. As a generalization, photonic fractional Hilbert transformers are also designed based on the same optical platform. In this general case, the resulting LPGs have multiple π-phase shifts along the grating length. Our numerical simulations confirm that all-optical Hilbert transformers capable of processing arbitrary optical signals with bandwidths well in the THz range can be implemented using feasible fiber/waveguide LPG designs.

Controlling Fringe Sensitivity of Electro-Optic Holography Systems Using Laser Diode Current Modulation

Science.gov (United States)

Bybee, Shannon J.

2001-01-01

Electro-Optic Holography (EOH) is a non-intrusive, laser-based, displacement measurement technique capable of static and dynamic displacement measurements. EOH is an optical interference technique in which fringe patterns that represent displacement contour maps are generated. At excessively large displacements the fringe density may be so great that individual fringes are not resolvable using typical EOH techniques. This thesis focuses on the development and implementation of a method for controlling the sensitivity of the EOH system. This method is known as Frequency Translated Electro-Optic Holography (FTEOH). It was determined that by modulating the current source of the laser diode at integer multiples of the object vibration, the fringe pattern is governed by higher order Bessel function of the first kind and the number of fringes that represent a given displacement can be controlled. The reduction of fringes is theoretically unlimited but physically limited by the frequency bandwidth of the signal generator, providing modulation to the laser diode. Although this research technique has been verified theoretically and experimentally in this thesis, due to the current laser diode capabilities it is a tedious and time consuming process to acquire data using the FTEOH technique.

Modulation of taste sensitivity by GLP-1 signaling in taste buds.

Science.gov (United States)

Martin, Bronwen; Dotson, Cedrick D; Shin, Yu-Kyong; Ji, Sunggoan; Drucker, Daniel J; Maudsley, Stuart; Munger, Steven D

2009-07-01

Modulation of sensory function can help animals adjust to a changing external and internal environment. Even so, mechanisms for modulating taste sensitivity are poorly understood. Using immunohistochemical, biochemical, and behavioral approaches, we found that the peptide hormone glucagon-like peptide-1 (GLP-1) and its receptor (GLP-1R) are expressed in mammalian taste buds. Furthermore, we found that GLP-1 signaling plays an important role in the modulation of taste sensitivity: GLP-1R knockout mice exhibit a dramatic reduction in sweet taste sensitivity as well as an enhanced sensitivity to umami-tasting stimuli. Together, these findings suggest a novel paracrine mechanism for the hormonal modulation of taste function in mammals.

Multirate diversity strategy of fractal modulation

International Nuclear Information System (INIS)

Yuan Yong; Shi Si-Hong; Luo Mao-Kang

2011-01-01

Previous analyses of fractal modulation were carried out mostly from a signle perspective or a subband, but the analyses from the perspective of multiscale synthesis have not been found yet; while multiscale synthesis is just the essence of the mutlirate diversity which is the most important characteristic of fractal modulation. As for the mutlirate diversity of fractal modulation, previous studies only dealt with the general outspread of its concept, lacked the thorough and intensive quantitative comparison and analysis. In light of the above fact, from the perspective of multiscale synthesis, in this paper we provide a comprehensive analysis of the multirate diversity of fractal modulation and corresponding quantitative analysis. The results show that mutlirate diversity, which is a fusion of frequency diversity and time diversity, pays an acceptable price in spectral efficiency in exchange for a significant improvement in bit error rate. It makes fractal modulation particularly suitable for the channels whose bandwidth and duration parameters are unknown or cannot be predicted to the transmitter. Surely it is clearly of great significance for reliable communications. Moreover, we also attain the ability to flexibly make various rate-bandwidth tradeoffs between the transmitter and the receiver, to freely select the reception time and to expediently control the total bandwidth. Furthermore, the acquisitions or improvements of these fine features could provide support of the technical feasibility for the electromagnetic spectrum control technology in a complex electromagnetic environment. (general)

Evoked responses of the superior olive to amplitude-modulated signals.

Science.gov (United States)

Andreeva, N G; Lang, T T

1977-01-01

Evoked potentials of some auditory centers of Rhinolophidae bats to amplitude-modulated signals were studied. A synchronization response was found in the cochlear nuclei (with respect to the fast component of the response) and in the superior olivary complex (with respect to both fast and slow components of the response) within the range of frequency modulation from 50 to 2000 Hz. In the inferior colliculus a synchronized response was recorded at modulation frequencies below 150 Hz, but in the medial geniculate bodies no such response was found. Evoked responses of the superior olivary complex were investigated in detail. The lowest frequencies of synchronization were recorded within the carrier frequency range of 15-30 and 80-86 kHz. The amplitude of the synchronized response is a function of the frequency and coefficient of modulation and also of the angle of stimulus presentation.

Ultra-Wideband Optical Modulation Spectrometer (OMS) Development

Science.gov (United States)

Gardner, Jonathan (Technical Monitor); Tolls, Volker

2004-01-01

The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

Polarization division multiple access with polarization modulation for LOS wireless communications

Directory of Open Access Journals (Sweden)

Cao Bin

2011-01-01

Full Text Available Abstract In this paper, we discuss a potential multiple access and modulation scheme based on polarized states (PS of electromagnetic (EM waves for line-of-sight (LOS communications. The proposed scheme is theoretic different from the existing polar modulation for EDGE and WCDMA systems. We propose the detailed bit representation (modulation and multiple access scheme using PS. Because of the inflexibility of polarization information in the time and frequency domains, as well as independence of frequency and space, the polarization information can be used independently for wireless communications, i.e., another independent resource domain that can be utilized. Due to the independence between the PS and the specific features of signals (such as waveform, bandwidth and data rate, the discussed polarization division multiple access (PDMA and polarization modulation (PM are expected to improve the spectrum utilization effectively. It is proved that the polarization filtering technique can be adopted in the PDMA-PM wireless communications to separate the multiuser signals and demodulate the bit information representing by PS for desired user. Some theoretical analysis is done to demonstrate the feasibility of the proposed scheme, and the simulation results are made to evaluate the performance of the suggested system.

Energy/bandwidth-Saving Cooperative Spectrum Sensing for Two-hopWRAN

Directory of Open Access Journals (Sweden)

Ming-Tuo Zhou

2014-07-01

Full Text Available A two-hop wireless regional area network (WRAN providing monitoring services operating in Television White Space (TVWS, i.e., IEEE P802.22b, may employ a great number of subscriber customer-premises equipments (S-CPEs possibly without mains power supply, leading to requirement of cost-effective and power-saving design. This paper proposes a framework of cooperative spectrum sensing (CSS and an energy/bandwidth saving CSS scheme to P802.22b. In each round of sensing, S-CPEs with SNRs lower than a predefined threshold are excluded from reporting sensing results. Numerical results show that the fused missed-detection probability and false alarmprobability could remainmeeting sensing requirements, and the overall fused error probability changes very little. With 10 S-CPEs, it is possible to save more than 40% of the energy/bandwidth on a Rayleigh channel. The principle proposed can apply to other advanced sensing technologies capable of detecting primary signals with low average SNR.

47 CFR 2.202 - Bandwidths.

Science.gov (United States)

2010-10-01

... three numerals and one letter. The letter occupies the position of the decimal point and represents the... quality desired Speech and music, M=4000, Bandwidth: 8000 Hz= 8 kHz 8K00A3E Sound broadcasting, single... desired Speech and music, M=4000, Bandwidth: 4000 Hz= 4 kHz 4K00R3E Sound broadcasting, single-sideband...

Wideband laser locking to an atomic reference with modulation transfer spectroscopy.

Science.gov (United States)

Negnevitsky, V; Turner, L D

2013-02-11

We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.

Microwave signal processing with photorefractive dynamic holography

Science.gov (United States)

Fotheringham, Edeline B.

Have you ever found yourself listening to the music playing from the closest stereo rather than to the bromidic (uninspiring) person speaking to you? Your ears receive information from two sources but your brain listens to only one. What if your cell phone could distinguish among signals sharing the same bandwidth too? There would be no "full" channels to stop you from placing or receiving a call. This thesis presents a nonlinear optical circuit capable of distinguishing uncorrelated signals that have overlapping temporal bandwidths. This so called autotuning filter is the size of a U.S. quarter dollar and requires less than 3 mW of optical power to operate. It is basically an oscillator in which the losses are compensated with dynamic holographic gain. The combination of two photorefractive crystals in the resonator governs the filter's winner-take-all dynamics through signal-competition for gain. This physical circuit extracts what is mathematically referred to as the largest principal component of its spatio-temporal input space. The circuit's practicality is demonstrated by its incorporation in an RF-photonic system. An unknown mixture of unknown microwave signals, received by an antenna array, constitutes the input to the system. The output electronically returns one of the original microwave signals. The front-end of the system down converts the 10 GHz microwave signals and amplifies them before the signals phase modulate optical beams. The optical carrier is suppressed from these beams so that it may not be considered as a signal itself to the autotuning filter. The suppression is achieved with two-beam coupling in a single photorefractive crystal. The filter extracts the more intense of the signals present on the carrier-suppressed input beams. The detection of the extracted signal restores the microwave signal to an electronic form. The system, without the receiving antenna array, is packaged in a 13 x 18 x 6″ briefcase. Its power consumption equals that

On Bandwidth Efficient Modulation for High-Data-Rate Wireless LAN Systems

Directory of Open Access Journals (Sweden)

Stolpman Victor

2002-01-01

Full Text Available We address the problem of high-data-rate orthogonal frequency division multiplexed (OFDM systems under restrictive bandwidth constraints. Based on recent theoretic results, multiple-input multiple-output (MIMO configurations are best suited for this problem. In this paper, we examine several MIMO configurations suitable for high rate transmission. In all scenarios considered, perfect channel state information (CSI is assumed at the receiver. In constrast, availability of CSI at the transmitter is addressed separately. We show that powerful space-time codes can be developed by combining some simple well-known techniques. In fact, we show that for certain configurations, these space-time MIMO configurations are near optimum in terms of outage capacity as compared to previously published codes. Performance evaluation of these techniques is demonstrated within the IEEE 802.11a framework via Monte Carlo simulations.

An amorphous silicon photodiode with 2 THz gain-bandwidth product based on cycling excitation process

Science.gov (United States)

Yan, Lujiang; Yu, Yugang; Zhang, Alex Ce; Hall, David; Niaz, Iftikhar Ahmad; Raihan Miah, Mohammad Abu; Liu, Yu-Hsin; Lo, Yu-Hwa

2017-09-01

Since impact ionization was observed in semiconductors over half a century ago, avalanche photodiodes (APDs) using impact ionization in a fashion of chain reaction have been the most sensitive semiconductor photodetectors. However, APDs have relatively high excess noise, a limited gain-bandwidth product, and high operation voltage, presenting a need for alternative signal amplification mechanisms of superior properties. As an amplification mechanism, the cycling excitation process (CEP) was recently reported in a silicon p-n junction with subtle control and balance of the impurity levels and profiles. Realizing that CEP effect depends on Auger excitation involving localized states, we made the counter intuitive hypothesis that disordered materials, such as amorphous silicon, with their abundant localized states, can produce strong CEP effects with high gain and speed at low noise, despite their extremely low mobility and large number of defects. Here, we demonstrate an amorphous silicon low noise photodiode with gain-bandwidth product of over 2 THz, based on a very simple structure. This work will impact a wide range of applications involving optical detection because amorphous silicon, as the primary gain medium, is a low-cost, easy-to-process material that can be formed on many kinds of rigid or flexible substrates.

Multiband Carrierless Amplitude Phase Modulation for High Capacity Optical Data Links

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Zuo, Tianjian; Jensen, Jesper Bevensee

2014-01-01

. The reported experiment uses MultiCAP to achieve 102.4 Gb/s transmission, corresponding to a data payload of 95.2 Gb/s error free transmission by using a 7% forward error correction (FEC) code. The signal is successfully recovered after 15 km of standard single mode fiber (SSMF) in a system limited by a 3 d......Short range optical data links are experiencing bandwidth limitations making it very challenging to cope with the growing data transmission capacity demands. Parallel optics appears as a valid short-term solution. It is, however, not a viable solution in the long-term because of its complex optical...... packaging. Therefore, increasing effort is now put into the possibility of exploiting higher order modulation formats with increased spectral efficiency and reduced optical transceiver complexity. As these type of links are based on intensity modulation and direct detection, modulation formats relying...

Frequency-dependent tACS modulation of BOLD signal during rhythmic visual stimulation.

Science.gov (United States)

Chai, Yuhui; Sheng, Jingwei; Bandettini, Peter A; Gao, Jia-Hong

2018-05-01

Transcranial alternating current stimulation (tACS) has emerged as a promising tool for modulating cortical oscillations. In previous electroencephalogram (EEG) studies, tACS has been found to modulate brain oscillatory activity in a frequency-specific manner. However, the spatial distribution and hemodynamic response for this modulation remains poorly understood. Functional magnetic resonance imaging (fMRI) has the advantage of measuring neuronal activity in regions not only below the tACS electrodes but also across the whole brain with high spatial resolution. Here, we measured fMRI signal while applying tACS to modulate rhythmic visual activity. During fMRI acquisition, tACS at different frequencies (4, 8, 16, and 32 Hz) was applied along with visual flicker stimulation at 8 and 16 Hz. We analyzed the blood-oxygen-level-dependent (BOLD) signal difference between tACS-ON vs tACS-OFF, and different frequency combinations (e.g., 4 Hz tACS, 8 Hz flicker vs 8 Hz tACS, 8 Hz flicker). We observed significant tACS modulation effects on BOLD responses when the tACS frequency matched the visual flicker frequency or the second harmonic frequency. The main effects were predominantly seen in regions that were activated by the visual task and targeted by the tACS current distribution. These findings bridge different scientific domains of tACS research and demonstrate that fMRI could localize the tACS effect on stimulus-induced brain rhythms, which could lead to a new approach for understanding the high-level cognitive process shaped by the ongoing oscillatory signal. © 2018 Wiley Periodicals, Inc.

Broadening the Efficiency Bandwidth Product of Electrically small Antenna through Direct Antenna Modulation (DAM) Transmitting

Science.gov (United States)

2017-12-04

time averaged real power would be half for 50% modulation. Given that the quality factor of each state is large, the state that does not resonant with...public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions...Project Contribution: International Collaboration: International Travel : National Academy Member: N Person Months Worked: 6.00 Funding

Mixed-signal instrumentation for large-signal device characterization and modelling

NARCIS (Netherlands)

Marchetti, M.

2013-01-01

This thesis concentrates on the development of advanced large-signal measurement and characterization tools to support technology development, model extraction and validation, and power amplifier (PA) designs that address the newly introduced third and fourth generation (3G and 4G) wideband

Large-area and highly crystalline MoSe2 for optical modulator

Science.gov (United States)

Yin, Jinde; Chen, Hao; Lu, Wei; Liu, Mengli; Li, Irene Ling; Zhang, Min; Zhang, Wenfei; Wang, Jinzhang; Xu, Zihan; Yan, Peiguang; Liu, Wenjun; Ruan, Shuangchen

2017-12-01

Transition metal dichalcogenides (TMDs) have been successfully used as broadband optical modulator materials for pulsed fiber laser systems. However, the nonlinear optical absorptions of exfoliated TMDs are strongly limited by their nanoflakes morphology with uncontrollable lateral size and thickness. In this work, we provide an effective method to fully explore the nonlinear optical properties of MoSe2. Large-area and high quality lattice MoSe2 grown by chemical vapor deposition method was adopted as an optical modulator for the first time. The large-area MoSe2 shows excellent nonlinear optical absorption with a large modulation depth of 21.7% and small saturable intensity of 9.4 MW cm-2. After incorporating the MoSe2 optical modulator into fiber laser cavity as a saturable absorber, a highly stable Q-switching operation with single pulse energy of 224 nJ is achieved. The large-area MoSe2 possessing superior nonlinear optical properties compared to exfoliated nanoflakes affords possibility for the larger-area two-dimensional materials family as high performance optical devices.

Amplitude Modulated Sinusoidal Signal Decomposition for Audio Coding

DEFF Research Database (Denmark)

Christensen, M. G.; Jacobson, A.; Andersen, S. V.

2006-01-01

In this paper, we present a decomposition for sinusoidal coding of audio, based on an amplitude modulation of sinusoids via a linear combination of arbitrary basis vectors. The proposed method, which incorporates a perceptual distortion measure, is based on a relaxation of a nonlinear least......-squares minimization. Rate-distortion curves and listening tests show that, compared to a constant-amplitude sinusoidal coder, the proposed decomposition offers perceptually significant improvements in critical transient signals....

A Reactance Compensated Three-Device Doherty Power Amplifier for Bandwidth and Back-Off Range Extension

Directory of Open Access Journals (Sweden)

Shichang Chen

2018-01-01

Full Text Available This paper proposes a new broadband Doherty power amplifier topology with extended back-off range. A shunted λ/4 short line or λ/2 open line working as compensating reactance is introduced to the conventional load modulation network, which greatly improves its bandwidth. Underlying bandwidth extension mechanism of the proposed configuration is comprehensively analyzed. A three-device Doherty power amplifier is implemented for demonstration based on Cree’s 10 W HEMTs. Measurements show that at least 41% drain efficiency is maintained from 2.0 GHz to 2.6 GHz at 8 dB back-off range. In the same operating band, saturation power is larger than 43.6 dBm and drain efficiency is higher than 53%.

Climatology of GPS signal loss observed by Swarm satellites

Directory of Open Access Journals (Sweden)

C. Xiong

2018-04-01

Full Text Available By using 3-year global positioning system (GPS measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20° magnetic latitude (MLAT and high latitudes above 60° MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20°, and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.

Climatology of GPS signal loss observed by Swarm satellites

Science.gov (United States)

Xiong, Chao; Stolle, Claudia; Park, Jaeheung

2018-04-01

By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20° magnetic latitude (MLAT) and high latitudes above 60° MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20°, and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.

Model-Based Evaluation Of System Scalability: Bandwidth Analysis For Smartphone-Based Biosensing Applications

DEFF Research Database (Denmark)

Patou, François; Madsen, Jan; Dimaki, Maria

2016-01-01

Scalability is a design principle often valued for the engineering of complex systems. Scalability is the ability of a system to change the current value of one of its specification parameters. Although targeted frameworks are available for the evaluation of scalability for specific digital systems...... re-engineering of 5 independent system modules, from the replacement of a wireless Bluetooth interface, to the revision of the ADC sample-and-hold operation could help increase system bandwidth....

Method of manufacturing a large-area segmented photovoltaic module

Science.gov (United States)

Lenox, Carl

2013-11-05

One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

Fluid limits for Bandwidth-Sharing Networks with Impatience.

NARCIS (Netherlands)

Remerova, M.; Reed, J.; Zwart, A.P.

2014-01-01

Bandwidth-sharing networks as introduced by Roberts and Massoulié [Roberts JW, Massoulié L (1998) Bandwidth sharing and admission control for elastic traffic. Proc. ITC Specialist Seminar, Yokohama, Japan], Massoulié and Roberts [Massoulié L, Roberts JW (1999) Bandwidth sharing: Objectives and

An FPGA-Based Adaptable 200 MHz Bandwidth Channel Sounder for Wireless Communication Channel Characterisation

Directory of Open Access Journals (Sweden)

David L. Ndzi

2011-01-01

Full Text Available This paper describes the development of a fast adaptable FPGA-based wideband channel sounder with signal bandwidths of up to 200 MHz and channel sampling rates up to 5.4 kHz. The application of FPGA allows the user to vary the number of real-time channel response averages, channel sampling interval, and duration of measurement. The waveform, bandwidth, and frequency resolution of the sounder can be adapted for any channel under investigation. The design approach and technology used has led to a reduction in size and weight by more than 60%. This makes the sounder ideal for mobile time-variant wireless communication channels studies. Averaging allows processing gains of up to 30 dB to be achieved for measurement in weak signal conditions. The technique applied also improves reliability, reduces power consumption, and has shifted sounder design complexity from hardware to software. Test results show that the sounder can detect very small-scale variations in channels.

Quasi-periodic synchronisation of self-modulation oscillations in a ring chip laser by an external periodic signal

International Nuclear Information System (INIS)

Aulova, T V; Kravtsov, Nikolai V; Lariontsev, E G; Chekina, S N

2011-01-01

The synchronisation of periodic self-modulation oscillations in a ring Nd:YAG chip laser under an external periodic signal modulating the pump power has been experimentally investigated. A new quasi-periodic regime of synchronisation of self-modulation oscillations is found. The characteristic features of the behaviour of spectral and temporal structures of synchronised quasi-periodic oscillations with a change in the external signal frequency are studied. (control of laser radiation parameters)

Directing Traffic: Managing Internet Bandwidth Fairly

Science.gov (United States)

Paine, Thomas A.; Griggs, Tyler J.

2008-01-01

Educational institutions today face budgetary restraints and scarce resources, complicating the decision of how to allot bandwidth for campus network users. Additionally, campus concerns over peer-to-peer networking (specifically outbound Internet traffic) have increased because of bandwidth and copyright issues. In this article, the authors…

Studies of bandwidth dependence of laser plasma instabilities driven by the Nike laser

Science.gov (United States)

Weaver, J.; Kehne, D.; Obenschain, S.; Serlin, V.; Schmitt, A. J.; Oh, J.; Lehmberg, R. H.; Brown, C. M.; Seely, J.; Feldman, U.

2012-10-01

Experiments at the Nike laser facility of the Naval Research Laboratory are exploring the influence of laser bandwidth on laser plasma instabilities (LPI) driven by a deep ultraviolet pump (248 nm) that incorporates beam smoothing by induced spatial incoherence (ISI). In early ISI studies with longer wavelength Nd:glass lasers (1054 nm and 527 nm),footnotetextObenschain, PRL 62(1989);Mostovych, PRL 62(1987);Peyser, Phys. Fluids B 3(1991). stimulated Raman scattering, stimulated Brillouin scattering, and the two plasmon decay instability were reduced when wide bandwidth ISI (δν/ν˜0.03-0.19%) pulses irradiated targets at moderate to high intensities (10^14-10^15 W/cm^2). The current studies will compare the emission signatures of LPI from planar CH targets during Nike operation at large bandwidth (δν˜1THz) to observations for narrower bandwidth operation (δν˜0.1-0.3THz). These studies will help clarify the relative importance of the short wavelength and wide bandwidth to the increased LPI intensity thresholds observed at Nike. New pulse shapes are being used to generate plasmas with larger electron density scale-lengths that are closer to conditions during pellet implosions for direct drive inertial confinement fusion.

A wide-bandwidth and high-sensitivity robust microgyroscope

International Nuclear Information System (INIS)

Sahin, Korhan; Sahin, Emre; Akin, Tayfun; Alper, Said Emre

2009-01-01

This paper reports a microgyroscope design concept with the help of a 2 degrees of freedom (DoF) sense mode to achieve a wide bandwidth without sacrificing mechanical and electronic sensitivity and to obtain robust operation against variations under ambient conditions. The design concept is demonstrated with a tuning fork microgyroscope fabricated with an in-house silicon-on-glass micromachining process. When the fabricated gyroscope is operated with a relatively wide bandwidth of 1 kHz, measurements show a relatively high raw mechanical sensitivity of 131 µV (° s −1 ) −1 . The variation in the amplified mechanical sensitivity (scale factor) of the gyroscope is measured to be less than 0.38% for large ambient pressure variations such as from 40 to 500 mTorr. The bias instability and angle random walk of the gyroscope are measured to be 131° h −1 and 1.15° h −1/2 , respectively

Combined Coding And Modulation Using Runlength Limited Error ...

African Journals Online (AJOL)

In this paper we propose a Combined Coding and Modulation (CCM) scheme employing RLL/ECCs and MPSK modulation as well as RLL/ECC codes and BFSK/MPSK modulation with a view to optimise on channel bandwidth. The CCM codes and their trellis are designed and their error performances simulated in AWGN ...

A standardized way to select, evaluate, and test an analog-to-digital converter for ultrawide bandwidth radiofrequency signals based on user's needs, ideal, published,and actual specifications

Science.gov (United States)

Chang, Daniel Y.; Rowe, Neil C.

2012-06-01

The most important adverse impact on the Electronic Warfare (EW) simulation is that the number of signal sources that can be tested simultaneously is relatively small. When the number of signal sources increases, the analog hardware, complexity and costs grow by the order of N2, since the number of connections among N components is O(N*N) and the signal communication is bi-directional. To solve this problem, digitization of the signal is suggested. In digitizing a radiofrequency signal, an Analog-to-Digital Converter (ADC) is widely used. Most research studies on ADCs are conducted from designer/test engineers' perspective. Some research studies are conducted from market's perspective. This paper presents a generic way to select, evaluate and test ultra high bandwidth COTS ADCs and generate requirements for digitizing continuous time signals from the perspective of user's needs. Based on user's needs, as well as vendor's published, ideal and actual specifications, a decision can be made in selecting a proper ADC for an application. To support our arguments and illustrate the methodology, we evaluate a Tektronix TADC-1000, an 8-bit and 12 gigasamples per second ADC. This project is funded by JEWEL lab, NAWCWD at Point Mugu, CA.

Controlling Laser Plasma Instabilities Using Temporal Bandwidths Under Shock Ignition Relevant Conditions

Science.gov (United States)

Tsung, Frank; Weaver, J.; Lehmberg, R.

2017-10-01

We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temporal bandwidth under plasma conditions relevant to experiments on the Nike laser with induced spatial incoherence (ISI). With ISI, the instantaneous laser intensity can be 3-4 times larger than the average intensity, leading to the excitation of additional TPD modes and producing electrons with larger angular spread. In our simulations, we observe that although ISI can increase the interaction regions for short bursts of time, time-averaged (over many pico-seconds) laser plasma interactions can be reduced by a factor of 2 in systems with sufficiently large bandwidths (where the inverse bandwidth is comparable with the linear growth time). We will quantify these effects and investigate higher dimensional effects such as laser speckles and the effects of Coulomb collisions. Work supported by NRL, NNSA, and NSF.

High-modulation-efficiency, integrated waveguide modulator-laser diode at 448 nm

KAUST Repository

Shen, Chao

2016-01-25

To date, solid-state lighting (SSL), visible light communication (VLC) and optical clock generation functionalities in the blue-green color regime have been demonstrated based on discrete devices, including light-emitting diodes, laser diodes, and transverse-transmission modulators. This work presents the first integrated waveguide modulator-laser diode (IWM-LD) at 448 nm, offering the advantages of small-footprint, high-speed, and low power-consumption. A high modulation efficiency of 2.68 dB/V, deriving from a large extinction ratio of 9.4 dB and a low operating voltage range of 3.5 V, was measured. The electroabsorption characteristics revealed that the modulation effect, as observed from the red-shifting of the absorption edge, was resulted from the external-field-induced quantum-confined-Stark-effect (QCSE). A comparative analysis of the photocurrent versus wavelength spectra in semipolar- and polar-plane InGaN/GaN quantum wells (QWs) confirmed that the IWM-LD based on semipolar (20¯2 ¯1) QWs was able to operate in a manner similar to other III-V materials typically used in optical telecommunications, due to the reduced piezoelectric field. Utilizing the integrated modulator, a -3dB bandwidth of ~1 GHz was measured, and a data rate of 1 Gbit/s was demonstrated using on-off keying (OOK) modulation. Our experimental investigation highlighted the advantage of implementing the IWM-LD on the same semipolar QW epitaxy in enabling a high-efficiency platform for SSL-VLC dual-functionalities.

High-modulation-efficiency, integrated waveguide modulator-laser diode at 448 nm

KAUST Repository

Shen, Chao; Ng, Tien Khee; Leonard, John T.; Pourhashemi, Arash; Oubei, Hassan M.; Alias, Mohd Sharizal; Nakamura, Shuji; DenBaars, Steven P.; Speck, James S.; Alyamani, Ahmed Y.; Eldesouki, Munir M.; Ooi, Boon S.

2016-01-01

To date, solid-state lighting (SSL), visible light communication (VLC) and optical clock generation functionalities in the blue-green color regime have been demonstrated based on discrete devices, including light-emitting diodes, laser diodes, and transverse-transmission modulators. This work presents the first integrated waveguide modulator-laser diode (IWM-LD) at 448 nm, offering the advantages of small-footprint, high-speed, and low power-consumption. A high modulation efficiency of 2.68 dB/V, deriving from a large extinction ratio of 9.4 dB and a low operating voltage range of 3.5 V, was measured. The electroabsorption characteristics revealed that the modulation effect, as observed from the red-shifting of the absorption edge, was resulted from the external-field-induced quantum-confined-Stark-effect (QCSE). A comparative analysis of the photocurrent versus wavelength spectra in semipolar- and polar-plane InGaN/GaN quantum wells (QWs) confirmed that the IWM-LD based on semipolar (20¯2 ¯1) QWs was able to operate in a manner similar to other III-V materials typically used in optical telecommunications, due to the reduced piezoelectric field. Utilizing the integrated modulator, a -3dB bandwidth of ~1 GHz was measured, and a data rate of 1 Gbit/s was demonstrated using on-off keying (OOK) modulation. Our experimental investigation highlighted the advantage of implementing the IWM-LD on the same semipolar QW epitaxy in enabling a high-efficiency platform for SSL-VLC dual-functionalities.

Real-time photonic sampling with improved signal-to-noise and distortion ratio using polarization-dependent modulators

Science.gov (United States)

Liang, Dong; Zhang, Zhiyao; Liu, Yong; Li, Xiaojun; Jiang, Wei; Tan, Qinggui

2018-04-01

A real-time photonic sampling structure with effective nonlinearity suppression and excellent signal-to-noise ratio (SNR) performance is proposed. The key points of this scheme are the polarization-dependent modulators (P-DMZMs) and the sagnac loop structure. Thanks to the polarization sensitive characteristic of P-DMZMs, the differences between transfer functions of the fundamental signal and the distortion become visible. Meanwhile, the selection of specific biases in P-DMZMs is helpful to achieve a preferable linearized performance with a low noise level for real-time photonic sampling. Compared with the quadrature-biased scheme, the proposed scheme is capable of valid nonlinearity suppression and is able to provide a better SNR performance even in a large frequency range. The proposed scheme is proved to be effective and easily implemented for real time photonic applications.

High-Bandwidth Dynamic Full-Field Profilometry for Nano-Scale Characterization of MEMS

International Nuclear Information System (INIS)

Chen, L-C; Huang, Y-T; Chang, P-B

2006-01-01

The article describes an innovative optical interferometric methodology to delivery dynamic surface profilometry with a measurement bandwidth up to 10MHz or higher and a vertical resolution up to 1 nm. Previous work using stroboscopic microscopic interferometry for dynamic characterization of micro (opto)electromechanical systems (M(O)EMS) has been limited in measurement bandwidth mainly within a couple of MHz. For high resonant mode analysis, the stroboscopic light pulse is insufficiently short to capture the moving fringes from dynamic motion of the detected structure. In view of this need, a microscopic prototype based on white-light stroboscopic interferometry with an innovative light superposition strategy was developed to achieve dynamic full-field profilometry with a high measurement bandwidth up to 10MHz or higher. The system primarily consists of an optical microscope, on which a Mirau interferometric objective embedded with a piezoelectric vertical translator, a high-power LED light module with dual operation modes and light synchronizing electronics unit are integrated. A micro cantilever beam used in AFM was measured to verify the system capability in accurate characterisation of dynamic behaviours of the device. The full-field seventh-mode vibration at a vibratory frequency of 3.7MHz can be fully characterized and nano-scale vertical measurement resolution as well as tens micrometers of vertical measurement range can be performed

High-Bandwidth Dynamic Full-Field Profilometry for Nano-Scale Characterization of MEMS

Energy Technology Data Exchange (ETDEWEB)

Chen, L-C [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Huang, Y-T [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Chang, P-B [Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China)

2006-10-15

The article describes an innovative optical interferometric methodology to delivery dynamic surface profilometry with a measurement bandwidth up to 10MHz or higher and a vertical resolution up to 1 nm. Previous work using stroboscopic microscopic interferometry for dynamic characterization of micro (opto)electromechanical systems (M(O)EMS) has been limited in measurement bandwidth mainly within a couple of MHz. For high resonant mode analysis, the stroboscopic light pulse is insufficiently short to capture the moving fringes from dynamic motion of the detected structure. In view of this need, a microscopic prototype based on white-light stroboscopic interferometry with an innovative light superposition strategy was developed to achieve dynamic full-field profilometry with a high measurement bandwidth up to 10MHz or higher. The system primarily consists of an optical microscope, on which a Mirau interferometric objective embedded with a piezoelectric vertical translator, a high-power LED light module with dual operation modes and light synchronizing electronics unit are integrated. A micro cantilever beam used in AFM was measured to verify the system capability in accurate characterisation of dynamic behaviours of the device. The full-field seventh-mode vibration at a vibratory frequency of 3.7MHz can be fully characterized and nano-scale vertical measurement resolution as well as tens micrometers of vertical measurement range can be performed.

All-optical wavelength conversion and signal regeneration using an electroabsorption modulator

DEFF Research Database (Denmark)

Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

1999-01-01

All-optical wavelength conversion in an InGaAsP quantum well electroabsorption modulator is studied at different bit-rates. We present theoretical results showing wavelength conversion efficiency in agreement with existing experimental results, and signal regeneration capability is demonstrated....

A High-Linearity Low-Noise Amplifier with Variable Bandwidth for Neural Recoding Systems

Science.gov (United States)

Yoshida, Takeshi; Sueishi, Katsuya; Iwata, Atsushi; Matsushita, Kojiro; Hirata, Masayuki; Suzuki, Takafumi

2011-04-01

This paper describes a low-noise amplifier with multiple adjustable parameters for neural recording applications. An adjustable pseudo-resistor implemented by cascade metal-oxide-silicon field-effect transistors (MOSFETs) is proposed to achieve low-signal distortion and wide variable bandwidth range. The amplifier has been implemented in 0.18 µm standard complementary metal-oxide-semiconductor (CMOS) process and occupies 0.09 mm2 on chip. The amplifier achieved a selectable voltage gain of 28 and 40 dB, variable bandwidth from 0.04 to 2.6 Hz, total harmonic distortion (THD) of 0.2% with 200 mV output swing, input referred noise of 2.5 µVrms over 0.1-100 Hz and 18.7 µW power consumption at a supply voltage of 1.8 V.

Low and Expensive Bandwidth Remains Key Bottleneck for ...

African Journals Online (AJOL)

These bottlenecks have dwarfed the expectations of the citizens to fully participate in the new world economic order galvanized by e-commerce and world trade. It is estimated that M.I.T in Boston USA has bandwidth allocation that surpasses all the bandwidth allocated to Nigeria put together. Low bandwidth has been found ...

Constellation modulation - an approach to increase spectral efficiency.

Science.gov (United States)

Dash, Soumya Sunder; Pythoud, Frederic; Hillerkuss, David; Baeuerle, Benedikt; Josten, Arne; Leuchtmann, Pascal; Leuthold, Juerg

2017-07-10

Constellation modulation (CM) is introduced as a new degree of freedom to increase the spectral efficiency and to further approach the Shannon limit. Constellation modulation is the art of encoding information not only in the symbols within a constellation but also by encoding information by selecting a constellation from a set of constellations that are switched from time to time. The set of constellations is not limited to sets of partitions from a given constellation but can e.g., be obtained from an existing constellation by applying geometrical transformations such as rotations, translations, scaling, or even more abstract transformations. The architecture of the transmitter and the receiver allows for constellation modulation to be used on top of existing modulations with little penalties on the bit-error ratio (BER) or on the required signal-to-noise ratio (SNR). The spectral bandwidth used by this modulation scheme is identical to the original modulation. Simulations demonstrate a particular advantage of the scheme for low SNR situations. So, for instance, it is demonstrated by simulation that a spectral efficiency increases by up to 33% and 20% can be obtained at a BER of 10 -3 and 2×10 -2 for a regular BPSK modulation format, respectively. Applying constellation modulation, we derive a most power efficient 4D-CM-BPSK modulation format that provides a spectral efficiency of 0.7 bit/s/Hz for an SNR of 0.2 dB at a BER of 2 × 10 -2 .

Immune evasion of porcine enteric coronaviruses and viral modulation of antiviral innate signaling.

Science.gov (United States)

Zhang, Qingzhan; Yoo, Dongwan

2016-12-02

Porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV) are emerged and reemerging viruses in pigs, and together with transmissible gastroenteritis virus (TGEV), pose significant economic concerns to the swine industry. These viruses infect epithelial cells of the small intestine and cause watery diarrhea, dehydration, and a high mortality in neonatal piglets. Type I interferons (IFN-α/β) are major antiviral cytokines forming host innate immunity, and in turn, these enteric coronaviruses have evolved to modulate the host innate immune signaling during infection. Accumulating evidence however suggests that IFN induction and signaling in the intestinal epithelial cells differ from other epithelial cells, largely due to distinct features of the gut epithelial mucosal surface and commensal microflora, and it appears that type III interferon (IFN-λ) plays a key role to maintain the antiviral state in the gut. This review describes the recent understanding on the immune evasion strategies of porcine enteric coronaviruses and the role of different types of IFNs for intestinal antiviral innate immunity. Copyright © 2016 Elsevier B.V. All rights reserved.

On the actual bandwidth of some dynamic fiber optic strain/temperature interrogators

Science.gov (United States)

Preizler, Rotem R.; Davidi, R.; Motil, Avi; Botsev, Yakov; Hahami, Meir; Tur, Moshe

2017-04-01

The measurement accuracy of dynamic fiber-optic sensing interrogators, which use frequency scanning to determine the value of the measured, err as either the event bandwidth approaches half the instrument sampling frequency or when the event dynamic range comes close to the instrument designed value. One main source of error is the common practice of assigning sampling at a non-uniform grid to a uniform one. Harmonics higher than -20 dB are observed for signal frequencies exceeding 25% of the sampling rate and/or for signal amplitudes higher than 15% of the instrument dynamic range. These findings have applications to fiber-Bragg-grating and Brillouin interrogators.

Bandwidth Assessment for MultiRotor UAVs

Directory of Open Access Journals (Sweden)

Ferrarese Gastone

2017-06-01

Full Text Available This paper is a technical note about the theoretical evaluation of the bandwidth of multirotor helicopters. Starting from a mathematical linear model of the dynamics of a multirotor aircraft, the transfer functions of the state variables that deeply affect the stability characteristics of the aircraft are obtained. From these transfer functions, the frequency response analysis of the system is effected. After this analysis, the bandwidth of the system is defined. This result is immediately utilized for the design of discrete PID controllers for hovering flight stabilization. Numeric simulations are shown to demonstrate that the knowledge of the bandwidth is a valid aid in the design of flight control systems of these machines.

Variable reflectivity signal mirrors and signal response measurements

International Nuclear Information System (INIS)

Vine, Glenn de; Shaddock, Daniel A; McClelland, David E

2002-01-01

Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations

Variable reflectivity signal mirrors and signal response measurements

CERN Document Server

Vine, G D; McClelland, D E

2002-01-01

Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations.

Large scale modulation of high frequency acoustic waves in periodic porous media.

Science.gov (United States)

Boutin, Claude; Rallu, Antoine; Hans, Stephane

2012-12-01

This paper deals with the description of the modulation at large scale of high frequency acoustic waves in gas saturated periodic porous media. High frequencies mean local dynamics at the pore scale and therefore absence of scale separation in the usual sense of homogenization. However, although the pressure is spatially varying in the pores (according to periodic eigenmodes), the mode amplitude can present a large scale modulation, thereby introducing another type of scale separation to which the asymptotic multi-scale procedure applies. The approach is first presented on a periodic network of inter-connected Helmholtz resonators. The equations governing the modulations carried by periodic eigenmodes, at frequencies close to their eigenfrequency, are derived. The number of cells on which the carrying periodic mode is defined is therefore a parameter of the modeling. In a second part, the asymptotic approach is developed for periodic porous media saturated by a perfect gas. Using the "multicells" periodic condition, one obtains the family of equations governing the amplitude modulation at large scale of high frequency waves. The significant difference between modulations of simple and multiple mode are evidenced and discussed. The features of the modulation (anisotropy, width of frequency band) are also analyzed.

Identifying colon cancer risk modules with better classification performance based on human signaling network.

Science.gov (United States)

Qu, Xiaoli; Xie, Ruiqiang; Chen, Lina; Feng, Chenchen; Zhou, Yanyan; Li, Wan; Huang, Hao; Jia, Xu; Lv, Junjie; He, Yuehan; Du, Youwen; Li, Weiguo; Shi, Yuchen; He, Weiming

2014-10-01

Identifying differences between normal and tumor samples from a modular perspective may help to improve our understanding of the mechanisms responsible for colon cancer. Many cancer studies have shown that signaling transduction and biological pathways are disturbed in disease states, and expression profiles can distinguish variations in diseases. In this study, we integrated a weighted human signaling network and gene expression profiles to select risk modules associated with tumor conditions. Risk modules as classification features by our method had a better classification performance than other methods, and one risk module for colon cancer had a good classification performance for distinguishing between normal/tumor samples and between tumor stages. All genes in the module were annotated to the biological process of positive regulation of cell proliferation, and were highly associated with colon cancer. These results suggested that these genes might be the potential risk genes for colon cancer. Copyright © 2013. Published by Elsevier Inc.

Electrical system for pulse-width modulated control of a power inverter using phase-shifted carrier signals and related operating methods

Science.gov (United States)

Welchko, Brian A [Torrance, CA

2012-02-14

Systems and methods are provided for pulse-width modulated control of power inverter using phase-shifted carrier signals. An electrical system comprises an energy source and a motor. The motor has a first set of windings and a second set of windings, which are electrically isolated from each other. An inverter module is coupled between the energy source and the motor and comprises a first set of phase legs coupled to the first set of windings and a second set of phase legs coupled to the second set of windings. A controller is coupled to the inverter module and is configured to achieve a desired power flow between the energy source and the motor by modulating the first set of phase legs using a first carrier signal and modulating the second set of phase legs using a second carrier signal. The second carrier signal is phase-shifted relative to the first carrier signal.

Electroabsorption modulators used for all-optical signal processing and labelling

DEFF Research Database (Denmark)

Xu, Lin

2004-01-01

This thesis concerns the applications of semiconductor components, primarily electroabsorption modulators (EAMs), in optical signal processing and labelling for future all optical communication networks. An introduction to electroabsorption modulators is given and several mechanisms that form...... function of an EAM is frequency dependent and the main improvement from an EAM-based regenerator is the enhancement of the ER and the suppression of the noise in a space bit. Applications of EAMs in optical label processing using various orthogonal labelling schemes are discussed. Through EAM...... encoding are –25.6/-28.1 dBm and –23.7/-21 dBm, respectively. Using an EAM for optical label insertion and a MZ-SOA for optical label erasure and payload regeneration in the ASK(10 Gb/s)/ Frequency Shift Keying (312 Mb/s) orthogonal modulation format, the complete functionality of a network node including...

Wideband Spectroscopy: The Design and Implementation of a 3 GHz Bandwidth, 8192 Channel, Polyphase Digital Spectrometer

Science.gov (United States)

Monroe, Ryan M.

2011-01-01

A family of state-of-the-art digital Fourier transform spectrometers has been developed, with a combination of high bandwidth and fine resolution unavailable elsewhere. Analog signals consisting of radiation emitted by constituents in planetary atmospheres or galactic sources are downconverted and subsequently digitized by a pair of interleaved Analog-to-Digital Converters, (ADC). This 6 Gsps (giga-sample per second) digital representation of the analog signal is then processed through an FPGA-based streaming Fast Fourier Transform (FFT), the key development described below. Digital spectrometers have many advantages over previously used analog spectrometers, especially in terms of accuracy and resolution, both of which are particularly important for the type of scientific questions to be addressed with next-generation radiometers. the implementation, results and underlying math for this spectrometer, as well as, potential for future extension to even higher bandwidth, resolution and channel orthogonality, needed to support proposed future advanced atmospheric science and radioastronomy, are discussed.

Analysis of Filter-Bank-Based Methods for Fast Serial Acquisition of BOC-Modulated Signals

Directory of Open Access Journals (Sweden)

Elena Simona Lohan

2007-09-01

Full Text Available Binary-offset-carrier (BOC signals, selected for Galileo and modernized GPS systems, pose significant challenges for the code acquisition, due to the ambiguities (deep fades which are present in the envelope of the correlation function (CF. This is different from the BPSK-modulated CDMA signals, where the main correlation lobe spans over 2-chip interval, without any ambiguities or deep fades. To deal with the ambiguities due to BOC modulation, one solution is to use lower steps of scanning the code phases (i.e., lower than the traditional step of 0.5 chips used for BPSK-modulated CDMA signals. Lowering the time-bin steps entails an increase in the number of timing hypotheses, and, thus, in the acquisition times. An alternative solution is to transform the ambiguous CF into an “unambiguous” CF, via adequate filtering of the signal. A generalized class of frequency-based unambiguous acquisition methods is proposed here, namely the filter-bank-based (FBB approaches. The detailed theoretical analysis of FBB methods is given for serial-search single-dwell acquisition in single path static channels and a comparison is made with other ambiguous and unambiguous BOC acquisition methods existing in the literature.

Nano-optomechanical transducer

Science.gov (United States)

Rakich, Peter T; El-Kady, Ihab F; Olsson, Roy H; Su, Mehmet Fatih; Reinke, Charles; Camacho, Ryan; Wang, Zheng; Davids, Paul

2013-12-03

A nano-optomechanical transducer provides ultrabroadband coherent optomechanical transduction based on Mach-wave emission that uses enhanced photon-phonon coupling efficiencies by low impedance effective phononic medium, both electrostriction and radiation pressure to boost and tailor optomechanical forces, and highly dispersive electromagnetic modes that amplify both electrostriction and radiation pressure. The optomechanical transducer provides a large operating bandwidth and high efficiency while simultaneously having a small size and minimal power consumption, enabling a host of transformative phonon and signal processing capabilities. These capabilities include optomechanical transduction via pulsed phonon emission and up-conversion, broadband stimulated phonon emission and amplification, picosecond pulsed phonon lasers, broadband phononic modulators, and ultrahigh bandwidth true time delay and signal processing technologies.

Physically Connected Stacked Patch Antenna Design with 100% Bandwidth

KAUST Repository

Klionovski, Kirill; Shamim, Atif

2017-01-01

Typically, stacked patch antennas are parasitically coupled and provide larger bandwidth than a single patch antenna. Here, we show a stacked patch antenna design where square patches with semi-circular cutouts are physically connected to each other. This arrangement provides 100% bandwidth from 23.9–72.2 GHz with consistent high gain (5 dBi or more) across the entire bandwidth. In another variation, a single patch loaded with a superstrate provides 83.5% bandwidth from 25.6–62.3 GHz. The mechanism of bandwidth enhancement is explained through electromagnetic simulations. Measured reflection coefficient, radiation patterns and gain results confirm the extremely wideband performance of the design.

Physically Connected Stacked Patch Antenna Design with 100% Bandwidth

KAUST Repository

Klionovski, Kirill

2017-11-01

Typically, stacked patch antennas are parasitically coupled and provide larger bandwidth than a single patch antenna. Here, we show a stacked patch antenna design where square patches with semi-circular cutouts are physically connected to each other. This arrangement provides 100% bandwidth from 23.9–72.2 GHz with consistent high gain (5 dBi or more) across the entire bandwidth. In another variation, a single patch loaded with a superstrate provides 83.5% bandwidth from 25.6–62.3 GHz. The mechanism of bandwidth enhancement is explained through electromagnetic simulations. Measured reflection coefficient, radiation patterns and gain results confirm the extremely wideband performance of the design.

Modulation format dependence of digital nonlinearity compensation performance in optical fibre communication systems.

Science.gov (United States)

Xu, Tianhua; Shevchenko, Nikita A; Lavery, Domaniç; Semrau, Daniel; Liga, Gabriele; Alvarado, Alex; Killey, Robert I; Bayvel, Polina

2017-02-20

The relationship between modulation format and the performance of multi-channel digital back-propagation (MC-DBP) in ideal Nyquist-spaced optical communication systems is investigated. It is found that the nonlinear distortions behave independent of modulation format in the case of full-field DBP, in contrast to the cases of electronic dispersion compensation and partial-bandwidth DBP. It is shown that the minimum number of steps per span required for MC-DBP depends on the chosen modulation format. For any given target information rate, there exists a possible trade-off between modulation format and back-propagated bandwidth, which could be used to reduce the computational complexity requirement of MC-DBP.

Large-signal modeling method for power FETs and diodes

Energy Technology Data Exchange (ETDEWEB)

Sun Lu; Wang Jiali; Wang Shan; Li Xuezheng; Shi Hui; Wang Na; Guo Shengping, E-mail: sunlu_1019@126.co [School of Electromechanical Engineering, Xidian University, Xi' an 710071 (China)

2009-06-01

Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.

Large-signal modeling method for power FETs and diodes

International Nuclear Information System (INIS)

Sun Lu; Wang Jiali; Wang Shan; Li Xuezheng; Shi Hui; Wang Na; Guo Shengping

2009-01-01

Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.

Weiss oscillations in the electronic structure of modulated graphene

International Nuclear Information System (INIS)

Tahir, M; Sabeeh, K; MacKinnon, A

2007-01-01

We present a theoretical study of the electronic structure of modulated graphene in the presence of a perpendicular magnetic field. The density of states and the bandwidth for the Dirac electrons in this system are determined. The appearance of unusual Weiss oscillations in the bandwidth and density of states is the main focus of this work

Nanobody-Based Biologics for Modulating Purinergic Signaling in Inflammation and Immunity

Directory of Open Access Journals (Sweden)

Stephan Menzel

2018-03-01

Full Text Available Adenosine triphosphate (ATP and nicotinamide adenine dinucleotide (NAD+ are released as danger signals from cells during infection and sterile inflammation. In the extracellular compartment ATP is converted by CD39, CD73, and other ecto-enzymes into metabolites that modulate the activity of T cells and macrophages. While ATP mediates pro-inflammatory signals via P2X7 and other P2 receptors, adenosine triggers anti-inflammatory signaling via the adenosine 2a receptor (Adora2a and other P1 receptors. The latter also plays a role in maintaining an immunosuppressive tumor microenvironment. NAD+ is converted by CD38, CD203 and other ecto-enzymes to the Ca2+ mobilizing messengers cyclic ADP-ribose and ADP-ribose, and to adenosine. Recent findings on the roles of CD38, CD39, CD73, CD203, P2X7, and Adora2a in inflammation and immunity underscore the potential of these proteins as drug targets. However, available small molecule inhibitors often lack specificity and mediate unwanted off-target toxicity. Nanobodies – single domain antibodies derived from heavy chain antibodies that naturally occur in camelids – display a propensity to bind functional epitopes not accessible to conventional antibodies. Like conventional antibodies, nanobodies and nanobody-based biologics are highly specific and have well-understood, tunable in vivo pharmacodynamics with little if any toxicity. Nanobodies thus represent attractive alternatives to small molecule inhibitors for modulating purinergic signaling in inflammation and immunity. Here we review recent progress made in developing nanobodies against key targets of purinergic signaling.

Nanobody-Based Biologics for Modulating Purinergic Signaling in Inflammation and Immunity.

Science.gov (United States)

Menzel, Stephan; Schwarz, Nicole; Haag, Friedrich; Koch-Nolte, Friedrich

2018-01-01

Adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NAD + ) are released as danger signals from cells during infection and sterile inflammation. In the extracellular compartment ATP is converted by CD39, CD73, and other ecto-enzymes into metabolites that modulate the activity of T cells and macrophages. While ATP mediates pro-inflammatory signals via P2X7 and other P2 receptors, adenosine triggers anti-inflammatory signaling via the adenosine 2a receptor (Adora2a) and other P1 receptors. The latter also plays a role in maintaining an immunosuppressive tumor microenvironment. NAD + is converted by CD38, CD203 and other ecto-enzymes to the Ca 2+ mobilizing messengers cyclic ADP-ribose and ADP-ribose, and to adenosine. Recent findings on the roles of CD38, CD39, CD73, CD203, P2X7, and Adora2a in inflammation and immunity underscore the potential of these proteins as drug targets. However, available small molecule inhibitors often lack specificity and mediate unwanted off-target toxicity. Nanobodies - single domain antibodies derived from heavy chain antibodies that naturally occur in camelids - display a propensity to bind functional epitopes not accessible to conventional antibodies. Like conventional antibodies, nanobodies and nanobody-based biologics are highly specific and have well-understood, tunable in vivo pharmacodynamics with little if any toxicity. Nanobodies thus represent attractive alternatives to small molecule inhibitors for modulating purinergic signaling in inflammation and immunity. Here we review recent progress made in developing nanobodies against key targets of purinergic signaling.

Large-signal stability analysis of PWM converters

Energy Technology Data Exchange (ETDEWEB)

Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering

1995-12-31

Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.

Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

DEFF Research Database (Denmark)

Vienne, Guillaume; Xu, Yong; Jakobsen, Christian

2004-01-01

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in t...... in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m....

Dama annual modulation from electron recoils

OpenAIRE

Foot, R.

2018-01-01

Plasma dark matter, which arises in dissipative dark matter models, can give rise to large annual modulation signals from keV electron recoils. Previous work has argued that the DAMA annual modulation signal might be explained in such a scenario. Detailed predictions are difficult due to the inherent complexities involved in modelling the halo plasma interactions with Earth bound dark matter. Here, we consider a simplified phenomenological model for the dark matter density and temperature nea...

Running spectral index from large-field inflation with modulations revisited

Energy Technology Data Exchange (ETDEWEB)

Czerny, Michael, E-mail: mczerny@tuhep.phys.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Kobayashi, Takeshi, E-mail: takeshi@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Takahashi, Fuminobu, E-mail: fumi@tuhep.phys.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Kavli IPMU, TODIAS, University of Tokyo, Kashiwa 277-8583 (Japan)

2014-07-30

We revisit large field inflation models with modulations in light of the recent discovery of the primordial B-mode polarization by the BICEP2 experiment, which, when combined with the Planck+WP+highL data, gives a strong hint for additional suppression of the CMB temperature fluctuations at small scales. Such a suppression can be explained by a running spectral index. In fact, it was pointed out by two of the present authors (TK and FT) that the existence of both tensor mode perturbations and a sizable running of the spectral index is a natural outcome of large inflation models with modulations such as axion monodromy inflation. We find that this holds also in the recently proposed multi-natural inflation, in which the inflaton potential consists of multiple sinusoidal functions and therefore the modulations are a built-in feature.

A molecular-sized optical logic circuit for digital modulation of a fluorescence signal

Science.gov (United States)

Nishimura, Takahiro; Tsuchida, Karin; Ogura, Yusuke; Tanida, Jun

2018-03-01

Fluorescence measurement allows simultaneous detection of multiple molecular species by using spectrally distinct fluorescence probes. However, due to the broad spectra of fluorescence emission, the multiplicity of fluorescence measurement is generally limited. To overcome this limitation, we propose a method to digitally modulate fluorescence output signals with a molecular-sized optical logic circuit by using optical control of fluorescence resonance energy transfer (FRET). The circuit receives a set of optical inputs represented with different light wavelengths, and then it switches high and low fluorescence intensity from a reporting molecule according to the result of the logic operation. By using combinational optical inputs in readout of fluorescence signals, the number of biomolecular species that can be identified is increased. To implement the FRET-based circuits, we designed two types of basic elements, YES and NOT switches. An YES switch produces a high-level output intensity when receiving a designated light wavelength input and a low-level intensity without the light irradiation. A NOT switch operates inversely to the YES switch. In experiments, we investigated the operation of the YES and NOT switches that receive a 532-nm light input and modulate the fluorescence intensity of Alexa Fluor 488. The experimental result demonstrates that the switches can modulate fluorescence signals according to the optical input.

Nuclear Instrumentation Module (NIM) standard logic processor as a portal signal analyzer

International Nuclear Information System (INIS)

Minges, G.P.

1978-01-01

A general purpose electronic logic processor has been designed into a 2 wide NIM (Nuclear Instrumentation Module) bin module. The unit utilizes a microprocessor to achieve necessary versatility. The processor's first use is as a new generation signal analyzer for use in radiometric personnel and vehicle portal monitors. Significant improvements have been obtained in sensitivity and stability over existing analog discriminators. The new analyzer is presently being used to update personnel and vehicle portal monitoring systems

Modulation of Hippocampal Neural Plasticity by Glucose-Related Signaling

Directory of Open Access Journals (Sweden)

Marco Mainardi

2015-01-01

Full Text Available Hormones and peptides involved in glucose homeostasis are emerging as important modulators of neural plasticity. In this regard, increasing evidence shows that molecules such as insulin, insulin-like growth factor-I, glucagon-like peptide-1, and ghrelin impact on the function of the hippocampus, which is a key area for learning and memory. Indeed, all these factors affect fundamental hippocampal properties including synaptic plasticity (i.e., synapse potentiation and depression, structural plasticity (i.e., dynamics of dendritic spines, and adult neurogenesis, thus leading to modifications in cognitive performance. Here, we review the main mechanisms underlying the effects of glucose metabolism on hippocampal physiology. In particular, we discuss the role of these signals in the modulation of cognitive functions and their potential implications in dysmetabolism-related cognitive decline.

Spectral bandwidth of interictal fast epileptic activity characterizes the seizure onset zone

Directory of Open Access Journals (Sweden)

Marcel Heers

2018-01-01

Full Text Available The foremost aim of presurgical epilepsy evaluation is the delineation of the seizure onset zone (SOZ. There is increasing evidence that fast epileptic activity (FEA, 14–250 Hz occurring interictally, i.e. between seizures, is predominantly localized within the SOZ. Currently it is unknown, which frequency band of FEA performs best in identifying the SOZ, although prior studies suggest highest concordance of spectral changes with the SOZ for high frequency changes. We suspected that FEA reflects dampened oscillations in local cortical excitatory-inhibitory neural networks, and that interictal FEA in the SOZ is a consequence of reduced oscillatory damping. We therefore predict a narrowing of the spectral bandwidth alongside increased amplitudes of spectral peaks during interictal FEA events. To test this hypothesis, we evaluated spectral changes during interictal FEA in invasive EEG (iEEG recordings of 13 patients with focal epilepsy. In relative spectra of beta and gamma band changes (14–250 Hz during FEA, we found that spectral peaks within the SOZ indeed were significantly more narrow-banded and their power changes were significantly higher than outside the SOZ. In contrast, the peak frequency did not differ within and outside the SOZ. Our results show that bandwidth and power changes of spectral modulations during FEA both help localizing the SOZ. We propose the spectral bandwidth as new source of information for the evaluation of EEG data.

Cutter Connectivity Bandwidth Study

Science.gov (United States)

2002-10-01

The goal of this study was to determine how much bandwidth is required for cutters to meet emerging data transfer requirements. The Cutter Connectivity Business Solutions Team with guidance front the Commandant's 5 Innovation Council sponsored this study. Today, many Coast Guard administrative and business functions are being conducted via electronic means. Although our larger cutters can establish part-time connectivity using commercial satellite communications (SATCOM) while underway, there are numerous complaints regarding poor application performance. Additionally, smaller cutters do not have any standard means of underway connectivity. The R&D study shows the most important factor affecting web performance and enterprise applications onboard cutters was latency. Latency describes the time it takes the signal to reach the satellite and come back down through space. The latency due to use of higher orbit satellites is causing poor application performance and inefficient use of expensive SATCOM links. To improve performance, the CC must, (1) reduce latency by using alternate communications links such as low-earth orbit satellites, (2) tailor applications to the SATCOM link and/or (3) optimize protocols used for data communication to minimize time required by present applications to establish communications between the user and the host systems.

Average Bandwidth Allocation Model of WFQ

Directory of Open Access Journals (Sweden)

Tomáš Balogh

2012-01-01

Full Text Available We present a new iterative method for the calculation of average bandwidth assignment to traffic flows using a WFQ scheduler in IP based NGN networks. The bandwidth assignment calculation is based on the link speed, assigned weights, arrival rate, and average packet length or input rate of the traffic flows. We prove the model outcome with examples and simulation results using NS2 simulator.

Energy efficiency in elastic-bandwidth optical networks

DEFF Research Database (Denmark)

Vizcaino, Jorge Lopez; Ye, Yabin; Tafur Monroy, Idelfonso

2011-01-01

of elastic bandwidth allocation, opens new horizons in the operation of optical networks. In this paper, we compare the network planning problem in an elastic bandwidth CO-OFDM-based network and a fixed-grid WDM network. We highlight the benefits that bandwidth elasticity and the selection of different......The forecasted growth in the Internet traffic has made the operators and industry to be concerned about the power consumption of the networks, and to become interested in alternatives to plan and operate the networks in a more energy efficient manner. The introduction of OFDM, and its property...

Noise Pulses in Large Area Optical Modules

International Nuclear Information System (INIS)

Aiello, Sebastiano; Leonora, Emanuele; Giordano, Valentina

2013-06-01

A great number of large area photomultipliers are widely used in neutrino and astro-particle detector to measure Cherenkov light in medium like water or ice. The key element of these detectors are the so-called 'optical module', which consist in photodetectors closed in a transparent pressure-resistant container to protect it and ensure good light transmission. The noise pulses present on the anode of each photomultiplier affect strongly the performance of the detector. A large study was conducted on noise pulses of large area photomultipliers, considering time and charge distributions of dark pulses, prepulses, delayed pulses, and after pulses. The contribution to noise pulses due to the presence of the external glass spheres was also studied, even comparing two vessels of different brands. (authors)

Improved slow-light performance of 10 Gb/s NRZ, PSBT and DPSK signals in fiber broadband SBS.

Science.gov (United States)

Yi, Lilin; Jaouen, Yves; Hu, Weisheng; Su, Yikai; Bigo, Sébastien

2007-12-10

We have demonstrated error-free operations of slow-light via stimulated Brillouin scattering (SBS) in optical fiber for 10-Gb/s signals with different modulation formats, including non-return-to-zero (NRZ), phase-shaped binary transmission (PSBT) and differential phase-shiftkeying (DPSK). The SBS gain bandwidth is broadened by using current noise modulation of the pump laser diode. The gain shape is simply controlled by the noise density function. Super-Gaussian noise modulation of the Brillouin pump allows a flat-top and sharp-edge SBS gain spectrum, which can reduce slow-light induced distortion in case of 10-Gb/s NRZ signal. The corresponding maximal delay-time with error-free operation is 35 ps. Then we propose the PSBT format to minimize distortions resulting from SBS filtering effect and dispersion accompanied with slow light because of its high spectral efficiency and strong dispersion tolerance. The sensitivity of the 10-Gb/s PSBT signal is 5.2 dB better than the NRZ case with a same 35-ps delay. The maximal delay of 51 ps with error-free operation has been achieved. Futhermore, the DPSK format is directly demodulated through a Gaussian-shaped SBS gain, which is achieved using Gaussian-noise modulation of the Brillouin pump. The maximal error-free time delay after demodulation of a 10-Gb/s DPSK signal is as high as 81.5 ps, which is the best demonstrated result for 10-Gb/s slow-light.

Large scale analysis of signal reachability.

Science.gov (United States)

Todor, Andrei; Gabr, Haitham; Dobra, Alin; Kahveci, Tamer

2014-06-15

Major disorders, such as leukemia, have been shown to alter the transcription of genes. Understanding how gene regulation is affected by such aberrations is of utmost importance. One promising strategy toward this objective is to compute whether signals can reach to the transcription factors through the transcription regulatory network (TRN). Due to the uncertainty of the regulatory interactions, this is a #P-complete problem and thus solving it for very large TRNs remains to be a challenge. We develop a novel and scalable method to compute the probability that a signal originating at any given set of source genes can arrive at any given set of target genes (i.e., transcription factors) when the topology of the underlying signaling network is uncertain. Our method tackles this problem for large networks while providing a provably accurate result. Our method follows a divide-and-conquer strategy. We break down the given network into a sequence of non-overlapping subnetworks such that reachability can be computed autonomously and sequentially on each subnetwork. We represent each interaction using a small polynomial. The product of these polynomials express different scenarios when a signal can or cannot reach to target genes from the source genes. We introduce polynomial collapsing operators for each subnetwork. These operators reduce the size of the resulting polynomial and thus the computational complexity dramatically. We show that our method scales to entire human regulatory networks in only seconds, while the existing methods fail beyond a few tens of genes and interactions. We demonstrate that our method can successfully characterize key reachability characteristics of the entire transcriptions regulatory networks of patients affected by eight different subtypes of leukemia, as well as those from healthy control samples. All the datasets and code used in this article are available at bioinformatics.cise.ufl.edu/PReach/scalable.htm. © The Author 2014

On semidefinite programming bounds for graph bandwidth

NARCIS (Netherlands)

de Klerk, E.; Nagy, M.; Sotirov, R.

2013-01-01

In this paper, we propose two new lower bounds on graph bandwidth and cyclic bandwidth based on semidefinite programming (SDP) relaxations of the quadratic assignment problem. We compare the new bounds with two other SDP bounds reported in [A. Blum, G. Konjevod, R. Ravi, and S. Vempala,

Scalable modulation technology and the tradeoff of reach, spectral efficiency, and complexity

Science.gov (United States)

Bosco, Gabriella; Pilori, Dario; Poggiolini, Pierluigi; Carena, Andrea; Guiomar, Fernando

2017-01-01

Bandwidth and capacity demand in metro, regional, and long-haul networks is increasing at several tens of percent per year, driven by video streaming, cloud computing, social media and mobile applications. To sustain this traffic growth, an upgrade of the widely deployed 100-Gbit/s long-haul optical systems, based on polarization multiplexed quadrature phase-shift keying (PM-QPSK) modulation format associated with coherent detection and digital signal processing (DSP), is mandatory. In fact, optical transport techniques enabling a per-channel bit rate beyond 100 Gbit/s have recently been the object of intensive R and D activities, aimed at both improving the spectral efficiency and lowering the cost per bit in fiber transmission systems. In this invited contribution, we review the different available options to scale the per-channel bit-rate to 400 Gbit/s and beyond, i.e. symbol-rate increase, use of higher-order quadrature amplitude modulation (QAM) modulation formats and use of super-channels with DSP-enabled spectral shaping and advanced multiplexing technologies. In this analysis, trade-offs of system reach, spectral efficiency and transceiver complexity are addressed. Besides scalability, next generation optical networks will require a high degree of flexibility in the transponders, which should be able to dynamically adapt the transmission rate and bandwidth occupancy to the light path characteristics. In order to increase the flexibility of these transponders (often referred to as "flexponders"), several advanced modulation techniques have recently been proposed, among which sub-carrier multiplexing, hybrid formats (over time, frequency and polarization), and constellation shaping. We review these techniques, highlighting their limits and potential in terms of performance, complexity and flexibility.

Pseudo-differential CMOS analog front-end circuit for wide-bandwidth optical probe current sensor

Science.gov (United States)

Uekura, Takaharu; Oyanagi, Kousuke; Sonehara, Makoto; Sato, Toshiro; Miyaji, Kousuke

2018-04-01

In this paper, we present a pseudo-differential analog front-end (AFE) circuit for a novel optical probe current sensor (OPCS) aimed for high-frequency power electronics. It employs a regulated cascode transimpedance amplifier (RGC-TIA) to achieve a high gain and a large bandwidth without using an extremely high performance operational amplifier. The AFE circuit is designed in a 0.18 µm standard CMOS technology achieving a high transimpedance gain of 120 dB Ω and high cut off frequency of 16 MHz. The measured slew rate is 70 V/µs and the input referred current noise is 1.02 pA/\\sqrt{\\text{Hz}} . The magnetic resolution and bandwidth of OPCS are estimated to be 1.29 mTrms and 16 MHz, respectively; the bandwidth is higher than that of the reported Hall effect current sensor.

Experiences in Traceroute and Bandwidth Change Analysis

Energy Technology Data Exchange (ETDEWEB)

Logg, C

2004-06-23

SLAC has been studying end-to-end WAN bandwidth availability and achievability for 2.5 years via IEPM-BW [1]. IEPM-BW performs network intensive tests every 90 minutes. Based on that experience we have also developed a light weight available bandwidth (ABwE [2]) measurement tool that can make a measurement within a second. We are now extending this to a WAN measurement and detection system (IEPM-LITE) aimed at more quickly detecting and troubleshooting network performance problems and also to be more friendly on lower performance paths. IEPM-LITE uses ping, forward traceroutes, and ABwE sensors to monitor, in close to real-time, Round Trip Times (RTT), changes in available bandwidth and routes to and from target hosts. This paper discusses the experiences, techniques and algorithms used to detect and report on significant traceroute and bandwidth changes. The ultimate aim is to develop a lightweight WAN network performance monitoring system that can detect, in near real time, significant changes and generate alerts.

Experiences in Traceroute and Bandwidth Change Analysis

International Nuclear Information System (INIS)

Logg, C

2004-01-01

SLAC has been studying end-to-end WAN bandwidth availability and achievability for 2.5 years via IEPM-BW [1]. IEPM-BW performs network intensive tests every 90 minutes. Based on that experience we have also developed a light weight available bandwidth (ABwE [2]) measurement tool that can make a measurement within a second. We are now extending this to a WAN measurement and detection system (IEPM-LITE) aimed at more quickly detecting and troubleshooting network performance problems and also to be more friendly on lower performance paths. IEPM-LITE uses ping, forward traceroutes, and ABwE sensors to monitor, in close to real-time, Round Trip Times (RTT), changes in available bandwidth and routes to and from target hosts. This paper discusses the experiences, techniques and algorithms used to detect and report on significant traceroute and bandwidth changes. The ultimate aim is to develop a lightweight WAN network performance monitoring system that can detect, in near real time, significant changes and generate alerts

25 Gbit/s differential phase-shift-keying signal generation using directly modulated quantum-dot semiconductor optical amplifiers

International Nuclear Information System (INIS)

Zeghuzi, A.; Schmeckebier, H.; Stubenrauch, M.; Bimberg, D.; Meuer, C.; Schubert, C.; Bunge, C.-A.

2015-01-01

Error-free generation of 25-Gbit/s differential phase-shift keying (DPSK) signals via direct modulation of InAs quantum-dot (QD) based semiconductor optical amplifiers (SOAs) is experimentally demonstrated with an input power level of −5 dBm. The QD SOAs emit in the 1.3-μm wavelength range and provide a small-signal fiber-to-fiber gain of 8 dB. Furthermore, error-free DPSK modulation is achieved for constant optical input power levels from 3 dBm down to only −11 dBm for a bit rate of 20 Gbit/s. Direct phase modulation of QD SOAs via current changes is thus demonstrated to be much faster than direct gain modulation

Compact silicon photonics-based multi laser module for sensing

Science.gov (United States)

Ayotte, S.; Costin, F.; Babin, A.; Paré-Olivier, G.; Morin, M.; Filion, B.; Bédard, K.; Chrétien, P.; Bilodeau, G.; Girard-Deschênes, E.; Perron, L.-P.; Davidson, C.-A.; D'Amato, D.; Laplante, M.; Blanchet-Létourneau, J.

2018-02-01

A compact three-laser source for optical sensing is presented. It is based on a low-noise implementation of the Pound Drever-Hall method and comprises high-bandwidth optical phase-locked loops. The outputs from three semiconductor distributed feedback lasers, mounted on thermo-electric coolers (TEC), are coupled with micro-lenses into a silicon photonics (SiP) chip that performs beat note detection and several other functions. The chip comprises phase modulators, variable optical attenuators, multi-mode-interference couplers, variable ratio tap couplers, integrated photodiodes and optical fiber butt-couplers. Electrical connections between a metallized ceramic and the TECs, lasers and SiP chip are achieved by wirebonds. All these components stand within a 35 mm by 35 mm package which is interfaced with 90 electrical pins and two fiber pigtails. One pigtail carries the signals from a master and slave lasers, while another carries that from a second slave laser. The pins are soldered to a printed circuit board featuring a micro-processor that controls and monitors the system to ensure stable operation over fluctuating environmental conditions. This highly adaptable multi-laser source can address various sensing applications requiring the tracking of up to three narrow spectral features with a high bandwidth. It is used to sense a fiber-based ring resonator emulating a resonant fiber optics gyroscope. The master laser is locked to the resonator with a loop bandwidth greater than 1 MHz. The slave lasers are offset frequency locked to the master laser with loop bandwidths greater than 100 MHz. This high performance source is compact, automated, robust, and remains locked for days.

Efficient Bandwidth Management for Ethernet Passive Optical Networks

KAUST Repository

Elrasad, Amr

2016-01-01

The increasing bandwidth demands in access networks motivates network operators, networking devices manufacturers, and standardization institutions to search for new approaches for access networks. These approaches should support higher bandwidth

HSP27 phosphorylation modulates TRAIL-induced activation of Src-Akt/ERK signaling through interaction with β-arrestin2.

Science.gov (United States)

Qi, Shimei; Xin, Yinqiang; Qi, Zhilin; Xu, Yimiao; Diao, Ying; Lan, Lei; Luo, Lan; Yin, Zhimin

2014-03-01

Heat shock protein 27 (HSP27) regulates critical cellular functions such as development, differentiation, cell growth and apoptosis. A variety of stimuli induce the phosphorylation of HSP27, which affects its cellular functions. However, most previous studies focused on the role of HSP27 protein itself in apoptosis, the particular role of its phosphorylation state in signaling transduction remains largely unclear. In the present study, we reported that HSP27 phosphorylation modulated TRAIL-triggered pro-survival signaling transduction. In HeLa cells, suppression of HSP27 phosphorylation by specific inhibitor KRIBB3 or MAPKAPK2 (MK2) knockdown and by overexpression of non-phosphorylatable HSP27(3A) mutant demonstrated that hindered HSP27 phosphorylation enhanced the TRAIL-induced apoptosis. In addition, reduced HSP27 phosphorylation by KRIBB3 treatment or MK2 knockdown attenuated the TRAIL-induced activation of Akt and ERK survival signaling through suppressing the phosphorylation of Src. By overexpression of HSP27(15A) or HSP27(78/82A) phosphorylation mutant, we further showed that phosphorylation of HSP27 at serine 78/82 residues was essential to TRAIL-triggered Src-Akt/ERK signaling transduction. Co-immunoprecipitation and confocal microscopy showed that HSP27 interacted with Src and scaffolding protein β-arrestin2 in response of TRAIL stimulation and suppression of HSP27 phosphorylation apparently disrupted the TRAIL-induced interaction of HSP27 and Src or interaction of HSP27 and β-arrestin2. We further demonstrated that β-arrestin2 mediated HSP27 action on TRAIL-induced Src activation, which was achieved by recruiting signaling complex of HSP27/β-arrestin2/Src in response to TRAIL. Taken together, our study revealed that HSP27 phosphorylation modulates TRAIL-triggered activation of Src-Akt/ERK pro-survival signaling via interacting with β-arrestin2 in HeLa cells. Copyright © 2013 Elsevier Inc. All rights reserved.

Very broad bandwidth klystron amplifiers

Science.gov (United States)

Faillon, G.; Egloff, G.; Farvet, C.

Large surveillance radars use transmitters at peak power levels of around one MW and average levels of a few kW, and possibly several tens of kW, in S band, or even C band. In general, the amplification stage of these transmitters is a microwave power tube, frequently a klystron. Although designers often turn to klystrons because of their good peak and average power capabilities, they still see them as narrow band amplifiers, undoubtedly because of their resonant cavities which, at first sight, would seem highly selective. But, with the progress of recent years, it has now become quite feasible to use these tubes in installations requiring bandwidths in excess of 10 - 12 percent, and even 15 percent, at 1 MW peak for example, in S-band.

Hybrid Online Labs: Making Remote Laboratories Usable Under Unfavorable Bandwidth Conditions

Directory of Open Access Journals (Sweden)

Kayode Peter Ayodele

2012-11-01

Full Text Available One of few limitations of remote laboratory technology is the fact that access and usability of such laboratories depend largely on the existence of favorable bandwidth conditions between the remote user and the system under test. This dependence is regrettable because some of the institutions likely to find remote laboratories attractive are also those most likely to have severe bandwidth limitations. Also, a typical remote laboratory will be completely unusable to remote students in the event of an outright network downtime. In this paper, we propose a hybrid online laboratory architecture that allows the automatic generation of accurate software models of remote laboratories. Such models can be hosted closer to the student and during periods of unfavorable bandwidth conditions, students can successfully interact with such models in lieu of the real hardware. We identify the challenges that need to be resolved for such a scheme to be useful and discuss the process by which suitable modeling bases were chosen. Finally we present and discuss data from a first test of the system and conclude that such a scheme holds considerable promise in changing the way remote laboratories are used and viewed.

High-speed Si/GeSi hetero-structure Electro Absorption Modulator.

Science.gov (United States)

Mastronardi, L; Banakar, M; Khokhar, A Z; Hattasan, N; Rutirawut, T; Bucio, T Domínguez; Grabska, K M; Littlejohns, C; Bazin, A; Mashanovich, G; Gardes, F Y

2018-03-19

The ever-increasing demand for integrated, low power interconnect systems is pushing the bandwidth density of CMOS photonic devices. Taking advantage of the strong Franz-Keldysh effect in the C and L communication bands, electro-absorption modulators in Ge and GeSi are setting a new standard in terms of device footprint and power consumption for next generation photonics interconnect arrays. In this paper, we present a compact, low power electro-absorption modulator (EAM) Si/GeSi hetero-structure based on an 800 nm SOI overlayer with a modulation bandwidth of 56 GHz. The device design and fabrication tolerant process are presented, followed by the measurement analysis. Eye diagram measurements show a dynamic ER of 5.2 dB at a data rate of 56 Gb/s at 1566 nm, and calculated modulator power is 44 fJ/bit.