Sample records for fm chirp waveforms

  1. Planetary Radar Astronomy with Linear FM (chirp) Waveforms J.L. Margot

    E-print Network

    (2(f0t + Kt2 /2)), -p/2 t p/2, (1) where f0 is the carrier frequency, K the rate of change extending to infinity. Linear FM waveforms may therefore result in better klystron performance and may/100 of the carrier frequency f0. The time-bandwidth product is 1023. In the example above, a modulation bandwidth

  2. From Chirps to Random-FM Excitations in Pulse Compression Ultrasound Systems

    E-print Network

    Callegari, Sergio; Caporale, Salvatore; Monticelli, Marcello; Eroli, Massimiliano; Senni, Luca; Rovatti, Riccardo; Setti, Gianluca; Burrascano, Pietro

    2013-01-01

    Pulse compression is often practiced in ultrasound Non Destructive Testing (NDT) systems using chirps. However, chirps are inadequate for setups where multiple probes need to operate concurrently in Multiple Input Multiple Output (MIMO) arrangements. Conversely, many coded excitation systems designed for MIMO miss some chirp advantages (constant envelope excitation, easiness of bandwidth control, etc.) and may not be easily implemented on hardware originally conceived for chirp excitations. Here, we propose a system based on random-FM excitations, capable of enabling MIMO with minimal changes with respect to a chirp-based setup. Following recent results, we show that random-FM excitations retain many advantages of chirps and provide the ability to frequency-shape the excitations matching the transducers features.

  3. Generation of a widely tunable linearly chirped microwave waveform based on spectral filtering and unbalanced dispersion.

    PubMed

    Zhang, Hao; Zou, Weiwen; Chen, Jianping

    2015-03-15

    We propose a method to generate a widely tunable linearly chirped microwave waveform based on spectral filtering and unbalanced dispersion. Heterodyne beating between two differently dispersed optical pulses in a photodetector produces the linearly chirped microwave waveform. Desired waveforms with flexible and independent control of the center frequency and sweep bandwidth can be obtained by simply tuning two optical filters. Simulation and experimental investigations are carried out, and the results are in good agreement. The measured microwave waveform has ?5.2-ns pulse duration and ?64-GHz sweep bandwidth, corresponding to a time-bandwidth product of ?166.4 and a compression ratio of ?248. PMID:25768188

  4. Ultrafast chirped optical waveform recording using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent

    2010-06-15

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  5. Ultrafast chirped optical waveform recorder using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent (Livermore, CA)

    2011-11-22

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  6. Frequency modulation coherent anti-Stokes Raman scattering (FM-CARS) microscopy based on spectral focusing of chirped laser pulses

    Microsoft Academic Search

    Bi-Chang Chen; Jiha Sung; Sang-Hyun Lim

    2010-01-01

    We demonstrate a new CARS microscopy method based on fast switching of effective vibrational excitation frequency from chirped femtosecond laser pulses. Broadband pump and Stokes pulses excite a single vibrational mode with a high spectral resolution when the two pulses are identically chirped and their pulse durations are approaching the dephasing time of the excited vibrational state. This \\

  7. Frequency modulation coherent anti-Stokes Raman scattering (FM-CARS) microscopy based on spectral focusing of chirped laser pulses

    NASA Astrophysics Data System (ADS)

    Chen, Bi-Chang; Sung, Jiha; Lim, Sang-Hyun

    2010-02-01

    We demonstrate a new CARS microscopy method based on fast switching of effective vibrational excitation frequency from chirped femtosecond laser pulses. Broadband pump and Stokes pulses excite a single vibrational mode with a high spectral resolution when the two pulses are identically chirped and their pulse durations are approaching the dephasing time of the excited vibrational state. This "spectral focusing" mechanism is applied to CARS microscopy with a single broadband Ti:Sapphire laser. The vibrational excitation frequency is controlled simply by the time delay between the pump and Stokes pulses and fast switching of the excitation frequency (~100 kHz) is achieved with a Pockels cell and polarization optics. Lock-in detection of the difference between the two CARS signals at nearby vibrational frequencies not only eliminates the non-resonant background but also generates a spectral line shape similar to the spontaneous Raman scattering. We demonstrate both micro-spectroscopy and vibrational imaging with various samples.

  8. A chirp scaling approach for processing squint mode SAR data

    Microsoft Academic Search

    G. W. Davidson; I. G. Cumming; M. R. Ito

    1996-01-01

    Image formation from squint mode synthetic aperture radar (SAR) is limited by image degradations caused by neglecting the range-variant filtering required by secondary range compression (SRC). Introduced here is a nonlinear FM chirp scaling, an extension of the chirp scaling algorithm, as an efficient and accurate approach to range variant SRC. Two methods of implementing the approach are described. The

  9. Varying FM rates in adaptive processing for distributed radar apertures

    Microsoft Academic Search

    Earnest Lock; Raviraj S. Adve

    2007-01-01

    Previous work in waveform diversity for distributed apertures for target detection has focused largely on orthogonal transmissions. This paper investigates an alternative approach; implementing waveform diversity based on differing slopes of the linear FM pulse to the application of target detection for a distributed radar aperture system in the presence of noise and clutter. This paper add develop the required

  10. Coherent multiple-frequency chirp exciter for L band radars

    Microsoft Academic Search

    Zdzislaw Sawicki

    2004-01-01

    This work presents design examples of coherent multiple-frequency chirp exciter for long distance L band surveillance radars. The implemented technique for pulse compression is the use of linear frequency modulation during the pulse. Long-duration linear FM pulses are obtained by the use of cascade two dispersive SAW delay lines and are converted to the desired carrier frequency. The set of

  11. The Theta Laser A Low Noise Chirped Pulse Laser

    E-print Network

    Van Stryland, Eric

    The Theta Laser A Low Noise Chirped Pulse Laser Dimitrios Mandridis dmandrid@creol.ucf.edu April 29, 2011 CREOL Affiliates Day 2011 #12;2 Objective: Frequency Swept (FM) Mode-locked Laser · Develop a frequency swept laser, · linear f-sweep, · uniform-intensity, · low noise, · with long-term stability

  12. Phase-locking and coherent power combining of broadband linearly chirped optical waves.

    PubMed

    Satyan, Naresh; Vasilyev, Arseny; Rakuljic, George; White, Jeffrey O; Yariv, Amnon

    2012-11-01

    We propose, analyze and demonstrate the optoelectronic phase-locking of optical waves whose frequencies are chirped continuously and rapidly with time. The optical waves are derived from a common optoelectronic swept-frequency laser based on a semiconductor laser in a negative feedback loop, with a precisely linear frequency chirp of 400 GHz in 2 ms. In contrast to monochromatic waves, a differential delay between two linearly chirped optical waves results in a mutual frequency difference, and an acoustooptic frequency shifter is therefore used to phase-lock the two waves. We demonstrate and characterize homodyne and heterodyne optical phase-locked loops with rapidly chirped waves, and show the ability to precisely control the phase of the chirped optical waveform using a digital electronic oscillator. A loop bandwidth of ~ 60 kHz, and a residual phase error variance of < 0.01 rad(2) between the chirped waves is obtained. Further, we demonstrate the simultaneous phase-locking of two optical paths to a common master waveform, and the ability to electronically control the resultant two-element optical phased array. The results of this work enable coherent power combining of high-power fiber amplifiers-where a rapidly chirping seed laser reduces stimulated Brillouin scattering-and electronic beam steering of chirped optical waves. PMID:23187338

  13. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2006-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital one's or zero's. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental physical laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  14. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2004-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital ONEs or ZEROs. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental natural laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  15. Waveform analysis

    NASA Astrophysics Data System (ADS)

    2010-04-01

    Accurate characterization of ultrafast optical pulses is important for applications such as spectroscopy and communications research. S. J. Ben Yoo from the University of California at Davis explains his team's scheme for real-time measurement of the amplitude and phase of arbitrary and non-repetitive waveforms.

  16. Frequency modulation (FM) spectroscopy

    Microsoft Academic Search

    G. C. Bjorklund; M. D. Levenson; W. Lenth; C. Ortiz

    1983-01-01

    Frequency modulation (FM) spectroscopy is a new method of optical heterodyne spectroscopy capable of sensitive and rapid measurement of the absorption or dispersion associated with narrow spectral features. The absorption or dispersion is measured by detecting the heterodyne beat signal that occurs when the FM optical spectrum of the probe wave is distorted by the spectral feature of interest. A

  17. Chirp signal matching and signal power optimization in pulse-echo mode ultrasonic nondestructive testing

    Microsoft Academic Search

    Martin Pollakowski; Helmut Ermert

    1994-01-01

    Chirp pulse compression is a signal correlation technique that uses frequency modulated pulses as transmitted signals. Usually, signals with linear frequency modulation are applied. They can be generated rather easily, but their spectra are not totally matched to the transfer function of ultrasonic systems. In pulse-echo mode operation, with signal duration and consequently the time-bandwidth product being critical parameters, waveforms

  18. Chirp Tunable Pure Dispersion Slope Compensator using Two Chirp FBG

    E-print Network

    Park, Namkyoo

    Chirp Tunable Pure Dispersion Slope Compensator using Two Chirp FBG *1),2) , 2) , 1) 1 , , , . , , . , . 1 . , S . , . , , FBG1 , FBG2 . beam , (a) Movable pivot Fixed pivot Uniform FBG Metal Beam L/2 1/3L Metal beam supporter ` FBG 1

  19. Waveform design for detection of weapons based on signature exploitation

    NASA Astrophysics Data System (ADS)

    Ahmad, Fauzia; Amin, Moeness G.; Dogaru, Traian

    2010-04-01

    We present waveform design based on signature exploitation techniques for improved detection of weapons in urban sensing applications. A single-antenna monostatic radar system is considered. Under the assumption of exact knowledge of the target orientation and, hence, known impulse response, matched illumination approach is used for optimal target detection. For the case of unknown target orientation, we analyze the target signatures as random processes and perform signal-to-noise-ratio based waveform optimization. Numerical electromagnetic modeling is used to provide the impulse responses of an AK-47 assault rifle for various target aspect angles relative to the radar. Simulation results depict an improvement in the signal-to-noise-ratio at the output of the matched filter receiver for both matched illumination and stochastic waveforms as compared to a chirp waveform of the same duration and energy.

  20. Transionospheric chirp event classifier

    SciTech Connect

    Argo, P.E.; Fitzgerald, T.J.; Freeman, M.J.

    1995-09-01

    In this paper we will discuss a project designed to provide computer recognition of the transionospheric chirps/pulses measured by the Blackbeard (BB) satellite, and expected to be measured by the upcoming FORTE satellite. The Blackbeard data has been perused by human means -- this has been satisfactory for the relatively small amount of data taken by Blackbeard. But with the advent of the FORTE system, which by some accounts might ``see`` thousands of events per day, it is important to provide a software/hardware method of accurately analyzing the data. In fact, we are providing an onboard DSP system for FORTE, which will test the usefulness of our Event Classifier techniques in situ. At present we are constrained to work with data from the Blackbeard satellite, and will discuss the progress made to date.

  1. FM use of BM PPT 

    E-print Network

    Brady, L.

    2012-01-01

    ? 10-20 pupils have obsessive compulsive disorder BIM Design and FM Integration Concept Design Scheme / Detailed Design Pre-Construction Construction Operational / FM/Lifecycle Design Development Considering FM and Operational requirements... FM Team Embedded within Design development MCC : Cabinet Office BIM Workshops MCC : Cabinet Office Soft Landings Workshop Transferring BIM data for operational use. C-Pad C O B i e - U K - 2 0 1 2 Manual Data EDMS Content...

  2. The IT Vision in FM.

    ERIC Educational Resources Information Center

    NeSmith, Jerry

    2002-01-01

    Provides a forward-looking vision, including goals, objectives, and principles, of information technology (IT) use within facilities management (FM). This vision includes the evolution of the FM/IT organization from an operational role to a strategic role--from an FM divisional role to an enterprise role. (EV)

  3. Generation of Arbitrary UWB Waveforms by Spectral Pulse Shaping and Thermally-Controlled Apodized FBGs

    Microsoft Academic Search

    Mohammad Abtahi; Mansour Dastmalchi; Sophie Larochelle; Leslie A. Rusch

    2009-01-01

    We propose and experimentally demonstrate an arbitrary UWB pulse generator. The proposed technique is based on spectral pulse shaping and frequency-to-time conversion. The reconfigurability of this technique comes from changing the apodizaton of a chirped fiber Bragg grating (FBG) using a series of heating elements (HE). By setting the appropriate temperature set to the HEs, any predesigned UWB waveforms can

  4. Experimental photonic generation of chirped pulses using nonlinear dispersion-based incoherent processing.

    PubMed

    Rius, Manuel; Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

    2015-05-18

    We experimentally demonstrate, for the first time, a chirped microwave pulses generator based on the processing of an incoherent optical signal by means of a nonlinear dispersive element. Different capabilities have been demonstrated such as the control of the time-bandwidth product and the frequency tuning increasing the flexibility of the generated waveform compared to coherent techniques. Moreover, the use of differential detection improves considerably the limitation over the signal-to-noise ratio related to incoherent processing. PMID:26074613

  5. Brain chirps: spectrographic signatures of epileptic seizures

    Microsoft Academic Search

    Steven J Schiff; David Colella; Gary M Jacyna; Elizabeth Hughes; Joseph W Creekmore; Angela Marshall; Maribeth Bozek-Kuzmicki; George Benke; William D Gaillard; Joan Conry; Steven R Weinstein

    2000-01-01

    Objective: A chirp is a brief signal within which the frequency content changes rapidly. Spectrographic chirps are found in signals produced from many biological and physical phenomena. In radar and sonar engineering, signals with chirps are used to localize direction and range to the signal source. Although characteristic frequency changes during epileptic seizures have long been observed, the correlation with

  6. Frequency-chirped subwavelength nanoantennas.

    PubMed

    Yaacobi, Ami; Watts, Michael R

    2012-12-01

    Herein we propose, theoretically investigate, and numerically demonstrate the first use to our knowledge of frequency chirping to achieve broadband, efficient subwavelength vertical emission from a dielectric waveguide. We demonstrate this unique and effective approach in the telecom C band in a nanophotonic frequency-chirped dipole antenna. The structure utilizes a plasmonic antenna placed above an Si3N4 waveguide and a ground plane to enhance emission efficiency. Three-dimensional finite-difference time-domain simulations reveal up to 55% vertical emission efficiency, and a bandwidth of 500 nm is possible in a structure less than half a wavelength long. The design methodology and theoretical underpinnings of frequency-chirped nanophotonic antennas coupled to dielectric waveguides are presented. PMID:23202110

  7. FM 6-22 (FM 22-100) Army Leadership

    E-print Network

    US Army Corps of Engineers

    FM 6-22 (FM 22-100) Army Leadership Competent, Confident, and Agile OCTOBER 2006 DISTRIBUTION RESTRICTION. Approved for public release; distribution is unlimited. Headquarters, Department of the Army #12;Foreword Competent leaders of character are necessary for the Army to meet the challenges in the dangerous

  8. Tone signal generator for producing multioperator tone signals using an operator circuit including a waveform generator, a selector and an enveloper

    DOEpatents

    Dong, Q.; Jenkins, M.V.; Bernadas, S.R.

    1997-09-09

    A frequency modulation (FM) tone signal generator for generating a FM tone signal is disclosed. The tone signal generator includes a waveform generator having a plurality of wave tables, a selector and an enveloper. The waveform generator furnishes a waveform signal in response to a phase angle address signal. Each wave table stores a different waveform. The selector selects one of the wave tables in response to a plurality of selection signals such that the selected wave table largely provides the waveform signal upon being addressed largely by the phase angle address signal. Selection of the selected wave table varies with each selection signal. The enveloper impresses an envelope signal on the waveform signal. The envelope signal is used as a carrier or modulator for generating the FM tone signal. 17 figs.

  9. Subcarrier placement in a PCM-FM-FM/FM modulation scheme

    NASA Astrophysics Data System (ADS)

    Moser, Juliette L.

    PCM-FM-FM/FM modulation scheme with pulse-code-modulated (PCM) signals and FM subcarrier modulated signals are described in terms of the interference power of the PCM signal that is passed by the subcarrier signals' bandpass filters. The effect of the interference power can be reduced when the subcarrier frequencies are chosen to coincide with the zero-crossing frequencies of the PCM signal. It will be shown that this choice results in a lower interference power than when the subcarrier frequencies come between the zero crossings. The PCM signal used in this study is of polar nonreturn-to-zero format.

  10. Structured Chirped Fiber Bragg Gratings

    Microsoft Academic Search

    Marco Pisco; Agostino Iadicicco; Stefania Campopiano; Antonello Cutolo; Andrea Cusano

    2008-01-01

    In this paper, a theoretical and numerical analysis of novel in-fiber photonic devices based on a structured chirped fiber Bragg gratings (CFBGs) for sensing and communication applications is presented. The investigated structure consists in a CFBG with single or multiple defects obtained by a deep and localized stripping of the cladding layer along the grating structure. The thinning of the

  11. GEORGEBUSHDR. NRD(FM2154)

    E-print Network

    Behmer, Spencer T.

    Green COKE GEORGEBUSHDR. BIZZELL OLDMAINDR. W LAMAR JOEROUTT HOUSTON NRD(FM2154) LEWIS LUBBOCK E LAMAR MOSHER CENTRAL LAMAR NAGLE COKE THROCKMORTON COKE THROCKMORTON STON SPENCE WELLBORNRD(FM GEORGE BUSH DR. R U SSEL CENTER GOLF CLUBHOUSE O&M BUILDINGPAVILION DUNCAN HALL COKE HART NAGLE DUNN MOSHERASTON COMMONS WELLS

  12. Nuclear fission of Fm isotopes

    SciTech Connect

    Asano, T. [VBL, Hokkaido University, Sapporo (Japan); Wada, T. [Department of Pure and Applied Physics, Kansai University, Suita (Japan); Ohta, M. [Hirao School of Management, Konan University, Nishinomoya (Japan); Chiba, S. [Advanced Science Research Center, JAEA Tokai, Naka (Japan)

    2010-06-01

    Multi-modal fission has been systematically investigated for the series of isotopes of Fm and Cf. The multi-dimensional Langevin-type stochastic differential equation is used for the dynamical calculation. The primary fission mode changes from mass-asymmetric fission to mass-symmetric fission with the increase of neutron numbers for both Fm and Cf cases.

  13. Waveform: Acoustics/Electroacoustics

    NSDL National Science Digital Library

    This webpage from the Handbook for Acoustic Ecology provides a description of waveform, a pattern of sound pressure variation. Information includes linked explanations of numerous related terms like sound pressure, amplitude, and the law of superposition. Also incorporated into the site are sound clips of various waveforms such as sine, sawtooth, and triangle waves.

  14. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater spectral efficiency than the MSK waveform, such as linear frequency modulation (LFM) and Costas frequency hopping, have a fixed peak sidelobe level that is therefore not configurable, and can be exceeded by high contrast targets. Furthermore, in the case of a multistatic experiment observing a target in motion, self-interference from the transmitter to the receiver is mitigated by the MSK waveform. Waveforms that have delay Doppler coupling, such as LFM, provide no such protection.

  15. Conversion of chirp in fiber compression.

    PubMed

    Dombi, Péter; Rácz, Péter; Veisz, Laszlo; Baum, Peter

    2014-04-15

    Focusing positively chirped femtosecond pulses into nonlinear fibers provides significant spectral broadening and compression at higher pulse energies than achievable conventionally because self-focusing and damage are avoided. Here, we investigate the transfer of input to output chirp in such an arrangement. Our measurements show that the group delay dispersion of the output pulse, originating from the nonlinearities, is considerably reduced as compared to the initial value, by about a factor of 10. The mechanism of chirp reduction is understood by an interplay of self-phase modulation with initial chirp within the fiber. A simple model calculation based on this picture yields satisfactory agreement with the observations and predicts significant chirp reduction for input pulses up to the ?J regime. In practice, the reduction of chirp observed here allows for compressing the spectrally broadened intense pulses by ultrabroadband dispersive multilayer mirrors of quite moderate dispersion. PMID:24978959

  16. Hybrid chirped pulse amplification system

    DOEpatents

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  17. Altimeter waveform software design

    NASA Technical Reports Server (NTRS)

    Hayne, G. S.; Miller, L. S.; Brown, G. S.

    1977-01-01

    Techniques are described for preprocessing raw return waveform data from the GEOS-3 radar altimeter. Topics discussed include: (1) general altimeter data preprocessing to be done at the GEOS-3 Data Processing Center to correct altimeter waveform data for temperature calibrations, to convert between engineering and final data units and to convert telemetered parameter quantities to more appropriate final data distribution values: (2) time "tagging" of altimeter return waveform data quantities to compensate for various delays, misalignments and calculational intervals; (3) data processing procedures for use in estimating spacecraft attitude from altimeter waveform sampling gates; and (4) feasibility of use of a ground-based reflector or transponder to obtain in-flight calibration information on GEOS-3 altimeter performance.

  18. Coherent combining of pulsed fiber amplifiers in the nonlinear chirp regime with intra-pulse phase control.

    PubMed

    Palese, Stephen; Cheung, Eric; Goodno, Gregory; Shih, Chun-Ching; Di Teodoro, Fabio; McComb, Timothy; Weber, Mark

    2012-03-26

    Two high pulse contrast (> 95 dB) polarization maintaining all-fiber amplifier chains were coherently combined to generate 0.42 mJ, 1 ns 25 kHz pulses with 79% efficiency despite 38 radians of intra-pulse phase distortion. A recursive intra-pulse phase compensation method was utilized to correct for the large nonlinear chirp providing a path for improved coherent waveform control of nanosecond pulse trains. PMID:22453422

  19. Arterial waveform analysis.

    PubMed

    Esper, Stephen A; Pinsky, Michael R

    2014-12-01

    The bedside measurement of continuous arterial pressure values from waveform analysis has been routinely available via indwelling arterial catheterization for >50 years. Invasive blood pressure monitoring has been utilized in critically ill patients, in both the operating room and critical care units, to facilitate rapid diagnoses of cardiovascular insufficiency and monitor response to treatments aimed at correcting abnormalities before the consequences of either hypo- or hypertension are seen. Minimally invasive techniques to estimate cardiac output (CO) have gained increased appeal. This has led to the increased interest in arterial waveform analysis to provide this important information, as it is measured continuously in many operating rooms and intensive care units. Arterial waveform analysis also allows for the calculation of many so-called derived parameters intrinsically created by this pulse pressure profile. These include estimates of left ventricular stroke volume (SV), CO, vascular resistance, and during positive-pressure breathing, SV variation, and pulse pressure variation. This article focuses on the principles of arterial waveform analysis and their determinants, components of the arterial system, and arterial pulse contour. It will also address the advantage of measuring real-time CO by the arterial waveform and the benefits to measuring SV variation. Arterial waveform analysis has gained a large interest in the overall assessment and management of the critically ill and those at a risk of hemodynamic deterioration. PMID:25480767

  20. Low frequency AC waveform generator

    DOEpatents

    Bilharz, Oscar W. (Scotia, NY)

    1986-01-01

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stabilization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform itself. The cosine is synthesized by squaring the triangular waveform, raising the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  1. Detection and frequency tracking of chirping signals

    SciTech Connect

    Elliott, G.R.; Stearns, S.D.

    1990-08-01

    This paper discusses several methods to detect the presence of and track the frequency of a chirping signal in broadband noise. The dynamic behavior of each of the methods is described and tracking error bounds are investigated in terms of the chirp rate. Frequency tracking and behavior in the presence of varying levels of noise are illustrated in examples. 11 refs., 29 figs.

  2. Study on the influence of dispersion and chirp on femtosecond Airy pulse propagation in Kerr media

    NASA Astrophysics Data System (ADS)

    Song, Zhenming; Lin, Yuxian

    2015-05-01

    We present the influence of second order dispersion(GVD), third-order dispersion(TOD), and initial chirp on femtosecond Airy pulse propagation in Kerr media by solving the Nonlinear Schrodinger Equation with the split-step Fourier Method. In the time duration of femtosecond pulse, the effect of TOD should not be neglected. TOD can lead to waveform distortion and lower the quality of optical pulses. We also study the propagation of femtoscond Airy pulse in anomalous dispersion Kerr media. According to the numerical results, we show that when the parameter of the TOD and the propagation distance are selected as some typical values, the pulses will broadening first and then appear a process of compression. Finally, we discussed the influence of the initial pulse chirp on the propagation of the pulse profile and broadening factor.

  3. Population inversion by chirped pulses

    SciTech Connect

    Lu Tianshi [Department of Mathematics and Statistics, Wichita State University, Wichita, Kansas 67260-0033 (United States)

    2011-09-15

    In this paper, we analyze the condition for complete population inversion by a chirped pulse over a finite duration. The nonadiabatic transition probability is mapped in the two-dimensional parameter space of coupling strength and detuning amplitude. Asymptotic forms of the probability are derived by the interference of nonadiabatic transitions for sinusoidal and triangular pulses. The qualitative difference between the maps for the two types of pulses is accounted for. The map is used for the design of stable inversion pulses under specific accuracy thresholds.

  4. WELLBORNRD(FM2154) HORTICULTURE

    E-print Network

    Behmer, Spencer T.

    CHERS BLEACHERS YELL COKE OLDMAINDR. W LAMAR JOEROUTT HOUSTON OLSENBLVD OLSENBLVD OLSENBLVD WELLBORNRD(FM2154) HORTICULTURE RD GEORGEBUSHDR. LEWIS CENTRALLAMAR NAGLE COKE THROCKMORTON COKE THROCKMORTON CORPSOFCADETS CENTER BEUTEL HEALTH CTR. HEEP CENTER HARRINGTON EDUCATION CENTER DUNCAN HALL REED ARENA YMCA COKE

  5. Low frequency ac waveform generator

    DOEpatents

    Bilharz, O.W.

    1983-11-22

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stablization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  6. FM 3-04.113 (FM 1-113) Utility and Cargo Helicopter Operations

    E-print Network

    US Army Corps of Engineers

    FM 3-04.113 (FM 1-113) Utility and Cargo Helicopter Operations December 2007 DISTRIBUTION Helicopter Operations Contents Page PREFACE ........................................................................................ 1-3 Assault Helicopter Battalion

  7. Detection of frequency-hopped waveforms embedded in interference waveforms

    Microsoft Academic Search

    Christopher Brown; K. Kowalske; C. Robertson

    2005-01-01

    Military communication systems do not necessarily operate within FCC frequency bands. Hence, they may be subject to interference from other waveforms using the same frequency band. In this paper we first investigate a technique to estimate the spectrum of competing signals utilizing the same bandwidth as a desired frequency-hopped waveform. Next, we show that the desired frequency-hopped waveform can be

  8. Waveform diversity via mutual information

    Microsoft Academic Search

    Jaime R. Roman; Dennis W. Davis; John W. Garnham; Paul Antonik

    2009-01-01

    A novel criterion for waveform diversity in radar systems is presented that is based on the information theoretic concept of Shannon mutual information (MI). In general, waveform diversity refers to adaptively changing a transmitted waveform based on the target and interference environment. MI is a measure of the information in a random variable or vector about another random variable or

  9. Optical waveform generation using a directly modulated laser

    NASA Astrophysics Data System (ADS)

    Cartledge, John C.; Karar, Abdullah S.; Roberts, Kim

    2013-10-01

    The capability of a directly modulated laser (DML) can be dramatically enhanced through precise control of the drive current waveform based on digital signal processing (DSP) and a digital-to-analog convertor (DAC). In this paper, a novel method to pre-compensate fiber dispersion for metro and regional networks is described for a bit rate of 10.709 Gb/s using a DML. A look-up table (LUT) for the drive current is optimized for dispersion mitigation. The entries of the LUT are determined based on the effects of the DML adiabatic and transient chirp on pulse propagation, the nonlinear mapping between the input current and the output optical power, and the bandwidth of the DML package. A DAC operating at 2 samples per bit (21.418 GSa/s with 6 bit resolution) converts the digital samples at the output of the LUT to an analog current waveform driving the DML. Experimental results for a bit rate of 10.709 Gb/s and on-off keying demonstrate a transmission reach of 252 km using a DML intended for 2.5 Gb/s operation and 608 km using a chirp managed laser intended for 10 Gb/s operation. Using this approach (DSP + DAC), the generation of 10.709 Gb/s differential phase shift keying (DPSK) and 56 Gb/s 16-ary quadrature amplitude modulation, sub-carrier multiplexed (QAM SCM) optical signals using the direct modulation of a passive feedback laser is also presented. 6-bit DACs operating at sampling rates of 21.418 GSa/s and 28 GSa/s, respectively, was used to generate the requisite analog current waveform.

  10. Optical chirped beam amplification and propagation

    DOEpatents

    Barty, Christopher P.

    2004-10-12

    A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

  11. Categorical perception of nonspeech chirps and bleats

    Microsoft Academic Search

    Richard E. Pastore; Xiao-Feng Li; Jody Kaplan Layer

    1990-01-01

    Mattingly, Liberman, Syrdal, and Halwes, (1971) claimed to demonstrate that subjects cannot classify nonspeech chirp and bleat\\u000a continua, but that they can classify into three categories a syllable place continuum whose variation is physically identical\\u000a to the nonspeech chirp and bleat continua. This finding for F2 transitions, as well as similar findings for F3 transitions,\\u000a has been cited as one

  12. GSSR Waveforms for Lunar Observations

    NASA Astrophysics Data System (ADS)

    Quirk, K. J.; Srinivasan, M.

    2013-02-01

    To increase the resolution of the Goldstone Solar System Radar (GSSR) for lunar observations, a new ranging waveform must be developed. Several candidate waveforms are identified and analytically characterized, including the existing GSSR biphase-coded (BPC) waveform; two commonly used waveforms, linear frequency modulation (LFM) and Costas frequency-hopped (Costas-FH); and a novel minimum-shift keying (MSK) type waveform developed during the course of this study. A set of requirements taking into consideration the spectrum allocation of the GSSR, the limitations of the transmit power amplifier, and the science objectives for a lunar observation were developed and used as selection criteria for the candidate waveforms. Windowed LFM, windowed Costas-FH, and MSK were identified as suitable for development consideration as a new GSSR ranging waveform for lunar observations.

  13. a Chirped-Pulse Fourier Transform Spectrometer Operating from 110 TO 170 GHZ

    NASA Astrophysics Data System (ADS)

    Bernier, Lauren E.; Shipman, Steven

    2014-06-01

    A chirped-pulse Fourier transform spectrometer operating from 110 - 170 GHz was constructed. The design of this spectrometer is directly adapted from that of the 260 - 295 GHz chirped-pulse spectrometer built by Steber and co-workers at the University of Virginia. In this instrument, an arbitrary waveform generator (AWG) produces a chirped pulse which is frequency shifted to a range between 9.2 and 14.1 GHz and then multiplied by a factor of 12 via an active multiplier chain to a range between 110 and 170 GHz. As in the Pate lab design, the AWG also serves as a local oscillator (LO) source; this LO is multiplied and used to downconvert the molecular emission, allowing it to be collected by a 40 GS/s digitizer. Benchmark measurements were taken for methanol at room temperature, and details of the instrument's performance will be discussed. A.L. Steber, B.J. Harris, J.L. Neill, and B.H. Pate, J. Mol. Spectrosc., 280, 3 (2012)

  14. Chirp-pulse-compression three-dimensional lidar imager with fiber optics.

    PubMed

    Pearson, Guy N; Ridley, Kevin D; Willetts, David V

    2005-01-10

    A coherent three-dimensional (angle-angle-range) lidar imager using a master-oscillator-power-amplifier concept and operating at a wavelength of 1.5 microm with chirp-pulse compression is described. A fiber-optic delay line in the local oscillator path enables a single continuous-wave semiconductor laser source with a modulated drive waveform to generate both the constant-frequency local oscillator and the frequency chirp. A portion of this chirp is gated out and amplified by a two-stage fiber amplifier. The digitized return signal was compressed by cross correlating it with a sample of the outgoing pulse. In this way a 350-ns, 10-microJ pulse with a 250-MHz frequency sweep is compressed to a width of approximately 8 ns. With a 25-mm output aperture, the lidar has been used to produce three-dimensional images of hard targets out to a range of approximately 2 km with near-diffraction-limited angular resolution and submeter range resolution. PMID:15678779

  15. FM/CW radar system

    NASA Technical Reports Server (NTRS)

    Brey, H.; Geise, P. E., Jr. (inventors)

    1978-01-01

    An FM/CW radar system is presented with improved noise discrimination in which the received signal is multiplied by a sample of the transmitted signal, and the product signal is employed to deflect a laser beam as a function of frequency. The position of the beam is thus indicative of a discrete frequency, and it is detected by the frequency encoded positions of an array of photodiodes. The outputs of the photodiodes are scanned, then threshold detected, and used to obtain the range and velocity of a target.

  16. Bulk chirped Bragg reflectors for light pulse compression and expansion

    NASA Astrophysics Data System (ADS)

    Tournois, Pierre; Hartemann, Pierre

    1995-02-01

    Bulk chirped Bragg reflectors are proposed as optical dispersive devices for the chirp pulse amplification technique. These transversal filters allow to synthesize any monotonous group delay time law versus optical frequency with a positive or negative slope.

  17. Radar waveform diversity for tracking

    NASA Astrophysics Data System (ADS)

    Grishin, Yury

    2009-06-01

    The paper presents a brief survey of the main approaches for solving the problem of radar waveform selection for optimal tracking. The traditional approach to the system design has been to treat the detection and tracking subsystems as completely separate entities. In last years some new types of radars equipped with highly agile software driven waveform generators have appeared. This makes it possible to change the transmitted waveform at each time step for obtaining minimal tracking errors. Thus the problem of the waveform selection can be formulated as the optimisation problem of the following form: for given class of signals and target movement model to find the tracking filter structure and waveform parameter sequence which result in a minimum variance estimate of the target state vector. Two main approaches to waveform optimising have been considered in the paper: the control theoretic approach and information theoretic approach. The relationships between sensor characteristics and tracking algorithm are discussed.

  18. High precision triangular waveform generator

    DOEpatents

    Mueller, Theodore R. (Oak Ridge, TN)

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  19. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...the input signals of FM translator or FM booster stations. 73.827 Section 73.827...the input signals of FM translator or FM booster stations. (a) An authorized LPFM...continue to operate if an FM translator or FM booster station demonstrates that the LPFM...

  20. Good code sets based on Piecewise Linear FM

    NASA Astrophysics Data System (ADS)

    Qazi, Farhan Aslam

    In this dissertation, classes of good analog and polyphase code sets, based on Piecewise Linear FM (PLFM) are introduced. The analog code sets, designed using pieces of Linear FM waveforms, have good autocorrelation and cross-correlation properties, i.e. they have small autocorrelation sidelobe peaks and cross-correlation peaks. They also possess the ability to both tolerate and detect Doppler shift. By concatenating sections of P3/P4 polyphase codes, new polyphase code sets are constructed, which can be considered as polyphase counterparts of the analog PLFM based code sets. Like the analog code sets, the polyphase PLFM code sets have good correlation properties and stand out in being the only class of polyphase code sets that can both tolerate and detect Doppler shift. The receiver is modeled as a matched filter, decomposed into two parallel parts, in order to extract information on the radial direction of a target in addition to its radial speed. At the cost of a slight degradation in the correlation properties and a small SNR loss, the Doppler properties of the proposed analog and digital code sets can be improved further by extending the matched filter parts in either direction.

  1. High spectral resolution multiplex CARS spectroscopy using chirped pulses

    E-print Network

    Cohen, Ronald C.

    . This new chirped (c-CARS) technique should prove useful for chemically-selective imaging applicationsHigh spectral resolution multiplex CARS spectroscopy using chirped pulses K.P. Knutsen, J (CARS) spectra with a fem- tosecond laser system is presented. A linearly chirped and stretched ($10 ps

  2. CHIRP's potential to introduce a new USAF space acquisition paradigm

    Microsoft Academic Search

    Joseph Simonds; George Sullivan

    2012-01-01

    The objectives of this paper are: (1) to explore lessons learned from the United States Air Force's (USAF) Commercially Hosted Infrared Payload (CHIRP); and (2) how those lessons can be applied to acquire operational space assets quickly and less expensively in the future. CHIRP is a payload configured with a SES-WorldSkies comsat. The goals of the CHIRP program are to

  3. Chirped Brillouin dynamic gratings for storing and compressing light.

    PubMed

    Winful, Herbert G

    2013-04-22

    We demonstrate theoretically that chirped dynamic gratings can be created in optical fibers through stimulated Brillouin scattering with frequency-chirped "signal" and "write" pulses. When the grating is interrogated with a third pulse of the opposite chirp, a compressed signal pulse is retrieved. This provides a method to regenerate stored pulses and enhance signal levels for communications applications. PMID:23609709

  4. Chirp excitation of ultrasonic probes and algorithm for filtering transit times in high-rangeability gas flow metering.

    PubMed

    Folkestad, T; Mylvaganam, K S

    1993-01-01

    The signal processing used in an ultrasonic high-rangeability gas flow meter using times of flight is presented. The flow meter under discussion uses a combination of continuous wave and chirp signals to measure at low flow velocities, below 20 m/s, and chirp signals alone to measure high flow velocities, above 20 m/s. Because of the need for a pulse compression technique in the signal waveform design the technique of pulse compression and the choice of signal waveforms are discussed. The advantages and disadvantages of amplitude weighting vis-a-vis frequency domain manipulations of the waveforms are also discussed. To eliminate spurious times of flight, a special filtering technique is used, based on assessing the gradient of ascendingly ordered time series of time-of-flight measurements. A summary of user experience with high-rangeability gas flow meters in use on different offshore platforms and in refineries is given. Long-term tests that examined the accuracy of the high-rangeability flow meter are also described. PMID:18263174

  5. The fiber optic device for signal positive chirping by interferential method with tuning of chirp size

    NASA Astrophysics Data System (ADS)

    Vinogradova, Irina L.; Sultanov, Albert K.; Meshkov, Ivan K.; Andrianova, Anna V.; Abdrahmanova, Guzel I.; Gorodetsky, Ivan I.; Nizamov, Timir R.; Chirikov, Roman Y.

    2015-03-01

    The device for positive chirping of a signal in a fiber optical line is offered. The device is based on two Fabry-Perot resonator with additional fiber optical cannels. If to execute the amalgamator from an erbium doped material, the device will supply amplification of a target signal, which is important for distribution access systems (for example, Radio-over- Fiber systems (RoF)). The device provides selectivity for spectral components of entrance radiation, that allows to operate of chirp. Built-in the converter of length provides in additional fiber optical cannels tuning the chirp under the given size.

  6. Detection of a chirping electromagnetic signal

    SciTech Connect

    Stearns, S.D.

    1989-01-01

    A matched chirp transform (MCT) method for detecting a dispersive electromagnetic pulse is described. The unique feature of this transform is that it gives a distribution of signal amplitude over time rather than frequency, and thereby simplifies signal detection and identification in the case described here. In the MCT method, the incoming signal is matched to a set of signal segments that chirp in accordance with an expected model of the dispersive medium. The performance of the MCT method is compared with that of a standard periodogram method of frequency measurement. 6 refs., 5 figs.

  7. Degeneracy between mass and spin in black-hole-binary waveforms

    E-print Network

    Emily Baird; Stephen Fairhurst; Mark Hannam; Patricia Murphy

    2012-11-02

    We explore the degeneracy between mass and spin in gravitational waveforms emitted by black-hole binary coalescences. We focus on spin-aligned waveforms and obtain our results using phenomenological models that were tuned to numerical-relativity simulations. A degeneracy is known for low-mass binaries (particularly neutron-star binaries), where gravitational-wave detectors are sensitive to only the inspiral phase, and the waveform can be modelled by post-Newtonian theory. Here, we consider black-hole binaries, where detectors will also be sensitive to the merger and ringdown, and demonstrate that the degeneracy persists across a broad mass range. At low masses, the degeneracy is between mass ratio and total spin, with chirp mass accurately determined. At higher masses, the degeneracy persists but is not so clearly characterised by constant chirp mass as the merger and ringdown become more significant. We consider the importance of this degeneracy both for performing searches (including searches where only non-spinning templates are used) and in parameter extraction from observed systems. We compare observational capabilities between the early (~2015) and final (2018 onwards) versions of the Advanced LIGO detector.

  8. FM 2-22.3 (FM 34-52) HUMAN INTELLIGENCE

    E-print Network

    US Army Corps of Engineers

    FM 2-22.3 (FM 34-52) HUMAN INTELLIGENCE COLLECTOR OPERATIONS HEADQUARTERS, DEPARTMENT OF THE ARMY Washington, DC, 6 September 2006 Human Intelligence Collector Operations Contents Page PREFACE...................................................................................................1-1 Intelligence Battlefield Operating System

  9. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph; Mortensen, Dale

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. The extension of STRS to the SSP hardware will promote easier waveform reconfiguration and reuse. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. A FPGA-based transmit waveform implementation of the proposed standard interfaces on a laboratory breadboard SDR will be discussed.

  10. Analysis of the ambiguity function for an FM signal derived from the Lorenz chaotic flow

    NASA Astrophysics Data System (ADS)

    Pappu, Chandra S.; Flores, Benjamin C.; deBroux, Patrick

    2012-06-01

    In prior work, we showed that any one of the state variables of the Lorenz chaotic flow can be used effectively as the instantaneous frequency of an FM signal. We further investigated a method to improve chaotic-wideband FM signals for high resolution radar applications by introducing a compression factor to the Lorenz flow equations and by varying two control parameters, namely ? and ?, to substantially increase the bandwidth of the signal. In this paper, we obtain an empirical quadratic relationship between these two control parameters that yields a high Lyapunov exponent which allows the Lorenz flow to quickly diverge from its initial state. This, in turn, results in an FM signal with an agile center frequency that is also chaotic. A time-frequency analysis of the FM signal shows that variable time-bandwidth products of the order of 105 and wide bandwidths of approximately 10 GHz are achievable over short segments of the signal. Next, we compute the average ambiguity function for a large number of short segments of the signal with positive range-Doppler coupling. The resulting ambiguity surface is shaped as a set of mountain ridges that align with multiple range-Doppler coupling lines with low self-noise surrounding the peak response. Similar results are achieved for segments of the signal with negative range-Doppler coupling. The characteristics of the ambiguity surface are directly attributed to the frequency agility of the FM signal which could be potentially used to counteract electronic counter measures aimed at traditional chirp radars.

  11. On the relationship between pump chirp and single-photon chirp in spontaneous parametric downconversion

    E-print Network

    X. Sanchez-Lozano; A. B. U'Ren; J. L. Lucio

    2012-06-04

    We study the chronocyclic character, i.e. the joint temporal and spectral properties, of the single-photon constituents of photon pairs generated by spontaneous parametric down conversion. In particular we study how single photon properties, including purity and single-photon chirp, depend on photon pair properties, including the type of signal-idler spectral and correlations and the level of pump chirp.

  12. Chirped pulse amplification with a nonlinearly chirped fiber Bragg grating matched to the Treacy compressor

    NASA Astrophysics Data System (ADS)

    Imeshev, G.; Hartl, I.; Fermann, M. E.

    2004-04-01

    We demonstrate a fiber chirped pulse amplification system that uses an engineered nonlinearly chirped fiber Bragg grating stretcher dispersion matched to the Treacy compressor. The seed pulses at 1558 nm are stretched to 720 ps, amplified by more than 50 dB to 6.5-µJ energy, and recompressed to 940 fs. After almost 1000 times compression the pulses are within 30% of the bandwidth limit and have a contrast ratio of better than 30 dB.

  13. 47 CFR 74.1204 - Protection of FM broadcast, FM Translator and LP100 stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Broadcast Translator Stations and FM Broadcast Booster Stations § 74.1204 Protection of...application for an FM translator or an FM booster station that is 53 or 54 channels removed...will be treated as Class A stations and booster stations will be treated the same as...

  14. HEADQUARTERS FM 3-23.35 (FM 23-35) DEPARTMENT OF THE ARMY

    E-print Network

    US Army Corps of Engineers

    HEADQUARTERS FM 3-23.35 (FM 23-35) DEPARTMENT OF THE ARMY COMBAT TRAINING WITH PISTOLS, M9 AND M11 publication is available at Army Knowledge Online (www.us.army.mil) and General Dennis J. Reimer Training and Doctrine Digital Library at (http://www.train.army.mil). #12;FM 3-23.35, C4 Change 4 Headquarters

  15. pathChirp: Efficient Available Bandwidth Estimation for Network Paths

    SciTech Connect

    Cottrell, Les

    2003-04-30

    This paper presents pathChirp, a new active probing tool for estimating the available bandwidth on a communication network path. Based on the concept of ''self-induced congestion,'' pathChirp features an exponential flight pattern of probes we call a chirp. Packet chips offer several significant advantages over current probing schemes based on packet pairs or packet trains. By rapidly increasing the probing rate within each chirp, pathChirp obtains a rich set of information from which to dynamically estimate the available bandwidth. Since it uses only packet interarrival times for estimation, pathChirp does not require synchronous nor highly stable clocks at the sender and receiver. We test pathChirp with simulations and Internet experiments and find that it provides good estimates of the available bandwidth while using only a fraction of the number of probe bytes that current state-of-the-art techniques use.

  16. Extension of harmonic cutoff in a multicycle chirped pulse combined with a chirp-free pulse

    SciTech Connect

    Xu Junjie; Zeng Bin; Yu Yongli [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

    2010-11-15

    We demonstrate high-order harmonic generation in a wave form synthesized by a multicycle 800-nm chirped laser pulse and a chirp-free laser pulse. Compared with the case of using only a chirped pulse, both the harmonic cutoff and the extreme ultraviolet supercontinuum can be extended when a weak chirp-free pulse is combined with the chirped pulse. When chirp-free pulse intensity grows, the cutoff energy and bandwidth of the supercontinuum grow as well. It is found that the broad supercontinuum can be achieved for a driving pulse with long duration even though the driving pulse reaches 10 optical cycles. An isolated attosecond pulse with duration of about 59 as is obtained, and after appropriate phase compensation with a duration of about 11 as. In addition, by performing time-frequency analyses and the classical trajectory simulation, the difference in supercontinuum generation between the preceding wave form and a similar wave form synthesized by an 800-nm fundamental pulse and a 1600-nm subharmonic pulse is investigated.

  17. Chirp technique approach for objects' identification

    Microsoft Academic Search

    V. Genis; I. Oboznenko; J. M. Reid; P. A. Lewin; K. Soetanto

    1991-01-01

    Identification of inhomogeneities is of importance in the areas of tissue characterization, nondestructive evaluation and underwater acoustics. An approach to the identification of inhomogeneities by using a pulsed swept frequency technique (chirping) is presented. This technique allows frequency domain data to be determined directly from time domain data without using a Fourier transform algorithm and vice versa. The combined information

  18. Managing effectiveness and efficiency through FM blueprinting

    Microsoft Academic Search

    Christian Coenen; Daniel von Felten; Mirjam Schmid

    2011-01-01

    Purpose – The purpose of this paper is to investigate the specifics of facilities management (FM) process modelling and the application of the service blueprinting technique within the field of FM. The paper aims to develop a visualisation method for optimised management of process interfaces to better integrate core and support processes and increase effectiveness and efficiency. Design\\/methodology\\/approach – Based

  19. FY05 FM Dial Summary Report

    Microsoft Academic Search

    Warren W. Harper; Jana D. Strasburg; Elizabeth C. Golovich; Jason S. Thompson; Timothy L. Stewart; Michael T. Batdorf

    2005-01-01

    Pacific Northwest National Laboratory's Infrared Sensors team is focused on developing methods for standoff detection of nuclear proliferation. In FY05, PNNL continued the development of the FM DIAL (frequency-modulated differential absorption LIDAR) experiment. Additional improvements to the FM DIAL trailer provided greater stability during field campaigns which made it easier to explore new locations for field campaigns. In addition to

  20. The Climate Hazards group InfraRed Precipitation (CHIRP) with Stations (CHIRPS): Development and Validation

    NASA Astrophysics Data System (ADS)

    Peterson, P.; Funk, C. C.; Husak, G. J.; Pedreros, D. H.; Landsfeld, M.; Verdin, J. P.; Shukla, S.

    2013-12-01

    CHIRP and CHIRPS are new quasi-global precipitation products with daily to seasonal time scales, a 0.05° resolution, and a 1981 to near real-time period of record. Developed by the Climate Hazards Group at UCSB and scientists at the U.S. Geological Survey Earth Resources Observation and Science Center specifically for drought early warning and environmental monitoring, CHIRPS provides moderate latency precipitation estimates that place observed hydrologic extremes in their historic context. Three main types of information are used in the CHIRPS: (1) global 0.05° precipitation climatologies, (2) time-varying grids of satellite-based precipitation estimates, and (3) in situ precipitation observations. CHIRP: The global grids of long-term (1980-2009) average precipitation were estimated for each month based on station data, averaged satellite observations, and physiographic parameters. 1981-present time-varying grids of satellite precipitation were derived from spatially varying regression models based on pentadal cold cloud duration (CCD) values and TRMM V7 training data. The CCD time-series were derived from the CPC and NOAA B1 datasets. Pentadal CCD-percent anomaly values were multiplied by pentadal climatology fields to produce low bias pentadal precipitation estimates. CHIRPS: The CHG station blending procedure uses the satellite-observed spatial covariance structure to assign relative weights to neighboring stations and the CHIRP values. The CHIRPS blending procedure is based on the expected correlation between precipitation at a given target location and precipitation at the locations of the neighboring observation stations. These correlations are estimated using the CHIRP fields. The CHG has developed an extensive archive of in situ daily, pentadal and monthly precipitation totals. The CHG database has over half a billion daily rainfall observations since 1980 and another half billion before 1980. Most of these observations come from four sets of global climate observations: the monthly Global Historical Climate Network version 2 archive, the daily Global Historical Climate Network archive, the Global Summary of the Day dataset (GSOD), and the daily Global Telecommunication System (GTS) archive provided by NOAA's Climate Prediction Center (CPC). A screening procedure was developed to flag and remove potential false zeros from the daily data, since these potentially spurious data can artificially suppress rainfall totals. Validation: Our validation focused on precipitation products with global coverage, long periods of record and near real-time availability: CHIRP, CHIRPS, CPC-Unified, CFS Reanalysis and ECMWF datasets were compared to GPCC and high quality datasets from Uganda, Colombia and the Sahel. The CHIRP and CHIRPS are shown to have low systematic errors (bias) and low mean absolute errors. Analyses in Uganda, Colombia and the Sahel indicate that the ECMWF, CPC-Unified and CFS-Reanalysis have large inhomogeneities, making them unsuitable for drought monitoring. The CHIRPS performance appears quite similar to research quality products like the GPCC and GPCP, but with higher resolution and lower latency.

  1. Design constraints of optical parametric chirped pulse amplification based on chirped quasi-phase-matching gratings.

    PubMed

    Phillips, C R; Mayer, B W; Gallmann, L; Fejer, M M; Keller, U

    2014-04-21

    Chirped quasi-phase-matching (QPM) gratings offer efficient, ultra-broadband optical parametric chirped pulse amplification (OPCPA) in the mid-infrared as well as other spectral regions. Only recently, however, has this potential begun to be realized [1]. In this paper, we study the design of chirped QPM-based OPCPA in detail, revealing several important constraints which must be accounted for in order to obtain broad-band, high-quality amplification. We determine these constraints in terms of the underlying saturated nonlinear processes, and explain how they were met when designing our mid-IR OPCPA system. The issues considered include gain and saturation based on the basic three-wave mixing equations; suppression of unwanted non-collinear gain-guided modes; minimizing and characterizing nonlinear losses associated with random duty cycle errors in the QPM grating; avoiding coincidentally-phase-matched nonlinear processes; and controlling the temporal/spectral characteristics of the saturated nonlinear interaction in order to maintain the chirped-pulse structure required for OPCPA. The issues considered place constraints both on the QPM devices as well as the OPCPA system. The resulting experimental guidelines are detailed. Our results represent the first comprehensive discussion of chirped QPM devices operated in strongly nonlinear regimes, and provide a roadmap for advancing and experimentally implementing OPCPA systems based on these devices. PMID:24787850

  2. Propagation stability of a chirped soliton in birefringent fibers

    NASA Astrophysics Data System (ADS)

    Zheng, Hongjun; Liu, Shanliang; Li, Xin; Wu, Chongqing

    2011-02-01

    The propagation stability of a chirped soliton at anomalous dispersion region in birefringent fibers is numerically studied by using the split-step Fourier-method. It is found that initial linear chirp can change obviously the threshold value Ath above which soliton stably propagates in birefringent fibers, the Ath increases with the decrease of the polarization angle | /4- |. The positive chirp makes obviously the Ath smaller for group velocity mismatch parameter >0.5, the negative one makes the Ath larger for <0.5. The effect of initial positive chirp on the Ath is greater than that of negative chirp for high birefringent fibers, is less than that of negative chirp for low birefringent fibers.

  3. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. Current standards were researched and new standard interfaces were proposed. The implementation of the proposed standard interfaces on a laboratory breadboard SDR will be presented.

  4. 47 CFR 73.317 - FM transmission system requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...false FM transmission system requirements. 73...317 FM transmission system requirements. (a...broadcast stations employing transmitters authorized after...broadcast stations employing transmitters installed or...

  5. 47 CFR 73.317 - FM transmission system requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false FM transmission system requirements. 73...317 FM transmission system requirements. (a...broadcast stations employing transmitters authorized after...broadcast stations employing transmitters installed or...

  6. 47 CFR 73.295 - FM subsidiary communications services.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Section 73.295 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.295 FM subsidiary communications services. (a) Subsidiary...

  7. 47 CFR 73.295 - FM subsidiary communications services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Section 73.295 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.295 FM subsidiary communications services. (a) Subsidiary...

  8. 47 CFR 73.295 - FM subsidiary communications services.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Section 73.295 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.295 FM subsidiary communications services. (a) Subsidiary...

  9. Chirping the probe pulse in a coherent transients experiment

    SciTech Connect

    Weber, Sebastien; Girard, Bertrand; Chatel, Beatrice [CNRS-Universite de Toulouse, UPS, Laboratoire Collisions, Agregats Reactivite, IRSAMC, F-31062 Toulouse (France)

    2010-02-15

    Coherent transients occur when a chirped pump pulse excites a two-level transition. They have been observed with an ultrashort probe pulse. Several studies have been dedicated to using various pump shapes. In this study, the roles of the pump and the probe pulses are reversed. With a Fourier-transform-limited pump pulse followed by a chirped-probe pulse, similar effects can be observed. Finally, the case of two pulses with opposite chirps is considered.

  10. Supercontinuum spectrum control in microstructure fibers by initial chirp management.

    PubMed

    Driben, Rodislav; Zhavoronkov, Nickolai

    2010-08-01

    Experiments and numerical simulation were performed for verification of the role of femtosecond pulse chirp for supercontinuum generation in photonic crystal fiber. We demonstrate that injection of high power negatively chirped pulses near zero dispersion point brings an advantage over positively chirped pulses resulting in additional collision between solitons and in development of a significantly broader spectrum. Coupling between Raman induced solitons and dispersive waves generated by higher order dispersion was proven to be the key mechanism behind the results. PMID:20721063

  11. The generation of group delay ripple of chirped fiber gratings

    NASA Astrophysics Data System (ADS)

    Tan, Zhongwei; Liu, Yan; Ning, Tigang; Jian, Shuisheng

    2004-01-01

    The analysis of the group delay ripple (GDR) generated by chirped fiber gratings is developed based on the Fabry-Perot (F-P) resonator. It shows clearly how the GDR is generated and why the periods of GDR varies along the chirped fiber gratings. It could also explain why apodization could suppress the GDR and how apodization affects the chirp of the grating. The theory could be used to devise the apodization of fiber gratings.

  12. Mechanism of electron acceleration by chirped laser pulse

    SciTech Connect

    Wu, X. Y.; Wang, P. X. [Department of Nuclear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai 200433, China and Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education (China); Kawata, S. [Department of Advanced Interdisciplinary Science, Center for Optical Research and Education, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan)

    2012-05-28

    We studied the mechanism of electron acceleration by a chirped laser pulse. We found that, because of the chirp effect, a region exists where the laser wave phase experienced by the electron varies slowly, so that the electron can be accelerated for a long time. The mechanism of chirped laser acceleration is different to that of the capture and acceleration scenario, although both of them have a main acceleration stage in which the electrons are trapped for long periods.

  13. Hi! I'm Your FM Trainer!

    ERIC Educational Resources Information Center

    Million, Helen

    1992-01-01

    Amusing cartoon pictures can personalize the young deaf child's relationship with his FM (frequency modulation) auditory trainer. The pictures can serve as reminders to turn the trainer on, to utilize it fully, and to care for it properly. (DB)

  14. Recent EISCAT heating results using chirped ISR

    Microsoft Academic Search

    B. Isham; C. La Hoz; H. Kohl; T. Hagfors; T. B. Leyser; M. T. Rietveld

    1996-01-01

    The chirp technique has recently become fully operational on the EISCAT UHF radar system and has been used for daytime observations of the HF-modified ionosphere over Ramfjordmoen in November 1992 and March 1993. During certain periods the UHF observations show a difference in the frequencies of the photoelectron-enhanced plasma line and the HF-enhanced plasma line (HFPL) similar to the one

  15. Point Response Characteristics for the CERES/EOS-PM, FM3 & FM4 instruments.

    NASA Technical Reports Server (NTRS)

    Paden, Jack; Smith, G. Louis; Lee, Robert B., III; Pandey, Dhirendra K.; Priestley, Kory J.; Thomas, Susan; Wilson, Robert S.

    1999-01-01

    This paper describes the point source functions (PSF s) of the Clouds and the Earth s Radiant Energy System (CERES,) Earth Observing System (EOS,) afternoon platform (PM,) Flight Model 3 (FM3,) and Flight Model 4 (FM4) scanning instruments. The PSF (also known as the Point Response Function, or PRF) is vital to the accurate geo-location of the remotely sensed radiance measurements acquired by the instrument. This paper compares the characteristics of the FM3 and FM4 instruments with the earlier Proto Flight Model (PFM) on the Tropical Rainfall Measuring Mission (TRMM) platform, and the FM1 and FM2 Models on the EOS morning orbiting (AM) platform, which has recently been renamed "Terra". All of the PSF s were found to be quite comparable, and the previously noted "spreading" characteristic of the window (water vapor) channel PSF is analyzed Keywords: PSF, PRF, CERES, TRMM, EOS, Earth Radiation Budget

  16. Categorical perception of nonspeech chirps and bleats.

    PubMed

    Pastore, R E; Li, X F; Layer, J K

    1990-08-01

    Mattingly, Liberman, Syrdal, and Halwes, (1971) claimed to demonstrate that subjects cannot classify nonspeech chirp and bleat continua, but that they can classify into three categories a syllable place continuum whose variation is physically identical to the nonspeech chirp and bleat continua. This finding for F2 transitions, as well as similar findings for F3 transitions, has been cited as one source of support for theories that different modes or modules underlie the perception of speech and nonspeech acoustic stimuli. However, this pattern of finding for speech and nonspeech continua may be the result of research methods rather than a true difference in subject ability. Using tonal stimuli based on the nonspeech stimuli of Mattingly et al., we found that subjects, with appropriate practice, could classify nonspeech chirp, short bleat, and bleat continua with boundaries equivalent to the syllable place continuum of Mattingly et al. With the possible exception of the higher frequency boundary for both our bleats and the Mattingly syllables, ABX discrimination peaks were clearly present and corresponded in location to the given labeling boundary. PMID:2385489

  17. SAR processing with stepped chirps and phased array antennas.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  18. FM 3-34.170/MCWP 3-17.4 (FM 5-170) ENGINEER RECONNAISSANCE

    E-print Network

    US Army Corps of Engineers

    .us.army.mil> and General Dennis J. Reimer Training and Doctrine Digital Library at train.army.mil>. #12;*FM Coordination ............................................................................... 2-4 Geospatial

  19. Chirped pulse amplification with a nonlinearly chirped fiber Bragg grating matched to the Treacy compressor.

    PubMed

    Imeshev, G; Hartl, I; Fermann, M E

    2004-04-01

    We demonstrate a fiber chirped pulse amplification system that uses an engineered nonlinearly chirped fiber Bragg grating stretcher dispersion matched to the Treacy compressor. The seed pulses at 1558 nm are stretched to 720 ps, amplified by more than 50 dB to 6.5-microJ energy, and recompressed to 940 fs. After almost 1000 times compression the pulses are within 30% of the bandwidth limit and have a contrast ratio of better than 30 dB. PMID:15072356

  20. FM 3-60 (FM 6-20-10) The Targeting Process

    E-print Network

    US Army Corps of Engineers

    ................................................................................ 3-10 Chapter 4 BRIGADE COMBAT TEAM AND BATTALION TASK FORCE TARGETING . 4-1 FunctionsFM 3-60 (FM 6-20-10) The Targeting Process NOVEMBER 2010 DISTRIBUTION RESTRICTION: Approved is available at Army Knowledge Online (www.us.army.mil) and General Dennis J. Reimer Training and Doctrine

  1. FM 4-02.18 (FM 8-10-18) VETERINARY SERVICE

    E-print Network

    US Army Corps of Engineers

    FM 4-02.18 (FM 8-10-18) VETERINARY SERVICE TACTICS, TECHNIQUES, AND PROCEDURES DECEMBER 2004 2004 VETERINARY SERVICE TACTICS, TECHNIQUES, AND PROCEDURES TABLE OF CONTENTS Page PREFACE ... .................................................................................... v CHAPTER 1. VETERINARY SUPPORT IN MILITARY OPERATIONS ........... 1-1 Section I. Mission

  2. Chirped optical solitons in single-mode birefringent fibers

    NASA Astrophysics Data System (ADS)

    Mahmood, M. F.

    1996-12-01

    The trapping behavior of two chirped solitons forming a bound state in a single-mode birefringent fiber is investigated on the basis of a model of coupled nonlinear Schroedinger equations. The positive initial chirp plays an important role in controlling the threshold amplitude for soliton trapping without causing excessive pulse broadening.

  3. Chirping noise of laser diodes under small signal modulation

    Microsoft Academic Search

    Zang Huai-quan; Duan Hui

    2009-01-01

    Distributed feedback laser diodes are of high modulation frequency response. They can be used as light sources and be directly modulated for high bit rate optical communication. As the case of conventional laser diodes, direct intensity modulation of DFB laser diodes brings about chirping, which affects the performance of optical transmission systems. In this paper, chirping characteristics of DFB laser

  4. MULTICOMPONENT CHIRP DEMODULATION USING DISCRETE FRACTIONAL FOURIER ANALYSIS

    E-print Network

    Santhanam, Balu

    MULTICOMPONENT CHIRP DEMODULATION USING DISCRETE FRACTIONAL FOURIER ANALYSIS Lakshmikanth Reddy S, there has been significant interest in the area of discrete fractional Fourier analysis (DFRFT) because of multicomponent chirp demodulation using the recently introduced multi angle-centered discrete fractional fourier

  5. Frequency chirping in semiconductor-optical fiber ring laser

    SciTech Connect

    Zhang, Jiangping; Ye, Peida (Beijing Univ. of Posts and Telecommunications (China))

    1990-01-01

    In this letter, a complete small-signal analysis for frequency chirping in the semiconductor-optical fiber ring laser is presented. It shows that chirp-to-power ratio (CPR) strongly depends on the junction phase shift, the optical coupling, and the phase detuning between two cavities, especially if the modulation frequency is below the gigahertz range. 7 refs.

  6. Chirp and cw linewidth measurements of integrated external cavity lasers

    NASA Astrophysics Data System (ADS)

    Dutta, N. K.; Cella, T.; Piccirilli, A. B.; Brown, R. L.; Green, C.

    1988-01-01

    Single-frequency integrated external cavity distributed Bragg reflector lasers emitting near 1.5 ?m have been fabricated. The chirp and cw linewidth measurements of these devices show that lasers with long external cavity exhibit lower chirp and lower cw linewidth compared to lasers with short external cavity. The experimental data are explained by using theoretical calculations.

  7. Interferometric fiber sensor with a chirped Bragg grating sensing element

    NASA Astrophysics Data System (ADS)

    Kersey, Alan D.; Davis, Michael A.

    1994-09-01

    An interferometric sensor based on the use of a chirped Bragg grating reflector is described. It is shown that strain applied to the chirped grating can induce a large path length change in an interferometer, equivalent to that obtained with a multi-meter length of fiber when strained directly.

  8. Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers

    E-print Network

    Xie, Xiaoliang Sunney

    Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers Dan Fu, Gary imaging system using chirped femtosecond lasers to achieve rapid Raman spectra acquisition while retaining laser beams with an energy difference tuned to the vibrational frequency of the molecule of interest

  9. Chirp: a practical global filesystem for cluster and Grid computing

    Microsoft Academic Search

    Douglas Thain; Christopher Moretti; Jeffrey Hemmes

    2009-01-01

    Traditional distributed £lesystem technologies designed for local and campus area networks do not adapt well to wide area grid computing environments. To address this problem, we have designed the Chirp distributed £lesystem, which is designed from the ground up to meet the needs of grid computing. Chirp is easily deployed without special privileges, provides strong andexible security mechanisms, tunable consistency

  10. Waveform-dependent absorbing metasurfaces

    E-print Network

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  11. Waveform-dependent absorbing metasurfaces.

    PubMed

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2013-12-13

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW's), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications. PMID:24483674

  12. Waveform-Dependent Absorbing Metasurfaces

    NASA Astrophysics Data System (ADS)

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J.; Sievenpiper, Daniel F.

    2013-12-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW’s), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  13. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Interference to the input signals of FM translator...Broadcast Stations (LPFM) § 73.827 Interference to the input signals of FM translator...that the LPFM station is causing actual interference to the FM translator or FM...

  14. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Interference to the input signals of FM translator...Broadcast Stations (LPFM) § 73.827 Interference to the input signals of FM translator...that the LPFM station is causing actual interference to the FM translator or FM...

  15. CHIRPED PULSE AMPLIFICATION OF HGHG-FEL FACILITY AT BNL.

    SciTech Connect

    DOYURAN,A.ET AL.

    2003-09-08

    The DUV-FEL facility has been in operation in High Gain Harmonic Generation (HGHG) mode for one year producing 266 nm output from 177 MeV electrons. In this paper we present preliminary results of the Chirped Pulse Amplification (CPA) of HGHG radiation. In the normal HGHG process, a 1 ps electron beam is seeded by chirped 9 ps long 800 nm Ti:Sapphire laser. The electron beam sees only a narrow fraction of the seed laser bandwidth. However, in the CPA case the seed laser pulse length is reduced to 1 ps, and the electron beam sees the full bandwidth. We introduce an energy chirp on electron beam to match the chirp of the seed pulse, enabling the resonant condition for the whole beam. We present measurements of the spectrum bandwidth for various chirp conditions.

  16. Frequency chirping during a fishbone burst

    NASA Astrophysics Data System (ADS)

    Marchenko, V. S.; Reznik, S. N.

    2011-12-01

    It is shown that frequency chirping during fishbone activity can be attributed to the reactive torque exerted on the plasma during the instability burst, which slows down plasma rotation inside the q = 1 surface and reduces the mode frequency in the lab frame. Estimates show that the peak value of this torque can exceed the neutral beam torque in modern tokamaks. The simple line-broadened quasilinear burst model (Berk et al 1995 Nucl. Fusion 35 1661), properly adapted for the fishbone case, is capable of reproducing the key features of the bursting mode.

  17. Parameter Biases Introduced by Approximate Gravitational Waveforms

    NASA Astrophysics Data System (ADS)

    Farr, Benjamin; Coughlin, Scott; Le, John; Skeehan, Connor; Kalogera, Vicky

    2013-04-01

    The production of the most accurate gravitational waveforms from compact binary mergers require Einstein's equations to be solved numerically, a process far too expensive to produce the ˜10^7 waveforms necessary to estimate the parameters of a measured gravitational wave signal. Instead, parameter estimation depends on approximate or phenomenological waveforms to characterize measured signals. As part of the Ninja collaboration, we study the biases introduced by these methods when estimating the parameters of numerically produced waveforms.

  18. WAVEFORM ANALYSIS TECHNIQUES IN AIRBORNE LASER SCANNING

    Microsoft Academic Search

    W. Wagner; A. Roncat; T. Melzer; A. Ullrich

    2007-01-01

    Small-footprint airborne laser scanners with waveform-digitising capabilities are becoming increasingly available. Waveform- digitising is particularly advantageous when the backscattered echo waveform is complex because it allows selecting processing algorithms adjusted to the task. In addition, waveform-digitising laser scanners depict the physical measurement process in its entire complexity. This opens the possibility to derive the backscatter cross section which is a

  19. OFDM waveforms for multistatic radars

    Microsoft Academic Search

    Y. Paichard

    2010-01-01

    In this paper, the benefits of OFDM waveforms are analyzed for multistatic radar systems, where several radar stations cooperate in the same frequency band. The signal is coded over a 2D pattern, in the time and the frequency domains, using orthogonal Golay complementary sets derived from Reed-Muller codes. Binary data are also encoded in the signal. The obtained ambiguity and

  20. Handset antenna design for FM reception

    Microsoft Academic Search

    Jaume Anguera; David Aguilar; Jordi Vergés; Miquel Ribó; Carles Puente

    2008-01-01

    A passive internal handset antenna for FM reception is presented. Several prototypes have been simulated and tested showing the interesting potential of this solution to eliminate the long cable 1 meter length used at the present time in some mobiles phones.

  1. FM 7-100.4 Opposing Force

    E-print Network

    US Army Corps of Engineers

    for the COE. The Deputy Chief of Staff for Intelligence (DCSINT) of the U.S. Army Training and Doctrine for Intelligence (ODCSINT) has created a flexible baseline for an OPFOR that can be adapted to meet a variety organizations outlined in FM 7-100.4 and the associated online organizational directories represent a realistic

  2. FM Clerkship Update Helping Students do well

    E-print Network

    Maxwell, Bruce D.

    References #12;Key Teaching Points #12;+ Student log data # cases completed # cards within case completed Honors Family Medicine Pediatrics Internal Medicine Psychiatry #12;+ FM Clerkship Final Grade Mid-clerkship and annual basis. · All statistical analyses were conducted with SPSS (v19, 2010). ACKNOWLEDGEMENTS

  3. October 22002 FM Crew Collaborates on

    E-print Network

    Webb, Peter

    to a considerable amount of damage control and a quick clean up of this incident. FM Fights Flood in Football. They discovered that the release valve on the boiler was stuck open and the drain in the mechanical room situations. Thank you to each and every one of you who responded to the chemistry explosion in Amundson Hall

  4. FM 3-04.111 Aviation Brigades

    E-print Network

    US Army Corps of Engineers

    FM 3-04.111 Aviation Brigades DECEMBER 2007 DISTRIBUTION RESTRICTION: Approved for public release-04.111 Headquarters Department of the Army Washington, D.C., 7 December 2007 Aviation Brigades Contents Page PREFACE ................................................................................ 1-4 Heavy, Medium, and Light Combat Aviation Brigades....................................... 1

  5. Automated Analysis, Classification, and Display of Waveforms

    NASA Technical Reports Server (NTRS)

    Kwan, Chiman; Xu, Roger; Mayhew, David; Zhang, Frank; Zide, Alan; Bonggren, Jeff

    2004-01-01

    A computer program partly automates the analysis, classification, and display of waveforms represented by digital samples. In the original application for which the program was developed, the raw waveform data to be analyzed by the program are acquired from space-shuttle auxiliary power units (APUs) at a sampling rate of 100 Hz. The program could also be modified for application to other waveforms -- for example, electrocardiograms. The program begins by performing principal-component analysis (PCA) of 50 normal-mode APU waveforms. Each waveform is segmented. A covariance matrix is formed by use of the segmented waveforms. Three eigenvectors corresponding to three principal components are calculated. To generate features, each waveform is then projected onto the eigenvectors. These features are displayed on a three-dimensional diagram, facilitating the visualization of the trend of APU operations.

  6. Three-Dimensional Analysis of Frequency-Chirped FELs

    SciTech Connect

    Huang, Z.

    2010-09-14

    Frequency-chirped free-electron lasers (FELs) are useful to generate a large photon bandwidth or a shorter x-ray pulse duration. In this paper, we present a three-dimensional analysis of a high-gain FEL driven by the energy-chirped electron beam. We show that the FEL eigenmode equation is the same for a frequency-chirped FEL as for an undulator-tapered FEL. We study the transverse effects of such FELs including mode properties and transverse coherence.

  7. Determinism in synthesized chaotic waveforms.

    PubMed

    Corron, Ned J; Blakely, Jonathan N; Hayes, Scott T; Pethel, Shawn D

    2008-03-01

    The output of a linear filter driven by a randomly polarized square wave, when viewed backward in time, is shown to exhibit determinism at all times when embedded in a three-dimensional state space. Combined with previous results establishing exponential divergence equivalent to a positive Lyapunov exponent, this result rigorously shows that such reverse-time synthesized waveforms appear equally to have been produced by a deterministic chaotic system. PMID:18517561

  8. The NINJA-2 Waveform Catalog

    NASA Astrophysics Data System (ADS)

    Pekowsky, Larne

    2012-03-01

    Two important advances have occurred in recent years which have brought us closer to the goal of observing and interpreting gravitational waves from coalescing compact objects: the successful construction and operation of a world-wide network of ground-based gravitational-wave detectors and the impressive success of numerical relativity in successfully simulating the merger phase of Binary Black Hole (BBH) coalescence. The aim of the NINJA project is to study the sensitivity of gravitational-wave analysis pipelines to numerical simulations of waveforms and foster close collaboration between numerical relativists and data analysts. NINJA-1 was a huge success, over 75 numerical relativists and data analysis participated in the contribution of a simulated data set containing numerical waveforms, analysis of this data and interpreting the results of this analysis. The follow-up project, NINJA-2 is currently underway. We present some of the goals of NINJA-2 and discuss aspects of the construction of the catalog of waveforms which will be used.

  9. 75 FR 65521 - FM Approvals; Expansion of Recognition

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ...Conditioners UL 521 Heat Detectors for Fire Protective Signaling Systems UL 1480 Speakers for Fire Alarm, Emergency, and Commercial and Professional...Signaling FM 3210 Heat Detectors for Automatic Fire Alarm Signaling FM 7260 Electrostatic...

  10. An Evaluation of FCC Policy on FM Ownership.

    ERIC Educational Resources Information Center

    Soley, Lawrence C.

    1979-01-01

    An examination of data on FM construction permits shows that independent FM broadcasters have obtained construction permits in markets with larger adjusted populations than those where AM licensees were granted same-market permits. (GT)

  11. Quantum Fluctuations in the Chirped Pendulum

    E-print Network

    K. W. Murch; R. Vijay; I. Barth; O. Naaman; J. Aumentado; L. Friedland; I. Siddiqi

    2010-08-26

    An anharmonic oscillator when driven with a fast, frequency chirped voltage pulse can oscillate with either small or large amplitude depending on whether the drive voltage is below or above a critical value-a well studied classical phenomenon known as autoresonance. Using a 6 GHz superconducting resonator embedded with a Josephson tunnel junction, we have studied for the first time the role of noise in this non-equilibrium system and find that the width of the threshold for capture into autoresonance decreases as the square root of T, and saturates below 150 mK due to zero point motion of the oscillator. This unique scaling results from the non-equilibrium excitation where fluctuations, both quantum and classical, only determine the initial oscillator motion and not its subsequent dynamics. We have investigated this paradigm in an electrical circuit but our findings are applicable to all out of equilibrium nonlinear oscillators.

  12. Rb saturation spectroscopy with an optically narrowed FM diode laser

    Microsoft Academic Search

    G. P. Barwood; P. Gill; W. R. C. Rowley

    1991-01-01

    A fast-frequency modulated (FM) diode laser has been optically narrowed using the technique of resonant optical feedback, to provide linewidths in each FM mode of ~ 200 kHz peak-to-peak. With a drive frequency of 50 MHz and modulation index of 0.2, the FM laser has been used for the first time to obtain Doppler-free FM spectra of the Rb D1

  13. CERES (FM2) field campaigns of 2008

    NASA Astrophysics Data System (ADS)

    Szewczyk, Z. Peter; Priestley, Kory J.

    2009-09-01

    A Clouds and the Earth's Radiant Energy System instrument (FM2) on board the Terra satellite has been used in field campaigns to provide TOA radiance measurements. Using a special programmable azimuth plan scan (PAPS) mode, a scanner collects data over a specified Earth target or of a prescribed spatial orientation. This paper covers operational aspects of four field campaigns in which FM2 participated in 2008. These include the annual CERES/GERB comparison campaign carried out at the summer and winter solstices, an aerosol campaign over Beijing ran before, during and after Summer Olympics, calibration and validation of GERB radiances at the ground station in Alacar/Spain, and also a bi-weekly true long-track scan for comparison to true nadir instruments.

  14. Techniques for High-Bandwidth (?30 GHz) Chirped-Pulse Submillimeter-Wave Spectroscopy

    NASA Astrophysics Data System (ADS)

    Neill, Justin L.; Steber, Amanda L.; Harris, Brent J.; Pate, Brooks H.; Douglass, Kevin O.; Plusquellic, David F.; Gerecht, Eyal

    2011-06-01

    Due to the increased availability of active multiplier chains for converting microwave pulses into the millimeter/submillimeter with reasonably high power (?1 mW), chirped pulses with high phase stability and complete arbitrary waveform generator (AWG) frequency agility can be created and employed for high-sensitivity molecular spectroscopy, as demonstrated at the Symposium in the past few years. The bandwidths of multiplier chains, however, can exceed the current limitations on digitizer bandwidth. Therefore, in order to obtain ?30 GHz spectra in ~1 ms or less, techniques are being developed in which a two-channel AWG creates both the chirped pulses for molecular irradiation and a local oscillator pulse for heterodyne detection. These approaches reduce the digitizer bandwidths to 500 MHz or less to collect a high-bandwidth spectrum. A single instrument design can be used to measure both absorption and emission spectra, only requiring that the AWG pulses are changed. Due to the phase stability of the pulse generation and detection, coherent time-domain signal averaging can be performed to enhance sensitivity as desired. Preliminary results from prototype instruments designed at UVa and NIST will be presented, with sensitivity, frequency accuracy, and measurement speed comparisons to current millimeter/submillimeter-wave spectrometers. G.B. Park, A.H. Steeves, K. Kuyanov-Prozument, A.P. Colombo, R.W. Field, J.L. Neill, and B.H. Pate, RH07, 64th International Symposium on Molecular Spectroscopy (2009) K.O. Douglass, D.F. Plusquellic, and E. Gerecht, WH09, 65th International Symposium on Molecular Spectroscopy (2010).

  15. Characterisation of Semiconductor Laser FM Response Leif A Johansson

    E-print Network

    Haddadi, Hamed

    of the measurement is 1.2%. Fig. 1: Measured FM response of 16 quantum well DFB laser. The left scale shows characterisation of the FM response for a typical DFB laser and a frequency stable external cavity laser. 2. Theory and is the coherence efficiency of the interaction between the two signals. Assuming a laser FM response of df/di, we

  16. Translating military experiences of managing innovation and innovativeness into FM

    Microsoft Academic Search

    John Hinks; Martin Alexander; Graham Dunlop

    2007-01-01

    Purpose – This is a conceptual paper for facilities management (FM) practitioners and FM researchers. The paper seeks to analyse a number of well-documented successes and failures in military exploitation of innovation, and identify several recurrent facets that resonate with the contemporary approach to, and difficulties with achieving innovation in FM. Design\\/methodology\\/approach – Several military cases are selected for their

  17. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 4 2010-10-01 2010-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  18. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 4 2013-10-01 2013-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  19. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 4 2012-10-01 2012-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  20. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 4 2011-10-01 2011-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  1. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 4 2014-10-01 2014-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  2. Chirp signalling offers modulation scheme for underwater communications

    Microsoft Academic Search

    Wireless communication can be conducted in the underwater acoustic (UWA) channel through sonar signalling. We propose using the frequency-vs-time slope of sonar 'chirps' to transmit information in a robust scheme for a spread-spectrum underwa- ter communications system. Digitaldatacanberepresented bytheslope of chirpsignals.In the simplest binary case, an 'up' chirp (i.e., a signal with instan- taneous frequency that linearly increases with time)

  3. Automatic frequency control for FM transmitter

    NASA Technical Reports Server (NTRS)

    Honnell, M. A. (inventor)

    1974-01-01

    An automatic frequency control circuit for an FM television transmitter is described. The frequency of the transmitter is sampled during what is termed the back porch portion of the horizontal synchronizing pulse which occurs during the retrace interval, the frequency sample compared with the frequency of a reference oscillator, and a correction applied to the frequency of the transmitter during this portion of the retrace interval.

  4. Phase-locked loop FM demodulator

    NASA Technical Reports Server (NTRS)

    Kirkham, Harold (Inventor); Jackson, Shannon P. (Inventor)

    1992-01-01

    A conventional phase-locked loop is improved by replacing its phase detector with one comprising a linear ramp generator and a sample-and-hold circuit, thus eliminating the need for a lowpass loop filter, although the output of the sample-and-hold circuit may be filtered in the case of a very low level modulating signal on the incoming FM signal, but then filtering is not a difficult problem as in a conventional phase-locked loop. The result is FM demodulation by zero-order estimation. For FM demodulation by first-order estimation, the arithmetic difference between adjacent samples is formed, and using a second sample-and-hold circuit an arithmetic difference signal is produced as an input to a second ramp generator that is reset after each sampling cycle to generate a ramp the slope of which is a function of the arithmetic difference signal stored in the second sample-and-hold circuit. The ramp thus generated by the second ramp generator is arithmetically summed with the zero-estimation signal from the first sample-and-hold circuit to form a first-order estimation signal. Filtering such a first-order estimation signal is less of a problem than filtering a zero-order estimation signal.

  5. High-precision triangular-waveform generator

    DOEpatents

    Mueller, T.R.

    1981-11-14

    An ultra-linear ramp generator having separately programmable ascending and decending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  6. Lightning current waveform measuring system

    NASA Technical Reports Server (NTRS)

    Wojtasinski, R. J.; Fuchs, J. C.; Grove, C. H. (inventors)

    1978-01-01

    An apparatus is described for monitoring current waveforms produced by lightning strikes which generate currents in an elongated cable. These currents are converted to voltages and to light waves for being transmitted over an optical cable to a remote location. At the remote location, the waves are reconstructed back into electrical waves for being stored into a memory. The information is stored within the memory with a timing signal so that only different signals need be stored in order to reconstruct the wave form.

  7. FD-CHIRP: hosted payload system engineering lessons

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2012-10-01

    The Commercially Hosted Infrared Payload (CHIRP) Flight Demonstration (FD-CHIRP) launched 21 Sept 2011 was designated a "resounding success" as the first Wide Field-of-View (WFOV) staring infrared (IR) sensor flown in geostationary earth orbit (GEO) with a primary mission of Missile Warning (MW). FD-CHIRP was an Air Force research and development project initiated in July 2008 via an unsolicited industry proposal aimed to mature and reduce the risk of WFOV sensors and ground processing technologies. Unlike the Defense Support Program (DSP) and the Space Based Infrared System (SBIRS) which were acquired via traditional integrated sensor and satellite design, FDCHIRP was developed using the "commercially hosted" approach. The FD-CHIRP host spacecraft and sensor were independently designed, creating significant development risk to the industry proposer, especially under a Firm Fixed Price contract. Yet, within 39 months of contract initiation, FD-CHIRP was launched and successfully operated in GEO to 30 June 2012 at a total cost of 111M including the 82.9M CHIRP commercial-hosting contract and a $28M sensor upgrade. The commercial-hosting contract included sensor and spacecraft modifications, integration and test, design and development of secure Mission Operations and Analysis Centers, launch, and nearly a year of GEO operations with 70 Mbps secure data acquisition. The Air Force extended the contract for six months to continue operations through the end of calendar 2012. This paper outlines system engineering challenges FD-CHIRP overcame and key lessons to smooth development of future commercially hosted missions.

  8. Multiple mechanisms shape FM sweep rate selectivity: complementary or redundant?

    PubMed Central

    Williams, Anthony J.; Fuzessery, Zoltan M.

    2012-01-01

    Auditory neurons in the inferior colliculus (IC) of the pallid bat have highly rate selective responses to downward frequency modulated (FM) sweeps attributable to the spectrotemporal pattern of their echolocation call (a brief FM pulse). Several mechanisms are known to shape FM rate selectivity within the pallid bat IC. Here we explore how two mechanisms, stimulus duration and high-frequency inhibition (HFI), can interact to shape FM rate selectivity within the same neuron. Results from extracellular recordings indicated that a derived duration-rate function (based on tonal response) was highly predictive of the shape of the FM rate response. Longpass duration selectivity for tones was predictive of slowpass rate selectivity for FM sweeps, both of which required long stimulus durations and remained intact following iontophoretic blockade of inhibitory input. Bandpass duration selectivity for tones, sensitive to only a narrow range of tone durations, was predictive of bandpass rate selectivity for FM sweeps. Conversion of the tone duration response from bandpass to longpass after blocking inhibition was coincident with a change in FM rate selectivity from bandpass to slowpass indicating an active inhibitory component to the formation of bandpass selectivity. Independent of the effect of duration tuning on FM rate selectivity, the presence of HFI acted as a fastpass FM rate filter by suppressing slow FM sweep rates. In cases where both mechanisms were present, both had to be eliminated, by removing inhibition, before bandpass FM rate selectivity was affected. It is unknown why the auditory system utilizes multiple mechanisms capable of shaping identical forms of FM rate selectivity though it may represent distinct but convergent modes of neural signaling directed at shaping response selectivity for important biologically relevant sounds. PMID:22912604

  9. Photonically-assisted Arbitrary Millimeter Waveform Generation

    E-print Network

    Purdue University

    Generation · Fourier Transform (FT) pulse shapers widely used for arbitrary optical waveform generation. ** A (UWB) · Secure · Multiple access Pulsed Radar SensingW aveform ReturnW aveform Current commercial-waveforms of >100ps duration! · Novel DST pulse shaper enables pulse shaping pulse shaping over the >100ps temporal

  10. Radar waveform design for detection of weapons

    Microsoft Academic Search

    Fauzia Ahmad; Moeness G. Amin

    2010-01-01

    We present waveform design based on signature exploitation techniques for improved detection of weapons in urban sensing applications. We consider a single-antenna monostatic radar system. Under the assumption of exact knowledge of the target orientation and, hence, known impulse response, matched illumination approach is used for optimal target detection. For the case of unknown target orientation, we propose waveform design

  11. Connecting Communications Waveforms for Combat Effectiveness

    Microsoft Academic Search

    Siamak Dastangoo; Steven A. Davidson; Thomas G. Macdonald

    2007-01-01

    Future networks, and in particular military networks, will connect numerous types of homogeneous networks, where a homogeneous network is one that uses the same communications waveform and algorithms to inter-connect all the users of the network. There are a number of challenges in inter-networking disparate waveforms including interacting with a network that does not behave in the same manner as

  12. Principal component analysis of lifting waveforms

    Microsoft Academic Search

    Allan T. Wrigley; Wayne J. Albert; Kevin J. Deluzio; Joan M. Stevenson

    2006-01-01

    Background. One limiting factor in lifting research design has been the inability to effectively analyze waveform data, especially when differences in body mass, height, and load magnitude influence the derived kinetic variables. The purpose of this study was to demon- strate the sensitivity of principal component analysis to quantify clinically relevant differences in kinetic lifting waveforms over three load magnitudes

  13. Resolving Lithospheric Interfaces Using SS Waveform Stacks

    Microsoft Academic Search

    C. A. Rychert; P. M. Shearer

    2009-01-01

    We image lithospheric interfaces globally using variations in the character of SS waveform stacks. The variations are caused by reflected phases, i.e., underside reflections (SS precursors) and topside multiples (SS reverberations), created at discontinuities near the midpoint of the SS raypath. Stacks from continental versus oceanic bouncepoint regions produce distinctly different SS waveforms, consistent with the large continent\\/ocean difference in

  14. Arithmetic coding in lossless waveform compression

    Microsoft Academic Search

    S. D. Stearns

    1995-01-01

    A method for applying arithmetic coding to lossless waveform compression is discussed. Arithmetic coding has been used widely in lossless text compression and is known to produce compression ratios that are nearly optimal when the symbol table consists of an ordinary alphabet. In lossless compression of digitized waveform data, however, if each possible sample value is viewed as a “symbol”

  15. Optical arbitrary waveform characterization using linear spectrograms

    PubMed Central

    Jiang, Zhi; Leaird, Daniel E.; Long, Christopher M.; Boppart, Stephen A.; Weiner, Andrew M.

    2010-01-01

    We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms. PMID:21359161

  16. Optimal Adaptive Waveform Selection for Target Tracking

    E-print Network

    Rezaeian, Mohammad-Jafar

    Optimal Adaptive Waveform Selection for Target Tracking Barbara La Scala Mohammad Rezaeian Bill algorithms. This paper describes an optimal adaptive waveform selection algorithm for target tracking scheduling for target tracking as a stochastic dy- namic programming problem. The result is a scheduling

  17. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    SciTech Connect

    Unruh, W.P.; Wolf, M.A.; Bluestein, H.B.

    1988-01-01

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm. 2 refs., 2 figs.

  18. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    NASA Astrophysics Data System (ADS)

    Unruh, Wesley P.; Wolf, Michael A.; Bluestein, Howard B.

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm.

  19. Quasimonoenergic collimated electrons from the ionization of nitrogen by a chirped intense laser pulse

    SciTech Connect

    Singh, Kunwar Pal [Singh Simutech Pvt. Ltd., Bharatpur, Rajasthan 321201 (India); Sajal, Vivek [Department of Physics, Jaypee Institute of Information Technology University, Noida 201 307, Uttar Pradesh (India)

    2009-04-15

    A scheme is proposed for quasimonoenergic collimated GeV electrons generated during ionization of nitrogen by a chirped intense laser pulse. The electrons accelerated by a laser pulse without a frequency chirp are known for poor-quality beams. If a suitable frequency chirp is introduced, then the energy of the electrons increases significantly. It is shown that quasimonoenergic collimated GeV electrons can be produced using a right choice of laser spot size, frequency chirp, and pulse duration.

  20. Interpolation in waveform space: enhancing the accuracy of gravitational waveform families using numerical relativity

    E-print Network

    Cannon, Kipp; Hanna, Chad; Keppel, Drew; Pfeiffer, Harald

    2012-01-01

    Matched-filtering for the identification of compact object mergers in gravitational-wave antenna data involves the comparison of the data stream to a bank of template gravitational waveforms. Typically the template bank is constructed from phenomenological waveform models since these can be evaluated for an arbitrary choice of physical parameters. Recently it has been proposed that singular value decomposition (SVD) can be used to reduce the number of templates required for detection. As we show here, another benefit of SVD is its removal of biases from the phenomenological templates along with a corresponding improvement in their ability to represent waveform signals obtained from numerical relativity (NR) simulations. Using these ideas, we present a method that calibrates a reduced SVD basis of phenomenological waveforms against NR waveforms in order to construct a new waveform approximant with improved accuracy and faithfulness compared to the original phenomenological model. The new waveform family is giv...

  1. Subjective evaluation of FM\\/FM protection radio for television broadcasting by satellite, appendices

    Microsoft Academic Search

    C. Loo; G. Chouinard; W. B. Tonner

    1980-01-01

    Subjective measurements of the interference between two FM TV signals at the same carrier frequency and at different carrier frequencies are described. There is no masking of the interference due to additive Gaussian noise in the wanted channel. The results do not support the conclusion that an impairment grade of 4.5 on the CCIR scale is subjectively equivalent to just

  2. Project Summary MRI: Development of a Chirped-Pulse, Fourier-Transform mm-Wave Pulsed

    E-print Network

    Baskaran, Mark

    Project Summary MRI: Development of a Chirped-Pulse, Fourier-Transform mm-Wave Pulsed Uniform technologies: chirped-pulse Fourier-transform mm-wave spectroscopy and pulsed uniform supersonic flows: The instrument will leverage the ultra-broadband Chirped-pulse Fourier-transform Microwave (CP

  3. Effect of chirped gratings on reflective optical bistability in DFB semiconductor laser amplifiers

    Microsoft Academic Search

    Drew N. Maywar; Govind P. Agrawal

    1998-01-01

    We use spatial chirp of the built-in grating to improve optical bistability on reflection from distributed feedback semiconductor laser amplifiers. We show that improvements in the on-off switching ratio occur because spatial chirp greatly affects the saturation behavior of the reflectivity resonances, allowing access to states of low reflection during bistable switching. We also show that spatial chirp modifies the

  4. An efficient Non-Linear Chirp Scaling method of focusing bistatic SAR images

    Microsoft Academic Search

    Yew Lam Neo; Frank Wong; Ian Cumming

    Bistatic SAR data processing parameters, unlike monostatic SAR data, are generally azimuth-variant. The Non-Linear Chirp Scaling (NLCS) algorithm introduced in this paper is able to handle the azimuth variance. It focuses a bistatic image by first introducing a bulk linear range cell migration correction followed by a chirp scaling process to equalize the azimuth chirp rates for all targets in

  5. Frequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa...

    E-print Network

    Geddes, Cameron Guy Robinson

    Frequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa... C. B excitation in a self-modulated laser wakefield accelerator is examined. Laser pulse shape and frequency chirp negative frequency chirp enhances suppresses the growth rate of the Raman forward scattering and near

  6. Fiber Bragg grating strain sensor demodulator using a chirped fiber grating

    Microsoft Academic Search

    Sungchul Kim; Seungwoo Kim; Jaejoon Kwon; Byoungho Lee

    2001-01-01

    A fiber Bragg grating (FBG) sensor demodulator using a chirped fiber grating is proposed. The demodulator uses UV-induced birefringence of chirped fiber grating to interrogate the wavelength shift of a sensor FBG. The demodulator is composed of a polarizing beam splitter, a polarization controller, a single-mode fiber, and a chirped fiber grating. The proposed demodulator is immune to light power

  7. Chirp Multiplication by Four Wave Mixing for Wideband Swept-Frequency Sources for High Resolution Imaging

    Microsoft Academic Search

    Naresh Satyan; George Rakuljic; Amnon Yariv

    2010-01-01

    We present an analysis and demonstration of the doubling of the chirp rate and total chirp bandwidth of a frequency chirped optical signal by the process of four-wave mixing in a non-linear optical medium. The effects of chromatic dispersion and input power on the maximum achievable output bandwidth are analyzed, and a dispersion compensation technique for phase matching is described.

  8. On a Pseudo-Subspace Framework for Discrete Fractional Fourier Transform Based Chirp

    E-print Network

    Santhanam, Balu

    On a Pseudo-Subspace Framework for Discrete Fractional Fourier Transform Based Chirp Parameter to develop a pseudo-subspace approach towards chirp parameter estimation. Keywords: Discrete Fractional to the pseudo signal subspace and small values corresponding to the pseudo noise subspace. transform based chirp

  9. Schwinger vacuum pair production in chirped laser pulses

    SciTech Connect

    Dumlu, Cesim K. [Department of Physics, University of Connecticut, Storrs Connecticut 06269-3046 (United States)

    2010-08-15

    The recent developments of high intensity ultrashort laser pulses have raised the hopes of observing Schwinger vacuum pair production which is one of the important nonperturbative phenomena in QED. The quantitative analysis of realistic high intensity laser pulses is vital for understanding the effect of the field parameters on the momentum spectrum of the produced particles. In this study, we analyze chirped laser pulses with a subcycle structure, and investigate the effects of the chirp parameter on the momentum spectrum of the produced particles. The combined effect of the chirp and carrier phase of the laser pulse is also analyzed. These effects are qualitatively explained by investigating the turning-point structure of the potential within the framework of the complex WKB scattering approach to pair production.

  10. Excitation of Chirping Whistler Waves in a Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Pribyl, P.; Gekelman, W.

    2015-06-01

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified.

  11. Edge effects in chirped-pulse Fourier transform microwave spectra

    NASA Astrophysics Data System (ADS)

    Park, G. Barratt; Field, Robert W.

    2015-06-01

    Recent applications of chirped-pulse Fourier transform microwave and millimeter wave spectroscopy have motivated the use of short (10-50 ns) chirped excitation pulses. In this regime, individual transitions within the chirped pulse bandwidth do not all, in effect, experience the same frequency sweep through resonance from far above to far below (or vice versa), and "edge effects" may dominate the relative intensities. We analyze this effect and provide simplifying expressions for the linear fast passage polarization response in the limit of long and short excitation pulses. In the long pulse limit, the polarization response converges to a rectangular function of frequency, and in the short pulse limit, the polarization response morphs into a form proportional to the window function of the Fourier-transform-limited excitation pulse.

  12. Effects of collisions on energetic particle-driven chirping burstsa)

    NASA Astrophysics Data System (ADS)

    Lesur, M.

    2013-05-01

    In the presence of an energetic particle population in a dissipative plasma, self-trapped structures in phase-space (holes and clumps) emerge from nonlinear wave-particle interactions. Their dynamics can lead to a nonlinear continuous shifting of the wave frequency (chirping). The effects of collisions on chirping characteristics are investigated, with a one-dimensional kinetic model. Existing analytic theory is extended to account for Krook-like collisions, which quantitatively explains a significant departure from widely accepted square-root time dependency. Relaxation oscillations, associated with chirping bursts, are investigated in the presence of dynamical friction and velocity-diffusion. The period increases with decreasing drag and weakly increases with decreasing diffusion. The mechanism is clarified with a simple semi-analytic model of hole/clump pair, which satisfies a Fokker-Planck equation. The model shows that the linear growth rate cannot be obtained simply by fitting an exponential to the amplitude time-series.

  13. Latent Fingerprint Analysis Using an AM-FM Model

    Microsoft Academic Search

    Marios Pattichis; Alan Bovik

    We adapt a novel AM-FM (amplitude-modulation, frequency-modulation) image representation to process latent fingerprint images.\\u000a The AM-FM representation captures, in a very natural way, the global flow of fingerprint patterns. Discontinuities in this\\u000a flow are easily detectable as potential fingerprint minutiae. We demonstrate application of an AM-FM-based system to actual\\u000a latent fingerprints and make comparison to expert human analysis.

  14. AM-FM separation using auditory-motivated filters

    Microsoft Academic Search

    Thomas F. Quatieri; Thomas E. Hanna; G. C. O'Leary

    1997-01-01

    An approach to the joint estimation of sine-wave amplitude modulation (AM) and frequency modulation (FM) is described based on the transduction of frequency modulation into amplitude modulation by linear filters, being motivated by the hypothesis that the auditory system uses a similar transduction mechanism in measuring sine-wave FM. An AM-FM estimation algorithm is described that uses the amplitude envelope of

  15. AM-FM separation using auditory-motivated filters

    Microsoft Academic Search

    T. F. Quatieri; T. E. Hanna; G. C. O'Leary

    1996-01-01

    A new approach to the joint estimation of sine-wave amplitude modulation (AM) and frequency modulation (FM) is presented based on the transduction of frequency modulation into amplitude modulation by digital filters, being motivated by the hypothesis that the auditory front end uses a similar transduction mechanism in measuring sine-wave FM. An AM-FM estimation algorithm is derived which uses the amplitude

  16. ATTP 3-34.80 (FM 3-34.230, FM 5-33, and TC 5-230) GEOSPATIAL ENGINEERING

    E-print Network

    US Army Corps of Engineers

    ATTP 3-34.80 (FM 3-34.230, FM 5-33, and TC 5-230) July 2010 GEOSPATIAL ENGINEERING DISTRIBUTION. Reimer Training and Doctrine Digital Library at train.army.mil>. #12;*ATTP 3-34.80 (FM 3-34.230, FM. *This publication will supersede FM 3-34.230, 3 August 2000; FM 5-33, 11 July 1990; and Training

  17. Mode-selective excitation using ultrafast chirped laser pulses

    NASA Astrophysics Data System (ADS)

    Malinovskaya, S. A.

    2006-03-01

    We propose a method to control population transfer and coherence in a multimode system using a transform-limited pump and a linearly chirped Stokes pulse in stimulated Raman scattering. Simultaneously applied pump and Stokes pulse are shown to induce the ac Stark shifts that result in nonadiabatic coupling of the dressed states, through which the pulse chirp governs population distribution. The method may be applied to selectively excite Raman transitions having the frequency difference less than the bandwidth of a transform-limited pulse.

  18. Effects of frequency chirp on magnetron injection locking

    SciTech Connect

    Pengvanich, P.; Lau, Y. Y.; Luginsland, J. W.; Gilgenbach, R. M.; Cruz, E. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Schamiloglu, E. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2008-07-15

    The injection locking of a magnetron is theoretically analyzed when either the free running oscillator or the drive signal has a frequency chirp. It is found that complete phase locking of the signal cannot be achieved in either case. However, as long as the locking condition of Adler is well-satisfied instantaneously, a high degree of locking occurs during a major duration of the frequency chirps. The expected output phase variation is computed in terms of the noise in the free-running magnetron oscillator for the case of constant drive frequency.

  19. Dense Monoenergetic Proton Beams from Chirped Laser-Plasma Interaction

    NASA Astrophysics Data System (ADS)

    Galow, Benjamin J.; Salamin, Yousef I.; Liseykina, Tatyana V.; Harman, Zoltán; Keitel, Christoph H.

    2011-10-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (107 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 1021W/cm2.

  20. Chirped pulse excitation of two-atom Rydberg states

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Elena

    2015-07-01

    We analyze the excitation of two ground state atoms to a double Rydberg state by a two-photon chirped optical pulse in the regime of adiabatic rapid passage (ARP). For intermediate Rydberg–Rydberg interaction strengths relevant for atoms separated by ?ten ?m, adiabatic excitation can be achieved at experimentally feasible Rabi frequencies and chirp rates of the pulses, resulting in high transfer efficiencies. We also study the adiabatic transfer between ground and Rydberg states as a means to realize a controlled phase gate between atomic qubits.

  1. Power losses of Finemet using nonsinusoidal waveforms

    NASA Astrophysics Data System (ADS)

    Ramin, D.; Riehemann, W.

    1999-08-01

    Though many practical applications preferably take advantage of nonsinusoidal induction waveforms the characterisation of soft magnetic materials is performed under sinusoidal induction waveforms. Therefore, it would be useful if results from magnetic measurements could be transformed to be valid for applications using different waveforms. This also enables to compare results obtained from measurements where sinusoidal waveforms could not be realised and thus makes them independent of the measuring device used. The dynamic hysteresis loops of differently prepared Finemet ribbons were measured with a computer controlled device at different frequencies and polarisations using sinusoidal and triangular waveforms of the magnetic field which leads to induction waveforms varying with frequency, amplitude of polarisation, waveform of the magnetising field and preparation of specimen material. The samples measured were strips of Fe 73.5Si 13.5Cu 1Nb 3B 9 nanocrystallised at 580°C for 1 h. Different types of samples were used which includes specimens surface treated prior to heat treatment in order to achieve domain refinement. A one to one functional dependency between power loss, frequency, and k-factor was found that enables the comparison of power losses for different induction signals characterised by their form factor as it is already known for grain oriented silicon steel sheets. This dependency is valid for all types of specimen investigated regardless of their different magnetic properties.

  2. Length requirements for numerical-relativity waveforms

    E-print Network

    Mark Hannam; Sascha Husa; Frank Ohme; P. Ajith

    2010-09-15

    One way to produce complete inspiral-merger-ringdown gravitational waveforms from black-hole-binary systems is to connect post-Newtonian (PN) and numerical-relativity (NR) results to create "hybrid" waveforms. Hybrid waveforms are central to the construction of some phenomenological models for GW search templates, and for tests of GW search pipelines. The dominant error source in hybrid waveforms arises from the PN contribution, and can be reduced by increasing the number of NR GW cycles that are included in the hybrid. Hybrid waveforms are considered sufficiently accurate for GW detection if their mismatch error is below 3% (i.e., a fitting factor about 0.97). We address the question of the length requirements of NR waveforms such that the final hybrid waveforms meet this requirement, considering nonspinning binaries with q = M_2/M_1 \\in [1,4] and equal-mass binaries with \\chi = S_i/M_i^2 \\in [-0.5,0.5]. We conclude that for the cases we study simulations must contain between three (in the equal-mass nonspinning case) and ten (the \\chi = 0.5 case) orbits before merger, but there is also evidence that these are the regions of parameter space for which the least number of cycles will be needed.

  3. What FM can offer DFCS design

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1990-01-01

    The results of aircrafts and spacecrafts flight tests are reported. It is shown that the problems of Digital Flight Control Systems (DFCS) are the problems of systems whose complexity has exceeded the reach of the intellectual tools employed. It is also shown that intuition, experience, and techniques derived from mechanical and analog systems are insufficient for complex, integrated, digital systems. Formal Methods (FM) of computer science can offer DFCS systematic techniques for the construction of trustworthy software, including: techniques for the precise specification of requirements and the development of designs; systematic approaches to the design and structuring of distributed and concurrent systems; fault tolerance algorithms; and systematic methods of testing and analytic methods of verification.

  4. Superfluid dynamics of 258Fm fission

    E-print Network

    Guillaume Scamps; Cédric Simenel; Denis Lacroix

    2015-01-15

    Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

  5. Optimal pseudorandom pulse position modulation ladar waveforms.

    PubMed

    Fluckiger, David U; Boland, Brian F; Marcus, Eran

    2015-03-20

    An algorithm for generating optimal pseudorandom pulse position modulation (PRPPM) waveforms for ladar ranging is presented. Bistatic ladar systems using Geiger-mode avalanche photodiodes require detection of several pulses in order to generate sufficient target statistics to satisfy some detection decision rule. For targets with large initial range uncertainty, it becomes convenient to transmit a pulse train with large ambiguity range. One solution is to employ a PRPPM waveform. An optimal PRPPM waveform will have minimal sidelobes: equivalent to 1 or 0 counts after the pulse correlation filter (compression). This can be accomplished by generating PRPPM pulse trains with optimal or minimal sidelobe autocorrelation. PMID:25968498

  6. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect

    Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

    2014-06-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  7. Higher Order Combination Tones Applied To Sonar Waveform Design And Underwater Digital Communications

    NASA Astrophysics Data System (ADS)

    Fogg, Stephen L.

    2006-05-01

    Nonlinear `parametric' sonar is distinguished by highly predictable in-water formations of identifiable von Helmholtz spectral energies produced directly as a result of two or more preselected primaries simultaneously contained in a transmit waveform. In the nearly half-century of scientific endeavors within the field of parametric sonar, the methodical investigation into formulation techniques and practical applications using higher-order combination tones has been noticeably lagging the attention received by their more commonly recognized kin of second-order sum and difference frequencies. Generalized mathematical and graphical viewing techniques are presented for elucidating the abundance of cross-band complexities and facilitating preliminary design efforts specifically employing any of these higher-order parametric frequency components on operational systems. Recent sonar experiments implementing pulsed parametric transmit waveforms intended to fully exploit their intrinsic broadband nonlinear energy have demonstrated the potential for improved underwater target detection and classification in acoustically harsh environments. However, research efforts could benefit from more efficient and universal tools for predetermining all of the desired in-water spectral-temporal characteristics. New developments utilizing this methodology have led to unique approaches for designing stepped CW, LFM and hyperbolic FM detection waveforms incorporating enhanced signal processing qualities and constructing coding schemes for reliable underwater acoustic digital communications.

  8. Take Anything Else, but Leave My Classroom FM System!

    ERIC Educational Resources Information Center

    Nelson, Denise Grau; Schmidt, Michele

    1993-01-01

    FM (frequency modulation) classroom amplification systems are described. Advantages for students with only minimal hearing losses as well as those more seriously affected are noted. Research on FM classroom systems and input from 20 teachers support the use of this technology with students who need a slightly higher volume level of instruction.…

  9. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  10. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  11. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  12. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  13. Preparing Students to Take SOA/CAS Exam FM/2

    ERIC Educational Resources Information Center

    Marchand, Richard J.

    2014-01-01

    This paper provides suggestions for preparing students to take the actuarial examination on financial mathematics, SOA/CAS Exam FM/2. It is based on current practices employed at Slippery Rock University, a small public liberal arts university. Detailed descriptions of our Theory of Interest course and subsequent Exam FM/2 prep course are provided…

  14. Embroidered Wearable Multiresonant Folded Dipole Antenna for FM Reception

    Microsoft Academic Search

    Jung-Sim Roh; Yong-Seung Chi; Jae-Hee Lee; Youndo Tak; Sangwook Nam; Tae Jin Kang

    2010-01-01

    A wearable textile antenna with multiple resonance frequencies is proposed for the reception of FM signals using conductive embroidery of metal composite embroidery yarn (MCEY) on a polyester woven substrate. This embroidered FM antenna comprises five individual folded dipoles connected in parallel so that the bandwidth can be broadened via multiple resonances. The MCEY embroidered multiresonant folded dipole (MRFD) antenna

  15. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  16. FM: Clinically Meaningful Rorschach Index with Minority Children?

    ERIC Educational Resources Information Center

    Scott, Ralph

    1981-01-01

    Uses a case vignette to consider the possibility that the Rorschach FM index may be a forerunner of abstract thinking. Data support the major finding that FM may enable educational diagnosticians to more accurately estimate the intellectual capabilities of some preschool minority and other culturally disadvantaged children. (Author/JAC)

  17. Developments in IRS Multi-Mode Waveforms

    NASA Astrophysics Data System (ADS)

    Kelly, Bernard; Baker, John

    2013-04-01

    The IRS picture [Baker et al. PRD 78:044046 (2008); Kelly et al. 84:084009 (2011)] visualises black-hole-binary late-inspiral/merger/ringdown gravitational waveforms as being generated by a single rotating source, with most important waveform angular modes being locked in phase through merger into ringdown. This led to the development of late-merger/ringdown waveform templates for the dominant modes of the binary for nonspinning black holes, and for holes with aligned (non-precessing) spins. During development of the IRS model, it was noticed that certain subdominant modes --- most notably the (3,2) mode --- suffered from non-monotonic bumps in both frequency and amplitude, indicative of some kind of mode-mixing behavior. We report on the resolution of this ``bumpy'' behavior, and of consequent developments to the IRS waveforms across multiple significant angular modes.

  18. Analysis and Application of LIDAR Waveform Data Using a Progressive Waveform Decomposition Method

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Zhang, Z.; Hu, X.; Li, Z.

    2011-09-01

    Due to rich information of a full waveform of airborne LiDAR (light detection and ranging) data, the analysis of full waveform has been an active area in LiDAR application. It is possible to digitally sample and store the entire reflected waveform of small-footprint instead of only discrete point clouds. Decomposition of waveform data, a key step in waveform data analysis, can be categorized to two typical methods: 1) the Gaussian modelling method such as the Non-linear least-squares (NLS) algorithm and the maximum likelihood estimation using the Exception Maximization (EM) algorithm. 2) pulse detection method—Average Square Difference Function (ASDF). However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform. In this paper, we proposed a fast algorithm—Progressive Waveform Decomposition (PWD) method to extract local maxims and fit the echo with Gaussian function, and calculate other parameters from the raw waveform data. On the one hand, experiments are implemented to evaluate the PWD method and the results demonstrate its robustness and efficiency. On the other hand, with the PWD parametric analysis of the full-waveform instead of a 3D point cloud, some special applications are investigated afterward.

  19. Optimization of apodized linearly chirped fiber gratings for optical communications

    Microsoft Academic Search

    Karin Ennser; N. Zervas; Richard I. Laming

    1998-01-01

    The dispersion characteristics of apodized, linearly chirped fiber Bragg gratings and their potential as dispersion compensators have been studied systematically. It is shown that the positive hyperbolic-tangent profile results in an overall superior performance, as it provides highly linearized time-delay characteristics with minimum reduction in the linear dispersion. To compensate for the linear dispersion of 100 km of standard telecom

  20. MULTICOMPONENT SUBSPACE CHIRP PARAMETER ESTIMATION USING DISCRETE FRACTIONAL FOURIER ANALYSIS

    E-print Network

    Santhanam, Balu

    MULTICOMPONENT SUBSPACE CHIRP PARAMETER ESTIMATION USING DISCRETE FRACTIONAL FOURIER ANALYSIS Albuquerque, NM, USA: 87131 jpeacock,bsanthan@unm.edu ABSTRACT The Discrete Fractional Fourier Transform- processing, and presents a quantitative analysis of its per- formance as compared to the Cram´er-Rao lower

  1. Focusing Bistatic SAR Images using Non-Linear Chirp Scaling

    Microsoft Academic Search

    Y. L. Neo; F. H. Wong; I. Cumming

    2004-01-01

    Non-Linear Chirp Scaling is an innovative way to focus bistatic SAR images and has been demonstrated to work on the configuration where the transmitter imaging on broadside and the receiver is stationary. This paper improves and extends the method to the configuration where both the receiver and the transmitter are imaging at a squint angle and moving in a parallel

  2. Pulse compression on the Mark III FEL using energy chirping

    Microsoft Academic Search

    Eric B. Szarmes; Stephen V. Benson; John M. J. Madey

    1990-01-01

    We have performed preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and have demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse. In a typical case, we project pulse

  3. Influence of nonideal chirped fiber grating characteristics on dispersion cancellation

    Microsoft Academic Search

    K. Ennser; M. Ibsen; M. Durkin; M. N. Zervas; R. I. Laming

    1998-01-01

    The effect of nonideal dispersion and reflection characteristics of chirped fiber gratings on the performance of 10-Gb\\/s nonreturn-to-zero-transmission systems operating over standard fiber is investigated. The system penalty for different amplitude and period ripples are quantified. Analyses of an experimental grating confirm that current fabrication technology can meet the requirements for <1-dB-penalty operation

  4. Effects of Frequency Chirping in Electro-Magnetically Induced Transparency

    NASA Astrophysics Data System (ADS)

    Narducci, Frank A.; Davis, Jon P.

    2006-05-01

    Under the right conditions, electro-magnetically induced transparency can lead to ultra-narrow resonances. In this paper, we explore theoretically the effects of rapidly chirping the frequency of the probe laser on the observed lineshapes. For a proper choice of parameters, the lineshape can become distorted and show asymmetric ringing-like behavior. Experimental results will also be discussed.

  5. Numerical studies of driven, chirped Bernstein, Greene, and Kruskal modes

    E-print Network

    Wurtele, Jonathan

    Numerical studies of driven, chirped Bernstein, Greene, and Kruskal modes F. Peinetti University-amplitude periodic density fluctuations, were induced by driving the plasma with a weak oscillating drive, whose in plasmas. These waves are usually strongly Landau damped; however, if destabilizing mecha- nisms

  6. High Squint SAR Processing Using Modified Extended Chirp Scaling

    Microsoft Academic Search

    Duan Shizhong; Li Junxian

    2006-01-01

    This paper proposes a novel approach for high squint missile borne SAR raw data processing using a modified extended chirp scaling algorithm to accommodate the condition of high squint and short wave wavelength. Compared with the tradition synthesis aperture radar (SAR), the missile borne SAR has important characteristics including high flight speed, non-straight movement with non-constant velocity and big squint

  7. Chirped microlens arrays for diode laser circularization and beam expansion

    NASA Astrophysics Data System (ADS)

    Schreiber, Peter; Dannberg, Peter; Hoefer, Bernd; Beckert, Erik

    2005-08-01

    Single-mode diode lasers are well-established light sources for a huge number of applications but suffer from astigmatism, beam ellipticity and large manufacturing tolerances of beam parameters. To compensate for these shortcomings, various approaches like anamorphic prism pairs and cylindrical telescopes for circularization as well as variable beam expanders based on zoomed telescopes for precise adjustment of output beam parameters have been employed in the past. The presented new approach for both beam circularization and expansion is based on the use of microlens arrays with chirped focal length: Selection of lenslets of crossed cylindrical microlens arrays as part of an anamorphic telescope enables circularization, astigmatism correction and divergence tolerance compensation of diode lasers simultaneously. Another promising application of chirped spherical lens array telescopes is stepwise variable beam expansion for circular laser beams of fiber or solid-state lasers. In this article we describe design and manufacturing of beam shaping systems with chirped microlens arrays fabricated by polymer-on-glass replication of reflow lenses. A miniaturized diode laser module with beam circularization and astigmatism correction assembled on a structured ceramics motherboard and a modulated RGB laser-source for photofinishing applications equipped with both cylindrical and spherical chirped lens arrays demonstrate the feasibility of the proposed system design approach.

  8. Wide-band nonlinear chirp transducers for planar acoustooptic deflectors

    Microsoft Academic Search

    K. Anemogiannis; P. Russer; R. Weigel

    1989-01-01

    The design, fabrication, and performance characteristics of LiNbO 3-based wideband nonlinear interdigital chirp transducers are reported. A 54% bandwidth centered at 720 MHz has been obtained for a collinear deflector on a YX substrate. A 66% bandwidth at a midband frequency of 600 MHz has been designed for a Bragg deflector on a YZ substrate with electrodes tilted to satisfy

  9. Training Sequence Aided Signature Waveform Estimation

    Microsoft Academic Search

    Hasan Amca; Ahmet Rizaner; Kadri Hacio?lu; Ali H. Ulusoy

    2006-01-01

    In code division multiple access channels multiuser detection techniques are known to be effective strategies to counter the\\u000a presence of multiuser interference towards improving spectral efficiency. Generally, multiuser detectors can provide excellent\\u000a performance only when the signature waveforms of all users are precisely known. Hence, the estimation of signature waveforms\\u000a is a challenging issue in mobile communication systems. In this

  10. Research on the PWM Waveform Compensation Algorism

    Microsoft Academic Search

    Li Nianqiang; Zhang Lu; Wei Changzhi

    2007-01-01

    In this paper, dynamic PWM waveform compensation algorithm is introduced in detail. The PWM waveform is generated with FPGA (field programmable gate array). The hardware is based on the Altera's FPGA-Cyclone-II EP2C8 and its configuration device-EPC2LC20. The software is developed under the Altera's development environment qartusII 6.0 and NIOS II CPU in FPGA. In this paper,PID algorithm is adopted. Simulation

  11. GRC GSFC TDRSS Waveform Metrics Report

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.

    2013-01-01

    The report presents software metrics and porting metrics for the GGT Waveform. The porting was from a ground-based COTS SDR, the SDR-3000, to the CoNNeCT JPL SDR. The report does not address any of the Operating Environment (OE) software development, nor the original TDRSS waveform development at GSFC for the COTS SDR. With regard to STRS, the report presents compliance data and lessons learned.

  12. Waveform inversion using a logarithmic wavefield

    Microsoft Academic Search

    Changsoo Shin; Dong-Joo Min

    2006-01-01

    Although waveform inversion has been studied extensively since its beginning 20 years ago, applications to seismic field data have been limited, and most of those applications have been for global-seismology- or engineering-seismology-scale problems, not for exploration-scale data. As an alternative to classical waveform inversion, we propose the use of a new, ob- jective function constructed by taking the logarithm of

  13. Q-bursts waveforms: model and experiment

    Microsoft Academic Search

    M. Hayakawa; A. P. Nickolaenko; T. Ogawa; M. Komatsu

    Experimental and model waveforms of Q-bursts are compared. Vertical electric field was recorded with 16 kHz sampling rate in the wide frequency band by the ball antenna in fair weather conditions at Kochi (33.3° N and 133.4° E) during 2003 - 2004. Computations were performed for the uniform Earth-ionosphere cavity having the linear frequency dependence of ELF propagation constant. Waveforms

  14. Slit-scan flow cytometer for recording simultaneous waveforms

    NASA Astrophysics Data System (ADS)

    Johnston, R. G.; Bartholdi, M. F.; Hiebert, R. D.; Parson, J. D.; Cram, L. S.

    1985-05-01

    We have developed a slit-scan flow cytometer for recording the transient, simultaneous light scattering and fluorescence waveforms from individual metaphase chromosomes flowing through a focused laser beam. The two waveforms are recorded on a single-memory waveform recorder by delaying one of the waveforms and switching between them. The light scattering and fluorescence waveforms contain complementary information on chromosome structure. The delay and switching electronics developed here may be useful in other contexts.

  15. 50 CFR 660.393 - Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours. 660.393 Section 660.393 ...Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours....

  16. 50 CFR 660.72 - Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours. 660.72 Section 660.72 Wildlife...Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours....

  17. 50 CFR 660.73 - Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours. 660.73 Section 660.73 Wildlife...Latitude/longitude coordinates defining the 100 fm (183 m) through 150 fm (274 m) depth contours....

  18. 50 CFR 660.391 - Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours. 660.391 Section 660.391...Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours....

  19. 50 CFR 660.392 - Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours. 660.392 Section 660.392 ...Latitude/longitude coordinates defining the 50 fm (91 m) through 75 fm (137 m) depth contours....

  20. 50 CFR 660.71 - Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours. 660.71 Section 660.71 Wildlife...Latitude/longitude coordinates defining the 10-fm (18-m) through 40-fm (73-m) depth contours....

  1. 50 CFR 660.394 - Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours. 660.394 Section 660.394 ...Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours....

  2. 50 CFR 660.74 - Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours. 660.74 Section 660.74 Wildlife...Latitude/longitude coordinates defining the 180 fm (329 m) through 250 fm (457 m) depth contours....

  3. Interpolation in waveform space: enhancing the accuracy of gravitational waveform families using numerical relativity

    E-print Network

    Kipp Cannon; J. D. Emberson; Chad Hanna; Drew Keppel; Harald Pfeiffer

    2012-11-29

    Matched-filtering for the identification of compact object mergers in gravitational-wave antenna data involves the comparison of the data stream to a bank of template gravitational waveforms. Typically the template bank is constructed from phenomenological waveform models since these can be evaluated for an arbitrary choice of physical parameters. Recently it has been proposed that singular value decomposition (SVD) can be used to reduce the number of templates required for detection. As we show here, another benefit of SVD is its removal of biases from the phenomenological templates along with a corresponding improvement in their ability to represent waveform signals obtained from numerical relativity (NR) simulations. Using these ideas, we present a method that calibrates a reduced SVD basis of phenomenological waveforms against NR waveforms in order to construct a new waveform approximant with improved accuracy and faithfulness compared to the original phenomenological model. The new waveform family is given numerically through the interpolation of the projection coefficients of NR waveforms expanded onto the reduced basis and provides a generalized scheme for enhancing phenomenological models.

  4. Preemphasis for an S-band constant bandwidth FM/FM system.

    NASA Technical Reports Server (NTRS)

    Wallace, G. R.; Salter, W. E.

    1973-01-01

    Preemphasis schedules are given for 11 constant-bandwidth FM subcarriers modulating an S-band transmitter at various receiver SNRs (9 dB, 15 dB and 25 dB). The criterion for establishing these preemphasis curves is the achievement, at various receiver IF SNR, of equal receiver output SNR for all channels. The empirically derived results are compared with a simplified, analytically derived schedule and the primary differences are explained. The S-band preemphasis schedule is also found to differ from the lower frequency VHF case.

  5. SCA Waveform Development for Space Telemetry

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.; Kifle, Multi; Hall, C. Steve; Quinn, Todd M.

    2004-01-01

    The NASA Glenn Research Center is investigating and developing suitable reconfigurable radio architectures for future NASA missions. This effort is examining software-based open-architectures for space based transceivers, as well as common hardware platform architectures. The Joint Tactical Radio System's (JTRS) Software Communications Architecture (SCA) is a candidate for the software approach, but may need modifications or adaptations for use in space. An in-house SCA compliant waveform development focuses on increasing understanding of software defined radio architectures and more specifically the JTRS SCA. Space requirements put a premium on size, mass, and power. This waveform development effort is key to evaluating tradeoffs with the SCA for space applications. Existing NASA telemetry links, as well as Space Exploration Initiative scenarios, are the basis for defining the waveform requirements. Modeling and simulations are being developed to determine signal processing requirements associated with a waveform and a mission-specific computational burden. Implementation of the waveform on a laboratory software defined radio platform is proceeding in an iterative fashion. Parallel top-down and bottom-up design approaches are employed.

  6. 47 CFR 73.201 - Numerical designation of FM broadcast channels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...available for FM broadcasting (including those...noncommercial educational broadcasting) are given numerical...the reception of FM broadcasting stations,...

  7. 47 CFR 73.201 - Numerical designation of FM broadcast channels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...available for FM broadcasting (including those...noncommercial educational broadcasting) are given numerical...the reception of FM broadcasting stations,...

  8. 47 CFR 73.201 - Numerical designation of FM broadcast channels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...available for FM broadcasting (including those...noncommercial educational broadcasting) are given numerical...the reception of FM broadcasting stations,...

  9. 47 CFR 73.201 - Numerical designation of FM broadcast channels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...available for FM broadcasting (including those...noncommercial educational broadcasting) are given numerical...the reception of FM broadcasting stations,...

  10. 47 CFR 73.201 - Numerical designation of FM broadcast channels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...available for FM broadcasting (including those...noncommercial educational broadcasting) are given numerical...the reception of FM broadcasting stations,...

  11. Role of spin polarization in FM/Al/FM trilayer film at low temperature

    NASA Astrophysics Data System (ADS)

    Lu, Ning; Webb, Richard

    2014-03-01

    Measurements of electronic transport in diffusive FM/normal metal/FM trilayer film are performed at temperature ranging from 2K to 300K to determine the behavior of the spin polarized current in normal metal under the influence of quantum phase coherence and spin-orbital interaction. Ten samples of Hall bar with length of 200 micron and width of 20 micron are fabricated through e-beam lithography followed by e-gun evaporation of Ni0.8Fe0.2, aluminum and Ni0.8Fe0.2 with different thickness (5nm to 45nm) in vacuum. At low temperature of 4.2K, coherent backscattering, Rashba spin-orbital interaction and spin flip scattering of conduction electrons contribute to magnetoresistance at low field. Quantitative analysis of magnetoresistance shows transition between weak localization and weak anti-localization for samples with different thickness ratio, which indicates the spin polarization actually affects the phase coherence length and spin-orbital scattering length. However, at temperature between 50K and 300K, only the spin polarization dominates the magnetoresistance.

  12. ATOMIC AND MOLECULAR PHYSICS: Ionization of atoms by chirped attosecond pulses

    NASA Astrophysics Data System (ADS)

    Tan, Fang; Peng, Liang-You; Gong, Qi-Huang

    2009-11-01

    We investigate the ionization dynamics of atoms by chirped attosecond pulses using the strong field approximation method. The pulse parameters are carefully chosen in the regime where the strong field approximation method is valid. We analyse the effects of the chirp of attosecond pulses on the energy distributions and the corresponding left-right asymmetry of the ionized electrons. For a single chirped attosecond pulse, the ionized electrons can be redistributed and the left-right asymmetry shows oscillations because of the introduction of the chirp. For time-delayed double attosecond pulses at different intensities with the weaker one chirped, exchanging the order of the two pulses shows a relative shift of the energy spectra, which can be explained by the different effective time delays of different frequency components because of the chirp.

  13. Model Waveform Accuracy Standards for Gravitational Wave Data Analysis

    E-print Network

    Lee Lindblom; Benjamin J. Owen; Duncan A. Brown

    2008-11-05

    Model waveforms are used in gravitational wave data analysis to detect and then to measure the properties of a source by matching the model waveforms to the signal from a detector. This paper derives accuracy standards for model waveforms which are sufficient to ensure that these data analysis applications are capable of extracting the full scientific content of the data, but without demanding excessive accuracy that would place undue burdens on the model waveform simulation community. These accuracy standards are intended primarily for broad-band model waveforms produced by numerical simulations, but the standards are quite general and apply equally to such waveforms produced by analytical or hybrid analytical-numerical methods.

  14. Diode-quad bridge for reactive transducers and FM discriminators

    NASA Technical Reports Server (NTRS)

    Harrison, D. R.; Dimeff, J.

    1972-01-01

    Diode-quad bridge circuit was developed for use with pressure-sensitive capacitive transducers, liquid-level measuring devices, proximity deflection sensors, and inductive displacement sensors. It may also be used as FM discriminator and as universal impedance bridge.

  15. An Inservice Training Model for Using the Classroom FM System.

    ERIC Educational Resources Information Center

    Van Dyke, Linda

    1982-01-01

    An inservice training model for successful implementation of FM (Frequency Modulation) transmission systems for hearing impaired students must take into account its purpose and functions, mechanics, and management. (CD)

  16. Haag, Elizabeth Nurse Manager FM Clin Serv Admin

    E-print Network

    H Haag, Elizabeth Nurse Manager FM Clin Serv Admin Mail Stop 654 Hackett, Timm Teaching Instructor English - Old Cafeteria G320 Mail Stop 555 Hackett, Denise ECU Staff Nurse Peds General Pediatrics Mail

  17. 56. Credit FM. East elevation taken from along penstock. Note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. Credit FM. East elevation taken from along penstock. Note additions to the east side and the north side of the building. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  18. 72. Credit FM. Overview of powerhouse from gallery. Notice cooling ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. Credit FM. Overview of powerhouse from gallery. Notice cooling duct on generator (now removed) and spare gate valve in far corner. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  19. 59. Credit FM. Flood waters on South Battle Creek next ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    59. Credit FM. Flood waters on South Battle Creek next to powerhouse. Note height of water in relation to tailraces. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  20. 68. Credit FM. Detail showing operators. Note cooling duct (now ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. Credit FM. Detail showing operators. Note cooling duct (now removed), governor (now removed), hand-operated needle valve controls (now removed). - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  1. FM 3-04.513 Aircraft Recovery Operations

    E-print Network

    US Army Corps of Engineers

    FM 3-04.513 Aircraft Recovery Operations July 2008 DISTRIBUTION RESTRICTION: Approved for public-04.513 Headquarters Department of the Army Washington, DC, 21 July 2008 Aircraft Recovery Operations Contents Page.............................................................................................. 1-1 Aircraft Recovery

  2. An analysis of As_(2)S_(3) chirped fiber grating formed by two-photon absorption effect

    NASA Astrophysics Data System (ADS)

    Wang, Huaisheng; Zhang, Zhigang; Chai, Lu; Wang, Qingyue

    2003-06-01

    When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As_(2)S_(3) fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As_(2)S_(3) material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system.

  3. Pulse compression on the Mark III FEL using energy chirping

    NASA Astrophysics Data System (ADS)

    Szarmes, Eric B.; Benson, Stephen V.; Madey, John M. J.

    1990-10-01

    We have performed preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and have demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse. In a typical case, we project pulse compression by a factor of 13.3, from an initial pulse width of 3.13 ps to a final pulse width of 236 fs, at a wavelength of 3.35 ?m and an electron energy chirp of +2% (energy increasing towards the back of the pulse). This represents an optical pulse less than half as short as the slippage length of 47 magnet periods for this wavelength.

  4. Excitation of the Morse oscillator by an ultrashort chirped pulse

    SciTech Connect

    Astapenko, V. A., E-mail: astval@mail.ru; Romadanovskii, M. S. [Moscow Institute of Physics and Technology (Russian Federation)

    2010-03-15

    The excitation of the classic Morse oscillator by an ultrashort electromagnetic pulse with a linear frequency chirp is studied theoretically. Formulas are derived for the oscillation amplitude and the radiation power averaged over a period as functions of the excitation energy for free oscillations of the Morse oscillator. Analytical expressions for describing the oscillator motion after the end of the pulse are obtained in the harmonic limit. In the general case of arbitrary parameters of the problem, the specific features of an excited Morse oscillator are analyzed numerically. Prominence is given to the effect of chirp on the excitation energy. The consideration is performed in terms of dimensionless variables, which makes it possible to apply the results obtained to a wide range of molecular systems and exciting-pulse parameters.

  5. Interaction of strongly chirped pulses with two-level atoms

    SciTech Connect

    Ibanez, S.; Peralta Conde, A.; Muga, J. G. [Departamento de Quimica Fisica, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Apdo. 644, Bilbao (Spain); Guery-Odelin, D. [Laboratoire Collisions Agregats Reactivite, CNRS UMR 5589, IRSAMC, Universite Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse CEDEX 4 (France)

    2011-07-15

    We study the effect of ultrachirped pulses on the population inversion of two-level atoms. Ultrachirped pulses are defined as those for which the frequency chirp is of the order of the transition frequency of the two-level atom. When the chirp is large enough, the resonance may be crossed twice, for positive and negative frequencies. In fact the decomposition of the field into amplitude and phase factors, and the corresponding definition of the instantaneous frequency, are not unique. The interaction pictures for different decomposition are strictly equivalent, but only as long as approximations are not applied. The domain of validity of the formal rotating wave approximation is dramatically enhanced by a suitable choice, the so-called analytic signal representation.

  6. Radial-modulation chirp imaging for high-resolution contrast detection

    Microsoft Academic Search

    Meng-Lin Li; Yu-Chen Kuo; Chih-Kuang Yeh

    2008-01-01

    In this study, we propose a radial-modulation chirp imaging method for contrast detection with high frequency ultrasound. This method detects microbubbles by extracting and then selectively compressing the radial-modulated chirp component of the response. The amplitude of the imaging chirp signal will be radial modulated at the resonance frequency due to the high-amplitude oscillation of the microbubble wall which are

  7. Chirped-pulse millimeter-wave spectroscopy: Spectrum, dynamics, and manipulation of Rydberg-Rydberg transitions

    SciTech Connect

    Colombo, Anthony P.; Zhou Yan; Prozument, Kirill; Coy, Stephen L.; Field, Robert W. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2013-01-07

    We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg-Rydberg transitions is that they have enormous electric dipole transition moments ({approx}5 kiloDebye at n*{approx} 40, where n* is the effective principal quantum number), so they interact strongly with the mm-wave radiation. After polarization by a mm-wave pulse in the 70-84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is {approx}100 kHz. Because of the large transition dipole moments, the available mm-wave power is sufficient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, we observe dynamics, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Since the waveform produced by the mm-wave source may be precisely controlled, we can populate states with high angular momentum by a sequence of pulses while recording the results of these manipulations in the time domain. We also probe the superradiant decay of the Rydberg sample using photon echoes. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed.

  8. Development of a Reduced-Cost Chirped Pulse Microwave Spectrometer

    NASA Astrophysics Data System (ADS)

    Finneran, Ian A.; Holland, Daniel B.; Carroll, P. Brandon; Blake, Geoffrey A.

    2013-06-01

    Chirped pulse Fourier transform microwave (CP-FTMW) spectroscopy has become a ubiquitous technique in the high-resolution molecular spectroscopy community. Unfortunately, many components of CP-FTMW spectrometers are extremely expensive. Here we report of the development of an inexpensive microwave circuit and we present spectra of tetrahydrofuran and methanol collected between 8-16 GHz. Possible applications in remote sensing will also be discussed.

  9. Design Of Chirped Grating Lenses In Planar Optical Waveguides

    Microsoft Academic Search

    William S. C. Chang; Siamak Forouhar; Jean-Marc Delavaux; Ron-Xin Lu

    1982-01-01

    Theoretical designs of chirped grating lenses have yielded very high efficiency and moderately large angular fields of view. Experimentally, high efficiency (0.7dB insertion loss) and large angular field of view (0.1 radians) have been obtained in low index glass waveguides. Performance in high index waveguides such as LiNbO 3 will be limited by the n eff-n\\/subs\\/, the index of the

  10. Identification of biological tissue using chirped probe THz imaging

    Microsoft Academic Search

    B. Ferguson; S. Wang; D. Gray; D. Abbott; X.-C Zhang

    2002-01-01

    We consider the application of pulsed THz imaging systems in biomedical diagnostics and mail\\/packaging inspection. The sub-millimetre spectroscopic measurements obtained from T-ray systems contain a wealth of information about the sample under test. We demonstrate that different types of tissue can be classified based on their terahertz response measured with the chirped probe pulse technique. We demonstrate the performance of

  11. A high-resolution chirp transform spectrometer for microwave measurements

    Microsoft Academic Search

    P. Hartogh; G. K. Hartmann

    1990-01-01

    A microwave heterodyne spectrometer consists of a radiometer front-end and a real-time spectrum analyzer back-end. Common spectrometer types are filterbanks, autocorrelators and acousto-optic spectrometers (AOS). In this paper a high-resolution chirp transform spectrometer using reflective array compressor (RAC) filters with a time bandwidth product of 6400 is presented. The spectrometer has 1600 channels within a 40 MHz input bandwidth and

  12. Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics.

    PubMed

    Harput, Sevan; McLaughlan, James; Cowell, David M J; Freear, Steven

    2014-11-01

    Superharmonic imaging improves the spatial resolution by using the higher order harmonics generated in tissue. The superharmonic component is formed by combining the third, fourth, and fifth harmonics, which have low energy content and therefore poor SNR. This study uses coded excitation to increase the excitation energy. The SNR improvement is achieved on the receiver side by performing pulse compression with harmonic matched filters. The use of coded signals also introduces new filtering capabilities that are not possible with pulsed excitation. This is especially important when using wideband signals. For narrowband signals, the spectral boundaries of the harmonics are clearly separated and thus easy to filter; however, the available imaging bandwidth is underused. Wideband excitation is preferable for harmonic imaging applications to preserve axial resolution, but it generates spectrally overlapping harmonics that are not possible to filter in time and frequency domains. After pulse compression, this overlap increases the range side lobes, which appear as imaging artifacts and reduce the Bmode image quality. In this study, the isolation of higher order harmonics was achieved in another domain by using the fan chirp transform (FChT). To show the effect of excitation bandwidth in superharmonic imaging, measurements were performed by using linear frequency modulated chirp excitation with varying bandwidths of 10% to 50%. Superharmonic imaging was performed on a wire phantom using a wideband chirp excitation. Results were presented with and without applying the FChT filtering technique by comparing the spatial resolution and side lobe levels. Wideband excitation signals achieved a better resolution as expected, however range side lobes as high as -23 dB were observed for the superharmonic component of chirp excitation with 50% fractional bandwidth. The proposed filtering technique achieved >50 dB range side lobe suppression and improved the image quality without affecting the axial resolution. PMID:25389159

  13. Beam focusing in reflection from flat chirped mirrors

    NASA Astrophysics Data System (ADS)

    Cheng, Y. C.; Peckus, M.; Kicas, S.; Trull, J.; Cojocaru, C.; Vilaseca, R.; Drazdys, R.; Staliunas, K.

    2013-04-01

    We propose and show by proof-of-principle calculations and experiments that beam focusing and imaging can be obtained in reflection from a flat interface of a micromodulated dielectric structure. We show, in particular, that a one-dimensionally modulated and chirped structure can focus a beam, performing an imaging of a light pattern, i.e., can act as a transversely invariant flat focusing mirror.

  14. Fully programmable spectrum sliced chirped microwave photonic filter.

    PubMed

    Leitner, Peter; Yi, Xiaoke; Li, Liwei; Huang, Thomas X H

    2015-02-23

    A novel chirped microwave photonic filter (MPF) capable of achieving a large radio frequency (RF) group delay slope and a single passband response free from high frequency fading is presented. The design is based upon a Fourier domain optical processor (FD-OP) and a single sideband modulator. The FD-OP is utilized to generate both constant time delay to tune the filter and first order dispersion to induce the RF chirp, enabling full software control of the MPF without the need for manual adjustment. An optimized optical parameter region based on a large optical bandwidth >750 GHz and low slicing dispersion < ± 1 ps/nm is introduced, with this technique greatly improving the RF properties including the group delay slope magnitude and passband noise. Experimental results confirm that the structure simultaneously achieves a large in-band RF chirp of -4.2 ns/GHz, centre frequency invariant tuning and independent reconfiguration of the RF amplitude and phase response. Finally, a stochastic study of the device passband noise performance under tuning and reconfiguration is presented, indicating a low passband noise <-120 dB/Hz. PMID:25836442

  15. Coherent chirped pulse laser network with Mickelson phase conjugator.

    PubMed

    Okulov, A Yu

    2014-04-10

    The mechanisms of nonlinear phase-locking of a large fiber amplifier array are analyzed. The preference is given to the most suitable configuration for a coherent coupling of thousands of fundamental spatial mode fiber beams into a single smooth beam ready for chirped pulse compression. It is shown that a Michelson phase-conjugating configuration with double passage through an array of fiber amplifiers has the definite advantage compared to a one-way fiber array coupled in a Mach-Zehnder configuration. Regardless of the amount of synchronized fiber amplifiers, the Michelson phase-conjugating interferometer is expected to do a perfect compensation of the phase-piston errors and collimation of backwardly amplified fiber beams on an entrance/output beam splitter. In both configurations, the nonlinear transformation of the stretched pulse envelope, due to gain saturation, is capable of randomizing the position of chirp inside an envelope; thus it may reduce the visibility of the interference pattern at an output beam splitter. Certain advantages are inherent to the sech-form temporal envelope because of the exponential precursor and self-similar propagation in gain medium. The Gaussian envelope is significantly compressed in a deep gain saturation regime, and the frequency chirp position inside pulse envelope is more deformed. PMID:24787398

  16. Harmonic chirp imaging method for ultrasound contrast agent.

    PubMed

    Borsboom, Jerome M G; Chin, Chien Ting; Bouakaz, Ayache; Versluis, Michel; de Jong, Nico

    2005-02-01

    Coded excitation is currently used in medical ultrasound to increase signal-to-noise ratio (SNR) and penetration depth. We propose a chirp excitation method for contrast agents using the second harmonic component of the response. This method is based on a compression filter that selectively compresses and extracts the second harmonic component from the received echo signal. Simulations have shown a clear increase in response for chirp excitation over pulse excitation with the same peak amplitude. This was confirmed by two-dimensional (2-D) optical observations of bubble response with a fast framing camera. To evaluate the harmonic compression method, we applied it to simulated bubble echoes, to measured propagation harmonics, and to B-mode scans of a flow phantom and compared it to regular pulse excitation imaging. An increase of approximately 10 dB in SNR was found for chirp excitation. The compression method was found to perform well in terms of resolution. Axial resolution was in all cases within 10% of the axial resolution from pulse excitation. Range side-lobe levels were 30 dB below the main lobe for the simulated bubble echoes and measured propagation harmonics. However, side-lobes were visible in the B-mode contrast images. PMID:15801312

  17. Spontaneous parametric down conversion in chirped, aperiodically-poled crystals

    E-print Network

    X. Sanchez-Lozano; Jose Luis Lucio

    2015-03-23

    We present a theoretical analysis of the process of spontaneous parametric down conversion (SPDC) in a non-linear crystal characterized by a linearly-chirped X(2) grating along the direction of propagation. Our analysis leads to an expression for the joint spectral amplitude, based on which we can derive various spectral-temporal properties of the photon pairs and of the heralded single photons obtained from the photon pairs, including: the single photon spectrum, the chronocyclic Wigner function and the Schmidt number. The simulations that we present are for the specific case of a collinear SPDC source based on a PPLN crystal with the signal and idler photons emitted close to the telecom window. We discuss the mechanism for spectral broadening due to the presence of a linearly chirped X(2) grating, showing that not only the width but also to some extent the shape of the SPDC spectrum maybe controlled. Also, we discuss how the fact that the different spectral components are emitted on different planes in the crystal leads to single-photon chirp.

  18. Chirp Z-transform spectral zoom optimization with MATLAB.

    SciTech Connect

    Martin, Grant D.

    2005-11-01

    The MATLAB language has become a standard for rapid prototyping throughout all disciplines of engineering because the environment is easy to understand and use. Many of the basic functions included in MATLAB are those operations that are necessary to carry out larger algorithms such as the chirp z-transform spectral zoom. These functions include, but are not limited to mathematical operators, logical operators, array indexing, and the Fast Fourier Transform (FFT). However, despite its ease of use, MATLAB's technical computing language is interpreted and thus is not always capable of the memory management and performance of a compiled language. There are however, several optimizations that can be made within the chirp z-transform spectral zoom algorithm itself, and also to the MATLAB implementation in order to take full advantage of the computing environment and lower processing time and improve memory usage. To that end, this document's purpose is two-fold. The first demonstrates how to perform a chirp z-transform spectral zoom as well as an optimization within the algorithm that improves performance and memory usage. The second demonstrates a minor MATLAB language usage technique that can reduce overhead memory costs and improve performance.

  19. Progress Towards Chirped-Pulse Fourier Transform Thz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Douglass, Kevin O.; Plusquellic, David F.; Gerecht, Eyal

    2010-06-01

    New opportunities are provided by the development of higher power THz frequency multiplier sources, the development of a broadband Chirped-Pulse FTMW spectroscopy technique at microwave and mm Wave frequencies, and recently demonstrated heterodyne hot electron bolometer detection technology in the THz frequency region with near quantum noise-limited performance and high spectral resolution. Combining these three technologies and extending the chirped-pulse technique to 0.85 THz enables a host of new applications. NIST is currently pursing applications as a point sensor for greenhouse gases, volatile organic compounds, and potentially human breath. The generation and detection of phase stable chirped pulses at 850 GHz will be demonstrated. A description of the experimental setup and preliminary data will be presented for nitrous oxide. G.G. Brown, B.C. Dian, K.O. Douglass, S.M. Geyer, S. Shipman and B.H. Pate, Rev.Sci.Instrum. 79 (2008) 053103. E. Gerecht, D. Gu, L. You, K.S. Yngvesson, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. 56, (2008) 1083.

  20. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...proposes to operate near an FM translator...Ed = predicted field strength (dBu) of...licensee and the Federal Communications Commission, Attention...direction of the Federal Communications Commission....

  1. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...proposes to operate near an FM translator...Ed = predicted field strength (dBu) of...licensee and the Federal Communications Commission, Attention...direction of the Federal Communications Commission....

  2. Radar altimeter waveform modeled parameter recovery. [SEASAT-1 data

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Satellite-borne radar altimeters include waveform sampling gates providing point samples of the transmitted radar pulse after its scattering from the ocean's surface. Averages of the waveform sampler data can be fitted by varying parameters in a model mean return waveform. The theoretical waveform model used is described as well as a general iterative nonlinear least squares procedures used to obtain estimates of parameters characterizing the modeled waveform for SEASAT-1 data. The six waveform parameters recovered by the fitting procedure are: (1) amplitude; (2) time origin, or track point; (3) ocean surface rms roughness; (4) noise baseline; (5) ocean surface skewness; and (6) altitude or off-nadir angle. Additional practical processing considerations are addressed and FORTRAN source listing for subroutines used in the waveform fitting are included. While the description is for the Seasat-1 altimeter waveform data analysis, the work can easily be generalized and extended to other radar altimeter systems.

  3. Post-Newtonian Computation of Binary Inspiral Waveforms

    E-print Network

    Luc Blanchet

    2001-04-25

    Contents: I. Introduction; II. Summary of optimal signal filtering; III. Newtonian binary polarization waveforms; IV. Newtonian orbital phase evolution; V. Post-Newtonian wave-generation; VI. Inspiral binary waveform.

  4. JTRS/SCA and Custom/SDR Waveform Comparison

    NASA Technical Reports Server (NTRS)

    Oldham, Daniel R.; Scardelletti, Maximilian C.

    2007-01-01

    This paper compares two waveform implementations generating the same RF signal using the same SDR development system. Both waveforms implement a satellite modem using QPSK modulation at 1M BPS data rates with one half rate convolutional encoding. Both waveforms are partitioned the same across the general purpose processor (GPP) and the field programmable gate array (FPGA). Both waveforms implement the same equivalent set of radio functions on the GPP and FPGA. The GPP implements the majority of the radio functions and the FPGA implements the final digital RF modulator stage. One waveform is implemented directly on the SDR development system and the second waveform is implemented using the JTRS/SCA model. This paper contrasts the amount of resources to implement both waveforms and demonstrates the importance of waveform partitioning across the SDR development system.

  5. Quasi-orthogonal wideband radar waveforms based on chaotic systems

    E-print Network

    Willsey, Matt (Matt S.)

    2007-01-01

    With the development of A/D converters possessing sufficiently high sampling rates, it is now feasible to use arbitrary, wideband waveforms in radar applications. Large sets of quasi-orthogonal, wideband waveforms can be ...

  6. Selecting the lorenz parameters for wideband radar waveform generation

    E-print Network

    Willsey, Matt S.

    Radar waveforms based on chaotic systems have occasionally been suggested for a variety of radar applications. In this paper, radar waveforms are constructed with solutions from a particular chaotic system, the Lorenz ...

  7. Waveform Selectivity at the Same Frequency

    NASA Astrophysics Data System (ADS)

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J.; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F.

    2015-04-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms.

  8. Waveform Selectivity at the Same Frequency

    PubMed Central

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J.; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F.

    2015-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071

  9. Waveform selectivity at the same frequency.

    PubMed

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F

    2015-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071

  10. How will waveform diversity affect electromagnetic compatibility?

    Microsoft Academic Search

    John W. Garnham; Jaime R. Roman

    2007-01-01

    This paper will provide a general overview of the new research area called waveform diversity (WD), and its potential impact to the EMC community. The scope of research that is considered WD is broad in both technical content and application. The two main application areas are radar and communications across the RF spectrum. WD is beginning to transition from theory

  11. Waveform Diversity for Different Multistatic Radar Configurations

    Microsoft Academic Search

    I. Bradaric; G. T. Capraro; M. C. Wicks

    2007-01-01

    The multistatic ambiguity function has recently been proposed as a tool for analyzing and designing multistatic radar systems. It was demonstrated through examples that multistatic radar system performances can be improved by shaping the multistatic ambiguity function through waveform selection and adequate weighting of different receivers during pre-detection fusion. In this work we study sensor repositioning as a third way

  12. Adaptive RF-photonic arbitrary waveform generator

    Microsoft Academic Search

    Jason Chou; Yan Han; Bahram Jalali

    2003-01-01

    Optical and radio-frequency waveforms with wide-band arbitrary modulation are generated using spectral shaping of a supercontinuum source followed by wavelength-to-time mapping. Adaptive computer control is used to mitigate the nonideal features inherent in the optical source and in the spectrum modulation process.

  13. Noise reduction by multiplicative waveforms decomposition

    Microsoft Academic Search

    Amina SERIR; Boualem SANSAL

    2003-01-01

    This paper introduces a novel multiplicative noise reduction method based on a particular association of structural and statistical analysis. The structural analysis is performed by a new, multiplicative matching pursuit decomposition (MMPD), that decomposes images containing the intrinsic variation into a nonlinear expansion of waveforms selected from a dictionary of functions. This selection is made in such a way to

  14. Binary black hole merger dynamics and waveforms

    Microsoft Academic Search

    John G. Baker; Joan Centrella; Dae-Il Choi; Michael Koppitz; James van Meter

    2006-01-01

    We study dynamics and radiation generation in the last few orbits and merger of a binary black hole system, applying recently developed techniques for simulations of moving black holes. Our analysis of the gravitational radiation waveforms and dynamical black hole trajectories produces a consistent picture for a set of simulations with black holes beginning on circular-orbit trajectories at a variety

  15. Extension of high-order harmonic generation cutoff via coherent control of intense few-cycle chirped laser pulses

    E-print Network

    Carrera, Juan J.; Chu, Shih-I

    2007-03-16

    We present an ab initio quantum investigation of the high-order harmonic generation (HHG) cutoff extension using intense few-cycle chirped laser pulses. For a few-cycle chirped driving laser pulse, it is shown that significant ...

  16. Symmetrical waveform generation based on temporal pulse shaping using

    E-print Network

    Yao, Jianping

    Symmetrical waveform generation based on temporal pulse shaping using amplitude-only modulator H. Chi and J. Yao Symmetrical waveform generation based on temporal pulse shaping using only an amplitude transform of a real and symmetrical waveform is still real and symmetrical. There- fore, it is possible

  17. Stability of Waveforms on Active Nonlinear Transmission Lines

    Microsoft Academic Search

    ALLEN G. LINDGREN; RICHARD J. BURATTI

    1969-01-01

    Steady propagation on both the taperedRC pm GandRLC pm Gnonlinear transmission lines is investigated and the existence of various types of neuristor waveforms demonstrated. A generalization of the direct method of Liapunov for distributed parameter systems is employed to determine the stability of the possible steady waveforms. It is shown that the criterion for waveform stability on such active nonlinear

  18. Variability of the ECG waveform in fetal and neonatal lambs

    Microsoft Academic Search

    H W Jongsma; A J Crevels; J J M Menssen

    1989-01-01

    Changes in the waveform of the fetal electrocardiogram (FECG) are being investigated by several groups for its clinical significance with regard to the assessment of fetal condition. During the present authors' experiments with fetal lambs they frequently observed spontaneous FECG waveform changes, also during steady state in control animals. From the examples presented they conclude that the FECG waveform can

  19. Waveform design for distributed aperture using Gram-Schmidt orthogonalization

    Microsoft Academic Search

    Can Evren Yarman; Trond Varslot; Birsen Yazici; Margaret Cheney

    2007-01-01

    In this work, we consider a distributed aperture radar system and present a method for clutter rejecting waveforms and reflectivity function reconstruction. This work generalizes the monostatic radar waveform design method for range-doppler imaging, developed in [1], [2] to distributed aperture radar systems. The designed waveforms also lead to a filtered backprojection type reconstruction of the reflectivity function which can

  20. Air Band Scanner with Retransmission over Local FM Radio Frequencies Using a

    E-print Network

    Yu, Chansu

    Air Band Scanner with Retransmission over Local FM Radio Frequencies Using a Software Defined Radio it uses [4]. Despite the frequencies only being slightly higher than the FM radio frequency range, air will then be retransmitted, using a BasicTX daughter, over an FM frequency that can be received using a standard FM radio

  1. CERES ERBE-like Monthly Geographical Averages (ES-4) in HDF (CER_ES4_PFM+FM1+FM2_Edition1)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The ERBE-like Monthly Geographical Averages (ES-4) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The ES-4 is also produced for combinations of scanner instruments. For each observed 2.5-degree spatial region, the daily average, the hourly average over the month, and the overall monthly average of shortwave and longwave fluxes at the Top-of-the-Atmosphere (TOA) from the CERES ES-9 product are spatially nested up from 2.5-degree regions to 5- and 10-degree regions, to 2.5-, 5-, and 10-degree zonal averages, and to global monthly averages. For each nested area, the albedo and net flux are given. For each region, the daily average flux is estimated from an algorithm that uses the available hourly data, scene identification data, and diurnal models. This algorithm is 'like' the algorithm used for the Earth Radiation Budget Experiment (ERBE). The following CERES ES4 data sets are currently available: CER_ES4_FM1+FM2_Edition1 CER_ES4_PFM+FM1+FM2_Edition1 CER_ES4_PFM+FM1+FM2_Edition2 CER_ES4_PFM+FM1_Edition1 CER_ES4_PFM+FM2_Edition1 CER_ES4_TRMM-PFM_Edition1 CER_ES4_TRMM-PFM_Edition2 CER_ES4_Terra-FM1_Edition1 CER_ES4_Terra-FM2_Edition1 CER_ES4_FM1+FM2_Edition2 CER_ES4_Terra-FM1_Edition2 CER_ES4_Terra-FM2_Edition2 CER_ES4_Aqua-FM3_Edition1 CER_ES4_Aqua-FM4_Edition1 CER_ES4_FM1+FM2+FM3+FM4_Edition1 CER_ES4_Aqua-FM3_Edition2 CER_ES4_Aqua-FM4_Edition2 CER_ES4_FM1+FM3_Edition2 CER_ES4_FM1+FM4_Edition2 CER_ES4_PFM+FM1_Edition2 CER_ES4_PFM+FM2_Edition2 CER_ES4_Aqua-FM3_Edition1-CV CER_ES4_Aqua-FM4_Edition1-CV CER_ES4_Terra-FM1_Edition1-CV CER_ES4_Terra-FM2_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=2.5 degree; Longitude_Resolution=2.5 degree; Horizontal_Resolution_Range=250 km - < 500 km or approximately 2.5 degrees - < 5.0 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  2. CERES ERBE-like Monthly Regional Averages (ES-9) in HDF (CER_ES9_PFM+FM1+FM2_Edition2)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The ERBE-like Monthly Regional Averages (ES-9) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The ES-9 is also produced for combinations of scanner instruments. All instantaneous shortwave and longwave fluxes at the Top-of-the-Atmosphere (TOA) from the CERES ES-8 product for a month are sorted by 2.5-degree spatial regions, by day number, and by the local hour of observation. The mean of the instantaneous fluxes for a given region-day-hour bin is determined and recorded on the ES-9 along with other flux statistics and scene information. For each region, the daily average flux is estimated from an algorithm that uses the available hourly data, scene identification data, and diurnal models. This algorithm is 'like' the algorithm used for the Earth Radiation Budget Experiment (ERBE). The ES-9 also contains hourly average fluxes for the month and an overall monthly average for each region. These average fluxes are given for both clear-sky and total-sky scenes. The following CERES ES9 data sets are currently available: CER_ES9_FM1+FM2_Edition1 CER_ES9_PFM+FM1+FM2_Edition1 CER_ES9_PFM+FM1+FM2_Edition2 CER_ES9_PFM+FM1_Edition1 CER_ES9_PFM+FM2_Edition1 CER_ES9_PFM+FM1_Edition2 CER_ES9_PFM+FM2_Edition2 CER_ES9_TRMM-PFM_Edition1 CER_ES9_TRMM-PFM_Edition2 CER_ES9_Terra-FM1_Edition1 CER_ES9_Terra-FM2_Edition1 CER_ES9_FM1+FM2_Edition2 CER_ES9_Terra-FM1_Edition2 CER_ES9_Terra-FM2_Edition2 CER_ES9_Aqua-FM3_Edition1 CER_ES9_Aqua-FM4_Edition1 CER_ES9_FM1+FM2+FM3+FM4_Edition1 CER_ES9_Aqua-FM3_Edition2 CER_ES9_Aqua-FM4_Edition2 CER_ES9_FM1+FM3_Edition2 CER_ES9_FM1+FM4_Edition2 CER_ES9_Aqua-FM3_Edition1-CV CER_ES9_Aqua-FM4_Edition1-CV CER_ES9_Terra-FM1_Edition1-CV CER_ES9_Terra-FM2_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=2.5 degree; Longitude_Resolution=2.5 degree; Horizontal_Resolution_Range=250 km - < 500 km or approximately 2.5 degrees - < 5.0 degrees; Temporal_Resolution=hourly, daily, monthly; Temporal_Resolution_Range=Hourly - < Daily, Daily - < Weekly, Monthly - < Annual].

  3. CERES ERBE-like Monthly Regional Averages (ES-9) in HDF (CER_ES9_PFM+FM1+FM2_Edition1)

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A. (Principal Investigator)

    The ERBE-like Monthly Regional Averages (ES-9) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The ES-9 is also produced for combinations of scanner instruments. All instantaneous shortwave and longwave fluxes at the Top-of-the-Atmosphere (TOA) from the CERES ES-8 product for a month are sorted by 2.5-degree spatial regions, by day number, and by the local hour of observation. The mean of the instantaneous fluxes for a given region-day-hour bin is determined and recorded on the ES-9 along with other flux statistics and scene information. For each region, the daily average flux is estimated from an algorithm that uses the available hourly data, scene identification data, and diurnal models. This algorithm is 'like' the algorithm used for the Earth Radiation Budget Experiment (ERBE). The ES-9 also contains hourly average fluxes for the month and an overall monthly average for each region. These average fluxes are given for both clear-sky and total-sky scenes. The following CERES ES9 data sets are currently available: CER_ES9_FM1+FM2_Edition1 CER_ES9_PFM+FM1+FM2_Edition1 CER_ES9_PFM+FM1+FM2_Edition2 CER_ES9_PFM+FM1_Edition1 CER_ES9_PFM+FM2_Edition1 CER_ES9_PFM+FM1_Edition2 CER_ES9_PFM+FM2_Edition2 CER_ES9_TRMM-PFM_Edition1 CER_ES9_TRMM-PFM_Edition2 CER_ES9_Terra-FM1_Edition1 CER_ES9_Terra-FM2_Edition1 CER_ES9_FM1+FM2_Edition2 CER_ES9_Terra-FM1_Edition2 CER_ES9_Terra-FM2_Edition2 CER_ES9_Aqua-FM3_Edition1 CER_ES9_Aqua-FM4_Edition1 CER_ES9_FM1+FM2+FM3+FM4_Edition1 CER_ES9_Aqua-FM3_Edition2 CER_ES9_Aqua-FM4_Edition2 CER_ES9_FM1+FM3_Edition2 CER_ES9_FM1+FM4_Edition2 CER_ES9_Aqua-FM3_Edition1-CV CER_ES9_Aqua-FM4_Edition1-CV CER_ES9_Terra-FM1_Edition1-CV CER_ES9_Terra-FM2_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=2.5 degree; Longitude_Resolution=2.5 degree; Horizontal_Resolution_Range=250 km - < 500 km or approximately 2.5 degrees - < 5.0 degrees; Temporal_Resolution=hourly, daily, monthly; Temporal_Resolution_Range=Hourly - < Daily, Daily - < Weekly, Monthly - < Annual].

  4. Chirped pulse enhancement of multiphoton absorption in molecular iodine Vladislav V. Yakovlev, Christopher J. Bardeen, Jianwe Che, Jianshu Cao,

    E-print Network

    Cao, Jianshu

    are observed for chirped pulses with respect to transform-limited, zero chirp pulses. Theoretical a negatively chirped pulse has the opposite ordering. A transform-limited pulse is of the shortest possible relative to the shortest, transform- limited pulse. Preliminary calculations suggest that this en

  5. Chirped Pulse Adiabatic Passage in CARS for Imaging of Biological Structure and Dynamics

    Microsoft Academic Search

    Svetlana A. Malinovskaya; Svetlana A

    2007-01-01

    We propose the adiabatic passage control scheme implementing chirped femtosecond laser pulses to maximize coherence in a predetermined molecular vibrational mode using two-photon Raman transitions. We investigate vibrational energy relaxation and collisional dephasing as factors of coherence loss, and demonstrate the possibility for preventing decoherence by the chirped pulse train. The proposed method may be used to advance noninvasive biological

  6. Fine-Grained Access Control in the Chirp Distributed File System Patrick Donnelly and Douglas Thain

    E-print Network

    Thain, Douglas

    Fine-Grained Access Control in the Chirp Distributed File System Patrick Donnelly and Douglas Thain filesystem. We have implemented this system in the context of the Chirp user-level distributed filesystem distributed computing systems such as clus- ters, clouds, and grids provide end users with access to virtually

  7. Classification of nonstationary narrowband signals using segmented chirp features and hidden Gauss-Markov models

    Microsoft Academic Search

    Phillip L. Ainsleigh; Stephen G. Greineder; Nasser Kehtarnavaz

    2005-01-01

    A method is provided for classifying finite-duration signals with narrow instantaneous bandwidth and dynamic instantaneous frequency (IF). In this method, events are partitioned into nonoverlapping segments, and each segment is modeled as a linear chirp, forming a piecewise-linear IF model. The start frequency, chirp rate, signal energy, and noise energy are estimated in each segment. The resulting sequences of frequency

  8. Chirped-pulsed frequency modulation (C-PFM) for fiber Bragg grating sensors multiplexing

    Microsoft Academic Search

    G. Breglio; A. Irace; A. Cusano; A. Cutolo

    2006-01-01

    In this paper, we present experimental demonstration of using chirped-pulsed frequency modulation technique (C-PFM) in order to increase the multiplexing capability of a multipoint fiber Bragg grating (FBG) sensor network without increasing the hardware complexity of the acquisition system. This technique, extensively used in radar applications, is based on the amplitude modulation of the emitted signal (pulsed) by a chirped

  9. Chirped fiber-Bragg grating as self-temperature referenced strain sensor in nonisothermal thermoset processing

    Microsoft Academic Search

    Andrea Cusano; Patrizio Capoluongo; Antonello Cutolo; Michele Giordano

    2006-01-01

    A partially embedded chirped fiber-Bragg grating (FBG) has been used to monitor the strain build up during nonisothermal curing of a model thermoset resin. The particular feature of the spectrum of a linearly chirped and strongly apodized FBG to encode position along the sensor has been used to simultaneously measure temperature and strain during the cure cycle of an epoxy-based

  10. Temperature-independent strain sensor using a chirped grating partially embedded in a glass tube

    Microsoft Academic Search

    Sungchul Kim; Jaejoong Kwon; Sungwoo Kim; Byoungho Lee

    2000-01-01

    A novel intensity-based temperature-independent strain sensor using a chirped grating is demonstrated. The longer reflection wavelength part of the chirped grating is fixed to a glass tube and, hence, the reflected power from the grating decreases linearly with strain and is independent of temperature perturbation

  11. Optimal Particle Filters for Tracking a Time-Varying Harmonic or Chirp Signal

    Microsoft Academic Search

    Efthimios E. Tsakonas; Nicholas D. Sidiropoulos; Ananthram Swami

    2008-01-01

    We consider the problem of tracking the time-varying (TV) parameters of a harmonic or chirp signal using particle fil- tering (PF) tools. Similar to previous PF approaches to TV spec- tral analysis, we assume that the model parameters (complex am- plitude, frequency, and frequency rate in the chirp case) evolve ac- cording to a Gaussian AR(1) model; but we concentrate

  12. Airborne SAR processing of highly squinted data using a chirp scaling approach with integrated motion compensation

    Microsoft Academic Search

    A. Moreira; Yonghong Huang

    1994-01-01

    Proposes a new approach for high-resolution airborne SAR data processing, which uses a modified chirp scaling algorithm to accommodate the correction of motion errors, as well as the variations of the Doppler centroid in range and azimuth. By introducing a cubic phase term in the chirp scaling phase, data acquired with a squint angle up to 30° can be processed

  13. Chirped Pulse Adiabatic Passage in CARS for Imaging of Biological Structure and Dynamics

    Microsoft Academic Search

    Svetlana A. Malinovskaya

    2008-01-01

    We propose the adiabatic passage control scheme implementing chirped femtosecond laser pulses to maximize coherence in a predetermined molecular vibrational mode using two-photon Raman transitions. We investigate vibrational energy relaxation and coUisional dephasing as factors of coherence loss, and demonstrate the possibility for preventing decoherence by the chirped pulse train. The proposed method may be used to advance noninvasive biological

  14. Effects of Energy Chirp on Echo-Enabled Harmonic Generation Free-Electron Lasers

    SciTech Connect

    Huang, Z.; Ratner, D.; Stupakov, G.; Xiang, D.; /SLAC

    2009-02-23

    We study effects of energy chirp on echo-enabled harmonic generation (EEHG). Analytical expressions are compared with numerical simulations for both harmonic and bunching factors. We also discuss the EEHG free-electron laser bandwidth increase due to an energy-modulated beam and its pulse length dependence on the electron energy chirp.

  15. Chirped-pulse amplification system based on chirp reversal and near-field spatial reversal with common tiled grating pair as stretcher and compressor.

    PubMed

    Wang, Xiao; Wei, Xiaofeng; Hu, Yao; Zeng, Xiaoming; Zuo, Yanlei; Hao, Xin; Zhou, Kainan; Xie, Na; Zhang, Ying

    2012-08-10

    Chirped-pulse amplification system based on chirp reversal in optical parametric chirped-pulse amplification is proposed and experimentally demonstrated. The operation of this system can be described as negative stretching-temporal chirp reversal-energy amplification-negative compression, in which the pulse is stretched and compressed with the same gratings. Stand-alone stretcher adopting lenses or concave mirrors with large aperture can be omitted. Simulations showed that this work mode can also increase the cut-off band-pass of the whole system and increase the output energy by 15-17%. In addition, the stability of a tiled-grating compressor can be improved with this work mode. PMID:22885574

  16. Fast estimation of dispersion and initial chirp penalties by using TRC parameters

    NASA Astrophysics Data System (ADS)

    Coskun, Tamer H.; Klein, Jackson

    2003-08-01

    We have developed a wavelength domain simulation approach that can estimate the dispersion penalty due to initial chirp. This method only requires estimation of two parameters, i.e. effective chirp duration and effective chirp peak value, from the measured time resolved chirp (TRC) data. It is very fast comparing to full time domain simulation since it does not require the calculation of the time domain signal propagation in fiber. The method is based on a simple phenomenological model that is capable to predict the dispersion/chirp-induced eye-closure penalty. Model can estimate other system performance indicators such as BER and Q factor by taking into account the effects such as ASE, thermal and shot noise, extinction ratio etc. We have compared our results with published experimental data and full time domain simulations and have observed very good agreement.

  17. Backward Raman amplification in plasmas with chirped wideband pump and seed pulses

    NASA Astrophysics Data System (ADS)

    Wu, Zhao-Hui; Wei, Xiao-Feng; Zuo, Yan-Lei; Liu, Lan-Qin; Zhang, Zhi-Meng; Li, Min; Zhou, Yu-Liang; Su, Jing-Qin

    2015-01-01

    Chirped wideband pump and seed pulses are usually considered for backward Raman amplification (BRA) in plasmas to achieve an extremely high-power laser pulse. However, current theoretical models only contain either a chirped pump or a chirped seed. In this paper, modified three-wave coupling equations are proposed for the BRA in the plasmas with both chirped wideband pump and seed. The simulation results can more precisely describe the experiments, such as the Princeton University experiment. The optimized chirp and bandwidth are determined based on the simulation to enhance the output intensity and efficiency. Project supported by the National Natural Science Foundation of China (Grant No. 11305157) and the Development Foundation of China Academy of Engineering Physics Laboratory (CAEPL) (Grant No. 2013A0401019).

  18. Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam

    SciTech Connect

    Thangaraj, J.; Ruan, J.; Johnson, A.S.; Thurman-Keup, R.; Lumpkin, A.H.; Santucci, J.; Sun, Y.-E; Maxwell, T.; Edwards, H.; /Fermilab

    2012-05-01

    Emittance exchange has been proposed to increase the performance of free electron lasers by tailoring the phase space of an electron beam. The principle of emittance exchange - where the transverse phase space of the electron beam is exchanged with the longitudinal phase space - has been demonstrated recently at the A0 photoinjector. The experiment used a low charge bunch (250 pC) with no energy chirp. Theory predicts an improvement in the emittance exchange scheme when the incoming beam has an energy chirp imparted on it. The energy chirp helps to overcome the thick lens effect of the deflecting mode cavity and other second order effects that might lead to an incomplete emittance exchange at higher charges. In this work, we report experimental and simulation results from operating the emittance exchange beam line using an energy chirped beam with higher charge (500 pC) at different RF-chirp settings.

  19. Control of laser induced molecular fragmentation of n-propyl benzene using chirped femtosecond laser pulses

    PubMed Central

    Goswami, Tapas; Karthick Kumar, S.K.; Dutta, Aveek; Goswami, Debabrata

    2009-01-01

    We present the effect of chirping a femtosecond laser pulse on the fragmentation of n-propyl benzene. An enhancement of an order of magnitude for the relative yields of C3H3+ and C5H5+ in the case of negatively chirped pulses and C6H5+ in the case of positively chirped pulses with respect to the transform-limited pulse indicates that in some fragmentation channel, coherence of the laser field plays an important role. For the relative yield of all other heavier fragment ions, resulting from the interaction of the intense laser field with the molecule, there is no such enhancement effect with the sign of chirp, within experimental errors. The importance of the laser phase is further reinforced through a direct comparison of the fragmentation results with the second harmonic of the chirped laser pulse with identical bandwidth. PMID:19696899

  20. Research on a kind of high precision and fast signal processing algorithm for FM/CW laser radar

    NASA Astrophysics Data System (ADS)

    Xu, Xinke; Liu, Guodong; Chen, Fengdong; Liu, Bingguo; Zhuang, Zhitao; Lu, Cheng; Gan, Yu

    2014-12-01

    Range accuracy and efficiency are two important indicators for Frequency modulated continuous wave (FM/CW) laser radar, improving the accuracy and efficiency of extracting beat frequency are key factors for them. Multiple Modulation Zoom Spectrum Analysis (ZFFT) and the Chirp-Z Transform (CZT) are two widely used methods for improving frequency estimation. The paper through analyze advantages and disadvantages of these methods, proposes a high accuracy and fast signal processing method which is ZFFT-CZT, it combines advantages that ZFFT can reduce data size, and CZT can zoom in frequency of any interested band. The processing of ZFFT-CZT is following: firstly ZFFT is conducted by conducting Fourier transform on short time signal to calculate amount of frequency shift, and transforming high-frequency signal into low-frequency signal of long time sampling, then CZT is conducted by choosing any interested band to continue subdividing the spectral peaks, which can reduce picket fence effect. By simulate experiment based on ZFFT-CZT method, two closed targets at distance of 50m and 50.001m are measured, and the measurement errors are 40?m and 34?m respectively. It proved that ZFFT-CZT has a small amount of calculation, which can meet the requirement of high precision frequency extraction.

  1. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Abeysekera, Chamara; Oldham, James; Prozument, Kirill; Joalland, Baptiste; Park, Barratt; Field, Robert W.; Sims, Ian; Suits, Arthur; Zack, Lindsay

    2014-06-01

    We present preliminary results describing the development of a new instrument that combines two powerful techniques: Chirped Pulse-Fourier Transform MicroWave (CP-FTMW) spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates and perform unique spectroscopic, kinetics and dynamics measurements. We have constructed a new high-power K_a-band, 26-40 GHz, chirped pulse spectrometer with sub-MHz resolution, analogous to the revolutionary CP-FTMW spectroscopic technique developed in the Pate group at University of Virginia. In order to study smaller molecules, the E-band, 60-90 GHz, CP capability was added to our spectrometer. A novel strategy for generating uniform supersonic flow through a Laval nozzle is introduced. High throughput pulsed piezo-valve is used to produce cold (30 K) uniform flow with large volumes of 150 cm^3 and densities of 1014 molecules/cm3 with modest pumping facilities. The uniform flow conditions for a variety of noble gases extend as far as 20 cm from the Laval nozzle and a single compound turbo-molecular pump maintains the operating pressure. Two competing design considerations are critical to the performance of the system: a low temperature flow is needed to maximize the population difference between rotational levels, and high gas number densities are needed to ensure rapid cooling to achieve the uniform flow conditions. At the same time, collision times shorter than the chirp duration will give inaccurate intensities and reduced signal levels due to collisional dephasing of free induction decay. Details of the instrument and future directions and challenges will be discussed.

  2. Chirped-Pulse Fourier Transform Microwave Spectroscopy of 3-VINYLBENZALDEHYDE

    NASA Astrophysics Data System (ADS)

    Smith, Miranda; Brown, Gordon G.

    2013-06-01

    The pure rotational spectrum of 3-vinylbenzaldehyde (3VBA) has been measured and assigned. Coker College's chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer was used to measure the rotational spectrum of 3VBA in the 7.5 - 18.5 GHz region of the microwave spectrum. The results have been analyzed to discover the rotational constants and centrifugal distortion constants of four distinct conformations of 3VBA: cis,cis-, cis,trans-, trans,cis-, and trans,trans-3VBA. The experimental rotational constants have been compared to the results of ab initio calculations. The performance of Coker's CP-FTMW spectrometer will also be discussed.

  3. Chirped laser dispersion spectroscopy with differential frequency generation source.

    PubMed

    Nikodem, Michal; Krzempek, Karol; Karwat, Renata; Dudzik, Grzegorz; Abramski, Krzysztof; Wysocki, Gerard

    2014-08-01

    A feasibility study of open-path methane detection at 3.4 ?m using chirped laser dispersion spectroscopy (CLaDS) based on nonlinear differential frequency generation (DFG) laser source is performed. Application of a DFG source based on telecom laser sources and modulators allows mid-infrared CLaDS system to be optimized for measurements of gases at atmospheric conditions for which modulation in the GHz range is required. Excellent agreement between observed CLaDS signals and spectroscopic models has been observed. PMID:25078192

  4. Attenuated total reflectance spectroscopy with chirped-pulse upconversion.

    PubMed

    Shirai, Hideto; Duchesne, Constance; Furutani, Yuji; Fuji, Takao

    2014-12-01

    Chirped-pulse upconversion technique has been applied to attenuated total reflectance (ATR) infrared spectroscopy. An extremely broadband infrared pulse was sent to an ATR diamond prism and the reflected pulse was converted to the visible by using four-wave mixing in krypton gas. Absorption spectra of liquids in the range from 200 to 5500 cm(-1) were measured with a visible spectrometer on a single-shot basis. The system was applied to observe the dynamics of exchanging process of two solvents, water and acetone, which give clear vibrational spectral contrast. We observed that the exchange was finished within ? 10 ms. PMID:25606893

  5. Plasma absorption evidence via chirped pulse spectral transmission measurements

    NASA Astrophysics Data System (ADS)

    Jedrkiewicz, Ottavia; Minardi, Stefano; Couairon, Arnaud; Jukna, Vytautas; Selva, Marco; Di Trapani, Paolo

    2015-06-01

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  6. First-harmonic approximation in nonlinear chirped-driven oscillators.

    PubMed

    Uzdin, Raam; Friedland, Lazar; Gat, Omri

    2014-01-01

    Nonlinear classical oscillators can be excited to high energies by a weak driving field provided the drive frequency is properly chirped. This process is known as autoresonance (AR). We find that for a large class of oscillators, it is sufficient to consider only the first harmonic of the motion when studying AR, even when the dynamics is highly nonlinear. The first harmonic approximation is also used to relate AR in an asymmetric potential to AR in a "frequency equivalent" symmetric potential and to study the autoresonance breakdown phenomenon. PMID:24580292

  7. First-harmonic approximation in nonlinear chirped-driven oscillators

    NASA Astrophysics Data System (ADS)

    Uzdin, Raam; Friedland, Lazar; Gat, Omri

    2014-01-01

    Nonlinear classical oscillators can be excited to high energies by a weak driving field provided the drive frequency is properly chirped. This process is known as autoresonance (AR). We find that for a large class of oscillators, it is sufficient to consider only the first harmonic of the motion when studying AR, even when the dynamics is highly nonlinear. The first harmonic approximation is also used to relate AR in an asymmetric potential to AR in a "frequency equivalent" symmetric potential and to study the autoresonance breakdown phenomenon.

  8. Pre-emphasis determination for an S-band constant bandwidth FM/FM station

    NASA Technical Reports Server (NTRS)

    Wallace, G. R.; Salter, W. E.

    1972-01-01

    Pre-emphasis schedules are given for 11 constant-bandwidth FM subcarriers modulating an S band transmitter at three receiver signal to noise ratios (i.e., 9, 15, and 25 dB). The criterion for establishing these pre-emphasis curves is the achievement, at various receiver intermediate frequency signal to noise ratios, of equal receiver output signal to noise ratios for all channels. It is realized that these curves may not be the optimum pre-emphasis curves based on overall efficiency or maximum utilization of the allotted spectrum, but they are near-optimum for data with channels which require equal output signal to noise ratios, such as spectral densities. The empirically derived results are compared with a simplified, analytically derived schedule and the primary differences are explained. The S band pre-emphasis schedule differs from the lower frequency VHF case. Since most proportional bandwidth and constant bandwidth systems use ground based recorders and some use flight recorders (as the Saturn systems did on VHF proportional bandwidth telemetry), the effects of these recorders are discussed and a modified pre-emphasis schedule is presented showing the results of this study phase.

  9. Modelling multiple modes of spinning merger waveforms

    NASA Astrophysics Data System (ADS)

    Kelly, Bernard; Baker, John; Boggs, William D.; van Meter, James

    2010-02-01

    The Implicit Rotating Source (IRS) ansatz provides a coherent model of the dominant modes of gravitational radiation from a merging black-hole binary. Building on work with unequal-mass nonspinning binaries [Baker et al. Phys. Rev. D vol. 78, 044046 (2008)], we have applied the IRS to mergers of aligned and anti- aligned spinning binaries to form useful multi-mode waveform templates. We also discuss issues of parameter selection and spin and mass measurement with the Goddard Hahndol code. )

  10. Waveforms Measured in Confined Thermobaric Explosion

    SciTech Connect

    Reichenbach, H; Neuwald, P; Kuhl, A L

    2007-05-04

    Experiments with 1.5-g Shock-Dispersed-Fuel (SDF) charges have been conducted in six different chambers. Both flake Aluminum and TNT were used as the fuel. Static pressure gauges on the chamber wall were the main diagnostic. Waveforms for explosions in air were significantly larger than those in nitrogen - thereby demonstrating a strong thermobaric (combustion) effect. This effect increases as the confinement volume decreases and the mixture richness approaches 1.

  11. Network Centric Waveform operation over the WGS

    Microsoft Academic Search

    Rohit Gupta; Christopher McLain; James Joseph Hant; Dexiang Wang; Janise McNair

    2011-01-01

    The capabilities of the channelizer-switch and the multi-beam\\/multi-band payload of the Wideband Global SATCOM (WGS) system introduce new bandwidth allocation, network design, and footprint coverage scenarios. The utilization of these capabilities at the ground segment is supported by the Network Centric Waveform (NCW) by allowing multi-beam operation in a single network with fan-in\\/fan-out strappings and multiple non-contiguous spectral allocations (across

  12. MIMO Radar Waveform Constraints for GMTI

    Microsoft Academic Search

    K. W. Forsythe; D. W. Bliss

    2010-01-01

    Ground moving-target indication (GMTI) provides both an opportunity and challenge for coherent multiple-input multiple-output (MIMO) radar. MIMO techniques can improve a radar's angle estimation and the minimum detectable velocity (MDV) for a target. However, the challenge of clutter mitigation places significant constraints on MIMO radar waveforms. In this paper, the loss of target return because of clutter mitigation (signal-to-noise ratio

  13. Radar waveform synthesis for target identification

    NASA Astrophysics Data System (ADS)

    Chen, K. M.

    1981-06-01

    A new scheme for radar detection and discrimination, the radar waveform synthesis method, is investigated. This scheme consists of synthesizing an aspect-independent waveform for the incident radar signal which excites an arbitrarily oriented target in such a way that the return radar signal from the target contains only a single natural resonance mode of the target in the late-time period. When the synthesized incident radar signal for exciting a particular natural mode of a known, preselected target is applied to a wrong target, the return radar signal will be significantly different from that of the expected natural mode, thus, the wrong target can be sensitively discriminated. The selection of an optimum pulse duration of the required incident signal for the purpose of shaping its waveform is also studied. Three kinds of targets, an arbitrarily oriented thin wire, a sphere and a normally oriented infinite cylinder, have been investigated. The cases of an arbitrarily oriented wire and a sphere have been completed and the results are reported in Parts 1 and 2. The case of infinite cylinder will be completed shortly and incomplete results of this case are outlined in Part 3.

  14. Photodissociation of D2 (+) induced by linearly chirped laser pulses.

    PubMed

    Csehi, András; Halász, Gábor J; Cederbaum, Lorenz S; Vibók, Ágnes

    2015-07-01

    Recently, it has been revealed that so-called light-induced conical intersections (LICIs) can be formed both by standing or by running laser waves even in diatomic molecules. Due to the strong nonadiabatic couplings, the existence of such LICIs has significant impact on the dynamical properties of a molecular system. In our former studies, the photodissociation process of the D2 (+) molecule was studied initiating the nuclear dynamics both from individual vibrational levels and from the superposition of all the vibrational states produced by ionizing D2. In the present work, linearly chirped laser pulses were used for initiating the dissociation dynamics of D2 (+). In contrast to the constant frequency (transform limited) laser fields, the chirped pulses give rise to LICIs with a varying position according to the temporal frequency change. To demonstrate the impact of these LICIs on the dynamical properties of diatomics, the kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the D2 (+) photofragments were calculated and discussed. PMID:26156481

  15. Chirped CPMG for well-logging NMR applications.

    PubMed

    Casabianca, Leah B; Mohr, Daniel; Mandal, Soumyajit; Song, Yi-Qiao; Frydman, Lucio

    2014-05-01

    In NMR well-logging, the measurement apparatus typically consists of a permanent magnet which is inserted into a bore, and the sample is the rock surrounding the borehole. When compared to the conditions of standard NMR experiments, this application is thus challenged by relatively weak and invariably inhomogeneous B0 and B1 fields. Chemical shift information is not generally obtained in these measurements. Instead, diffusivity, porosity and permeability information is collected from multi-echo decay measurements - most often using a Carr-Purcell Meiboom-Gill (CPMG) pulse sequence to enhance the experiment's limited sensitivity. In this work, we explore the consequences of replacing the hard square pulses used in a typical CPMG sequence with chirped pulses sweeping a range of frequencies. The greater bandwidths that for a maximum B1 level can be excited by chirped pulses translates into marked expansion of the detection volume, and thus significant signal-to-noise improvements when compared to standard CPMG acquisitions using hard pulses. This improvement, usually amounting to signal enhancements ?3, can be used to reduce the experimental time of NMR well-logging measurements, for measuring T2 even when B0 and B1 inhomogenieties complicate the measurements, and opening new opportunities in the determination of diffusional properties. PMID:24674888

  16. Chirped CPMG for well-logging NMR applications

    NASA Astrophysics Data System (ADS)

    Casabianca, Leah B.; Mohr, Daniel; Mandal, Soumyajit; Song, Yi-Qiao; Frydman, Lucio

    2014-05-01

    In NMR well-logging, the measurement apparatus typically consists of a permanent magnet which is inserted into a bore, and the sample is the rock surrounding the borehole. When compared to the conditions of standard NMR experiments, this application is thus challenged by relatively weak and invariably inhomogeneous B0 and B1 fields. Chemical shift information is not generally obtained in these measurements. Instead, diffusivity, porosity and permeability information is collected from multi-echo decay measurements - most often using a Carr-Purcell Meiboom-Gill (CPMG) pulse sequence to enhance the experiment’s limited sensitivity. In this work, we explore the consequences of replacing the hard square pulses used in a typical CPMG sequence with chirped pulses sweeping a range of frequencies. The greater bandwidths that for a maximum B1 level can be excited by chirped pulses translates into marked expansion of the detection volume, and thus significant signal-to-noise improvements when compared to standard CPMG acquisitions using hard pulses. This improvement, usually amounting to signal enhancements ?3, can be used to reduce the experimental time of NMR well-logging measurements, for measuring T2 even when B0 and B1 inhomogenieties complicate the measurements, and opening new opportunities in the determination of diffusional properties.

  17. Theoretical duration and amplitude of an FM click

    Microsoft Academic Search

    A. J. Rainal

    1980-01-01

    The exact initial behavior of the probability density of the duration of an FM click in the case of an unmodulated carrier plus narrowband stationary Gaussian noise is presented. A simple Maxwell probability density is developed to approximate the probability density of the duration. The development leads to the conjecture that the Maxwell probability density is the exact limiting probability

  18. A new demodulation method improving FM system interference immunity

    Microsoft Academic Search

    Z. D. Stojanovic; M. L. Dukic; I. S. Stojanovic

    1981-01-01

    A new algorithm for the process of demodulation is proposed on the basis of an investigation of interference into FM systems. The algorithm offers better immunity against the baseband interference noise than does the method using the conventional limiter-discriminator. Desired signal processing is carried out by the functional devices added to the conventional limiter-discriminator in such a way that this

  19. A New Demodulation Method Improving FM System Interference Immunity

    Microsoft Academic Search

    ZORKA D. STOJANOVIC; MIRQSLAV L. DUKIC; ILIJA S. STOJANOVIC

    1981-01-01

    As a result of investigation of interference into FM systems, a new algorithm for the process of demodulation is proposed. When compared to the method using the conventional limiter-discriminator, it offers better immunity against the baseband interference noise. Desired signal processing is performed by the functional devices added to the conventional limiter-discriminator in such a way that this new demodulator

  20. INDIRECT COSTS OF RESEARCH University Policy No: FM5400

    E-print Network

    Victoria, University of

    1 INDIRECT COSTS OF RESEARCH University Policy No: FM5400 Classification: Financial Management and maintenance of facilities and processes that support Research; the management of the entire Research process, animal care and environmental assessment). 5.00 Research Funding Agreement means funding provided through

  1. College of Medicine FM Family and Community Medicine

    E-print Network

    MacAdam, Keith

    College of Medicine FM Family and Community Medicine KEY: # = new course * = course changed, FAMILY MEDICINE. (1-3) With the advice and approval of his or her faculty adviser, the first-year student may choose approved electives offered by the Department of Family and Community Medicine. The intent

  2. Experimental results for the interference between FM television signals

    NASA Technical Reports Server (NTRS)

    Groumpos, P. P.; Vernon, G. D.

    1981-01-01

    Experimental results based on subjective evaluation of picture quality of FM television systems are presented. Curves indicating the variation in protection ratio with impairment grade are provided. Such an analysis would be useful to the broadcasting satellite system designer. The experimental procedures and test conditions followed are briefly summarized. The need for a theoretical planning method is briefly discussed.

  3. Local mass transport effects in the FM01 laboratory electrolyser

    Microsoft Academic Search

    C. J. Brown; D. Pletcher; F. C. Walsh; J. K. Hammond; D. Robinson

    1992-01-01

    A number of patterns of segmented line electrodes have been manufactured using copper printed circuit board technology. These segmented electrodes have been used to investigate local mass transport effects in ICI's FM01-LC parallel plate electrolyser. It is shown that in the absence of a turbulence promoter the current distribution is uneven. Along the direction of electrolyte flow, a tertiary current

  4. Effects of noise reduction on AM and FM perception.

    PubMed

    Ives, D Timothy; Calcus, Axelle; Kalluri, Sridhar; Strelcyk, Olaf; Sheft, Stanley; Lorenzi, Christian

    2013-02-01

    The goal of noise reduction (NR) algorithms in digital hearing aid devices is to reduce background noise whilst preserving as much of the original signal as possible. These algorithms may increase the signal-to-noise ratio (SNR) in an ideal case, but they generally fail to improve speech intelligibility. However, due to the complex nature of speech, it is difficult to disentangle the numerous low- and high-level effects of NR that may underlie the lack of speech perception benefits. The goal of this study was to better understand why NR algorithms do not improve speech intelligibility by investigating the effects of NR on the ability to discriminate two basic acoustic features, namely amplitude modulation (AM) and frequency modulation (FM) cues, known to be crucial for speech identification in quiet and in noise. Here, discrimination of complex, non-linguistic AM and FM patterns was measured for normal hearing listeners using a same/different task. The stimuli were generated by modulating 1-kHz pure tones by either a two-component AM or FM modulator with patterns changed by manipulating component phases. Modulation rates were centered on 3 Hz. Discrimination of AM and FM patterns was measured in quiet and in the presence of a white noise that had been passed through a gammatone filter centered on 1 kHz. The noise was presented at SNRs ranging from -6 to +12 dB. Stimuli were left as such or processed via an NR algorithm based on the spectral subtraction method. NR was found to yield small but systematic improvements in discrimination for the AM conditions at favorable SNRs but had little effect, if any, on FM discrimination. A computational model of early auditory processing was developed to quantify the fidelity of AM and FM transmission. The model captured the improvement in discrimination performance for AM stimuli at high SNRs with NR. However, the model also predicted a relatively small detrimental effect of NR for FM stimuli in contrast with the average psychophysical data. Overall, these results suggest that the lack of benefits of NR on speech intelligibility is partly caused by the limited effect of NR on the transmission of narrowband speech modulation cues. PMID:23180229

  5. Evolution of the frequency chirp of Gaussian pulses and beams when passing through a pulse compressor.

    PubMed

    Li, Derong; Lv, Xiaohua; Bowlan, Pamela; Du, Rui; Zeng, Shaoqun; Luo, Qingming

    2009-09-14

    The evolution of the frequency chirp of a laser pulse inside a classical pulse compressor is very different for plane waves and Gaussian beams, although after propagating through the last (4th) dispersive element, the two models give the same results. In this paper, we have analyzed the evolution of the frequency chirp of Gaussian pulses and beams using a method which directly obtains the spectral phase acquired by the compressor. We found the spatiotemporal couplings in the phase to be the fundamental reason for the difference in the frequency chirp acquired by a Gaussian beam and a plane wave. When the Gaussian beam propagates, an additional frequency chirp will be introduced if any spatiotemporal couplings (i.e. angular dispersion, spatial chirp or pulse front tilt) are present. However, if there are no couplings present, the chirp of the Gaussian beam is the same as that of a plane wave. When the Gaussian beam is well collimated, the introduced frequency chirp predicted by the plane wave and Gaussian beam models are in closer agreement. This work improves our understanding of pulse compressors and should be helpful for optimizing dispersion compensation schemes in many applications of femtosecond laser pulses. PMID:19770925

  6. Effect of atomic density on propagation and spectral property of femtosecond chirped Gaussian pulses

    NASA Astrophysics Data System (ADS)

    Wang, Zhendong; Gao, Feng

    2015-05-01

    We theoretically investigate the effect of the atomic densities N on propagation and spectral property of femtosecond chirped Gaussian pulse in a three-level ?-type atomic medium by using the numerical solution of the full Maxwell- Bloch equations. It is shown that, when the positive chirped pulse with area 3?, propagate in the medium with smaller N, pulse splitting doesn't occur and many small oscillations at the trailing edge of the pulse appear, in addition, the level |2< population ?22 of the pulse exhibits an oscillation feature with time evolution, moreover, the spectral component near the central frequency of the pulse shows an oscillation characteristic too, and the propagation and spectral property of the negative chirped 3? pulse is very similar to that of the positive chirped 3? pulse. For the positive chirped 3? pulse pulses, propagate in the medium with larger N, pulse splitting also doesn't occur but many small oscillations both at leading edge and the trailing edge of the pulse appear, and the population ?22 of the pulse only exhibits an scarcely oscillation feature with time evolution, at the same time many oscillations both in blue shift and red shift components of the pulse appear but the spectral component near the central frequency of the pulse oscillate more severely, and the propagation and spectral property of the negative chirped 3? pulse is very similar to that of the positive chirped 3? pulse, but comparing with the case of the negative chirped 3? pulse, the propagation of the positive chirped 3? pulse is delayed at the same distance and the delayed time becomes longer with the distance increasing.

  7. Isolated attosecond pulse generation from pre-excited medium with a chirped and chirped-free two-color field.

    PubMed

    Du, Hongchuan; Luo, Laoyong; Wang, Xiaoshan; Hu, Bitao

    2012-04-23

    We theoretically investigate the isolated attosecond pulse generation from pre-excited medium with a chirped and chirped-free two-color field. It is found that the large initial population of the excited state can lead to the high density of the free electrons in the medium and the large distortion of the driving laser field after propagation, though it benefits large enhancement of harmonic intensity in single atom response. These effects can weaken the phase-match of the macroscopic supercontinuum. On the contrary, the small initial population of 4% can generate well phase-match intense supercontinuum. We also investigate an isolated attosecond pulse generation by using a filter centered on axis to select the harmonics in the far field. Our results reveal that the radius of the spatial filter should be chosen to be small enough to reduce the duration of the isolated attosecond pulse due to the curvature effect of spatiotemporal profiles of the generated attosecond pulses in the far field. PMID:22535063

  8. AM/FM development for a small electric utility or form partnerships to minimize AM/FM development costs

    SciTech Connect

    Hahne, R. [Chelan County Public Utility District, Wenatchee, WA (United States)

    1996-08-01

    Chelan County Public Utility District is a 32,000 customer electric utility in central Washington State. Being a small utility presents unique problems in developing a complex AM/FM system. With only a small staff assigned part-time to this project, partnering and outsourcing became essential for developing an AM/FM system. An incremental approach was also necessary. Our project started in 1992 in partnership with Chelan County and the City of Wenatchee for the development of a common landbase in ARC/INFO. For our AM/FM system, a purchased solution was much more feasible than in-house development. We decided against a big requirements definition phase or a formal RFP, and instead looked at available AM/FM systems to decide what was feasible for us. This paper shares the basics of our partnering strategy and outlines how our approach will allow the project to be completed in a fast-track of 40 months at a minimal cost to the Chelan P.U.D. ratepayers.

  9. Peculiarities of laser phase behavior associated with the accelerated electron in a chirped laser pulse

    SciTech Connect

    Song, Q.; Wu, X. Y. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); Wang, J. X. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China); Kawata, S. [Center for Optical Research and Education, Department of Advanced Interdisciplinary Science, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan); Wang, P. X., E-mail: wpx@fudan.edu.cn [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); Center for Optical Research and Education, Department of Advanced Interdisciplinary Science, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan)

    2014-05-15

    In this paper, we qualitatively analyzed peculiarities of laser phase behavior associated with the accelerated electron in a chirped laser pulse. We unveiled the relationship between the changes in the orientation of the electron trajectory and the cusps in magnitude of the phase velocity of the optical field along the electron trajectory in a chirped laser pulse. We also explained how the chirp effect induced the singular point of the phase velocity. Finally, we discussed the phase velocity and phase witnessed by the electron in the particle's moving instantaneous frame.

  10. Positive and negative chirping of laser pulses shorter than 100 fsec in a saturable absorber

    SciTech Connect

    Miranda, R.S.; Jacobovitz, G.R.; Brito Cruz, C.H.; Scarparo, M.A.F.

    1986-04-01

    We present a calculation of the chirp generated in laser pulses shorter than 100 fsec on propagation through a saturable absorber (DODCI in ethylene glycol). The calculation takes into account the absorber saturation and the solvent nonlinear refractive index. At pulse energies greater than 10 nJ the chirp tends to be predominantly positive, and it increases rapidly as the pulse duration becomes shorter than 50 fsec. At pulse energies in the 1--7-nJ range the chirp is mostly negative for pulses longer than 30 fsec.

  11. Multiscale modeling of vibrational predissociation spectra under a chirped laser pulse

    NASA Astrophysics Data System (ADS)

    Calvo, F.; Parneix, P.

    2012-06-01

    The vibrational predissociation spectrum of the argon-tagged ionic cluster (NaCl)32 due to exposure to a chirped infrared laser was theoretically calculated in a time multiscale framework. The response to the laser field is modeled explicitly by molecular dynamics simulations, and statistical rate theories are used to evaluate the long-time dissociation probability. Due to anharmonicities and multiphoton processes, the predissociation spectrum shows some small but systematic red shift in the main absorption line. Negative chirping toward lower frequencies further enhances this effect, and also alters the band intensity and the band width. Positive chirping attenuates the dissociation efficiency.

  12. Rate equation analysis of frequency chirp in optically injection-locked quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Wang, C.; Grillot, F.; Kovanis, V. I.; Bodyfelt, J. D.; Even, J.

    2014-03-01

    The frequency chirp characteristics of an optically injection-locked quantum cascade laser are theoretically investigated. The key parameter chirp-to-power ratio (CPR) is analytically derived from a full rate equation model. The CPR value can be efficiently reduced by increasing optical injection strength, especially at modulation frequencies less than 10 GHz. In contrast to interband lasers, both positive and negative frequency detuning increase the CPR. Since the frequency detuning is also predicted to enhance the intensity modulation response, a trade-off is required in the optical injection to simultaneously obtain a large modulation bandwidth and low frequency chirp.

  13. Self-deflecting plasmonic lattice solitons and sur-face modes in chirped plasmonic arrays

    E-print Network

    Li, Chunyan; Ye, Fangwei; Kartashov, Yaroslav V; Torner, Lluis; Chen, Xianfeng

    2015-01-01

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply-subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation,the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped arraythat form even in the absence of nonlinearity.

  14. Relation between chirp and linewidth reduction in external Bragg reflector semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Olsson, N. A.; Henry, C. H.; Kazarinov, R. F.; Lee, H. J.; Johnson, B. H.

    1987-07-01

    A 1.5-?m single longitudinal mode semiconductor laser, formed by butt coupling an external Bragg reflector to a standard Fabry-Perot laser, is shown to have greatly reduced wavelength chirp and emission linewidth. The linewidth reduction is found to be proportional to the square of the chirp reduction, in agreement with a previous theoretical prediction. The linewidth and chirp reduction factor can be varied by changing the operating point of the laser. With a 3-mm-long Bragg reflector, a linewidth of 1 MHz at 5 mW has been achieved.

  15. 47 CFR 73.7002 - Fair distribution of service on reserved band FM channels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Fair distribution of service on reserved band FM channels...Channels § 73.7002 Fair distribution of service on reserved band FM channels...substantially further the fair distribution of service goals enunciated in...

  16. 76 FR 81932 - Auction of FM Broadcast Construction Permits; Revised Construction Permit Number in Auction 93

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ...DA 11-2046] Auction of FM Broadcast Construction Permits; Revised Construction Permit Number in Auction 93 AGENCY: Federal...This document announces a change to the construction permit number for one of the FM...

  17. Few-cycle optical waveform synthesis

    Microsoft Academic Search

    A. Poppe; R. Holzwarth; A. Apolonski; G. Tempea; Ch. Spielmann; T. W. Hänsch; F. Krausz

    2001-01-01

    .   We demonstrate cycle-slip-free electronic control of the carrier-envelope phase evolution of few-femtosecond light pulses,\\u000a optical access to its sub-cycle fluctuations and suppression of the amplitude noise of a mode-locked laser by phase control.\\u000a As a result, few-cycle light waveforms can now be synthesized with electric and magnetic fields reproducible to within a known\\u000a phase error (<0.3 rad) and an unprecedentedly

  18. Auto-correlation based intelligent technique for complex waveform presentation and measurement

    Microsoft Academic Search

    K P S Rana; R Singh; K S Sayann

    2009-01-01

    Waveform acquisition and presentation forms the heart of many measurement systems. Particularly, data acquisition and presentation of repeating complex signals like sine sweep and frequency-modulated signals introduces the challenge of waveform time period estimation and live waveform presentation. This paper presents an intelligent technique, for waveform period estimation of both the complex and simple waveforms, based on the normalized auto-correlation

  19. Waveform preconditioning for clutter rejection in multipath for sparse distributed apertures

    Microsoft Academic Search

    T. Varslot; B. Yazici; C.-E. Yarman; M. Cheney; L. Scharf

    2007-01-01

    The idea of preconditioning transmit waveforms for optimal clutter rejection in radar imaging is presented. Waveform preconditioning involves determining a map on the space of transmit waveforms, and then applying this map to the waveforms before transmission. The work applies to systems with an arbitrary number of transmitand receive-antenna elements, and makes no assumptions about the elements being co-located. Waveform

  20. A combined waveform relaxation: waveform relaxation newton algorithm for efficient parallel circuit simulation

    Microsoft Academic Search

    Patrick Odent; Luc J. M. Claesen; Hugo De Man

    1990-01-01

    This paper presents two new techniques for accelerating circuit simulation. The first technique is an improvement of the parallel Waveform Relaxation Newton (WRN) method. The computations of all the timepoints are executed concurrently. Static task partitioning is shown to be an efficient method to limit the scheduling overhead. The second technique combines in a dynamic way the efficiency of the

  1. Chirped-Pulse Fourier Transform Microwave Spectroscopy of 3-METHOXYPROPYLAMINE

    NASA Astrophysics Data System (ADS)

    McCabe, Morgan N.; Shipman, Steven; Arnold, Sean; Chewning, J. Chase; Smith, Miranda; Brown, Gordon

    2014-06-01

    The rotational spectrum of 3-methoxypropylamine was collected from 8.0 to 18.5 GHz with the Coker College chirped-pulse FTMW molecular beam spectrometer. Ab initio predictions using the B3LYP-D3 dispersion-corrected density functional gave high quality starting geometries, enabling us to quickly assign the spectrum of the lowest energy conformer, which has a g'gt configuration (moving from the amine end to the methoxy end of the molecule). Attempts were also made to collect the spectrum of this molecule in the room-temperature waveguide instrument at New College, but these attempts were unsuccessful as the molecule rapidly reacts with the copper walls of the waveguide to produce ammonia.

  2. Femtosecond Chirp-Free Transient Absorption Method And Apparatus

    DOEpatents

    McBranch, Duncan W. (Santa Fe, NM); Klimov, Victor I. (White Rock, NM)

    2001-02-20

    A method and apparatus for femtosecond transient absorption comprising phase-sensitive detection, spectral scanning and simultaneous controlling of a translation stage to obtain TA spectra information having at least a sensitivity two orders of magnitude higher than that for single-shot methods, with direct, simultaneous compensation for chirp as the data is acquired. The present invention includes a amplified delay translation stage which generates a splittable frequency-doubled laser signal at a predetermined frequency f, a controllable means for synchronously modulating one of the laser signals at a repetition rate of f/2, applying the laser signals to a material to be sample, and acquiring data from the excited sample while simultaneously controlling the controllable means for synchronously modulating.

  3. Experimental demonstration of fiber optical parametric chirped-pulse amplification

    NASA Astrophysics Data System (ADS)

    Zhou, Yue; Cheung, Kim K. Y.; Chui, P. C.; Wong, Kenneth K. Y.

    2010-02-01

    A fiber optical parametric chirped-pulse amplifier (FOPCPA) is experimentally demonstrated. A 1.76 ps signal at 1542 nm with a peak power of 20 mW is broadened to 40 ps, and then amplified by a 100-ps pulsed pump at 1560 nm. The corresponding idler at 1578 nm is generated as the FOPCPA output. The same medium used to stretch the signal is deployed to compress the idler to 3.8 ps, and another spool of fiber is deployed to further compress the idler to 1.87 ps. The peak power of the compressed idler is 2 W, which corresponds to a gain of 20 dB.

  4. 75 FR 61752 - Auction of FM Broadcast Construction Permits Scheduled for March 29, 2011; Comment Sought on...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-06

    ...10-1711] Auction of FM Broadcast Construction Permits Scheduled for March 29, 2011...announces the auction of certain FM construction permits scheduled to commence on March...an auction of certain FM Broadcast construction permits. This auction, which is...

  5. Simultaneous occupational exposure to FM and UHF transmitters.

    PubMed

    Vali?, Blaž; Kos, Bor; Gajšek, Peter

    2012-01-01

    Occupational exposure caused by large broadcasting transmitters exceeds current reference levels. As it is common for different radio and TV transmitters to share the location, we analysed combined exposure on a 40-m high mast. The frequency modulation (FM) transmitter, located between the 10th and 30th metre, had the power of 25 kW, whereas an ultra-high frequency (UHF) transmitter of 5 kW occupied the top 8 m of the mast. Measured and calculated values of the electric field strength exceeded the reference levels up to 10 times; however, the results for the specific absorption rate (SAR) values show that the reference levels are very conservative for FM exposure, i.e., basic restrictions are not exceeded even when the reference levels are exceeded 10 times. However, for UHF exposure the reference levels are not conservative; they give a good prediction of real exposure. PMID:22721535

  6. Fabry-Pérot cavity based on chirped sampled fiber Bragg gratings.

    PubMed

    Zheng, Jilin; Wang, Rong; Pu, Tao; Lu, Lin; Fang, Tao; Li, Weichun; Xiong, Jintian; Chen, Yingfang; Zhu, Huatao; Chen, Dalei; Chen, Xiangfei

    2014-02-10

    A novel kind of Fabry-Pérot (FP) structure based on chirped sampled fiber Bragg grating (CSFBG) is proposed and demonstrated. In this structure, the regular chirped FBG (CFBG) that functions as reflecting mirror in the FP cavity is replaced by CSFBG, which is realized by chirping the sampling periods of a sampled FBG having uniform local grating period. The realization of such CSFBG-FPs having diverse properties just needs a single uniform pitch phase mask and sub-micrometer precision moving stage. Compared with the conventional CFBG-FP, it becomes more flexible to design CSFBG-FPs of diverse functions, and the fabrication process gets simpler. As a demonstration, based on the same experimental facilities, FPs with uniform FSR (~73 pm) and chirped FSR (varying from 28 pm to 405 pm) are fabricated respectively, which shows good agreement with simulation results. PMID:24663569

  7. A Multiterawatt Laser Using a High-Contrast, Optical Parametric Chirped-Pulse Presamplifier

    SciTech Connect

    Bagnoud, V.; Puth, J.; Begishev, I.; Guardalben, M.; Zuegel, J.D.; Forget, N.; LeBlanc, C.

    2005-09-30

    A laser has been built that uses optical parametric chirped-pulse preamplification and a glass booster amplifier. We review the performance of the 5-Hz, multijoule OPCPA pump laser, the 370-mJ OPCPA, and the overall laser.

  8. Bubble-Based Acoustic Radiation Force Using Chirp Insonation to Reduce Standing Wave Effects

    PubMed Central

    Erpelding, Todd N.; Hollman, Kyle W.; O’Donnell, Matthew

    2007-01-01

    Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young’s modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200, and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size. PMID:17306697

  9. Chirped-pulse millimeter-wave spectroscopy, dynamics, and manipulation of Rydberg-Rydberg Transitions

    E-print Network

    Colombo, Anthony P. (Anthony Paul)

    2013-01-01

    The chirped-pulse millimeter-wave (CPmmW) technique is applied to transitions between Rydberg states, and calcium atoms are used as the initial test system. The unique feature of Rydberg{Rydberg transitions is that they ...

  10. E-Learning Readiness in Medicine: Turkish Family Medicine (FM) Physicians Case

    ERIC Educational Resources Information Center

    Parlakkiliç, Alaattin

    2015-01-01

    This research investigates e-learning readiness level of family medicine physicians (FM) in Turkey. The study measures the level of e-learning readiness of Turkish FM physicians by an online e-learning readiness survey. According to results five areas are ready at Turkish FM physicians but need a few improvements:…

  11. DSP-based digital FM demodulation for GMSK signals

    Microsoft Academic Search

    B Ramamurthi; K Giridhar; M A Srinivas

    1996-01-01

    Demodulation of Gaussian Minimum Shift Keying (GMSK) using a limiter-discriminator is a low complexity alternative to coherent\\u000a demodulation. This so-called digital FM demodulation is followed by clock recovery, sampling, and thresholding. Conventionally,\\u000a clock recovery is done in hardware, and matched filtering is usually not possible when the Gaussian pulse is wider than a\\u000a bit duration. We propose a clock recovery

  12. Level structure of sup 256 Fm: Experiment vs theory

    SciTech Connect

    Bunker, M.E.; Starner, J.W.

    1990-01-01

    The amount of experimental data on intrinsic states in the even-even isotopes of the transcurium elements is rather limited, providing only a few tests of theoretical models in this region. Thus, it is of interest to determine to what extent the recent results on levels in {sup 256}Fm compare with existing theoretical calculations, such as those of Ivanova et al. 4 refs., 1 fig., 1 tab.

  13. A Power Spectral Density Analysis for Digital FM

    Microsoft Academic Search

    G. Garrison

    1975-01-01

    Except for rectangular-shaped modulating pulses, the specification of the power spectral density function (psdf) for digital FM is analytically perverse and only a few results are available in the journal literature. In this paper an analysis is presented based on the selection of an appropriate duration-limited\\/level-quantized approximation for the modulating pulses and equations suitable for machine computation are subsequently developed.

  14. Analytical Approaches to Guide SLS Fault Management (FM) Development

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    2012-01-01

    Extensive analysis is needed to determine the right set of FM capabilities to provide the most coverage without significantly increasing the cost, reliability (FP/FN), and complexity of the overall vehicle systems. Strong collaboration with the stakeholders is required to support the determination of the best triggers and response options. The SLS Fault Management process has been documented in the Space Launch System Program (SLSP) Fault Management Plan (SLS-PLAN-085).

  15. Target discrimination technique utilizing noise waveforms

    NASA Astrophysics Data System (ADS)

    Woodington, Gordon; DeLuca, Mark; Moro, Richard; Lemus, Daniel; Vela, Russell; Narayanan, Ram

    2011-06-01

    Noise waveforms generated using low cost diodes are a simple way for radars to transmit a wideband (> 4 GHz) multi-bit pseudorandom code for use in a cross correlation receiver. This type of waveform also has the advantage of being difficult to intercept and is less prone to interfere with adjacent systems. Radar designed to operate over this wide frequency range can take advantage of unique target Radar Cross Section (RCS) ripple versus frequency for objects of different materials and sizes. Specifically the periodicity and amplitude of the ripple is dependent on the shape and size of a target. Since background clutter does not display this variation, RCS variation determines whether a known target is present in a return. This paper will present the radar hardware and signal processing techniques used to maximize a target's unique spectral response against a cluttered background. The system operates CW over a 4-8 GHz bandwidth requiring the need to address issues regarding range resolution and far out undesired returns. Lessons learned from field observations and mitigation techniques incorporated in the system are included. This paper also deals with the signal processing technique used for detection, then discrimination. Detection thresholds are set and triggered by a simple correlation peak level. Discrimination involves inspection of the spectral return. A comparison performed in real time to a stored library value determines the presence of known objects. Measured data provided demonstrates the ability of the radar to discriminate multiple targets against multiple backgrounds.

  16. Chirp Frequency-Translated Reference Ultra-Wideband (UWB) Wireless Communication System

    Microsoft Academic Search

    Zhang Jian; Hu Han-Ying; Liu Luo-Kun; Wang Tao

    2008-01-01

    A chirp frequency-translated reference ultra-wideband system is proposed based on the time-domain and code-domain transmitted-reference impulse radio UWB systems. Mathematic derivation and simulation results show that while this system has similar performance to pulse-based UWB system without losing the merits, it has the advantages of chirp communication system as well. Meanwhile, this system not only offers a solution of simple

  17. Practical design of optical diagnostics for chirped-pulse free-electron lasers

    Microsoft Academic Search

    Eric B. Szarmes; John M. J. Madey

    1992-01-01

    In recent years there have been several proposals to operate rf-linac-driven FELs with chirped electron and optical micropulses for use in fast time-resolved experiments. We have been actively pursuing this application on the Mark-III infrared FEL at Duke University, and have designed and procured an apparatus to achieve broad-band compression of chirped optical pulses between roughly 2.5 mum and 4.1

  18. Joint transform time-integrating acousto-optic correlator for chirp spectrum analysis

    Microsoft Academic Search

    P. S. Guilfoyle; D. L. Hecht; D. L. Steinmetz

    1980-01-01

    A time-integrating optical processor is configured for one-dimensional chirp correlation spectrum analysis. A unique optical implementation, utilizing TeO2 shear wave acousto-optic cells, is designed to operate in a configuration which allows wide bandwidth diffraction to both the positive and negative first diffraction orders. The result is high optical throughput efficiency, excellent fringe visibility, and a coaxial system design. Chirp linearity

  19. Spectral transmission characteristics of weakly tilted and tilted chirped fiber gratings: comparative studies

    NASA Astrophysics Data System (ADS)

    Osuch, Tomasz; Jurek, Tomasz; Jedrzejewski, Kazimierz

    2013-10-01

    In this paper the comparative study of spectral transmission characteristics of tilted Bragg gratings made using uniform phase mask and chirped phase mask are presented. Results are focused on low tilt angles with special interest on cladding modes behavior. The spectral characteristic shape for simultaneously tilted and chirped Bragg gratings point out its potential applications as amplitude discriminator in fiber sensing applications and gain flattening element for EDFA.

  20. Spatial-chirp compensation in dynamical holograms reconstructed with ultrafast lasers

    NASA Astrophysics Data System (ADS)

    Martínez-León, Lluís; Clemente, Pere; Tajahuerce, Enrique; Mínguez-Vega, Gladys; Mendoza-Yero, Omel; Fernández-Alonso, Mercedes; Lancis, Jesús; Climent, Vicent; Andrés, Pedro

    2009-01-01

    A computer generated hologram (CGH) reconstructed with a sub-100-fs laser pulse at the focal plane of a conventional refractive lens experiences a large amount of spatial chirp. We report the shaping of a 12 fs laser pulsed beam by means of a Fourier CGH implemented onto a spatial light modulator, using a hybrid diffractive-refractive lens triplet that provides spatial-chirp compensation. Experimental results demonstrate that parallel, arbitrary, and high-resolution patterning is possible with the proposed device.

  1. Widely Tunable Negative-Chirp SG-DBR Laser/EA-Modulated Transmitter

    NASA Astrophysics Data System (ADS)

    Raring, J. W.; Skogen, E. J.; Johansson, L. A.; Sysak, M. N.; Denbaars, S. P.; Coldren, L. A.

    2005-01-01

    Ten Gb/s low power penalty (< 0.5 dB) error-free transmission was achieved through 75 km using a high-performance sampled-grating (SG) distributed Bragg reflector (DBR) laser/EAM transmitter. Large signal chirp measurements show negative chirp operation across the entire tuning range of the devices. An integration-oriented quantum-well-intermixing (QWI) process was employed for the realization of these devices.

  2. Temporal self-imaging effect for chirped laser pulse sequences: Repetition rate and duty cycle tunability

    Microsoft Academic Search

    J. Lancis; J. Caraquitena; P. Andrés; M. A. Muriel

    2005-01-01

    We express parabolic-dispersion-induced transformations of a linearly chirped signal in terms of those suffered by the unchirped version of the same input signal. Specifically, we unveil that any amount of chirping and dispersion produces, aside from a scale factor, the same pulse-distortion effect as a certain parabolic dispersion in the unchirped input. This relevant result allows us to derive, as

  3. Fiber Ring Laser Operated by Dynamic Local Phase Shifting of a Chirped Grating

    Microsoft Academic Search

    Ana Gonzalez-Segura; Pere Perez-Millan; JosÉ Luis Cruz; Miguel V. Andres

    2009-01-01

    An ultranarrow linewidth erbium-doped fiber ring laser is presented. It is based on the filtering properties of a phase-shifted chirped fiber Bragg grating, which is inserted inside the cavity of the laser. A dynamic control of the phase shifting, which is induced by a magnetostrictive transducer, permits both tunable continuous-wave and actively Q-switched operation. The use of a chirped grating

  4. XPM and SPM response of a chirped DFBSOA all-optical flip-flop

    Microsoft Academic Search

    M. Jabbari; M. K. Moravvej-Farshi; R. Ghayour; A. Zarifkar

    2008-01-01

    In this paper, deriving a dynamic model based on the coupled-mode and carrier rate equations, we have proposed a new technique to switch ON and OFF of a chirped DFB-SOA all-optical flip-flop based on self phase modulation (SPM) and cross phase modulation (XPM). We have shown that with this technique in an optimized condition into a DFB-SOA with chirped grating

  5. A coupling-of-modes analysis of chirped transducers containing reflective electrode geometries

    Microsoft Academic Search

    B. P. Abbott; C. S. Hartmann; D. C. Malocha

    1989-01-01

    An accurate and numerically efficient model for analyzing chirped transducers incorporating internal reflections is presented. The model results in a complete three-port characterization of the transducer. The three-port description of the transducer (two acoustic ports and one electric port) is obtained by representing the response of the chirped transducer as that of a set of cascaded uniform sections. The three-port

  6. Fragment mass and kinetic-energy distributions from spontaneous fission of the neutron-deficient isotopes, 1. 2-s /sup 246/Fm and 38-s /sup 248/Fm

    SciTech Connect

    Hoffman, D.; Lee, D.; Ghiorso, A.; Nurmia, M.; Aleklett, K.

    1980-10-01

    We have measured the mass and kinetic-energy distributions for fragments from the spontaneous fission of 1.2-s /sup 246/Fm and 38-s /sup 248/Fm. The mass distributions are highly asymmetric and the average total kinetic energies of 199 +- 4 MeV and 198 +- 4 MeV, respectively, are consistent with systematics for lower Z actinides. Their properties are in contrast to those of /sup 258/Fm and /sup 259/Fm, whose spontaneous fission results in narrowly symmetric mass distributions accompanied by unusually high total kinetic energies.

  7. FM 3-34.22 (FM 3-34.221, 5-7-30, 5-71-2, 5-71-3) ENGINEER OPERATIONS--

    E-print Network

    US Army Corps of Engineers

    .us.army.mil) and General Dennis J. Reimer Training and Doctrine Digital Library at (www.train.army.mil). #12;*FM 3 .................................................................................... 2-6 Geospatial Support

  8. Recovering strain readings from chirping fiber Bragg gratings in composite overwrapped pressure vessels

    NASA Astrophysics Data System (ADS)

    Strutner, Scott M.; Pena, Frank; Piazza, Anthony; Parker, Allen R.; Richards, W. Lance; Carman, Gregory P.

    2014-04-01

    This study reports on signal recovery of optical fiber Bragg gratings embedded in a carbon fiber composite overwrapped pressure vessel's (COPV) structure which have become chirped due to microcracks. COPVs are commonly used for the storage of high pressure liquids and gases. They utilize a thin metal liner to seal in contents, with a composite overwrap to strengthen the vessel with minimal additional mass. A COPV was instrumented with an array of surface mounted and embedded fiber Bragg gratings (FBGs) for structural health monitoring (SHM) via strain sensing of the material. FBGs have been studied as strain sensors for the last couple decades. Many of the embedded FBGs reflected a multi-peak, chirped response which was not able to be interpreted well by the current monitoring algorithm. Literature and this study found that the chirping correlated with microcracks. As loading increases, so does the number of chirped FBGs and microcracks. This study uses optical frequency domain reflectometry (OFDR) to demultiplex the array of FBGs, and then sub- divide individual FBGs. When a FBG is sub-divided using OFDR, the gratings' strain along its length is recovered. The sub-divided chirped FBGs have strain gradients along their length from microcracks. Applying this to all chirped gratings, nearly the entirety of the embedded sensors' readings can be recovered into a series of single peak responses, which show very large local strains throughout the structure. This study reports on this success in recovering embedded FBGs signal, and the strain gradient from microcracks.

  9. Gravitational waveforms from the evaporating ACO cosmic string loop

    NASA Astrophysics Data System (ADS)

    Anderson, Malcolm

    2009-04-01

    The linearly polarized gravitational waveforms from a certain type of rotating, evaporating cosmic string—the Allen-Casper-Ottewill loop—are constructed and plotted over the lifetime of the loop. The formulae for the waveforms are simple and exact, and describe waves which attenuate self-similarly, with the amplitude and period of the waves falling off linearly with time.

  10. Wideband Waveform Optimization with Energy Detector Receiver in Cognitive Radio

    E-print Network

    Qiu, Robert Caiming

    Wideband Waveform Optimization with Energy Detector Receiver in Cognitive Radio Zhen Hu Department investigates the transmitted waveform optimization issues for wideband cognitive radio with energy detector receiver. The motivation is to provide a cheap cognitive radio network with simple and cheap cognitive

  11. Cognitive radio - an adaptive waveform with spectral sharing capability

    Microsoft Academic Search

    Vasu D. Chakravarthy; A. K. Shaw; Michael A. Temple; James P. Stephens

    2005-01-01

    The growth of wireless applications and spectral limitations are serious concerns for both the military and civilian communities. Cognitive radio (CR) technologies expand spectrum efficiency using elements of space, time and frequency diversity that up to now have not been exploited. An adaptive waveform (AW) generation technique is presented which adapts to the changing electromagnetic environment and synthesizes waveform features

  12. OPTIMIZED AND QUASI-OPTIMAL SCHWARZ WAVEFORM RELAXATION FOR THE

    E-print Network

    Halpern, Laurence

    two concepts: waveform relaxation, and optimized absorbing boundary conditions. This approach leads algorithm, based on the transparent continuous or discrete boundary condition, and the optimized complex waveform relaxation; Schrodinger equation; absorbing boundary conditions. AMS Subject Classi¯cation: 35J10

  13. Random Noise Radar\\/Sodar With Ultrawideband Waveforms

    Microsoft Academic Search

    Sune R. J. Axelsson

    2007-01-01

    Random noise waveforms with ultrawide bandwidth improve the range resolution and reduces the probability of intercept in radar\\/sodar. As a result of the nonperiodic waveform, the range ambiguity is removed as well. By transmitting a sine signal that is phase or frequency modulated by random noise, autocorrelation functions with improved side lobe suppression in range can be formed. There are

  14. Wavelet Analysis of Neuroelectric Waveforms: A Conceptual Tutorial

    Microsoft Academic Search

    Vincent J. Samar; Ajit Bopardikar; Raghuveer Rao; Kenneth Swartz

    1999-01-01

    This paper presents a nontechnical, conceptually oriented introduction to wavelet analysis and its application to neuroelectric waveforms such as the EEG and event related potentials (ERP). Wavelet analysis refers to a growing class of signal processing techniques and transforms that use wavelets and wavelet packets to decompose and manipulate time-varying, nonstationary signals. Neuroelectric waveforms fall into this category of signals

  15. Waveform bounding and combination techniques for direct drive testing

    Microsoft Academic Search

    Samuel Frazier; Edward Parimuha; Murali Tummala; Thomas F. Winnenberg

    1994-01-01

    This paper presents various methods to combine a set of measured test signals into a composite signal. The composite signal represents the set of measured test signals by retaining the significant attributes of the original set of measured test data. The composite waveforms are generated to obtain rigorous direct drive waveforms used during aircraft lightning and EMP assessments. Here we

  16. Method and apparatus for resonant frequency waveform modulation

    DOEpatents

    Taubman, Matthew S [Richland, WA

    2011-06-07

    A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.

  17. Waveform Libraries for Radar Tracking Applications: Maneuvering Targets

    E-print Network

    Nehorai, Arye

    Waveform Libraries for Radar Tracking Applications: Maneuvering Targets S. Suvorova and S. D target tracking to interacting multiple model (IMM) trackers to permit the modelling of maneuvering of the target from the next measurement. We also discuss the design of waveform libraries for target tracking

  18. Physician interpretation and quantitative measures of electrocardiographic ventricular fibrillation waveform

    Microsoft Academic Search

    Christopher B. Lightfoot; Thomas J. Sorensen; Michael D. Garfinkel; Lawrence D. Sherman; Clifton W. Callaway; James J. Menegazzi

    2001-01-01

    Objectives. The characteristics of the ventricular fibrillation (VF) waveform may influence treatment decisions and the likelihood of therapeutic success. However, assessment of VF as being fine or coarse and the distinction between fine VF and asystole are largely subjective. The authors sought to determine the level of agreement among physicians for interpretation of varying VF waveforms, and to compare these

  19. Coupled Waveform Analysis in Dynamic Characterization of Lossy Solids

    E-print Network

    Guzina, Bojan

    Coupled Waveform Analysis in Dynamic Characterization of Lossy Solids Bojan B. Guzina, M.ASCE,1 problem through a fully coupled viscoelastic analysis of the observed waveforms, the method provides of the back analysis. DOI: 10.1061/ ASCE 0733-9399 2002 128:4 392 CE Database keywords: Wave propagation

  20. Coherent control of ultracold {sup 85}Rb trap-loss collisions with nonlinearly frequency-chirped light

    SciTech Connect

    Pechkis, J. A. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Currently with the Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Carini, J. L.; Rogers, C. E. III; Gould, P. L. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Kallush, S. [Department of Physics and Optical Engineering, ORT Braude, P.O. Box 78, Karmiel (Israel); Kosloff, R. [Department of Physical Chemistry and the Fritz Haber Research Center for Molecular Dynamics, Hebrew University, IL-91094 Jerusalem (Israel)

    2011-06-15

    We present results on coherent control of ultracold trap-loss collisions using 40-ns pulses of nonlinearly frequency-chirped light. The chirps, either positive or negative, sweep {approx}1 GHz in 100 ns and are centered at various detunings below the D{sub 2} line of {sup 85}Rb. At each center detuning, we compare the collisional rate constant {beta} for chirps that are linear in time, concave-down, and concave-up. For positive chirps, we find that {beta} generally depends very little on the shape of the chirp. For negative chirps, however, we find that {beta} can be enhanced by up to 50(20)% for the case of the concave-down shape. This occurs at detunings where the evolution of the wave packet is expected to be coherent. An enhancement at these detunings is also seen in quantum-mechanical simulations of the collisional process.

  1. Wavelet analysis of electric adjustable speed drive waveforms

    SciTech Connect

    Czarkowski, D. [Polytechnic Univ., Brooklyn, NY (United States). Dept. of Electrical Engineering; Domijan, A. Jr. [Univ. of Florida, Gainesville, FL (United States). Dept. of Electrical and Computer Engineering

    1998-10-01

    The three most common adjustable speed drives (ASDs) used in HVAC equipment, namely, pulse-width modulated (PWM) induction drive, brushless-dc drive, and switched-reluctance drive, generate non-periodic and nonstationary electric waveforms with sharp edges and transients. Deficiencies of Fourier transform methods in analysis of such ASD waveforms prompted an application of the wavelet transform. Results of discrete wavelet transform (DWT) analysis of PWM inverter-fed motor waveforms are presented. The best mother wavelet for analysis of the recorded waveforms is selected. Data compression properties of the selected mother wavelet are compared to those of the fast Fourier transform (FFT). Multilevel feature detection of ASD waveforms using the DWT is shown.

  2. Source Wavelet Estimation in Full Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Sun, D.; Jiao, K.; Huang, W.; Vigh, D.; Coates, R. T.

    2013-12-01

    A common objective of the inverse problem in exploration seismology is to make inferences about physical features of subsurface models from seismograms recorded near the surface. As simulation of seismic wave propagation in realistic 3-D earth models becomes more and more computationally feasible, the nonlinear least-squares approach to this inverse problem has been enjoying a tremendous boost of interest, under the name full-waveform inversion (FWI), which is capable of reconstructing remarkably detailed models of subsurface structure. Full-waveform inversion (FWI) aims to achieve target models by means of minimizing the mean squared data misfit between simulated wavefields and observed seismograms. Because seismic responses and simulated wavefields are functions of model parameters and source signature, both of which are unknown in general, some authors have suggested treating the wavelet estimation as part of the inversion. And, in full-waveform inversion (FWI), a small disturbance in the source wavelet could lead to large discrepancies in the inverted model, which become larger as the depth increases due to error accumulation. Hence, an accurate source wavelet estimation becomes crucial in a successful inversion. On the other hand, an inaccurate model would jeopardize a wavelet estimation based on both simulated and observed data without proper constraints, which may in turn lead to wrong model updates and finally hazard the iterative inversion procedure. In this paper, we present a FWI flow for estimating both source signatures and subsurface models, in which the wavelet estimation is naturally embedded into FWI iterations as a variable reduction step by means of solving a least-squares-based filter estimation problem directly. Moreover, to mitigate the impact of an incorrect model on estimated wavelets, we restrict our wavelet estimation to part of the data that mainly consists of responses to shallow parts of models that are usually more reliably estimated. To demonstrate the feasibility and robustness of our approach, we present inversion experiments with both synthetic and real datasets, which suggest that shallow responses suffice to yield robust wavelet estimation that facilitates FWI.

  3. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, D; Tromp, J; Rodgers, A

    2007-07-16

    Comprehensive test ban monitoring in terms of location and discrimination has progressed significantly in recent years. However, the characterization of sources and the estimation of low yields remains a particular challenge. As the recent Korean shot demonstrated, we can probably expect to have a small set of teleseismic, far-regional and high-frequency regional data to analyze in estimating the yield of an event. Since stacking helps to bring signals out of the noise, it becomes useful to conduct comparable analyses on neighboring events, earthquakes in this case. If these auxiliary events have accurate moments and source descriptions, we have a means of directly comparing effective source strengths. Although we will rely on modeling codes, 1D, 2D, and 3D, we will also apply a broadband calibration procedure to use longer periods (P>5s) waveform data to calibrate short-period (P between .5 to 2 Hz) and high-frequency (P between 2 to 10 Hz) as path specify station corrections from well-known regional sources. We have expanded our basic Cut-and-Paste (CAP) methodology to include not only timing shifts but also amplitude (f) corrections at recording sites. The name of this method was derived from source inversions that allow timing shifts between 'waveform segments' (or cutting the seismogram up and re-assembling) to correct for crustal variation. For convenience, we will refer to these f-dependent refinements as CAP+ for (SP) and CAP++ for still higher frequency. These methods allow the retrieval of source parameters using only P-waveforms where radiation patterns are obvious as demonstrated in this report and are well suited for explosion P-wave data. The method is easily extended to all distances because it uses Green's function although there may be some changes required in t* to adjust for offsets between local vs. teleseismic distances. In short, we use a mixture of model-dependent and empirical corrections to tackle the path effects. Although we reply on the large TriNet array as a testbed for refining methods, we will present some preliminary results on Korea and Iran.

  4. Higher order chirp compensation of femtosecond mode-locked semiconductor lasers using optical fibers with different group-velocity dispersions

    Microsoft Academic Search

    Shin Arahira; Satoko Kutsuzawa; Yasuhiro Matsui; Yoh Ogawa

    1996-01-01

    Higher order chirp compensation of optical short pulses by using two types of optical fibers with different group-velocity dispersions was theoretically and experimentally investigated in detail. By optimizing the lengths of two types of optical fibers, both second- and third-order dispersion of chirped optical pulses were found to be simultaneously compensated. Pulse-compression experiments with chirped optical pulses from a mode-locked

  5. Waveform Synthesizer For Imaging And Ranging Applications

    DOEpatents

    DUDLEY, PETER A.; [et al

    2004-11-30

    Frequency dependent corrections are provided for quadrature imbalance. An operational procedure filters imbalance effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of quadrature imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  6. Waveform Selectivity at the Same Frequency

    E-print Network

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F

    2014-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of the circuit elements are then combined to absorb or tran...

  7. Waveform Synthesizer For Imaging And Ranging Applications

    DOEpatents

    Dubbert, Dale F. (Cedar Crest, NM); Dudley, Peter A. (Albuquerque, NM); Doerry, Armin W. (Albuquerque, NM); Tise, Bertice L. (Albuquerque, NM)

    2004-12-28

    Frequency dependent corrections are provided for Local Oscillator (LO) feed-through. An operational procedure filters LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver, unwanted energies, such as LO feed-through energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  8. Inversion method for initial tsunami waveform reconstruction

    NASA Astrophysics Data System (ADS)

    Voronin, V. V.; Voronina, T. A.; Tcheverda, V. A.

    2015-06-01

    This paper deals with the application of the r-solution method to recover the initial tsunami waveform in a tsunami source area by remote water-level measurements. Wave propagation is considered within the scope of a linear shallow-water theory. An ill-posed inverse problem is regularized by means of least square inversion using a truncated SVD (singular value decomposition) approach. The method presented allows one to control instability of the numerical solution and to obtain an acceptable result in spite of ill-posedness of the problem. It is shown that the accuracy of tsunami source reconstruction strongly depends on the signal-to-noise ratio, the azimuthal coverage of recording stations with respect to the source area and bathymetric features along the wave path. The numerical experiments were carried out with synthetic data and various computational domains including a real bathymetry.

  9. Using waveform information in nonlinear data assimilation

    NASA Astrophysics Data System (ADS)

    Rey, Daniel; Eldridge, Michael; Morone, Uriel; Abarbanel, Henry D. I.; Parlitz, Ulrich; Schumann-Bischoff, Jan

    2014-12-01

    Information in measurements of a nonlinear dynamical system can be transferred to a quantitative model of the observed system to establish its fixed parameters and unobserved state variables. After this learning period is complete, one may predict the model response to new forces and, when successful, these predictions will match additional observations. This adjustment process encounters problems when the model is nonlinear and chaotic because dynamical instability impedes the transfer of information from the data to the model when the number of measurements at each observation time is insufficient. We discuss the use of information in the waveform of the data, realized through a time delayed collection of measurements, to provide additional stability and accuracy to this search procedure. Several examples are explored, including a few familiar nonlinear dynamical systems and small networks of Colpitts oscillators.

  10. A Study of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Models for Nonstationary Acoustic Time Series

    PubMed Central

    MARTINEZ, Josue G.; BOHN, Kirsten M.; CARROLL, Raymond J.

    2013-01-01

    We describe a new approach to analyze chirp syllables of free-tailed bats from two regions of Texas in which they are predominant: Austin and College Station. Our goal is to characterize any systematic regional differences in the mating chirps and assess whether individual bats have signature chirps. The data are analyzed by modeling spectrograms of the chirps as responses in a Bayesian functional mixed model. Given the variable chirp lengths, we compute the spectrograms on a relative time scale interpretable as the relative chirp position, using a variable window overlap based on chirp length. We use 2D wavelet transforms to capture correlation within the spectrogram in our modeling and obtain adaptive regularization of the estimates and inference for the regions-specific spectrograms. Our model includes random effect spectrograms at the bat level to account for correlation among chirps from the same bat, and to assess relative variability in chirp spectrograms within and between bats. The modeling of spectrograms using functional mixed models is a general approach for the analysis of replicated nonstationary time series, such as our acoustical signals, to relate aspects of the signals to various predictors, while accounting for between-signal structure. This can be done on raw spectrograms when all signals are of the same length, and can be done using spectrograms defined on a relative time scale for signals of variable length in settings where the idea of defining correspondence across signals based on relative position is sensible. PMID:23997376

  11. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    NASA Astrophysics Data System (ADS)

    Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel

    2014-07-01

    We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ?L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a surrogate. As waveform generation is one of the dominant costs in parameter estimation algorithms and parameter space exploration, surrogate models offer a new and practical way to dramatically accelerate such studies without impacting accuracy. Surrogates built in this paper, as well as others, are available from GWSurrogate, a publicly available python package.

  12. DIODE LASER MEASUREMENTS OF HF CONCENTRATIONS PRODUCED FROM HEPTANE/AIR PAN FIRES EXTINGUISHED BY FE-36, FM-200, FE-36 PLUS APP, AND FM-200 PLUS APP

    EPA Science Inventory

    Tunable diode laser absorption spectroscopy (TDLAS) is used to measure the time evolution of hydrogen fluoride (HF) concentrations produced from a series of enclosed heptane/air pan fires extinguished by FE-36, FM-200, FE-35 plus ammonium polyphosphate (APP), or FM-200 plus APP. ...

  13. Shoreline Mapping Using Lidar Red-Channel Waveforms

    NASA Astrophysics Data System (ADS)

    Pe'Eri, S.; Philpot, W. D.; Guenther, G. C.; Gardner, J. V.

    2006-12-01

    The determination of the shoreline is the basis for defining boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone. Though the use of airborne lidar bathymetry (ALB) is not new, there is still a need for more reliable results using ALB in defining the shorelines. Previous algorithms for defining the shoreline (land-water determination) have used; (1) the presence of a saturated peak in the infrared-channel waveforms, or (2) a ratio between the green-channel, red- channel and infrared-channel waveforms. Research and development for both algorithms were applied to the older SHOALS-400 lidar that varies in dynamic range and waveform record length from the current SHOALS- 1000/3000 lidars. Observations of the red-channel waveforms show a strong dependence between the waveform and the presence of water. Different waveform characteristics are found from water and land returns (bare earth and vegetation coverage). We present here an algorithm for distinguishing land or water using the lidar red-channel waveforms. The data for this study are from (1) the 2000-2001 USGS surveys in Lake Michigan and Lake Tahoe, CA using the SHOALS-400 lidar system and (2) the NOAA survey in the Isles of Shoals, NH-ME using the SHOALS-1000. The algorithm shows good preliminary results both for the older and the current SHOALS systems. Aerial photogrammetry was used as reference data to support the findings.

  14. Suitability of hybrid gravitational waveforms for unequal-mass binaries

    NASA Astrophysics Data System (ADS)

    MacDonald, Ilana; Mroué, Abdul H.; Pfeiffer, Harald P.; Boyle, Michael; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Béla; Taylor, Nicholas W.

    2013-01-01

    This article studies sufficient accuracy criteria of hybrid post-Newtonian (PN) and numerical relativity (NR) waveforms for parameter estimation of strong binary black-hole sources in second-generation ground-based gravitational-wave detectors. We investigate equal-mass nonspinning binaries with a new 33-orbit NR waveform, as well as unequal-mass binaries with mass ratios 2, 3, 4 and 6. For equal masses, the 33-orbit NR waveform allows us to recover previous results and to extend the analysis toward matching at lower frequencies. For unequal masses, the errors between different PN approximants increase with mass ratio. Thus, at 3.5 PN, hybrids for higher-mass-ratio systems would require NR waveforms with many more gravitational-wave cycles to guarantee no adverse impact on parameter estimation. Furthermore, we investigate the potential improvement in hybrid waveforms that can be expected from fourth-order post-Newtonian waveforms and find that knowledge of this fourth post-Newtonian order would significantly improve the accuracy of hybrid waveforms.

  15. Variations in recorded acoustic gunshot waveforms generated by small firearms.

    PubMed

    Beck, Steven D; Nakasone, Hirotaka; Marr, Kenneth W

    2011-04-01

    Analysis of recorded acoustic gunshot signals to determine firearm waveform characteristics requires an understanding of the impulsive signal events, how the waveforms vary among different sources, and how the waveforms are affected by the environment and the recording system. This paper presents empirical results from waveforms produced by different small firearms and an analysis of their variations under different and controlled conditions. Acoustic signals were generated using multiple firearm makes and models firing different ammunition types. Simultaneous recordings from the microphones located at different distances from the source and at different azimuth angles (from the line-of-fire) were used to study source characteristics and sound propagation effects. The results indicate that recorded gunshot waveforms generally consist of multiple acoustic events, and these are observable depending on the received distance and azimuth angle. The source blast size, microphone distance, and microphone azimuth angle are the primary factors affecting the recorded muzzle blast characteristics. Ground or object reflections and ballistic shockwaves and their reflections can interfere with the muzzle blast waveform and its measurements. This experiment confirmed and quantified the wide range of correlation results between waveforms recorded from different source, microphone distance, and microphone angle configurations. PMID:21476632

  16. Reliability of complete gravitational waveform models for compact binary coalescences

    E-print Network

    Frank Ohme; Mark Hannam; Sascha Husa

    2011-09-12

    With recent advances in post-Newtonian (PN) theory and numerical relativity (NR) it has become possible to construct inspiral-merger-ringdown waveforms by combining both descriptions into one hybrid signal. While addressing the reliability of such waveforms, previous studies have identified the PN contribution as the dominant source of error, which can be reduced by incorporating longer NR simulations. Here we overcome the two outstanding issues that make it difficult to determine the minimum NR simulation length necessary to produce suitably accurate hybrids: (1) the criteria for a GW search is the mismatch between the true waveform and a set of model waveforms, optimized over all waveforms in the model, but for discrete hybrids this optimization was not yet possible. (2) these calculations typically require that numerical waveforms already exist, while we develop an algorithm to estimate hybrid mismatches errors without numerical data. Our procedure relies on combining supposedly equivalent PN models at highest available order with common data in the NR regime, and their difference serves as a measure of the uncertainty assumed in each waveform. Contrary to some earlier studies, we estimate that ~10 NR orbits before merger should allow for the construction of waveform families that are accurate enough for detection in a broad range of parameters, only excluding highly spinning, unequal-mass systems. Nonspinning systems, even with high mass-ratio (q>=20) are well modeled for astrophysically reasonable component masses. The parameter bias is only of the order of 1% for total mass and symmetric mass-ratio and less than 0.1 for the dimensionless spin magnitude. We take the view that similar NR waveform lengths will remain the state of the art in the advanced detector era, and begin to assess the limits of the science that can be done with them.

  17. Characterization of Silicon Sulfides by Chirped-Pulse Rotational Spectroscopy

    NASA Astrophysics Data System (ADS)

    McCarthy, Michael C.; Crabtree, Kyle N.; Martinez, Oscar; , Jr.

    2013-06-01

    Chirped-pulse Fourier transform microwave spectroscopy is used to characterize the electrical discharge products that are formed in a supersonic molecular beam through a dilute gas mixture of silane and hydrogen sulfide. The spectrum between 6 and 18 GHz is dominated by SiS: more than 175 transitions have been assigned to either its isotopic species, its vibrationally excited states, or both, on the basis of previous cavity measurements. Owing to the flat instrument response function and extensive vibrational excitation that has been observed, it is possible to derive a precise vibrational temperature for SiS, and determine the relative abundances of SiS, HSiS, and H_2SiS. Although rotational lines from more than 15 other silicon or sulfur molecules have been identified in the same discharge, more than 50% of lines that have been detected with a signal-to-noise ratio of three or greater are presently unassigned. Attempts to assign these many remaining lines, and efforts to benchmark the performance of our spectrometer will be highlighted as well.

  18. A chirp-compensated, injection-seeded alexandrite laser

    NASA Astrophysics Data System (ADS)

    Bakule, P.; Baird, P. E. G.; Boshier, M. G.; Cornish, S. L.; Heller, D. F.; Jungmann, K.; Lane, I. C.; Meyer, V.; Sandars, P. H. G.; Toner, W. T.; Towrie, M.; Walling, J. C.

    2000-07-01

    A Q-switched alexandrite laser suitable for high-resolution spectroscopy is described which produces pulses of 35 mJ energy in a 10 MHz bandwidth, with a high-purity TEM00 mode. The laser can be synchronised to external event to within 100 ns. The output pulse length is 120 ns and the repetition rate 25 Hz. The laser is injection-seeded by a Ti:sapphire laser operating around 730 nm. To preserve single-mode seeding under external triggering conditions, and to obtain small time-jitter, active cavity length control was used. In order to achieve the 10 MHz output bandwidth, intra-cavity electro-optic modulators were used to compensate for the frequency chirp. The refractive index of alexandrite was found to vary linearly with inversion density with a constant of proportionality equal to 1.6×10-24 cm3. In pulsed operation at 730 nm, the index change due to this effect is only partially compensated by changes due to ground state phonon relaxation.

  19. Chirped and divided-pulse Sagnac fiber amplifier

    NASA Astrophysics Data System (ADS)

    Guichard, Florent; Zaouter, Yoann; Hanna, Marc; Mai, Khanh-Lin; Morin, Franck; Hönninger, Clemens; Mottay, Eric; Georges, Patrick

    2015-03-01

    Femtosecond fiber chirped pulse amplifiers have numerous advantages, but are limited in energy because of the small interaction area with the fiber core. In this contribution, we create two orthogonally-polarized stretched pulse replicas in the time domain, following the divided-pulse amplification (DPA) principle. This beam is subsequently separated into two counter-propagating beams in a Sagnac interferometer to finally generate four pulse replicas. These pulses are amplified in two state-of-the-art large mode area rod-type fiber amplifiers in series, before final coherent combination and compression. Because the stretched-pulse duration is of the order of hundreds of picoseconds, the DPA delay is induced using a freespace interferometer with reasonable arm lengths of few tens of centimeters. The use of a common interferometer to divide and recombine temporal pulse replicas, together with the Sagnac geometry, results in an identical optical path for all four replicas. Therefore, the whole spatio-temporal combining architecture is passive, avoiding the need for active electronic stabilization systems. Because we only use two temporal replicas, the system is immune to differential saturation levels or B-integrals between successive pulses: this is compensated by controlling the amplitude of both pulses at the input of the amplifying setup. This setup allows the generation of 1 mJ, 300 fs compressed pulses at 50 kHz repetition rate, corresponding to 50 W output average power, with a combining efficiency above 90% at all power levels.

  20. Analysis of Dynamic Stall Through Chirp Signal Pitch Excursions

    NASA Astrophysics Data System (ADS)

    Heintz, Kyle; Coleman, Dustin; Wicks, Michael; Corke, Thomas; Thomas, Flint

    2013-11-01

    An augmentation of the typical pitching airfoil experiment has been performed where the pitching frequency and amplitude are dynamically varied in a short-time event to produce a ``chirp'' trajectory, ? (t) =?0 +?1 (t) sin (t? (t)) . The frequency evolution followed a Schroeder-phase relation, ? (t) =?min + K (?max -?min) . The frequencies ranged from 0.5 Hz to 30 Hz, resulting in reduced frequencies from 0.02 to 0.1. The free-stream Mach number ranged from Mach 0.4 to 0.6, giving chord Reynolds numbers from 5 ×105 to 3 ×106 . The airfoil was a NACA 23012 section shape that was fully instrumented with 31 flush-mounted high-bandwidth pressure transducers. The pressure transducer outputs were simultaneously sampled with the instantaneous angle of attack, ? (t) . The motivation for this study was to compare dynamic stall under non-equilibrium conditions. A particular interest is on the flow features that occur when dynamically passing between light and deep stall regimes. The results include phase analysis of aerodynamic loads, wavelet-based spectral analysis, and the determination of the intra-cycle aerodynamic damping factors.

  1. Gravitational radiation reaction and inspiral waveforms in the adiabatic limit.

    PubMed

    Hughes, Scott A; Drasco, Steve; Flanagan, Eanna E; Franklin, Joel

    2005-06-10

    We describe progress evolving an important limit of binaries in general relativity: stellar mass compact objects spiraling into much larger black holes. Such systems are of great observational interest. We have developed tools to compute for the first time the radiation from generic orbits. Using global conservation laws, we find the orbital evolution and waveforms for special cases. For generic orbits, inspirals and waveforms can be found by augmenting our approach with an adiabatic self-force rule due to Mino. Such waveforms should be accurate enough for gravitational-wave searches. PMID:16090377

  2. Sub-picosecond chirped pulse propagation in concave-dispersion-flattened fibers

    NASA Astrophysics Data System (ADS)

    Li, Xin; Zheng, Hong-jun; Yu, Hui-shan; Liu, Shan-liang

    2012-01-01

    Tianjin University of Technology and Springer-Verlag Berlin Heidelberg 2012 C We propose the sub-picosecond chirped soliton pulse propagation in concave-dispersion-flattened fibers (CDFF). The effects of pulse characteristics and the fiber dispersion parameters on propagation characteristics of the chirped soliton pulse are numerically investigated in the CDFF by the split-step Fourier method (SSFM). The unchirped soliton pulse can stably propagate with unchanged pulse width in the CDFF. The temporal full width at half maximum (FWHM) of the chirped soliton performs a damped oscillation with the increase of propagation distance. The period and amplitude of the oscillation increase with the increase of the chirp parameter | C|. The effect of high-order dispersion ( ? 3- ? 6) on soliton propagation characteristics can be neglected. The soliton pulse slightly broadens with the increase of propagation distance and still maintains soliton characteristics when the fiber loss (ATT) is further considered. The variation of root-meansquare (RMS) spectral width with propagation distance is opposite to that of the temporal width. The output spectrum of soliton has a single peak for the unchirped case, while has multi-peak for chirped case. The temporal width of the soliton obviously increases with the increase of the initial width, decreases with the increase of dispersion peak D 0 of the fiber, and slightly increases with the decrease of dispersion coefficients k 1 and k 2 of the fiber.

  3. Characteristics of nonlinear imaging of broadband laser stacked by chirped pulses

    NASA Astrophysics Data System (ADS)

    Wang, Youwen; You, Kaiming; Chen, Liezun; Lu, Shizhuan; Dai, Zhiping; Ling, Xiaohui

    2014-11-01

    Nanosecond-level pulses of specific shape is usually generated by stacking chirped pulses for high-power inertial confinement fusion driver, in which nonlinear imaging of scatterers may damage precious optical elements. We present a numerical study of the characteristics of nonlinear imaging of scatterers in broadband laser stacked by chirped pulses to disclose the dependence of location and intensity of images on the parameters of the stacked pulse. It is shown that, for sub-nanosecond long sub-pulses with chirp or transform-limited sub-pulses, the time-mean intensity and location of images through normally dispersive and anomalously dispersive self-focusing medium slab are almost identical; While for picosecond-level short sub-pulses with chirp, the time-mean intensity of images for weak normal dispersion is slightly higher than that for weak anomalous dispersion through a thin nonlinear slab; the result is opposite to that for strong dispersion in a thick nonlinear slab; Furthermore, for given time delay between neighboring sub-pulses, the time-mean intensity of images varies periodically with chirp of the sub-pulse increasing; for a given pulse width of sub-pulse, the time-mean intensity of images decreases with the time delay between neighboring sub-pulses increasing; additionally, there is a little difference in the time-mean intensity of images of the laser stacked by different numbers of sub-pulses. Finally, the obtained results are also given physical explanations.

  4. Extended chirp scaling algorithm for air- and spaceborne SAR data processing in stripmap and ScanSAR imaging modes

    Microsoft Academic Search

    A. Moreira; J. Mittermayer; R. Scheiber

    1996-01-01

    Presents a generalized formulation of the extended chirp scaling (ECS) approach for high precision processing of air- and spaceborne SAR data. Based on the original chirp scaling function, the ECS algorithm incorporates a new azimuth scaling function and a subaperture approach, which allow an effective phase-preserving processing of ScanSAR data without interpolation for azimuth geometric correction. The azimuth scaling can

  5. Seed Laser Chirping for Enhanced Backward Raman Amplification in Plasmas Z. Toroker, V. M. Malkin, and N. J. Fisch

    E-print Network

    Seed Laser Chirping for Enhanced Backward Raman Amplification in Plasmas Z. Toroker, V. M. Malkin is that, by chirping the seed pulse, the group velocity dispersion may in fact be used advantageously elements will likely have to be replaced by plasma. In a plasma, a short counter-propagating seed pulse

  6. Tuning range extension by active mode-locking of external cavity laser including a linearly chirped fiber Bragg grating

    Microsoft Academic Search

    Aurélien Bergonzo; Estelle Gohin; Jean Landreau; Olivier Durand; Romain Brenot; Guang-Hua Duan; Joel Jacquet

    2003-01-01

    We demonstrate electrical wavelength tuning by mode locking of an external cavity laser (ECL) with linearly chirped fiber Bragg grating (LCFBG). The configuration consists of a laser chip providing the gain coupled to an LCFBG with a large chip rate of 10 or 55 nm\\/cm providing the counter-reaction for laser oscillation. The laser chirp is electrically modulated by a sinusoidal

  7. High-repetition-rate optical parametric chirped-pulse amplifier producing 1-J, sub-100-fs pulses

    E-print Network

    Keller, Ursula

    a high-repetition-rate, femtosecond optical parametric chirped pulse amplifier (OPCPA). Its seed signal. Limpert, and A. Tünnermann, "High repetition rate fiber amplifier pumped sub-20 fs optical parametric, G. H. C. New, and K. Osvay, "Analysis and optimization of optical parametric chirped pulse

  8. Effects of pump laser chirp in high-order harmonics generated from various solid surfaces using femtosecond lasers

    Microsoft Academic Search

    C A Popovici; R A Ganeev; F Vidal; T Ozaki

    2012-01-01

    We investigate the effects of the pump laser chirp on high-order harmonic generation from solid surfaces of aluminium, indium and C60 film targets. Chirped pulses were produced by varying the distance between the two gratings of the laser compressor. We optimized the nanosecond contrast of our femtosecond laser pump (? = 35 fs, ? = 793 nm, I ? 1018

  9. Effects of pump laser chirp in high-order harmonics generated from various solid surfaces using femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Popovici, C. A.; Ganeev, R. A.; Vidal, F.; Ozaki, T.

    2012-02-01

    We investigate the effects of the pump laser chirp on high-order harmonic generation from solid surfaces of aluminium, indium and C60 film targets. Chirped pulses were produced by varying the distance between the two gratings of the laser compressor. We optimized the nanosecond contrast of our femtosecond laser pump (? = 35 fs, ? = 793 nm, I ˜ 1018 W cm-2) for surface harmonic generation by adjusting the trigger timing of the Pockels cell. Harmonics up to the 18th order (? = 44 nm) were observed. We show experimentally that for chirped pulses with the same pulse duration, those with negative chirp produced stronger harmonics, compared to those with positive chirp. This effect is attributed to the different rise time of the leading edge of the pulse due to the presence of high-order dispersion terms. We also show experimentally that the peak wavelength of the harmonics presents blueshift for pump lasers with negative chirp and redshift for those with positive chirp. This phenomenon appears to be due to the shift in the instantaneous wavelength of the pump laser at the maximum intensity for the different chirped pulses.

  10. Solving seismological problems using sgraph program: II-waveform modeling

    SciTech Connect

    Abdelwahed, Mohamed F. [Geological Hazards Research Unit, King Abdulaziz University (Saudi Arabia) and National Research Institute of Astronomy and Geophysics (NRIAG), Helwan (Egypt)

    2012-09-26

    One of the seismological programs to manipulate seismic data is SGRAPH program. It consists of integrated tools to perform advanced seismological techniques. SGRAPH is considered a new system for maintaining and analyze seismic waveform data in a stand-alone Windows-based application that manipulate a wide range of data formats. SGRAPH was described in detail in the first part of this paper. In this part, I discuss the advanced techniques including in the program and its applications in seismology. Because of the numerous tools included in the program, only SGRAPH is sufficient to perform the basic waveform analysis and to solve advanced seismological problems. In the first part of this paper, the application of the source parameters estimation and hypocentral location was given. Here, I discuss SGRAPH waveform modeling tools. This paper exhibits examples of how to apply the SGRAPH tools to perform waveform modeling for estimating the focal mechanism and crustal structure of local earthquakes.

  11. In silico estimates of cell electroporation by electrical incapacitation waveforms

    E-print Network

    Weaver, James C.

    We use a system model of a cell and approximate magnitudes of electrical incapacitation (EI) device waveforms to estimate conditions that lead to responses with or without electroporation (EP) of cell membranes near ...

  12. Waveform Diversity and Range-Coupled Adaptive Radar Signal Processing

    E-print Network

    Higgins, Thomas

    2011-12-31

    Waveform diversity may offer several benefits to radar systems though often at the cost of reduced sensitivity. Multi-dimensional processing schemes are known to offer many degrees of freedom, which can be exploited to suppress the ambiguity...

  13. Efficient implementation of ultrasound waveform tomography using data blending

    NASA Astrophysics Data System (ADS)

    Zhang, Zhigang; Huang, Lianjie

    2014-03-01

    Ultrasound waveform tomography is a promising tool for breast cancer characterization. However, the method is very time-consuming for large datasets acquired using a synthetic-aperture ultrasound tomography system consisting of hundreds to thousands of transducer elements. We introduce a data blending approach to ultrasound waveform tomography to greatly improves the computational efficiency. This method simultaneously simulates ultrasound waves emitted from multiple transducer elements. A random phase is applied to each source to distinguish the effect of different sources. The random phase helps eliminate the unwanted cross interference produced by different sources. This approach greatly reduces the computation time of ultrasound waveform tomography to one tenth of that for the original ultrasound waveform tomography.

  14. Wallops waveform analysis of SEASAT-1 radar altimeter data

    NASA Technical Reports Server (NTRS)

    Hayne, G. S.

    1980-01-01

    Fitting a six parameter model waveform to over ocean experimental data from the waveform samplers in the SEASAT-1 radar altimeter is described. The fitted parameters include a waveform risetime, skewness, and track point; from these can be obtained estimates of the ocean surface significant waveheight, the surface skewness, and a correction to the altimeter's on board altitude measurement, respectively. Among the difficulties encountered are waveform sampler gains differing from calibration mode data, and incorporating the actual SEASAT-1 sampled point target response in the fitted wave form. There are problems in using the spacecraft derived attitude angle estimates, and a different attitude estimator is developed. Points raised in this report have consequences for the SEASAT-1 radar altimeter's ocean surface measurements are for the design and calibration of radar altimeters in future oceanographic satellites.

  15. Quasi-Orthogonal Wideband Radar Waveforms Based on Chaotic Systems

    E-print Network

    Willsey, Matt S.

    Many radar applications, such as those involving multiple-input, multiple-output (MIMO) radar, require sets of waveforms that are orthogonal, or nearly orthogonal. As shown in the work presented here, a set of nearly ...

  16. Waveform synthesis for imaging and ranging applications

    DOEpatents

    Doerry, Armin W.; Dudley, Peter A.; Dubert, Dale F.; Tise, Bertice L.

    2004-12-07

    Frequency dependent corrections are provided for quadrature imbalance and Local Oscillator (LO) feed-through. An operational procedure filters imbalance and LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as LO feed-through and/or imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through and imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  17. Femtosecond Nanofocusing with Full Optical Waveform Control

    SciTech Connect

    Berweger, Samuel; Atkin, Joanna M.; Xu, Xiaoji G.; Olmon, Robert L.; Raschke, Markus Bernd

    2011-10-12

    The simultaneous nanometer spatial confinement and femtosecond temporal control of an optical excitation has been a long-standing challenge in optics. Previous approaches using surface plasmon polariton (SPP) resonant nanostructures or SPP waveguides have suffered from, for example, mode mismatch, or possible dependence on the phase of the driving laser field to achieve spatial localization. Here we take advantage of the intrinsic phase- and amplitude-independent nanofocusing ability of a conical noble metal tip with weak wavelength dependence over a broad bandwidth to achieve a 10 nm spatially and few-femtosecond temporally confined excitation. In combination with spectral pulse shaping and feedback on the second-harmonic response of the tip apex, we demonstrate deterministic arbitrary optical waveform control. In addition, the high efficiency of the nanofocusing tip provided by the continuous micro- to nanoscale mode transformation opens the door for spectroscopy of elementary optical excitations in matter on their natural length and time scales and enables applications from ultrafast nano-opto-electronics to single molecule quantum coherent control.

  18. Waveform Analysis of AE in Composites

    NASA Technical Reports Server (NTRS)

    Prosser, William H.

    1998-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been developed to evaluate damage mechanisms in the testing of composite materials. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. Much more precise source location can also be obtained in comparison to conventional, threshold crossing arrival time determination techniques. Two successful examples of the application of Modal AE are presented in this work. In the first, the initiation of transverse matrix cracking in cross-ply, tensile coupons was monitored. In these tests, it was documented that the same source mechanism, matrix cracking, can produce widely different AE signal amplitudes dependent on laminate stacking sequence and thickness. These results, taken together with well known propagation effects of attenuation and dispersion of AE signals in composite laminates, cast further doubt on the validity of simple amplitude or amplitude distribution analysis for AE source determination. For the second example, delamination propagation in composite ring specimens was monitored. Pressurization of these composite rings is used to simulate the stresses in a composite rocket motor case. AE signals from delamination propagation were characterized by large amplitude flexural plate mode components which have long signal durations because of the large dispersion of this mode.

  19. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  20. Using genetic algorithms for Spectrally Modulated Spectrally Encoded waveform design

    Microsoft Academic Search

    T. W. Beard; M. A. Temple; J. O. Miller; R. F. Mills

    2007-01-01

    A genetic algorithm (GA) is used to design Spectrally Modulated, Spectrally Encoded (SMSE) waveforms while characterizing the impact of parametric variation on coexistence. As recently proposed, the SMSE framework supports cognition-based, software defined radio (SDR) applications and is well-suited for coexistence analysis. For initial proof-of-concept, two SMSE waveform parameters (number of carriers and carrier bandwidth) are optimized in a coexistent

  1. Use and abuse of the model waveform accuracy standards

    SciTech Connect

    Lindblom, Lee [Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States)

    2009-09-15

    Accuracy standards have been developed to ensure that the waveforms used for gravitational-wave data analysis are good enough to serve their intended purposes. These standards place constraints on certain norms of the frequency-domain representations of the waveform errors. Examples are given here of possible misinterpretations and misapplications of these standards, whose effect could be to vitiate the quality control they were intended to enforce. Suggestions are given for ways to avoid these problems.

  2. Use and Abuse of the Model Waveform Accuracy Standards

    E-print Network

    Lindblom, Lee

    2009-01-01

    Accuracy standards have been developed to ensure that the waveforms used for gravitational-wave data analysis are good enough to serve their intended purposes. These standards place constraints on certain norms of the frequency-domain representations of the waveform errors. Examples are given here of possible misinterpretations and misapplications of these standards, whose effect could be to vitiate the quality control they were intended to enforce. Suggestions are given for ways to avoid these problems.

  3. OPTIMAL CONVOLUTION SOR ACCELERATION OF WAVEFORM RELAXATION WITH APPLICATION

    E-print Network

    ­Seidel (WGS) iteration equations, respectively, may be written as: ( d dt +D) \\Deltax k+1 (t) = (L +U for acceleration of WGS is a simple extension of algebraic SOR. To derive the waveform SOR iteration equation, compute a waveform â?? x k+1 i (t) on t 2 [0; T ], as in WGS: i d dt + a ii j â?? x k+1 i (t) = b i (t) \\Gamma

  4. Speech waveform encoding using contour gain vector quantization

    E-print Network

    Malone, Kevin Thomas

    1985-01-01

    1985 Major Subject: Electrical Engineering SPEECH WAVEFORM ENCODING USING CONTOUR GAIN VECTOR QUANTIZATION A Thesis by KEVIN THOMAS MALONE Approved as to style and content by: Thomas R. Fischer (Chairman of Committee) Noel R. Strader (Member...SPEECH WAVEFORM ENCODING USING CONTOUR GAIN VECTOR QUANTIZATION A Thesis by KEVIN THOMAS MALONE Submitted to the Graduate College of Texas A k M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May...

  5. Self-deflecting plasmonic lattice solitons and surface modes in chirped plasmonic arrays.

    PubMed

    Li, Chunyan; Cui, Ran; Ye, Fangwei; Kartashov, Yaroslav V; Torner, Lluis; Chen, Xianfeng

    2015-03-15

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation, the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped array that form even in the absence of nonlinearity. PMID:25768141

  6. Factorization of numbers with Gauss sums: II. Suggestions for implementations with chirped laser pulses

    E-print Network

    W. Merkel; S. Wölk; W. P. Schleich; I. Sh. Averbukh; B. Girard; G. G. Paulus

    2012-10-24

    We propose three implementations of the Gauss sum factorization schemes discussed in part I of this series: (i) a two-photon transition in a multi-level ladder system induced by a chirped laser pulse, (ii) a chirped one-photon transition in a two-level atom with a periodically modulated excited state, and (iii) a linearly chirped one-photon transition driven by a sequence of ultrashort pulses. For each of these quantum systems we show that the excitation probability amplitude is given by an appropriate Gauss sum. We provide rules how to encode the number N to be factored in our system and how to identify the factors of N in the fluorescence signal of the excited state.

  7. Greatly enhanced slow and fast light in chirped pulse semiconductor optical amplifiers: theory and experiments.

    PubMed

    Pesala, Bala; Sedgwick, Forrest; Uskov, Alexander V; Chang-Hasnain, Connie

    2009-02-16

    Chirped pulse scheme is shown to be highly effective to attain large tunable time shifts via slow and fast light for an ultra-short pulse through a semiconductor optical amplifier (SOA). We show for the first time that advance can be turned into delay by simply reversing the sign of the chirp. A large continuously tunable advance-bandwidth product (ABP) of 4.7 and delay-bandwidth product (DBP) of 4.0 are achieved for a negatively and positively chirped pulse in the same device, respectively. We show that the tunable time shift is a direct result of self-phase modulation (SPM). Theoretical simulation agrees well with experimental results. Further, our simulation results show that by proper optimization of the SOA and chirper design, a large continuously tunable DBP of 55 can be achieved. PMID:19219122

  8. Experimental Demonstration of Energy-Chirp Compensation by a Tunable Dielectric-Based Structure

    NASA Astrophysics Data System (ADS)

    Antipov, S.; Baturin, S.; Jing, C.; Fedurin, M.; Kanareykin, A.; Swinson, C.; Schoessow, P.; Gai, W.; Zholents, A.

    2014-03-01

    A tunable energy-chirp compensator was used to remove a correlated energy chirp from the 60-MeV beam at the Brookhaven National Laboratory Accelerator Test Facility. The compensator operates through the interaction of the wakefield of the electron bunch with itself and consists of a planar structure comprised of two alumina bars with copper-plated backs separated by an adjustable beam aperture. By changing the gap size, the correlated energy chirp of the electron bunch was completely removed. Calculations show that this device, properly scaled to account for the electron bunch charge and length, can be used to remove residual correlated energy spread at the end of the linacs used for free-electron lasers. The experimental results are shown to be in good agreement with numerical simulations. Application of this technique can significantly simplify linac design and improve free-electron lasers performance.

  9. Femtosecond X-ray Pulses from a Spatially Chirped Electron Bunch in a SASE FEL

    SciTech Connect

    Emma, P.

    2003-01-14

    We propose a simple method to produce short x-ray pulses using a spatially chirped electron bunch in a SASE FEL. The spatial chirp is generated using an rf deflector which produces a transverse offset (in y and/or y') correlated with the longitudinal bunch position. Since the FEL gain is very sensitive to an initial offset in the transverse phase space at the entrance of the undulator, only a small portion of the electron bunch with relatively small transverse offset will interact significantly with the radiation, resulting in an x-ray pulse length much shorter than the electron bunch length. The x-ray pulse is also naturally phase locked to the rf deflector and so allows high precision timing synchronization. We discuss the generation and transport of such a spatially chirped electron beam and show that tens of femtosecond long pulse can be generated for the linac coherent light source (LCLS).

  10. Chirp control of a single-mode, good beam quality, zigzag dye laser

    SciTech Connect

    Mandl, A.; Zavriyev, A.; Klimek, D.E. [Textron Systems Div., Wilmington, MA (United States)] [Textron Systems Div., Wilmington, MA (United States)

    1997-03-01

    The authors report a substantial reduction of frequency chirp of a single-mode laser-pumped zigzag dye laser. A linear optical cavity using counterpropagating orthogonally polarized waves was injection-seeded at 568 nm and operated with a laser output of about 1 J. The chirp was controlled by an intracavity Pockels cell that was configured to add optical density at a rate which counterbalanced the decrease in optical density due to dye-solvent heating during the {approximately}1-{micro}s laser pulse. Heterodyne measurements were used to determine that the bandwidth was near the transform limit and chirp rate of {approximately}1 MHz/{micro}s. The beam quality of the laser was measured at 10 Hz as 1.7 XDL.

  11. A simple photonic generation of linearly chirped microwave pulse with large time-bandwidth product and high compression ratio.

    PubMed

    Gao, Hongbiao; Lei, Cheng; Chen, Minghua; Xing, Fangjian; Chen, Hongwei; Xie, Shizhong

    2013-10-01

    Based on the heterodyne beating between the pre-chirped optical pulse and the continuous wave (CW) light in a wideband photodetector (PD), linearly chirped microwave pulse with time duration of 3.2ns and bandwidth of 33GHz, which yields a large time-bandwidth product (TBWP) of 106 and high compression ratio of 160, is generated in our experiment. Dispersion compensation fiber (DCF) with uniform response across broad bandwidth is used for providing the original linear chirp in our method, which shows the promise to generate linearly chirped microwave pulse with bandwidth of up to THz. The flexibility of the center frequency and the stability of the time-frequency performance are demonstrated by generating different types of linearly chirped microwave pulses. The range resolution of our generated microwave pulse is also verified by off-line processing. PMID:24104226

  12. Fast prediction and evaluation of gravitational waveforms using surrogate models

    E-print Network

    Scott E. Field; Chad R. Galley; Jan S. Hesthaven; Jason Kaye; Manuel Tiglio

    2014-02-28

    [Abridged] We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and in more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced-order model that can be used as a surrogate for the true/fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order m L + m c_f online operations where c_f denotes the fitting function operation count and, typically, m space exploration, surrogate models offer a new and practical way to dramatically accelerate such studies without impacting accuracy.

  13. A Time Domain Waveform for Testing General Relativity

    E-print Network

    Cédric Huwyler; Edward K. Porter; Philippe Jetzer

    2014-10-24

    Gravitational-wave parameter estimation is only as good as the theory the waveform generation models are based upon. It is therefore crucial to test General Relativity (GR) once data becomes available. Many previous works, such as studies connected with the ppE framework by Yunes and Pretorius, rely on the stationary phase approximation (SPA) to model deviations from GR in the frequency domain. As Fast Fourier Transform algorithms have become considerably faster and in order to circumvent possible problems with the SPA, we test GR with corrected time domain waveforms instead of SPA waveforms. Since a considerable amount of work has been done already in the field using SPA waveforms, we establish a connection between leading-order-corrected waveforms in time and frequency domain, concentrating on phase-only corrected terms. In a Markov Chain Monte Carlo study, whose results are preliminary and will only be available later, we will assess the ability of the eLISA detector to measure deviations from GR for signals coming from supermassive black hole inspirals using these corrected waveforms.

  14. Single-chip CCD waveform generator and sequencer

    NASA Astrophysics Data System (ADS)

    French, Marcus J.; Waltham, Nicholas R.; Newton, G. M.; Wade, Richard

    1998-07-01

    There are a number of application areas of CCDs in ground and space based astronomy and earth observation, which could benefit from compact but versatile control electronics. These include visible imaging and spectroscopy, auto-guiding, star tracking and wavefront sensors. We describe here our design of an Application Specific Integrated Circuit (ASIC) which integrates the complete functionality of a dedicated programmable waveform generator and waveform sequencer to provide a CCD controller on a single chip. The ASIC can sustain waveform state changes at the clock rate of up to 40 MHz, and can implement complete sequence changes on a frame by frame basis. The ASIC is designed specifically to provide programmable CCD waveform generation and sequencing, and thus yields significant shrinkage in component count, circuit complexity, PCB circuit size, and power dissipation compared to previous DSP or general purpose microprocessor-based design solutions. More compact and light weight cameras are thus realized without compromising the ability to program any complexity of CCD waveform patterns and waveform sequences such as multiple window and/or pixel binning readout format. A second generation ASIC is to be fabricated on a radiation hard silicon process for use in Space-borne CCD camera systems. Applications of our prototype ASIC will be presented along with future development plans.

  15. Design and Testing of Space Telemetry SCA Waveform

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.; Handler, Louis M.; Quinn, Todd M.

    2006-01-01

    A Software Communications Architecture (SCA) Waveform for space telemetry is being developed at the NASA Glenn Research Center (GRC). The space telemetry waveform is implemented in a laboratory testbed consisting of general purpose processors, field programmable gate arrays (FPGAs), analog-to-digital converters (ADCs), and digital-to-analog converters (DACs). The radio hardware is integrated with an SCA Core Framework and other software development tools. The waveform design is described from both the bottom-up signal processing and top-down software component perspectives. Simulations and model-based design techniques used for signal processing subsystems are presented. Testing with legacy hardware-based modems verifies proper design implementation and dynamic waveform operations. The waveform development is part of an effort by NASA to define an open architecture for space based reconfigurable transceivers. Use of the SCA as a reference has increased understanding of software defined radio architectures. However, since space requirements put a premium on size, mass, and power, the SCA may be impractical for today s space ready technology. Specific requirements for an SCA waveform and other lessons learned from this development are discussed.

  16. A Time Domain Waveform for Testing General Relativity

    NASA Astrophysics Data System (ADS)

    Huwyler, Cédric; Porter, Edward K.; Jetzer, Philippe

    2015-05-01

    Gravitational-wave parameter estimation is only as good as the theory the waveform generation models are based upon. It is therefore crucial to test General Relativity (GR) once data becomes available. Many previous works, such as studies connected with the ppE framework by Yunes and Pretorius, rely on the stationary phase approximation (SPA) to model deviations from GR in the frequency domain. As Fast Fourier Transform algorithms have become considerably faster and in order to circumvent possible problems with the SPA, we test GR with corrected time domain waveforms instead of SPA waveforms. Since a considerable amount of work has been done already in the field using SPA waveforms, we establish a connection between leading-order-corrected waveforms in time and frequency domain, concentrating on phase-only corrected terms. In a Markov Chain Monte Carlo study, whose results are preliminary and will only be available later, we will assess the ability of the eLISA detector to measure deviations from GR for signals coming from supermassive black hole inspirals using these corrected waveforms.

  17. Full Elastic Waveform Search Engine for Near Surface Imaging

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Zhang, X.

    2014-12-01

    For processing land seismic data, the near-surface problem is often very complex and may severely affect our capability to image the subsurface. The current state-of-the-art technology for near surface imaging is the early arrival waveform inversion that solves an acoustic wave-equation problem. However, fitting land seismic data with acoustic wavefield is sometimes invalid. On the other hand, performing elastic waveform inversion is very time-consuming. Similar to a web search engine, we develop a full elastic waveform search engine that includes a large database with synthetic elastic waveforms accounting for a wide range of interval velocity models in the CMP domain. With each CMP gather of real data as an entry, the search engine applies Multiple-Randomized K-Dimensional (MRKD) tree method to find approximate best matches to the entry in about a second. Interpolation of the velocity models at CMP positions creates 2D or 3D Vp, Vs, and density models for the near surface area. The method does not just return one solution; it gives a series of best matches in a solution space. Therefore, the results can help us to examine the resolution and nonuniqueness of the final solution. Further, this full waveform search method can avoid the issues of initial model and cycle skipping that the method of full waveform inversion is difficult to deal with.

  18. Frequency Correction for MIRO Chirp Transformation Spectroscopy Spectrum

    NASA Technical Reports Server (NTRS)

    Lee, Seungwon

    2012-01-01

    This software processes the flyby spectra of the Chirp Transform Spectrometer (CTS) of the Microwave Instrument for Rosetta Orbiter (MIRO). The tool corrects the effect of Doppler shift and local-oscillator (LO) frequency shift during the flyby mode of MIRO operations. The frequency correction for CTS flyby spectra is performed and is integrated with multiple spectra into a high signal-to-noise averaged spectrum at the rest-frame RF frequency. This innovation also generates the 8 molecular line spectra by dividing continuous 4,096-channel CTS spectra. The 8 line spectra can then be readily used for scientific investigations. A spectral line that is at its rest frequency in the frame of the Earth or an asteroid will be observed with a time-varying Doppler shift as seen by MIRO. The frequency shift is toward the higher RF frequencies on approach, and toward lower RF frequencies on departure. The magnitude of the shift depends on the flyby velocity. The result of time-varying Doppler shift is that of an observed spectral line will be seen to move from channel to channel in the CTS spectrometer. The direction (higher or lower frequency) in the spectrometer depends on the spectral line frequency under consideration. In order to analyze the flyby spectra, two steps are required. First, individual spectra must be corrected for the Doppler shift so that individual spectra can be superimposed at the same rest frequency for integration purposes. Second, a correction needs to be applied to the CTS spectra to account for the LO frequency shifts that are applied to asteroid mode.

  19. Numerical studies of driven, chirped Bernstein, Greene, and Kruskal modes

    NASA Astrophysics Data System (ADS)

    Peinetti, F.; Bertsche, W.; Fajans, J.; Wurtele, J.; Friedland, L.

    2005-06-01

    Recent experiments showed the possibility of creating long-lived, nonlinear kinetic structures in a pure-electron plasma. These structures, responsible for large-amplitude periodic density fluctuations, were induced by driving the plasma with a weak oscillating drive, whose frequency was adiabatically decreased in time [W. Bertsche, J. Fajans, and L. Friedland, Phys. Rev. Lett. 91, 265003 (2003)]. A one-dimensional analytical model of the system was developed [L. Friedland, F. Peinetti, W. Bertsche, J. Fajans, and J. Wurtele, Phys. Plasmas 11, 4305 (2004)], which pointed out the phenomenon responsible for the modifications induced by the weak drive in the phase-space distribution of the plasma (initially Maxwellian). In order to validate the theory and to perform quantitative comparisons with the experiments, a more accurate description of the system is developed and presented here. The new detailed analysis of the geometry under consideration allows for more precise simulations of the excitation process, in which important physical and geometrical parameters (such as the length of the plasma column) are evaluated accurately. The numerical investigations probe properties and features of the modes not accessible to direct measurement. Due to the presence of two distinct time scales (because of the adiabatic chirp of the drive frequency), a fully two-dimensional numerical study of the system is expected to be rather time consuming. This becomes particularly important when, as here, a large number of comparisons (covering a wide range of drive parameters) are performed. For this reason, a coupled one-dimensional, radially averaged model is derived and implemented in a particle-in-cell code.

  20. a Low-Cost Chirped-Pulse Fourier Transform Microwave Spectrometer for Undergraduate Physical Chemistry Lab

    NASA Astrophysics Data System (ADS)

    Carroll, Brandon; Finneran, Ian; Blake, Geoffrey

    2014-06-01

    We present the design and construction of a simple and low-cost waveguide chirped pulse Fourier transform microwave (CP-FTMW) spectrometer suitable for gas-phase rotational spectroscopy experiments in undergraduate physical chemistry labs as well as graduate level research. The spectrometer operates with modest bandwidth, using phased locked loop (PLL) microwave sources and a direct digital synthesis (DDS) chirp source, making it an affordable for undergraduate labs. The performance of the instrument is benchmarked by acquiring the pure rotational spectrum of the J = 1 - 0 transition OCS and its isotopologues from 11-12.5 GHz.

  1. Reflectivity of linear and nonlinear gamma radiated apodized chirped Bragg grating under ocean

    SciTech Connect

    Hamdalla, Taymour A. [Faculty of Science, Alexandria University, Alexandria (Egypt); Faculty of Science, Tabuk University, Tabuk (Saudi Arabia)

    2012-09-06

    In this paper, the effect Co{sup 60} gamma radiation is investigated on the effective refractive index of apodized chirped Bragg grating. Nine apodization profiles are considered. Comparison between the reflectivity of the gamma radiated and non radiated fiber Bragg grating has been carried out. The electric field of signals propagating through the apodized chirped fiber Bragg grating (ACFBG) is first calculated from which, new values for the refractive index are determined. The nonlinear effects appear on the ACFBG reflectivity. The effect of nonlinearity and undersea temperature and pressure on the grating is also studied.

  2. Injection-seeded optical parametric amplifier for generating chirped nanosecond pulses.

    PubMed

    Miyake, Shinichirou; Ohshima, Yasuhiro

    2013-03-11

    We constructed an optical parametric amplifier with BiBO crystals, which was injection seeded by a phase-modulated cw beam in the 1,040-1,070 nm region. Two-stage pre-amplification by Yb-doped fibers were implemented for stable injection to the OPA. The frequency chirp in the OPA pulse was actively controlled by adjusting the RF wave for the phase modulation and its synchronization to the OPA firing. Down/up chirps with up to 500 MHz shift were demonstrated. The output pulse energy was ~40 mJ, which is sufficient for future application of frequency conversion and coherent population transfer. PMID:23482098

  3. Practical design of optical diagnostics for chirped-pulse free-electron lasers

    NASA Astrophysics Data System (ADS)

    Szarmes, Eric B.; Madey, John M. J.

    1992-07-01

    In recent years there have been several proposals to operate rf-linac-driven FELs with chirped electron and optical micropulses for use in fast time-resolved experiments. We have been actively pursuing this application on the Mark-III infrared FEL at Duke University, and have designed and procured an apparatus to achieve broad-band compression of chirped optical pulses between roughly 2.5 ?m and 4.1 ?m, with subsequent measurement of pulse widths as short as 200 fs. The principles of design for this experiment will be reviewed, and extensions of the design to other wavelengths will be considered.

  4. Amplification of optical delay by use of matched linearly chirped fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Yang, Changhuei; Yazdanfar, Siavash; Izatt, Joseph

    2004-04-01

    We describe the use of a matched linearly chirped fiber Bragg grating (FBG) pair as a key element in an adjustable optical delay line. This delay line has the unique property that the achievable optical group delay is orders of magnitude greater (factor of 10 2 in our experiment) than the actual physical displacement. We demonstrate operation of such an optical delay line over a delay range of 3.5 mm using a pair of matched 1300-nm chirped FBGs with a bandwidth of 20 nm each.

  5. Chirped and phase-sampled fiber Bragg grating for tunable DBR fiber laser

    NASA Astrophysics Data System (ADS)

    Xu, Ximing; Dai, Yitang; Chen, Xiangfei; Jiang, Dianjie; Xie, Shizhong

    2005-05-01

    Chirped and phase-sampled fiber Bragg gratings are fabricated and used as reflectors in tunable DBR fiber laser for the first time. By controlling the phase of each sampling section, sampled Bragg gratings (SBG) with different channel spacing can be obtained using only a single chirped phase mask. A 30nm-wide tunable Erbium-doped fiber (EDF) laser is designed and experimentally demonstrated by utilizing the vernier effect of two such SBGs with channel spacing of 3.2nm and 3.6nm, respectively. The lasers' output power of different channels is almost identical (difference less than 1dB) within the tunable range.

  6. Chirped-Pulse Millimeter-Wave Spectroscopy of Rydberg-Rydberg Transitions

    SciTech Connect

    Prozument, Kirill; Colombo, Anthony P.; Zhou Yan; Park, G. Barratt; Petrovic, Vladimir S.; Coy, Stephen L.; Field, Robert W. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2011-09-30

    Transitions between Rydberg states of Ca atoms, in a pulsed, supersonic atomic beam, are directly detected by chirped-pulse millimeter-wave spectroscopy. Broadband, high-resolution spectra with accurate relative intensities are recorded instantly. Free induction decay (FID) of atoms, polarized by the chirped pulse, at their Rydberg-Rydberg transition frequencies, is heterodyne detected, averaged in the time domain, and Fourier transformed into the frequency domain. Millimeter-wave transient nutations are observed, and the possibility of FID evolving to superradiance is discussed.

  7. Selective and efficient control of coherent population transfer with time-separated chirped pulses

    SciTech Connect

    Yang Xihua; Zhang Zhenhua; Yan Xiaona; Li Chunfang [Department of Physics, Shanghai University, Shanghai 200444 (China)

    2010-03-15

    We propose a selective, efficient, and robust way to realize control of coherent population transfer in a {Lambda}-type four-level system with a closely spaced doublet in the final state with time-separated chirped pump pulse and Stokes pulse pair by merging stimulated Raman adiabatic passage, temporal coherent control, and chirped adiabatic passage techniques. Moreover, an arbitrary coherent superposition between the final doublet, or between the intermediate state and either of the doublets can be created. This method holds the ability to 'control with control' and has potential applications in coherent control of chemical reactions and quantum information processing.

  8. Effect of input pulse chirp on nonlinear energy deposition and plasma excitation in water

    NASA Astrophysics Data System (ADS)

    Milián, Carles; Jarnac, Amélie; Brelet, Yohann; Jukna, Vytautas; Houard, Aurélien; Mysyrowicz, André; Couairon, Arnaud

    2014-11-01

    We analyze numerically and experimentally the effect of the input pulse chirp on the nonlinear energy deposition from $5\\ \\mu$J fs-pulses at $800$ nm to water. Numerical results are also shown for pulses at $400$ nm, where linear losses are minimized, and for different focusing geometries. Input chirp is found to have a big impact on the deposited energy and on the plasma distribution around focus, thus providing a simple and effective mechanism to tune the electron density and energy deposition. We identify three relevant ways in which plasma features may be tuned.

  9. Nonlinear energy deposition in water from fs-laser pulses: effect of the input chirp

    NASA Astrophysics Data System (ADS)

    Milián, C.; Jarnac, Amelie; Brelet, Y.; Jukna, V.; Houard, A.; Mysyrowicz, A.; Couairon, A.

    2014-05-01

    We present numerical and experimental investigation of the effect that the input pulse chirp has on the energy transfer from 5 ?J fs-pulses at 800 nm to water. The chirp is seen to control efficiently the energy transfer and the geometrical properties of the excited plasma volumes. Agreement between simulations and experiments is obtained via a parametric study, the details of which are presented here. These results may find applications in the control of underwater bubble and sound wave formation, and also in laser surgery involving aqueous media.

  10. Coherent XUV pulse generation using a chirped pulse combined with a unipolar pulse

    NASA Astrophysics Data System (ADS)

    Feng, Liqiang; Liu, Hang

    2015-01-01

    High-order harmonic emission and attosecond XUV source generation have been theoretically investigated using a chirped pulse combined with a unipolar pulse. It shows that the harmonic plateau is very sensitive to the chirp parameter and the intensity, pulse duration and relative position of the unipolar pulse. Further, by optimizing the laser parameters, a 714?eV supercontinuum bandwidth with a single short quantum path contribution has been obtained. Finally, by superposing the selected harmonic spectrum from the 70th to the 470th orders, an isolated attosecond pulse with a duration of 36 as can be obtained.

  11. ATOMIC AND MOLECULAR PHYSICS: Lithium atom population transfer by population trapping in a chirped microwave pulse

    NASA Astrophysics Data System (ADS)

    Jia, Guang-Rui; Zhang, Xian-Zhou; Ren, Zhen-Zhong; Wu, Su-Ling

    2009-12-01

    Using a time-dependent multilevel approach, we demonstrate that lithium atoms can be transferred to states of lower principle quantum number by exposing them to a frequency chirped microwave pulse. The population transfer from n = 79 to n = 70 states of lithium atoms with more than 80% efficiency is achieved by means of the sequential two-photon ?n = -1 transitions. It is shown that the coherent control of the population transfer can be accomplished by the optimization of the chirping parameters and microwave field strength. The calculation results agree well with the experimental ones and novel explanations have been given to understand the experimental results.

  12. High-Fidelity Adiabatic Passage by Composite Sequences of Chirped Pulses

    NASA Astrophysics Data System (ADS)

    Torosov, Boyan T.; Guérin, Stéphane; Vitanov, Nikolay V.

    2011-06-01

    We present a method for optimization of the technique of adiabatic passage between two quantum states by composite sequences of frequency-chirped pulses with specific relative phases: composite adiabatic passage (CAP). By choosing the composite phases appropriately the nonadiabatic losses can be canceled to any desired order with sufficiently long sequences, regardless of the nonadiabatic coupling. The values of the composite phases are universal for they do not depend on the pulse shapes and the chirp. The accuracy of the CAP technique and its robustness against parameter variations make CAP suitable for high-fidelity quantum information processing.

  13. Femtosecond mode-locked Yb fiber laser for single-mode fiber chirped pulse amplification system

    Microsoft Academic Search

    K. Sumimura; H. Yoshida; H. Fujita; M. Nakatsuka

    2007-01-01

    High-peak-power laser systems are based on the chirped pulse amplification (CPA) technique. CPA laser system needs a mode-locked\\u000a laser oscillator for stable ultrashort pulse laser generation. We report a single-mode fiber CPA system which consists of\\u000a stable mode-locked Yb-doped fiber laser oscillator with a wide tuning range, chirped fiber Bragg grating stretcher, and two\\u000a Yb-doped fiber amplifiers. The single-mode fibers

  14. Acoustic change detection algorithm using an FM radio

    NASA Astrophysics Data System (ADS)

    Goldman, Geoffrey H.; Wolfe, Owen

    2012-06-01

    The U.S. Army is interested in developing low-cost, low-power, non-line-of-sight sensors for monitoring human activity. One modality that is often overlooked is active acoustics using sources of opportunity such as speech or music. Active acoustics can be used to detect human activity by generating acoustic images of an area at different times, then testing for changes among the imagery. A change detection algorithm was developed to detect physical changes in a building, such as a door changing positions or a large box being moved using acoustics sources of opportunity. The algorithm is based on cross correlating the acoustic signal measured from two microphones. The performance of the algorithm was shown using data generated with a hand-held FM radio as a sound source and two microphones. The algorithm could detect a door being opened in a hallway.

  15. Seismic waveforms and velocity model heterogeneity: Towards a full-waveform microseismic location algorithm

    NASA Astrophysics Data System (ADS)

    Angus, D. A.; Aljaafari, A.; Usher, P.; Verdon, J. P.

    2014-12-01

    Seismic forward modeling is an integral component of microseismic location algorithms, yet there is generally no one correct approach, but rather a range of acceptable approaches that can be used. Since seismic signals are band limited, the length scale of heterogeneities can significantly influence the seismic wavefronts and waveforms. This can be especially important for borehole microseismic monitoring, where subsurface heterogeneity can be strong and/or vary on length scales equivalent to or less than the dominant source wavelength. In this paper, we show that ray-based approaches are not ubiquitously suitable for all borehole microseismic applications. For unconventional reservoir settings, ray-based algorithms may not be suitably accurate for advanced microseismic imaging. Here we focus on exploring the feasibility of using one-way wave equations as forward propagators for full waveform event location techniques. As a feasibility study, we implement an acoustic wide-angle wave equation and use a velocity model interpolation approach to explore the computational efficiency and accuracy of the solution. We compare the results with an exact solution to evaluate travel-time and amplitude errors. The results show that accurate travel-times can be predicted to within 2 ms of the true solution for modest velocity model interpolation. However, for accurate amplitude prediction or for higher dominant source frequencies, a larger number of velocity model interpolations is required.

  16. Modularized seismic full waveform inversion based on waveform sensitivity kernels - The software package ASKI

    NASA Astrophysics Data System (ADS)

    Schumacher, Florian; Friederich, Wolfgang; Lamara, Samir; Gutt, Phillip; Paffrath, Marcel

    2015-04-01

    We present a seismic full waveform inversion concept for applications ranging from seismological to enineering contexts, based on sensitivity kernels for full waveforms. The kernels are derived from Born scattering theory as the Fréchet derivatives of linearized frequency-domain full waveform data functionals, quantifying the influence of elastic earth model parameters and density on the data values. For a specific source-receiver combination, the kernel is computed from the displacement and strain field spectrum originating from the source evaluated throughout the inversion domain, as well as the Green function spectrum and its strains originating from the receiver. By storing the wavefield spectra of specific sources/receivers, they can be re-used for kernel computation for different specific source-receiver combinations, optimizing the total number of required forward simulations. In the iterative inversion procedure, the solution of the forward problem, the computation of sensitivity kernels and the derivation of a model update is held completely separate. In particular, the model description for the forward problem and the description of the inverted model update are kept independent. Hence, the resolution of the inverted model as well as the complexity of solving the forward problem can be iteratively increased (with increasing frequency content of the inverted data subset). This may regularize the overall inverse problem and optimizes the computational effort of both, solving the forward problem and computing the model update. The required interconnection of arbitrary unstructured volume and point grids is realized by generalized high-order integration rules and 3D-unstructured interpolation methods. The model update is inferred solving a minimization problem in a least-squares sense, resulting in Gauss-Newton convergence of the overall inversion process. The inversion method was implemented in the modularized software package ASKI (Analysis of Sensitivity and Kernel Inversion), which provides a generalized interface to arbitrary external forward modelling codes. So far, the 3D spectral-element code SPECFEM3D (Tromp, Komatitsch and Liu, 2008) and the 1D semi-analytical code GEMINI (Friederich and Dalkolmo, 1995) in both, Cartesian and spherical framework are supported. The creation of interfaces to further forward codes is planned in the near future. ASKI is freely available under the terms of the GPL at www.rub.de/aski . Since the independent modules of ASKI must communicate via file output/input, large storage capacities need to be accessible conveniently. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full waveform inversion. In the presentation, we will show some aspects of the theory behind the full waveform inversion method and its practical realization by the software package ASKI, as well as synthetic and real-data applications from different scales and geometries.

  17. Waveform retracking for improving inland water heights from altimetry

    NASA Astrophysics Data System (ADS)

    Uebbing, Bernd; Forootan, Ehsan; Kusche, Jürgen

    2015-04-01

    For more than two decades, satellite radar altimeters have been providing valuable information on level changes of seas and oceans. In recent years, the usage of satellite altimetry to monitor the water level changes of lakes and rivers, as well as in hydrology applications, has become a topic of rising interest. The altimeter emits a radar pulse, which is reflected at the nadir-surface and measures the two-way travel time, as well as the returned energy as a function of time, resulting in a return waveform. Over the open ocean the waveform shape corresponds to a theoretical model which can be used to infer information on range corrections, significant wave height or wind speed. However, the waveforms over lakes and rivers show patterns which are significantly influenced by signals reflected from land present in the altimeter footprint. This results in a variety of different waveforms shapes ranging from waveforms similar to the theoretical ocean case to completely different ones such as those including only small leading edges and large peaks on the trailing edge. These peaks considerably influence the estimation of the parameters of interest, such as the time origin, connected to the range information, particularly if they are located very close to the leading edge. To mitigate this problem, we present a retracking approach, which combines the advantages of sub-waveform retracking with a flexible waveform model, that allows to model symmetric and asymmetric Gaussian peaks. Based on a preliminary waveform analysis step, a defined window is applied to the total waveform and the parameters are estimated by a flexible fitting procedure. We retracked Topex/Poseidon, Jason-1 and Jason-2 data over several lakes, including the African lakes Volta and Victoria. The inferred lake level heights are evaluated by comparisons to water heights from in situ gauge observations, the Global Reservoir and Lake Monitoring database, as well as those derived from applying conventional retrackers, such as the ?-5 model, threshold retrackers and the sub-waveform retrackers, including our new approach. Results show that sub-waveform retrackers are able to handle a broad spectrum of waveform shapes ranging from the theoretical ocean case to shapes which are significantly contaminated by peaks. The quality of water heights derived from these retrackers, e.g., over Lake Volta is usually better compared to conventional retracking methods, providing standard deviations with respect to gauge data of 32cm, 10cm and 8cm for Topex/Poseidon, Jason-1 and Jason-2, respectively. Results over Lake Victoria in an area with significant land contamination in the altimeter footprint confirmed the favorable performance of the sub-waveform approaches compared to conventional retrackers. Over smaller lakes, such as Lake Naivasha, the water heights still improved compared to the unretracked case, but conventional threshold retrackers showed better results for most of the observed waveforms, which were mostly categorized as singular, specular peaks.

  18. A LINEARIZATION METHOD FOR A UWB VCO-BASED CHIRP GENERATOR USING DUAL COMPENSATION

    E-print Network

    Gomez-Garcia Alvestegui, Daniel

    2011-12-31

    amplitude response aRX Reference Path Amplitude Waveform aREF Mixer Conversion Factor amplitude response K IF Stage amplitude response aIF Assuming a linearly frequency modulated signal, the amplitude waveforms in Table 2-1 correspond to the gain...

  19. High-energy, diode-pumped, picosecond Yb:YAG chirped-pulse regenerative amplifier for pumping optical parametric chirped-pulse amplification.

    PubMed

    Akahane, Y; Aoyama, M; Ogawa, K; Tsuji, K; Tokita, S; Kawanaka, J; Nishioka, H; Yamakawa, K

    2007-07-01

    A diode-pumped, cryogenic-cooled Yb:YAG regenerative amplifier utilizing gain-narrowing has been developed. A 1.2-ns chirped-seed pulse was simultaneously amplified and compressed in the regenerative amplifier, which generated a 35-ps pulse with ~8-mJ of energy without a pulse compressor. Second-harmonics of the amplified pulse was used to pump picosecond two-color optical parametric amplification. PMID:17603607

  20. The Suitability of Hybrid Waveforms for Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    MacDonald, Ilana; Pfeiffer, H.; Nissanke, S.; Mroue, A.

    2013-01-01

    General relativity predicts that the coalescence of two compact objects, such as black holes, will produce gravitational radiation; i.e., ripples in the curvature of space-time. Detectors like Advanced LIGO (the Laser Interferometry Gravitational-wave Observatory) are expected to measure such events within the next few years. In order to be able to characterize the gravitational waves they measure, these detectors require accurate waveform models, which can be constructed by fusing an analytical post-Newtonian inspiral waveform with a numerical relativity late-inspiral-merger-ringdown waveform. Numerical relativity, though the most accurate model, is computationally expensive: the longest simulations to date taking several months to run. Post-Newtonian theory, an analytic approximation to General Relativity, is easy to compute but becomes increasingly inaccurate near merger. Because of this trade-off, it is important to determine the optimal length of the numerical waveform, while maintaining the necessary accuracy for gravitational wave detectors. We present a study of the sufficient accuracy of post-Newtonian and numerical relativity waveforms for the most demanding usage case: parameter estimation of strong sources in advanced gravitational wave detectors. We perform a comprehensive analysis of errors that enter such “hybrid waveforms” in the case of equal-mass and unequal mass non-spinning binaries. We also explore the possibility of using these hybrid waveforms as a detection template bank for Advanced LIGO. Accurate hybrids play an important role in investigating the efficiency of gravitational wave search pipelines, as with NINJA (Numerical INJection Analysis); and also in constructing analytical models that span the entire parameter space of binary black hole mass ratios and spins, as with NRAR (Numerical Relativity and Analytic Relativity).

  1. The role of the FM component in shaping the number of impulses and response latency of inferior collicular neurons of Hipposideros armiger elicited by CF-FM sounds.

    PubMed

    Fu, Zi-Ying; Xu, Na; Wang, Jing; Tang, Jia; Jen, Philip Hung-Sun; Chen, Qi-Cai

    2014-07-25

    Previous studies show that when stimulated with constant frequency-frequency modulated (CF-FM) sounds, the inferior collicular neurons of the leaf-nosed bat, Hipposideros armiger, either discharge impulses only to the CF component (single-on, SO neurons) or to both CF and FM components (double-on, DO neurons). In this study, we specifically determine the role of the FM component in shaping the number of impulses and response latency of these two types of neurons in response to CF-FM sounds. Adding the FM component to the CF sounds significantly decreases the number of impulses of both SO and DO neurons but shortens the response latency of DO neurons in response to the CF component of the CF-FM sounds. The possible neural mechanisms underlying these seemingly paradoxical observations are briefly discussed based on our preliminary intracellular recording studies. Biological relevance of these findings in relation to different phases of bats' hunting is also discussed. PMID:24915297

  2. 47 CFR 73.809 - Interference protection to full service FM stations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Interference protection to full service FM stations...Broadcast Stations (LPFM) § 73.809 Interference protection to full service FM stations...is protected against any condition of interference to the direct reception of its...

  3. 47 CFR 73.809 - Interference protection to full service FM stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Interference protection to full service FM stations...Broadcast Stations (LPFM) § 73.809 Interference protection to full service FM stations...is protected against any condition of interference to the direct reception of its...

  4. 47 CFR 73.809 - Interference protection to full service FM stations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Interference protection to full service FM stations...Broadcast Stations (LPFM) § 73.809 Interference protection to full service FM stations...is protected against any condition of interference to the direct reception of its...

  5. 47 CFR 73.809 - Interference protection to full service FM stations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Interference protection to full service FM stations...Broadcast Stations (LPFM) § 73.809 Interference protection to full service FM stations...is protected against any condition of interference to the direct reception of its...

  6. 47 CFR 73.809 - Interference protection to full service FM stations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Interference protection to full service FM stations...Broadcast Stations (LPFM) § 73.809 Interference protection to full service FM stations...is protected against any condition of interference to the direct reception of its...

  7. A New Method for Evaluating the Communication Quality of FM Signal

    Microsoft Academic Search

    Wang Jixiang; Sun Guang

    2007-01-01

    FM communication, which has the stronger antijamming ability, has been applied in the military communication. The demodulation signals that evaluate the communication quality can not be obtained easily in most cases. To evaluate the FM signal communication quality efficiently, the key feature based on the envelop information was extracted and a new method was present. The results of simulation test

  8. AI4FM: A new project seeking challenges! Gudmund Grov and Cliff B. Jones

    E-print Network

    Southampton, University of

    COMPUTING SCIENCE AI4FM: A new project seeking challenges! Gudmund Grov and Cliff B. Jones AI4FM: A new project seeking challenges! G. Grov, C.B. Jones Abstract The proof obligations generated, Claremont Road, Newcastle upon Tyne, NE1 7RU, England. #12;Bibliographical details GROV, G., JONES, C.B. AI4

  9. Theoretical Analysis of the Coexistence of Direct Sequence Spread Spectrum and Analog FM Systems

    E-print Network

    Vouyioukas, Demosthenes

    Theoretical Analysis of the Coexistence of Direct Sequence Spread Spectrum and Analog FM Systems Spread Spectrum (SS) system is assumed to utilize direct sequence (DS) spreading, using maximal length of a Spread Spectrum system on the existing narrowband FM broadcasting system is presented. The overlaid

  10. im2005_talk.fm May 11, 2005 1/17 Packet Marking for Integrated Load

    E-print Network

    Li, Ming

    im2005_talk.fm May 11, 2005 1/17 Packet Marking for Integrated Load Control IM 2005, Nice, France.fm May 11, 2005 2/17 Presentation Overview Introduction System Design Admission Control Load Estimation System Prototype Evaluation Wrap Up Introduction System Design Admission Control Load Estimation System

  11. MICRO SYNTHETIC APERTURE RADAR USING FM/CW Ryan L. Smith

    E-print Network

    Long, David G.

    of gener- ating high quality images using frequency modulated, continuous wave (FM/CW) technology and it of a single target and shows that FM/CW based SAR produces compressed images. A 10 GHz prototype is de goes to my wife Michelle and daughter Hannah for their encouragement and support in completing

  12. Exploiting FM Radio Data System for Adaptive Clock Calibration in Sensor Networks

    E-print Network

    Exploiting FM Radio Data System for Adaptive Clock Calibration in Sensor Networks Liqun Li1 for Wireless Sensor Networks (WSNs) due to the need of inter-node coordination and collaborative infor- mation receiver that can extract a periodic pulse from FM broadcasts, referred to as RDS clock. We then conduct

  13. FM-dyes as experimental probes for dissecting vesicle trafficking in living plant cells

    Microsoft Academic Search

    S. Bolte; C. Talbot; Y. Boutte; O. Catrice; N. D. Read; B. Satiat-Jeunemaitre

    2004-01-01

    Summary FM-dyes are widely used to study endocytosis, vesicle traffick- ing and organelle organization in living eukaryotic cells. The increasing use of FM-dyes in plant cells has provoked much debate with regard to their suitability as endocytosis markers, which organelles they stain and the precise pathways they follow through the vesicle trafficking network. A primary aim of this article is

  14. Evidence for perception of fine echo delay and phase by the FM bat, Eptesicus fuscus

    Microsoft Academic Search

    J. A. Simmons

    1993-01-01

    The big brown bat, Eptesicus fuscus, can perceive small changes in the delay of FM sonar echoes and shifts in echo phase, which interact with delay. Using spectral cues caused by interference, Eptesicus also can perceive the individual delays of two overlapping FM echoes at small delay separations. These results have been criticized as due to spectral artifacts caused by

  15. Descriptive Study of Noncommercial FM Radio Stations Affiliated with Colleges and Universities.

    ERIC Educational Resources Information Center

    Leidman, Mary Beth; Lamberski, Richard J.

    Designed to establish a framework for current and future documentation of FM radio in institutions of higher education, this study examined the state of noncommercial FM radio stations affiliated with colleges and universities. Topics investigated included: (1) basic descriptions of institutions housing noncommercial radio stations; (2) operating…

  16. A Comparison of Common Users across Instagram and Ask.fm to Better Understand Cyberbullying

    E-print Network

    Han, Richard Y.

    A Comparison of Common Users across Instagram and Ask.fm to Better Understand Cyberbullying Homa social networks, Instagram and Ask.fm, that are often used for cyberbullying. An analysis increase in cyberbullying activities, especially among teenagers. Indeed, cyberbullying has become a major

  17. Extending empirical models for binary black hole merger-ringdown waveforms to include late inspiral

    NASA Astrophysics Data System (ADS)

    Baker, John; Kelly, Bernard

    2014-03-01

    Analytic and empirical models for gravitational merger waveforms are a valuable tool for efficiently encoding the information from expensive numerical relativity simulations. Such models can be applied as a practical intermediary for gravitational-wave data analysis studies and may provide interesting heuristics for interpretation of waveform phenomenology. In the Implicit Rotating Source description of waveforms, we exploit the simple structure of computed spherical harmonic components for near-circular mergers, to represent the waveforms through the secular development of a circularly polarized waveform. We have previously presented waveform models for the most powerful merger-ringdown portions of these waveforms following an approach which first describes rotational frequency as a function of time, then treats amplitude in terms of the phasing behavior. A parametric representation of time and frequency allows useful extension of the waveforms back through the late insprial. We present results showing precise fits for numerical relativity (l = 2 , m = 2) waveform phasing with the extended model.

  18. Effect of chromatic dispersion induced chirp on the temporal coherence property of individual beam from spontaneous four wave mixing

    E-print Network

    Xiaoxin Ma; Xiaoying Li; Liang Cui; Xueshi Guo; Lei Yang

    2011-05-18

    Temporal coherence of individual signal or idler beam, determined by the spectral correlation property of photon pairs, is important for realizing quantum interference among independent sources. To understand the effect of chirp on the temporal coherence property, two series of experiments are investigated by introducing different amount of chirp into either the pulsed pump or individual signal (idler) beam. In the first one, based on spontaneous four wave mixing in a piece of optical fiber, the intensity correlation function of the filtered individual signal beam, which characterizes the degree of temporal coherence, is measured as a function of the chirp of pump. The results demonstrate that the chirp of pump pulses decreases the degree of temporal coherence. In the second one, a Hong-Ou-Mandel type two-photon interference experiment with the signal beams generated in two different fibers is carried out. The results illustrate that the chirp of individual beam does not change the temporal coherence degree, but affect the temporal mode matching. To achieve high visibility, apart from improving the coherence degree by minimizing the chirp of pump, mode matching should be optimized by managing the chirps of individual beams.

  19. Development features of atmospheric LD ladar based on the CW-FM-range-finding principles

    NASA Astrophysics Data System (ADS)

    Agishev, Ravil R.; Comeron, Adolfo; Duch, Lluis; Sagdiev, Rafael K.; Dios, Victor F.; Cifuentes, Jose Carlos; Lopez, Miguel Angel

    2004-02-01

    Elements of spectroscopic continuous-wave, frequency-modulated ladar (CW-FM-ladar) concept based on principles of both CW-FM-range-finding and modulation spectroscopy, and also on modern techniques of optical signal transmission, reception and processing are presented. Features of heterodyning methods for ladar echo-signal reception are considered. The comparison of CW-FM-ladar with CW-FM-range-finder and incoherent pulse lidar is carried out. Estimations of the achievable signal-to-noise ratio, the operation range and the range resolution are performed using frequency-dependent parameters of the transmitting and receiving subsystems. Preliminary experimental results on the range-finding subsystem characteristics of the CW-FM-laser diode (LD)-ladar are discussed.

  20. Waveguide Chirped-Pulse Fourier Transform Microwave Spectroscopy of 2-ETHOXYETHANOL

    NASA Astrophysics Data System (ADS)

    Phillips, Maria A.; Shipman, Steven T.

    2013-06-01

    The pure rotational spectrum of 2-ethoxyethanol was recorded from 8.7 to 26.5 GHz at 250 K with a waveguide chirped-pulse Fourier transform microwave spectrometer. The full spectrum contains contributions from multiple vibrational states. Preliminary assignments have been made with a combination of ab initio calculations and an automated spectral fitting program that accelerates the initial fitting process.

  1. Active phase control and frequency chirp effects on supercontinuum generation in high birefringence photonic crystal fiber

    Microsoft Academic Search

    Y. Jiang; Y. Leng; X. Chen; X. Li; Z. Xu

    2008-01-01

    An acoustic-optics programmable dispersive filter (AOPDF) was first employed to actively control the linearly polarized femtosecond pump pulse frequency chirp for supercontinuum (SC) generation in a high birefringence photonic crystal fiber (PCF). By accurately controlling the second order phase distortion and polarization direction of incident pulses, the output SC spectrum can be tuned to various spectral energy distributions and bandwidths.

  2. Chirp-induced dynamics of femtosecond filaments Rachel Nuter, Stefan Skupin,* and Luc Berg

    E-print Network

    Skupin, Stefan

    the influence of a chirped phase on femtosecond pulses propagating in air. Pulses with an initially negative-power laser pulses self-focus under the Kerr re- sponse of air until their intensity exceeds the ioniza- tion, many practical applications have been suggested, such as lidar remote sensing and lightning protection

  3. Comparison of methods of determining meteoroid range rates from linear frequency modulated chirped pulses

    E-print Network

    Oppenheim, Meers

    frequency modulated (LFM) chirped pulse data from the ALTAIR radar. The first method is based on the simple capability of ALTAIR to solve for range rates based on the difference in the measured ranges due to range, are given for a large set of meteoroid head echoes taken from a data collection conducted with ALTAIR

  4. Effectiveness of nonlinear optical loop mirrors in chirped fiber gratings compensated

    E-print Network

    Wai, Ping-kong Alexander

    in CFGs randomly varies along the transmission line, which includes the amplifier noise in a 40 Gb/s DMJTuC1 Effectiveness of nonlinear optical loop mirrors in chirped fiber gratings compensated dispersion-managed transmission systems Y. H. C. Kwan, t K. Nakkeeran, and P. K. A. Wai Photonics Research

  5. TONE AND CHIRP DETECTION USING SUMS OF CONJUGATE PRODUCTS I. Vaughan L. Clarkson

    E-print Network

    Clarkson, Vaughan

    ] to perform an asymptotic analysis. We compare the performance of the detectors with the en- ergy detector call sums of conjugate products, for the purpose of detecting tones and chirps in noise their asymptotic statistics and compare their discriminating power against the energy detector. We find

  6. The monitoring and multiplexing of fiber optic sensors using chirped laser sources 

    E-print Network

    Wan, Xiaoke

    2004-09-30

    A wide band linearly chirped erbium-doped fiber laser has been developed. The erbium-doped fiber laser using a rotating mirror/grating combination as one of the reflectors in a Fabry-Perot laser cavity has been tuned over a 46 nm spectral range...

  7. Fundamental limitations in the performance of chirped grating lenses on planar optical waveguides

    Microsoft Academic Search

    J.-M. Delavaux; W. S. Chang

    1985-01-01

    The fundamental limitations in the performance of chirped grating lenses on planar optical waveguides caused by diffraction and by fabrication tolerances have been analyzed based on the generalized coupled mode theory (GCMT). The two most crucial lens parameters that affect the performance have been identified as the minimum grating periodicity and the maximum coupling coefficient. They have a strong effect

  8. Source of metastable H(2s) atoms using the Stark chirped rapid-adiabatic-passage technique

    Microsoft Academic Search

    L. P. Yatsenko; B. W. Shore; T. Halfmann; K. Bergmann

    1999-01-01

    We propose the use of Stark chirped rapid-adiabatic-passage method, a technique in which the energy of a target state is swept through resonance by a slowly varying dynamic Stark shift to induce complete population transfer from the ground 1s state to the metastable 2 s state of the hydrogen atom. Parasitic ionization pro- cesses are strongly reduced by using a

  9. Spectral and Noise Purity of Coherent Multiple-Frequency Chirp Exciter for L Band Radars

    Microsoft Academic Search

    Tomasz Cegielski; Zdzislaw Sawicki

    2006-01-01

    This paper presents results of spectral analysis and design performance of the up-converter module of the coherent multiple-frequency chirp exciter for long distance L Band surveillance radars. Some measured results of spectral and noise purity of the exciter with coherent frequency synthesizer driven from high stability oscillator source are included. The experimental results are in good agreement with requested values.

  10. Chirped porous silicon reflectors for thin-film epitaxial silicon solar cells

    Microsoft Academic Search

    Izabela J. Kuzma-Filipek; Filip Duerinckx; Emmanuel van Kerschaver; Kris van Nieuwenhuysen; Guy Beaucarne; Jef Poortmans

    2008-01-01

    The studies of porous silicon as a one-dimensional photonic crystal have led to solutions allowing the fabrication of broad photonic band gaps as large as several hundreds nanometers for various types of applications. In this work we demonstrate the use of the chirping process, i.e., the gradual increase in the spatial period of the structure, as it is used in

  11. Optical multi-coset sampling of GHz-band chirped signals

    NASA Astrophysics Data System (ADS)

    Valley, George C.; Sefler, George A.; Shaw, T. J.; Smith, Stephen L.

    2015-03-01

    Direct digitization of long, wideband chirped RF signals in the GHz band requires power hungry ADCs and produces large data sets. Here we present an optical scheme to perform multi-coset sampling of such signals with reduced power consumption and smaller data sets. In our scheme a repetitively pulsed femtosecond laser is dispersed to the interpulse time, the RF is modulated on the optical field, and the field is directed to a pair of wavelength-division demultiplexers (WDM). The channels of the WDM are attenuated with a pseudo-random sequence to form a coset pattern that repeats at the laser repetition rate. After a photodiode, the photocurrent is integrated for the duration of the dispersed optical pulse so that the coset pattern non-uniformly samples the RF signal. Since the laser repetition rate is uncorrelated with the RF, each coset provides an independent measurement of the RF. Experimental and numerical results show that 4 properties of the RF chirp pulse can be determined from the multiple coset samples: carrier frequency, chirp rate, start time, and pulse duration. Results are presented for a 20MHz chirp on a 13 microsecond pulse at a carrier of 2.473 GHz.

  12. Dynamics and performance of hybrid distributed Bragg reflector lasers including a chirped fiber grating

    NASA Astrophysics Data System (ADS)

    Duan, GuangHua; Helmers, H.; Leroy, A.; Brosson, Philippe; Jacquet, Joel

    2002-06-01

    In this work, we report the spectral and modulation characteristics, as well as bit-error-rate performances of stabilized hybrid distributed Bragg reflector lasers including a chirped fiber grating. An original analysis of such lasers based on a modified second order rate equation will also be presented to explain the observed stability behavior.

  13. REMOVAL OF RESIDUAL CHIRP IN COMPRESSED BEAMS USING A PASSIVE WAKEFIELD TECHNIQUE

    E-print Network

    Brookhaven National Laboratory

    of Bane and Stupakov [1], in RF-free residual chirp mitigation using only passive techniques. Beam in papers by Bane, Stupakov, and Emma [2] [3]. The longitudinal wakefield generated by a single electron and the circular pipe that was used in Stupakov and Bane's original derivation [4]. The wakefield produced

  14. Proposal of high-yield widely-tunable DBR lasers with equivalent-chirp grating reflectors

    Microsoft Academic Search

    Yitang Dai; Kun Xu; Jian Wu; Yan Li; Xiaobin Hong; Hongxiang Guo; Yong Zuo; Wei Li; Jintong Lin

    2010-01-01

    Equivalent-chirp technology is demonstrated to enable fabrication of flat-top-envelop comb gratings with conventional two-beam-interference lithography, instead of e-beam. Widely-tunable DBR semiconductor lasers using such gratings are studied numerically, showing excellent uniformity and SMSR during tuning.

  15. Scheme for measuring dispersion of chirped FBG using loop mirror configuration

    Microsoft Academic Search

    A. K. Atieh; I. Golub

    2001-01-01

    A novel scheme for measuring dispersion of chirped fiber Bragg gratings is demonstrated using loop mirror configuration. The measurement is insensitive to polarization or temperature variation. The technique is relatively simple, inexpensive, and requires only a broad-band light source

  16. Characterization of a fiber-optic direct modulation analog link with chirp radar signals

    Microsoft Academic Search

    Rossano Pardini; Umberto Bruno; Roberto Izzo

    2009-01-01

    This paper describes the experimental investigations carried out to evaluate the behaviour of a fiber-optic direct modulation analog link as a substitute of traditional transmission means, like coaxial cables or waveguides, for X-band chirp modulated radar signals. First of all, the link has been completely characterized, and the spurious frequency modulation has been measured in presence of pulsed signals. Afterwards,

  17. Quantum Phenomena in a Chirped Parametric Anharmonic Oscillator I. Barth and L. Friedland

    E-print Network

    Friedland, Lazar

    is the oscillator governed by the Hamiltonian H ¼ p2 2 þ ð1 þ cos Þ x2 2 þ x4 4 ð1Þ (here all variables and parameters are dimensionless). The frequency of the modulation is chirped, d=dt ¼ 2 þ t, passing the linear

  18. Analysis and modeling of click and chirp evoked auditory steady state responses

    Microsoft Academic Search

    Yuce Hekimoglu

    2003-01-01

    This study aims to investigate the possible advantages of using cochlear chirp stimulus instead of click for recording auditory steady-state responses (ASSRs), and to test the validity of the superposition hypothesis for the generation of the ASSRs through simulations, and modeling. Simulation of the ASSRs at different stimulation rates was achieved by shifting and adding of the transient auditory evoked

  19. Past applications and future uses of chirped ISR plasma line observations

    Microsoft Academic Search

    T. Hagfors; B. Isham

    1989-01-01

    The method of chirped incoherent scatter plasma wave observation is described. Applications of the method to the determination of electron density profiles, ionospheric irregularities, electron temperatures, electron gas vertical motion, field aligned currents, and plasma line enhancements caused by photoelectrons and precipitating auroral electrons are discussed. In all of these observations there is a large increase in the signal-to-noise ratio

  20. Fiber optical parametric chirped-pulse amplification in the femtosecond regime

    E-print Network

    Paris-Sud XI, Université de

    . J. Russell, "Continuous-wave tunable optical parametric generation in a photonic-crystal fiber," J to conventional OPCPA operating in bulk crystals, the fiber geometry offers a greater interaction lengthFiber optical parametric chirped-pulse amplification in the femtosecond regime Marc Hanna, Fr