Results 301 to 310 of about 281,646 (345)

Passive localization from Doppler shifted frequency measurements

[Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing, 1991
An efficient search scheme for an underwater radiating source is developed by introducing intermediate variables which are products of some of the unknowns. The search dimension is only two, in x-y position, instead of five. The resultant intermediate equations become linear and are easier to solve; the major calculation at each grid point requires an ...
Y.T. Chan, J.J. Towers
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Photonic Radio Frequency Memory with Controlled Doppler Frequency Shift

2019 International Topical Meeting on Microwave Photonics (MWP), 2019
A photonic Radio Frequency (RF) memory with coherent frequency shift and time gated amplifying recirculating delay line is proposed. It can simultaneously control Doppler frequency shift (DFS) and RF storage time. The coherent frequency shift is realized by the beat between the carrier with acoustic-optic modulator (AOM) frequency shift and sideband ...
Zhidan Ding, Fei Yang, Haiwen Cai, Yongxiang Weng, Mingjun Wang, Dongjin Wang   +5 more
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Doppler Frequency Tracking

1987
Continuous wave (CW), pulsed Doppler, and moving target indicator (MTI) radars, described in Chapters 13, 14, and 15, respectively, use the Doppler effect to discriminate between moving and stationary objects. These radars provide a method of detecting targets in the presence of ground clutter. Doppler frequency tracking provides clutter rejection that
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Sensing Doppler Frequencies

1998
To sort out the radar return from various objects according to doppler frequency, the receiver output is applied to a bank of narrowband filters. If sorting by range is also desired, a separate bank is provided for each range increment. The width of the passband of a narrowband filter is primarily determined by the filter's integration time but is ...
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Diode-laser frequency stabilization by two-frequency Doppler-broadened absorption spectroscopy

Applied Optics, 2004
We demonstrate a robust method for frequency stabilization of a diode laser by two Doppler-broadened absorption spectra of the cesium D2 line. This technique employs an acousto-optical modulator to generate another frequency component from a diode laser to perform the spectroscopy.
Jin-Long, Peng, Hyeyoung, Ahn
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Doppler bandwidth and mean frequency from time-frequency estimators

Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society, 2002
The performances of various time-frequency distribution (TFD) methods in the estimation of mean frequency and spectral bandwidth of the nonstationary Doppler blood flow signal are compared using simulated signals with known characteristics and different signal to noise ratios.
Cardoso, José C., Ruano, M. Graça, Fish, Peter   +2 more
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Performance of the mean frequency Doppler modulator

Ultrasound in Medicine & Biology, 1979
Abstract The mean frequency Doppler demodulator is of interest for quantitative measurement of blood flow, particularly in small or deep-lying vessels. It is thus desirable that the various potential sources of error be considered, and that their effects on its performance be quantified where possible.
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Displacement-Frequency Doppler Blood Flow Estimation

2007 IEEE International Symposium on Intelligent Signal Processing, 2007
This paper reports a novel method for representing the spectrum of pulsed Doppler ultrasound blood flow signals. It is an alternative to the time-frequency estimation method, that maintains the information contained in the time signal using a minimum computational cost solution.
Leiria, A, Ruano, MG, Evans, DH
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Single-frequency two dimensional Doppler imaging

Antennas and Propagation Society Symposium 1991 Digest, 2002
Using a unique form of target motion, two-dimensional images of the target are generated by a single-frequency CW (continuous wave) radar. This plus the limited range of aspect angles required for imaging places fewer constraints on the target than other known methods. As an example, a simulated three-target scene is imaged. >
U.H.W. Lammers, R.A. Marr
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Doppler Frequency Tolerant Synthetic Bandwidth Radar

2006 International Radar Symposium, 2006
Synthetic Bandwidth Radar (SBR) is one of the pulse radar which can obtain high range resolution. SBR has an advantage in that range resolution is not restricted by receiver bandwidth and/or sampling frequency of A/D converter. However, in the case of targets with non-zero relative velocity, accuracy of the measured range by SBR is getting worse ...
Teruyuki Hara, Takashi Sekiguchi
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