Modeling of Doppler Signal considering Sample Volume and Field Distribution

1989 ◽  
Vol 11 (3) ◽  
pp. 175-196 ◽  
Author(s):  
Yeong M. Kim ◽  
Song B. Park
Keyword(s):  
Power Spectrum ◽  
Field Distribution ◽  
Amplitude Spectrum ◽  
Pulse Length ◽  
Sample Volume ◽  
Doppler Signal ◽  
Intersection Angle ◽  
Transmitted Pulse ◽  
Beam Geometry ◽  
Doppler Power

The ultrasound Doppler amplitude spectrum for a single scatterer and the power spectrum for multiple scatterers were calculated in terms of the echo signal from scatterers crossing the sample volume, defined by the transmitted pulse and the diffracted field distribution for cw. The observation time for the Doppler signal is also considered. Statistical parameters such as mean and variance of the Doppler power spectrum are studied as continuous functions of the intersection angle between the beam axis and the flow direction, the pulse length and the viewing position. The derived equations are valid whether the transit time is governed by the pulse length, or beam geometry, or both. It is shown that the Doppler power spectra calculated by the proposed model and by the Doppler signal obtained from field theory are in good agreement. It is also shown that, when the Doppler signal broadening due to the transmitted pulse and beam geometry is constant without regard to the intersection angle, the degree of spread of the velocity distribution can be estimated from the variance of the Doppler power spectrum measured by the Doppler system once the intersection angle is known.

Doppler power spectrum from a Gaussian sample volume

Ultrasonics ◽  
2000 ◽  
Vol 37 (9) ◽  
pp. 623-632 ◽  
Author(s):  
Carlos A.C. Bastos ◽  
Peter J. Fish ◽  
Robin Steel ◽  
Francisco Vaz
Keyword(s):  
Power Spectrum ◽  
Sample Volume ◽  
Doppler Power ◽  
Gaussian Sample

scholarly journals An Estimator for Weather Radar Doppler Power Spectrum via Minimum Mean Square Error

2021 ◽  
pp. 1-16
Author(s):  
Eiichi Yoshikawa ◽  
Naoya Takizawa ◽  
Hiroshi Kikuchi ◽  
Tomoaki Mega ◽  
Tomoo Ushio
Keyword(s):  
Power Spectrum ◽  
Mean Square Error ◽  
Minimum Mean Square Error ◽  
Weather Radar ◽  
Mean Square ◽  
Doppler Power

Vector fields created by Fourier transform of video signals

2021 ◽  
Author(s):  
A.V. Bogoslovsky ◽  
V.A. Sukharev ◽  
I.V. Zhigulina ◽  
M.A. Pantyukhin
Keyword(s):  
Vector Field ◽  
Power Spectrum ◽  
Vector Fields ◽  
Amplitude Spectrum ◽  
Power Spectra ◽  
Field Work ◽  
Signal Process ◽  
Video Signals ◽  
Uniform Background ◽  
Pixel Brightness

The power spectrum and autocorrelation are widely used in video signals processing. The phase-frequency spectrum contains more information than the amplitude spectrum. However, the amplitude spectrum is used more often in the video signal process. It is possible to combine the advantages of these two spectra to obtain a vector function such as phase-energy spectrum. This spectrum is sensitive even to a small difference in pixel brightness but at the same time it is as stable as the power spectrum. In this paper, we explored the properties of the phase-power spectrum and related amplitude of partials vector field. We showed that phase-power spectrum has conservative as well as solenoidal components and so it creates curl’s vector field. We also found the components of phase-power spectra that contain pixels with a different degree of contrast on the uniform background. We showed the possibility to use solenoidal component of the phase-power vector field to find the circulation (i.e. field work). We concluded that the circulation along any of brightness contour constants, which is symmetrical to the origin, is equal zero. We explored two-dimensional vector field of the phase-power spectrum. Finally, we determined an effect of pixels with different degree of brightness and their relative position to the image’s edges on vector field’s components formation.

On the Doppler power spectrum at the mobile unit employing a directional antenna

2001 ◽  
Vol 5 (1) ◽  
pp. 13-15 ◽  
Author(s):  
Chang Qing Xu ◽  
Choi Look Law ◽  
S. Yoshida
Keyword(s):  
Power Spectrum ◽  
Directional Antenna ◽  
Mobile Unit ◽  
Doppler Power

Frequency Doubling of CW And Pulsed CO2 Lasers Using Diffusionbonded, Quasi-Phase-Matched Gaas Stacks

1997 ◽  
Vol 484 ◽  
Author(s):  
Melvin C. Ohmer ◽  
Shekhar Guha ◽  
Ronald E. Perrin ◽  
Laura S. Rea ◽  
Phil Won Yu ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Pulse Length ◽  
Central Area ◽  
Frequency Doubling ◽  
Power Spectrum Analysis ◽  
Co2 Lasers ◽  
Interface Quality ◽  
First Order ◽  
Near Ir ◽  
Transmission Data

AbstractWe describe the fabrication, characterization and frequency doubling properties of first order stacks of diffusion bonded 2″ diameter GaAs wafers. Near IR imaging through the stacks indicated that excellent bonding was obtained over 40%–70% of the central area of the wafers. A power spectrum analysis of the spectral noise (due to interface reflections) appearing in the transmission data is shown to be a quantitative diagnostic tool useful for determining interface quality and for accurately estimating the thickness of the bonded layers in a stack. The conversion efficiency for a four layer stack at 10.6 microns was found to be 0.03% or 3 mJ for a 10 mJ pulse with a 100 nanosecond pulse length. The corresponding efficiency for cw SHG was found to be 0.0002%.

scholarly journals A Novel Simulation Modeling Method and Hardware Implementation for Doppler Power Spectrum of LEO Satellite Based on Error Compensations by Parting Sinusoid with Random AOA and Correlation Piecewise Convergence

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 65
Author(s):  
Wenliang Lin ◽  
Yaohua Deng ◽  
Ke Wang ◽  
Zhongliang Deng ◽  
Hao Liu ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Simulation Modeling ◽  
Frequency Dispersion ◽  
Signal Propagation ◽  
Low Earth Orbit ◽  
Set Partitioning ◽  
Angle Of Arrival ◽  
Sixth Generation ◽  
Doppler Power ◽  
Leo Satellite

Low Earth Orbit (LEO) Satellite Internet Network (LEO-SIN) is a promising approach to global Gigabit per second (Gbps) broadband communications in the coming sixth-generation (6G) era. This paper mainly focuses on the innovation of accuracy improvement of simulation modeling of the Doppler Power Spectrum (DPS) of satellite channels in LEO-SIN. Existing DPS modeling methods are based on Rice’s Sum-of-Sinusoids (SOS) which have obvious modeling errors in scenarios with main signal propagation paths, asymmetrical power spectrum, and random multi-path signals with a random Angle of Arrival (AOA) in LEO-SIN. There are few state-of-art researches devoted to higher accuracy of DPS modeling for simulation. Therefore, this paper proposes a novel Random Method of Exact Doppler Spread method Set Partitioning (RMEDS-SP). Distinct from existed researches, we firstly model the DPS of LEO-SIN, which more accurately describes the characteristics of frequency dispersion with the main path and multi-path signals with random AOA. Furthermore, piecewise functions to the Autocorrelation Function (ACF) of RMEDS-SP is first exploited to converge the modeling error supposition with time by periodic changes, which further improve the accuracy of the DPS model. Experimental results show that the accuracy of DPS in our proposed model is improved by 32.19% and 18.52%, respectively when compared with existing models.

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