Results 301 to 310 of about 121,274 (339)

Non-Doppler frequency shift of Newton waves

Optik, 2018
Abstract The Doppler effect has widely applications in optics, physics, acoustics and cosmology. It is verified in vacuum and linear media such as air and water but the validity in complex materials is rarely tested. Now we propose a counter-example. There is an extra term proportional to the square of relative velocity u 2 for the Newton ...
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Surface profile detection by transverse Doppler frequency shift

2011 International Conference on Electric Information and Control Engineering, 2011
It is a common sense that the Doppler frequency shift is vanished when the speed of a planar interface is transverse to the wave incidence. However, our theoretical and experimental research shows that the Doppler frequency shift is non-zero for a curved interface with even purely transverse speed, and this physic effect can be used to detect the ...
null Lin Li, null Xiangdong Chen, null Xin-min Wang, Tian-lin Dong   +3 more
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Frequency shift discrimination: Can homing pigeons locate infrasounds by Doppler shifts?

Journal of Comparative Physiology ? A, 1981
Homing pigeons can detect small shifts in sound frequency at 1, 2, 5, 10, and 20 Hz. Their thresholds range from a 1% shift at 20 Hz to a 7% shift at 1 Hz. The frequency shifts used were designed to simulate the natural Doppler shifts resulting from changes in flight path.
Douglas B. Quine, Melvin L. Kreithen
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Doppler frequency shift in a refractive atmosphere

Journal of Aircraft, 1987
A general derivation is given for the Doppler-shifted received frequency due to source and receiver motion of uniform velocity in a steady-state, refractive medium with spatial gradients in velocity and temperature. The results from three cases of this generalized equation are especially important.
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Correlation-induced Doppler-type frequency shifts of spectral lines

Physical Review Letters, 1989
The question is examined whether there may be scattering media which could generate spectral frequency shifts in radiation from sources that are at rest relative to the observer and yet would imitate Doppler shifts. Scattering kernels of media whose physical properties fluctuate randomly in both space and time are presented which achieve this to a good
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Analysis of Doppler Frequency Shift Using Actually Measured Frequency-Height Diagram

2007 International Conference on Microwave and Millimeter Wave Technology, 2007
The equations for calculating the phase path and the Doppler frequency shift (DFS) on the basis of the actually measured frequency-height diagram were theoretically derived. As the example of observation, the DFS of the standard radio wave of BPM 10 MHz from the Dalian-Xi'an channel at sunrise was calculated and analyzed.
Zhang Yinghui, Wang Yizhuo
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Doppler shifts on high-frequency ground backscatter

Journal of Geophysical Research, 1969
Frequency changes (Doppler shifts) of high-frequency radio waves propagated by a changing ionosphere can be observed and measured both for ground backscatter and for ‘point-to-point’ circuits. However, the relationships between ionospheric change and frequency shift are different in the two cases.
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Dynamic Doppler Frequency Shift Errors: Measurement, Characterization, and Compensation

IEEE Transactions on Instrumentation and Measurement, 2015
Positioning calibration under dynamic conditions is becoming increasingly of interest for high precision fields, such as additive manufacturing and semiconductor lithography. Heterodyne interferometry is often used to calibrate a stage’s position because interferometry has a high dynamic range and direct traceability to the meter. When using heterodyne
Chen Wang, Jonathan D. Ellis
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Accurate Doppler Frequency Shift Estimation for any Satellite Orbit

2007 3rd International Conference on Recent Advances in Space Technologies, 2007
One of the most important parameters in satellite communication links, particularly in low earth orbits (LEO) and elliptical orbits is Doppler frequency shift (DFS) and Doppler frequency rate (DFR) at communication channels. This paper analyzes Doppler frequency effects in various satellite orbits.
Shervin Amiri, Mohammad Mehdipour
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Laser Doppler velocimeter with variable optical frequency shift

Optics & Laser Technology, 1975
Abstract An opto-electronic system that allows a stable accurate frequency shift, variable from 10 kHz to 50 MHz, to be introduced in a laser Doppler velocimeter (LDV) has been developed. The system combines a fixed optical-frequency shift obtained using a Bragg cell with an electronic shift which results from mixing the detector signal with a ...
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