Doppler shift

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Doppler shift

See Doppler effect.

Doppler shift

[′däp·lər ‚shift]
(physics)
The amount of the change in the observed frequency of a wave due to Doppler effect, usually expressed in hertz. Also known as Doppler frequency.

Doppler shift

Doppler shift
Doppler effect in moving receiver.
In airborne Doppler radar, a transmitter which, by means of a directional antenna, radiates energy toward the ground. This results in a situation in which both the transmitter and the receiver are moving relative to the ground; consequently the original frequency is changed twice. The difference between transmitted and received frequencies is known as the Doppler shift and is very nearly proportional to the relative motion between the aircraft and the ground along the direction of the radar beam. A moving target will cause the frequency of the echo signal to increase if it is approaching the radar or decrease if it is receding from the radar. Since the Doppler frequency shift is proportional to radial velocity, a radar system that measures such a shift in frequency can also provide the radial velocity of a target. The Doppler frequency shift also is used to separate moving targets from stationary ones even when the undesired clutter power might be much greater than the power of echo from the targets. Also called the Doppler effect.
References in periodicals archive ?
In the satellite to ground uplink system, for the Doppler shift signal exists, the uplink signals received at the satellite deviates from its actual frequency which the user terminal transmits.
This result was confirmed by other experiments: Miller 1925/26 gas mode Michelson interferometer, DeWitte 1991 coaxial cable RF speeds, Cahill 2009 Satellite Earth-flyby Doppler shift NASA data [6], Cahill 2012 dual coaxial cable RF speed [7], Cahill 2013-2014 [8,9] Zener diode 3-space quantum detectors.
A new method for estimating the Doppler shift and time delay of the overlapping echoes was presented by Qi et al.
Although statistical testing shows that the effect is very likely to be real due to the statistical power inherent in the repeated measures design, in many cases subjects who lifted an empty hand had greater Doppler shifts recorded than others when lifting a gallon jug of water (see Figure 1).
From the results, we can find that the values of Doppler shifts for HH- and VV-polarization are elevated by the TM and the HM.
The chamber motion is given by the paddle or stirrer movement but is relatively slow, creating a Doppler shift that is on the order of a few Hertz.
Because the difference in received frequency is caused by disparities in Doppler shift, FDOA is also called differential Doppler (DD).
The multipath fading emulator should be set to produce a Doppler shift of the test signal.
Although MPBC calculates the relative speed using Doppler shift and signal power, its calculated speed is not as precise as that of SCBCS.
The detection techniques include gas-mode Michelson interferometers, RF coaxial cable EM speed measurements, RF coaxial-cable optical fiber RF/EM speed measurements, EM speed measurements from spacecraft Earth-flyby Doppler shifts, zener-diode quantum detectors, within Digital Storage Oscilloscopes, and in so-called Random Event Generators (REG) [1, 4, 5].
The astronomers were looking for slight Doppler shifts in the star's light caused by an orbiting planet's pull.