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 ?
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.
The second effect is the Doppler shift factors 1/(1 [+ or -] v/c), giving the detected frequencies
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).
Doppler shift caused by skin acceleration was recorded during each procedure.
Results from Michelson-Morley [3,4], Miller [5], Torr and Kolen [6] and DeWitte [7], are now in remarkable agreement with the velocity of absolute motion of the earth determined from NASA spacecraft earth-flyby Doppler shift data [8,9], all revealing a light/EM speed anisotropy of some 486km/s in the direction RA=[4.
While the velocity field has been repeatedly detected since the Michelson-Morley 1887 experiment, the best detection has been using the spacecraft earth-flyby Doppler shift data [9], see Fig 1.
A Doppler shift of light underlies the new effects.
Because the surrounding crystal is designed to reject the light's elevated frequency, the light remains in the compression zone until its ever-increasing Doppler shift has moved its frequency into a higher range that the crystal accepts.
Then [theta] varies between [lambda] + [delta] - 90[degrees] = 20[degrees] and [lambda] - [delta] + 90[degrees] = 50[degrees], where [lambda] = 35[degrees] is the latitude of Adelaide, and [delta] = 75[degrees] is the declination of the 3-space flow from the flyby Doppler shift analysis, and with a speed of 486 km/s.
Here we have compared the results with those from the spacecraft earth-flyby Doppler shift data results.
In practice the Pound-Rebka experiment used motion induced Doppler shifts to make these measurements using the Mossbauer effect.
Doppler shift observations of spacecraft, such as Galileo, NEAR, Cassini, Rosetta and MESSENGER in earth flybys, have all revealed unexplained speed "anomalies"--that the Doppler-shift determined speeds are inconsistent with expected speeds.