Search results
Results from the WOW.Com Content Network
[1] [2] [3] The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842. A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer. Compared to the emitted frequency, the received frequency is higher during the approach ...
Doppler wishes that his frequency shift theory will soon be tested by another method to determine the radial velocity of stars. He thinks, without reason, that a confirmation of his theory would imply that light is not a transverse but a longitudinal wave. [12] § 7 Doppler argues that his
Doppler Effect: Change of wavelength and frequency caused by motion of the source. The formula for radar Doppler shift is the same as that for reflection of light by a moving mirror. [3] There is no need to invoke Albert Einstein's theory of special relativity, because all observations are made in the same frame of reference. [4]
Doppler shift with source moving at an arbitrary angle with respect to the line between source and receiver. The analysis used in section Relativistic longitudinal Doppler effect can be extended in a straightforward fashion to calculate the Doppler shift for the case where the inertial motions of the source and receiver are at any specified angle.
Doppler shifting of the returned signals is a function of the radar carrier frequency, as well as the speed of the radar source and target, with positive Doppler shift from surfaces moving toward the illuminator and negative shift of surfaces moving away from it. Moving surfaces impose a pulse width modulation.
Doppler positioning involves recording the Doppler shift of a radio signal of stable frequency emitted from a satellite as the satellite approaches and recedes from the observer. The observed frequency depends on the radial velocity of the satellite relative to the observer, which is constrained by orbital mechanics .
Initial attempts to measure the second order transverse Doppler effect in canal rays completely failed. For example, Stark's 1906 measurements showed systematic errors ten times the predicted effect. [5] The maximum speed achievable in early gas-discharge tubes was about 0.005 c, which implied a transverse Doppler shift of only about 1.25×10 ...
Phase coherent signals also allowed for the direct measurement of velocity via the Doppler shift of a single received signal. This can be fed into a bandpass filter to filter out any part of the return signal that does not show a frequency shift, thereby directly extracting the moving targets. This became common in the 1970s and especially the ...