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[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 ...
Radar pulsing causes a phenomenon called aliasing, which occurs when the Doppler frequency created by reflector motion exceeds the pulse repetition frequency (PRF). [1] This concept is related to range ambiguity resolution. Doppler frequency shift is introduced onto reflected signals used by radar.
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 ...
The Doppler shift is proportional to the electrophoretic mobility of a macromolecule. [10] From studies that have applied this method to poly (L-lysine) , ELS is believed to monitor fluctuation mobilities in the presence of solvents with varying salt concentrations. [ 11 ]
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]
In pulsed radar and sonar signal processing, an ambiguity function is a two-dimensional function of propagation delay and Doppler frequency, (,).It represents the distortion of a returned pulse due to the receiver matched filter [1] (commonly, but not exclusively, used in pulse compression radar) of the return from a moving target.
An example of a non-linear chirp pulse and the effects of Doppler are shown. The non-linear characteristic is chosen to achieve −50 dB sidelobes using Taylor weighting. The first figure shows the compressed pulse for a non-linear chirp, with bandwidth 10 MHz, pulse duration 10usec, so T×B = 100, and with no Doppler shift.
At radio frequencies the amount of bending cannot be measured directly; instead, the bending can be calculated using the Doppler shift of the signal given the geometry of the emitter and receiver. The amount of bending can be related to the refractive index by using an Abel transform on the formula relating bending angle to refractivity.