Doppler signal period distribution demodulation method of laser Doppler velocimeter

Abstract

The invention discloses a Doppler signal period distribution demodulation method of a laser Doppler velocimeter. The time domain processing principle based on a period counting method is adopted, the average frequency in all periods in each set time period is not calculated, but the time value distribution of each period in each time period is analyzed, and the most frequent time value in the time value distribution is taken as the period length in the time period and is converted into the signal frequency in the time period. The Doppler signal period distribution demodulation method has the main advantages of improving the calculation precision of Doppler frequency shift signal processing and effectively reducing the influence of widening or narrowing of the Doppler frequency shift signal period, losing of part of signals and noise, which are caused by the instability of the scattered light, on the test result of the target movement velocity.

Description

technical field [0001] The invention belongs to the technical field of laser Doppler velocimetry, and mainly relates to a time-domain demodulation method of a Doppler signal of a laser Doppler velocimeter, in particular to a heterodyne interferometer for measuring the velocity of a fixed moving target Doppler signal periodic distribution demodulation method. Background technique [0002] The Doppler effect will occur when the light source and the object move relative to each other. The laser Doppler velocimeter relies on the frequency shift between the scattered light of the moving particles and the irradiated light to obtain the velocity information. The commonly used optical heterodyne interferometer principle of the reference light mode See attached figure 1 . single frequency f 0 When the laser beam is irradiated on a moving object, the frequency of the received scattered light is f 0 +Δf D , where Δf D is the frequency shift between the scattered light and the ill...

AI Technical Summary

Problems solved by technology

Since the period count demodulation method of the Doppler signal is used to obtain a certain time period t g The average frequency of the entire cycle N in the cycle, the signal cycle change caused by the instability of the scattered light wave will affect the frequency demodulation result, which is the essential reason why the cycle counting demodulation method has poor anti-interference ability and will form glitches in the speed measurement curve

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