Comparative study of accuracy of major signal processing techniques in laser Doppler velocimetry

The random and bias errors of Doppler spectral shift measurements, correlation measurements and zero crossing techniques are discussed. It is shown that spectral shift measurement technique has advantage over other techniques in low signal-to-noise ratio region, whereas zero crossing technique based on analysis of probability density ensures lower random and bias errors at high enough SNR. The correlation technique has relatively low random error but shows considerable bias error in the region of low and moderate SNR when information about Doppler frequency is obtained from first zero of correlation function.