Estimating frequency and phase for velocity and size measurements [laser anemometry]

The estimation of frequency and phase of a narrowband signal obtained by light detection is considered in relation to the measurement of velocity and size of particles. A best performance is established and used for reference. The basic statistical features of the signals are established on the basis of photon statistics. A lower bound on both frequency and phase measurements is established on the basis of maximum-likelihood estimation. The actual performance of the covariance processor is then evaluated and compared with the ideal maximum likelihood estimators. A novel implementation of a processor which can process signals in frequency ranges from 120 kHz to 36 MHz with maximum data rates above 100 kHz is considered. Experimental verification of the performance is presented