ANALYSIS OF A FREQUENCY ESTIMATOR FOR A CLASS OF LASER SIGNALS WITH TIME-VARYING AMPLITUDE

The authors address the problem of estimating a particle's velocity in the vicinity of an aircraft by means of a laser velocimeter. A model for the signal generated by a particle of air passing through a probe volume consisting of equidistant bright and dark fringes is given. Fro m this model, a frequency estimator based on the phase of the correlat ion sequence of the signal is proposed. A theoretical analysis of the frequency estimator is presented. In particular, a formula for the var iance of the estimate is derived under the assumption of small estimat ion errors. Numerical examples confirm the validity of the analysis. I t is reported that this estimator, although simpler than the maximum l ikelihood approach, comes close to the Cramer-Rao bound. Finally, the effectiveness of the proposed algorithm is demonstrated on real data.