Estimation of LDA signal frequency using the autocovariance (ACV) lag ratio method

The autocovariance (ACV) lag ratio method of determining the frequency of single realisation LDA signals is introduced and examined in detail. Properties of this method and of the frequency estimator are derived analytically and verified using numerical simulation. The simulation is also used to investigate the performance of the estimator in terms of digitising parameters and to compare the results with an estimate based on the power spectral density. The ACV lag ratio method has been implemented experimentally using a transient recorder to digitise the Doppler signals and an optimised software routine to apply the method. Results from simulated and real Doppler signals show that the ACV lag ratio method maintains high accuracy over a wide effective bandwidth and is robust to the choice of digitising parameters.