AN ADAPTIVE APPROACH TO COMPUTING THE SPECTRUM AND MEAN FREQUENCY OF DOPPLER SIGNALS

Modern ultrasound Doppler systems are facing the problem of processing increasingly shorter data sets. Spectral analysis of the strongly non stationary Doppler signal needs to shorten the analysis window while m aintaining a low variance and high resolution spectrum. Color flow ima ging requires estimation of the Doppler mean frequency from even short er Doppler data sets to obtain both a high frame rate and high spatial resolution. We reconsider these two estimation problems in light of a daptive methods. A regularized parametric method for spectral analysis as well as an adapted mean frequency estimator are developed. The cho ice of the adaptive criterion is then addressed and adaptive spectral and mean frequency estimators are developed to minimize the mean squar e error on estimation in the presence of noise. Two suboptimal spectra l and mean-frequency estimators are then derived for real-time applica tions. Finally, their performance is compared to that of both the FFT based periodogram and the AR parametric spectral analysis for the spec tral estimator, and, to both the correlation angle and the Kristoffers en's [8] estimators for the mean frequency estimator using Doppler dat a recorded in vitro. (C) 1995 Academic Press. Inc.