The autocorrelation (AC) and second-order autoregressive (AR) estimators have been widely used to estimate the Doppler flow velocity. In this thesis we propose a compensation method to reduce estimation errors when the above two estimators are applied to a two-dimensional color flow mapping system where a relatively limited number of data are available due to the constraints of real-time imaging. And we investigate the effects of filters used to reduce clutter noise on the estimation performance of the blood flow velocity, and propose an effective algorithm to obtain a more accurate velocity estimate.
It has been found through computer simulations of the AC and AR estimators that the latter is much less affected by the clutter filter and can estimate relatively lower flow velocity than the former since the use of DC offset cancellation in the latter dose not incur any data loss in contrast to the use of filtering.
