The Performance of an Adaptive Rf-Domain Clutter Removal Filter
Ultrasound systems are widely used to visualize in real-time internal structures and blood flow velocity distributions. The latter are estimated from the received ultrasound radio frequency (RF) signals backscattered from moving red blood cells, using a mean frequency estimator. Since RF-signals contain not only scattering, but also reflections, reverberations and noise it is necessary to suppress the power of the reflections and/or reverberations (clutter removal) to estimate the temporal mean frequency of the signal component induced by scattering. Normally this is done with a static high-pass filter acting in the temporal direction with a fixed cut-off frequency. However, by using such a filter the time dependent aspect of the reflections is ignored. A more selective way is to use a band stop filter which adapts its rejection range to the mean frequency of the clutter. A great advantage of this adaptive filter (ADP-f) method is that the rejection range can be kept small.
KeywordsAdaptive Filter Estimation Window Infinite Impulse Response Filter Band Stop Filter Clutter Suppression
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