Temporal filtering of color doppler signal data

Abstract

An apparatus for temporal filtering in an ultrasonic imaging system. The apparatus has a means for storing previous imaging information from a previous time period and a means for storing current imaging information from a current time period. Means for determining the larger of the current and previous imaging information is provided and a means is provided for generating an alpha value responsive to the larger information. The alpha value ranges between a minimum and maximum values and has the maximum value when the larger information has a large frequency and has the minimum value when the larger information has a small frequency. Means for generating output imaging information is provided, the output imaging information generated by multiplying the current imaging information by alpha and summing it with the product of the maximum value minus alpha and the previous imaging information. The apparatus provides a means for heavily averaging the imaging information for small frequencies of the larger information and maintaining the pulsatility of large frequencies for fast moving blood velocities. In the preferred embodiment, errors and noise are minimized at frequencies near the baseline, and frequencies near Nyquist are not averaged at all. In one embodiment the apparatus comprises a lookup table.