Patent ID: 8062223

Claim:
A method of using pulsed-wave ultrasonography for determining an aliasing-free radial velocity spectrum of matter moving in a region, the method comprising: (a) transmitting into the region a plurality of pulse trains of sound waves at two or more different pulse repetition frequencies; (b) spectrally analyzing each said pulse train, for evaluating a Doppler frequency spectrum associated with each said pulse train; (c) combining frequency components of said Doppler frequency spectrum of each said pulse train, for obtaining an aliasing-free instantaneous Doppler frequency spectrum for the region, and solving a series of recursive equations, wherein each said recursive equation describes dependence of said frequency components of said Doppler frequency spectrum of each said pulse train on said aliasing-free instantaneous Doppler frequency spectrum for the region; (d) using Doppler effect for translating said aliasing-free Doppler frequency spectrum to the aliasing-free radial velocity spectrum of the matter moving in the region, and an initial condition for solving said series of recursive equations is where maximal non-zero Doppler frequency component of said aliasing-free instantaneous Doppler frequency spectrum is known a priori, or an analog low-pass filter is applied to signals returned for each said pulse train, and an initial condition for solving said series of recursive equations is where maximal non-zero Doppler frequency component of said aliasing-free instantaneous Doppler frequency spectrum is a pre-determined constant matching a transfer function of said low-pass filter.