A theory for resolving the problem of depth and velocity ambiguity is proposed by tracking frequencies close to and beyond the Nyquist frequency. To illustrate the feasibility of the new theory, some results are shown using pseudorandom system in vitro.
As second part, directional multigate pulsed Doppler system is discussed. The various methods for estimating the frequency of the Doppler signal are presented. Spectral analysis of Doppler information is performed. Preliminary results for multigate Doppler, obtained in vitro under flow simulated conditions, are reported.
