Abstract: Method and apparatus for synthesizing a continuous estimate signal of a Gaussian signal resulting from ultrasonic Doppler measurement on a fluid flow, from existing segments of the Gaussian signal. The segment signals are first stored and there is at the same time calculated a characteristic frequency parameter for each segment. The frequency parameter is combined with the first stored segment signal for transposition thereof to a base-band at or about the zero frequency point, and this base-band signal is used to generate coefficients in a controlled filter device which on the basis of a broad-band input signal gives a synthesized filter output signal which is a substantially Gaussian signal. The filter output signal is multiplied by a weighting or window function for smoothing the transitions between successive segments.

Abstract: Method and apparatus for generating a multidimensional map of blood velocities in the circulatory system of living species, using the Doppler effect of backscattered ultrasound from the blood, with real time presentation on a display device, with the ability to select small sample volumes in the flow map where the information can be presented as a function of time together with the moving multidimensional map in real time. There is transmitted a pulsed ultrasonic beam which is swept in two or more dimensions through the region of the biological structure which is to be investigated. The backscattered ultrasonic signal is sampled in a number of depth volumes along each beam direction of the transmitted ultrasonic pulses. For each depth and beam direction there is determined a velocity parameter of the blood flow by means of the Doppler principle, and the velocity parameters from the whole region investigated are read into an image memory.