Ultrasonic echograph for measuring high velocities of blood flows

Claim 1

An ultrasonic echograph for measuring velocity profiles of blood flows, comprising at least one ultrasonic transducer which is coupled to a transmission stage for transmission of a recurrent pulsed signal and to a receiving and processing stage for receiving echographic signals returned to the at least one transducer and for processing the signals received, said receiving and processing stage comprising a digital processing channel which comprises, in cascade, a circuit for suppressing fixed echoes, a memory means for storing digital samples, a correlation-interpolation circuit, and a validation circuit, wherein said transmission stage comprises first circuit means for transmitting said pulsed signal with two alternating, neighboring recurrent periods T 1 and T 2 , said circuit for suppressing fixed echoes comprises second circuit means for producing two outputs having even and odd indices, respectively, each output having a period equal to a sum T 1 +T 2 of the recurrent periods T 1 and T 2 , said correlation-interpolation circuit comprises third means for performing, for each velocity, two distinct correlation to obtain respective correlation functions, one of which is associated with the period T 1 and the other of which is associated with the period T 2 , for comparing these two correlation functions, and for deriving a non-ambiguous velocity value therefrom.