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Abstract

An ultrasonic pulse Doppler apparatus has: range gate (20) for separately performing range-gating of the respective received ultrasonic echo signals of the oscillation elements of an ultrasonic probe (1) each time the signals are respectively adjusted in correspondence with the direction of a received ultrasonic beam; pulse stretcher filter (21) for extending the duration of the respective plurality of range-gated received signals while storing the energy of the signals; phasing/adding stage (7a) for matching the phases of a plurality of output signals from the pulse stretcher filter and performing addition thereof; detection portion (12) for effecting coherent detection of an output signal from said phasing/adding stage; and Doppler signal generating components (15, 16) for respectively generating Doppler signals on the basis of an output signal from the detection portion. The received echo signal of each of the oscillation elements is range-gated, and the duration of the respective range-gated signals is extended by the pulse stretcher filter. Subsequently, the signals are matched in phase and added. Accordingly, the level of the received signal hardly reaches the limit of the dynamic range of a signal processing circuit employed.

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