| 摘要 |
An ultrasonic blood stream observing apparatus based on a pulse Doppler method utilizing as a transmission, a high frequency pulse signal. The frequency fPRF of a transmission pulse repetition signal and the frequency fR of a reference signal used for demodulating a Doppler component of an observed signal, are synchronized to each other. The frequency fPRF is a harmonic frequency. The output of an oscillator is frequency-divided to produce the transmission pulse repetition signal. A frequency multiplier generates an output signal used as the reference signal, synchronized to the transmission pulse repetition signal. The frequency multiplier frequency multiplies by n its input signal obtained directly or indirectly from the oscillator.
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