| 摘要 |
PURPOSE:To improve S/N of a Doppler signal in an ultrasonic wave receiving and phase adjusting circuit and an apparatus using this circuit. CONSTITUTION:This apparatus has a constitution provided with the first variable delay means B1-Bn performing delay within the period of sampling, the second variable delay means (C1-1)-(Cn-3) performing delay by means of parallel sampling, an addition means ADD1-ADD3 adding each output of the second variable delay means (C1-1)-(Cn-3), switching means W1-Wn switching outputs of the addition means between parallel-series switchings, a filtering means LPF filtering outputs of the switching means and a clock control means PG which controls in such a way that an integer-fold of a sampling frequency per phase of the second variable delay means (C1-1)0(Cn-3) becomes out of a Doppler signal region or coincides with the Doppler central frequency. |
