| 摘要 |
PURPOSE:To use a low speed operation type one as an A/D converting means and to reduce cost by applying A/D conversion to the blood flow data on one raster after the orthogonal phase detection of three receiving echoes obtained by performing the transmission and reception of an ultrasonic wave three times at rates different from each other. CONSTITUTION:Transmission driving is performed over three times at different rates in order to obtain three receiving echoes for obtaining the blood flow data on one raster and an ultrasonic receiving system obtains three receiving echoes by said driving. In a B-mode, one raster is obtained by the ultrasonic transmission and reception of one rate. Herein, when a receiving echo in a Doppler mode is set to v(t), v(t) receives the supply of reference signals cos2pif0t, sin2pif0t in mixers 8A, 8B to be subjected to orthogonal phase detection processing. The outputs x(t), y(t) of LPFs 9A, 9B are digitalized by A/D converters 10A, 10B but, since the signals x(t), y(t) subjected to A/D conversion by the A/D converters 10A, 10B are low frequency as compared with the receiving echo v(t), low speed operation type A/D converter (as compared with a conventional one) may be used as each of the A/D converters 10A, 10B. |
