| 摘要 |
PURPOSE:To correct a Doppler frequency being measured so as to prevent the erroneous measurement of the direction of blood stream, by providing a means for obtaining a corrected value by multiplying an angle obtained from a phase difference vector by T/T3 and a means for addition-correcting a deflection angle of a transmitting interval T. CONSTITUTION:A transmitting signal with a preset frequency omega0 is repetitively output from a transmitting circuit 11 of an acoustic transducer 1 at a transmitting interval T via the transducer 1 to a reflection object 2. The reflected wave from the reflection object 2 is detected by the acoustic transducer 1 and its detected signal is input via a receiving amplifier 12 to a phase comparator 3. The constitution of a phase difference detector 64 and that of another phase difference detector 4 are similar to each other. An output vector Z from an angle detector 7 is input to another angle detector 65 to obtain an angle QA which is equal to omegadT3. A multiplier 66 multiples the ratio (m) of T to T3 by QA to input m.argZ into a correction value detector 67. There, a corrected angle thetaalpha is selected and a corrected Doppler angular frequency omega'd is calculated by a divider 8 and is then displayed by a display 10. |
