| 摘要 |
PROBLEM TO BE SOLVED: To make receiving sensitivity uniform by preventing deterioration of receiving sensitivity during simultaneous transmission dynamic focusing using a plurality of ultrasonic waves with different frequencies and also to reduce the size of a circuit. SOLUTION: A transmission section 12 outputs to a vibrator 10 two transmission signals having different central frequencies f1 and f2 and an identical frequency band width. An orthogonal detection section 16 carries out orthogonal detection processing of an input signal. In detail, a mixer pair 18 carries out an orthogonal detection processing with respect to an input signal component corresponding to the central frequency f1, and a mixer pair 20 carries out an orthogonal detection processing with respect to an input signal component corresponding to the central frequency f2. Before carrying out a low-pass filer processing, complex components are added respectively and acquired addition signals are inputted into LPFs 34 and 36 respectively. Outputs from the LPFs are inputted into an absolute value computing element 38, and the amplitude of a reference signal supplied to each mixer is adjusted so as to carry out orthogonal detection and weighting processing simultaneously. COPYRIGHT: (C)2008,JPO&INPIT
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