| 摘要 |
PROBLEM TO BE SOLVED: To achieve transmission apodization at a low cost. SOLUTION: This invention includes transmitting elements 1-1, 1-2,...1-N for transmitting ultrasonic waves U1, U2,... a function generating part 2 for generating frequency control function signals Sf defining the frequencies of the ultrasonic waves U1, U2,... and window function signals Sw defining the amplitudes of the ultrasonic waves U1, U2,... a voltage controlling oscillator 3 outputting constant amplitude signals Sc which are subjected to FM charp modulation according to the signals Sf, phasers 4-1, 4-2,...4-N having the function of adjusting the phases of the constant-amplitude signals Sc, and binary amplifiers 5-1, 5-2,...5-N which drive the transmitting elements when turned on and which do not drive the transmitting elements when turned off. Beam steering and focusing are controlled by control of the phasers 4-1, 4-2,...4-N and the distribution of the ON/OFF states of the binary amplifiers is dynamically controlled according to changes in the window function signals Sw so as to substantially control transmission apodization.
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