| 摘要 |
PURPOSE:To execute an A/D conversion holding the number of effective digits even in the case of an ultrasonic wave receiving signal with a wide dynamic range by amplifying the same receiving signal with different plural amplification rates, A/D-converting the signal in parallel, selecting digital data not to be saturated, and converting the data to data with a large data length. CONSTITUTION:The receiving signal from an ultrasonic transducer 1 is amplified by an amplifier 2 and A/D-converted to an A/D converter 5. At such a time, the amplification rate of the amplifier 2 is made small, and the A/D converter 5 is prevented from being saturated even in the case of an intensive reflected signal from the shallow part of an object. A part of the output of the amplifier 2 is amplified further sixteen-fold by an amplifier 3 and A/D-converted by an A/D converter 6. A part of the output of the amplifier 3 is amplified further sixteen-fold by an amplifier 4 and A/D-converted in the same manner by an A/D converter 7. The digital data obtained respective A/D converters 5, 6 and 7 are inputted to a data converter 8. The data converter 8 prepares converted data with the digital data 9 having the largest number of effective digits among the digital data of the A/D converters 5, 6 and 7 to be unsaturated by means of an electronic digital signal processing, and the converter 8 outputs the data. |
