| 摘要 |
PURPOSE:To eliminate the ultrasonic wave noise which is caused when the ultrasonic wave is transmitted, by compressing the voice signal for a certain period of time and synchronously with the transmission of the ultrasonic wave. CONSTITUTION:A controller C produces the pulse output of a prescribed length synchronously with the transmission of the ultrasonic wave through a transmitting device 1 and controls the operation of a voice device 7. In other words, the voice signal supplied from an amplifier 7b of the device 7 is compressed for a certain period of time and synchronously with the transmission of the ultrasonic wave. The interruption of the voice is recognized in case the time of compression is <=10m sec. Thus the ultrasonic wave noise which is caused when the ultrasonic wave is transmitted is also compressed by compressing the output of the device 7. And the ultrasonic wave noise is not recorded to a recording medium 8. In such a way, the ultrasonic wave noise can be eliminated. |
