| 摘要 |
PURPOSE:To easily execute a wireless communication between scuba divers each other or between a scuba diver and a mother ship by modulating code information corresponding to a switch input to transmit as an ultrasonic signal and demodulating received data to output a sound signal corresponding to the code information on a reception end. CONSTITUTION:In a reception part, an encoder circuit 2 is made to be started by operating a switch 1 corresponding to a command and a signal in a specified format is generated. Next, the signal is modulated, for instance in terms of AM, in a modulation circuit 3 and amplified in a power amplifier 4 so as to radiate the ultrasonic signal into the water from an ultrasonic transducer 6 through a circulator 5. In the reception part, the signal is inputted in a pre- amplification part 7 via the circulator 5 and amplified. After the signal is detected in a demodulation circuit 8. It is transmitted to a decoder circuit 9 as a binary signal by a comparator. The demodulation circuit 8 transmits a carrier detection signal to the decoder circuit 9, from which the corresponding code is outputted to a voice synthesizing output circuit 10.
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