| 摘要 |
PURPOSE:To make demodulation possible without requiring manual operation at the reception side by switching the radio wave, which is transmitted with carrier wave suppressing balanced modulation or ordinary radio frequency modulation, with the same frequency as a carrier wave used for transmission in the reception side. CONSTITUTION:The radio wave subjected to radio frequency conversion by an audio waveform subjected to carrier wave suppressing balanced modulation at the transmission side is inputted to an antenna 7, and a detected output is obtained in a receiver 8. The same signal as the frequency used for transmission is set by an audio frequency oscillator 13, and a semiconductor analog switch 14 is turned on and off to allow the output to pass through an LPF15, and thus, the waveform signal of a microphone input is reproduced. In case of ordinary sound communication, the waveform signal of the microphone input is subjected to radio frequency conversion as it is, and the transmitted radio wave is received by the antenna 7. It is detected by the receiver 8 and is switched by the frequency of the oscillator 13 and passes through the LPF15 to reproduce the original transmission waveform. |
