| 摘要 |
PURPOSE:To perform transmission and reception of audio signals while performing remote control, without using an exclusive carrier, by transmitting the audio signals modulated with a control pilot signal. CONSTITUTION:At transmission section A, a switch 5 selects capacitors 6a-6c and the oscillating freuency of a pilot signal oscillator 4 is changed. After the level of a pilot signal is adjusted at a variable resistor 7, the signal is applied to a modulator 9 together with an audio signal from an amplifier 3. At reception sections B1-B3, the audio signal is outputted at speakers 17 via attenuators 15 and amplifiers 16. When a pilot signal coincident with a band pass filter 12 is received, a power supply 14 is turned on, the level of the pilot signal is detected 13 and the attenuator 15 is controlled in response to the level. |
