| 摘要 |
PURPOSE:To turn on/off a power supply for a speaker system in interlocking with the on/off of the power supply of a transmission unit and to attain simultaneous control of a sound volume of both channels at the speaker side by sending on/off information of the power supply of the transmission unit and sound volume control information while being multiplexed on an audio signal. CONSTITUTION:A 2-channel audio signal is converted into a digital signal by an A/D converter circuit 22 and the digital signal is inputted to a multiplexer circuit 24. On the other hand, sound volume control information and power supply ON/OFF information from a remote controller are received by a light receiving circuit 31, decoded signals 201, 202 by a signal extraction circuit 32 are fed to a signal processing circuit 33 together with an output signal 203 of the multiplexer circuit. The circuit 33 multiplexes each signal having a prescribed format and a modulation circuit 24 modulates the signal, and LEDs 34, 35 convert the signal into an optical signal, which is sent. A demodulation circuit of a receiver demodulates the signal, a signal demultiplexer circuit demultiplexes the demodulated signal into each signal, which is subject to prescribed control. Thus, the power supply ON/OFF and sound volume control are implemented between the transmitter and the receiver interlockingly with each other. |
