| 摘要 |
<P>PROBLEM TO BE SOLVED: To always maintain a receiving state of a receiver properly in a multi-channel communication by an infrared ray using a plurality of frequency bands. <P>SOLUTION: In order to receive infrared signals transmitted by different frequencies f1, f2 from infrared type microphones (infrared transmitters) M1, M2 by one receiver 10 via an infrared photodetector 21, respective received signals having different frequencies, output from the photodetector 21 are separated at the respective frequencies f1, f2 by filter circuits 22, 23, signal strengths of the separated respective signals are detected by signal strength detecting means 25, 26, and switches S1, S2 are controlled so that only the signals of the proper strengths are imparted to the receiver 10. <P>COPYRIGHT: (C)2004,JPO |
