| 摘要 |
PURPOSE:To provide multichannel spatial data communication at low cost. CONSTITUTION:Light from a floodlamp to perform pulse turn-on according to the modulated pulse signals of multiple channels at different carrier frequencies is converted into an electric signal by a light receiving circuit 31, amplified by an amplifier 32 and mixed with the signal of a local oscillator 35 by a frequency converter 34 after harmonic waves or low frequency noise is removed by a filter 33. When f01 is a communication frequency, f02 is supplied but when the f02 is the communication frequency, the f01 is supplied respectively by the local oscillator 35. A filter 36 extracts only a differential component ¦f02-f01¦ and sends it to an FM demodulation circuit 41. |
