| 摘要 |
PURPOSE:To execute switching without the degradation of signal quality by converting an optical signal, for which luminance modulation is executed with a pulse FM signal to include a control signal, to an electric signal, after that, changing-over a switch with the control signal and executing connection to an optical transmission part. CONSTITUTION:An optical signal 17 is converted to an electric signal 25 by an optical receiving part 18 and impressed to a signal switching part 19. For the signal 25, a digital switching can be used as the switching part 19 by the pulse FM signal, for which a picture, a sound and the control signal are multiplexed. An electric signal 26 to branch the signal 25 is demodulated to the pulse FM signal by a signal demodulating part 20 and after that, only a control signal 27 is fetched by a frequency filter, regenerated and impressed to a switch control part 21. In correspondence to the contents of the signal 27, the signal is switched and connected to any one of optical transmission parts 22-24. In the optical transmission parts 22-24, the luminance modulation is directly executed for the output light of an LED, etc., and the output light is sent to a transmission path as an optical signal 29. |
