CENTRALIZED MONITORING SYSTEM

PURPOSE: To provide a centralized monitoring system in which optical signals sent from plural light transmitters are received by a light receiver, the deterioration in a video image due to crosstalk is prevented and the equipment configuration is simplified. CONSTITUTION: Video signals picked up by monitor cameras 1a-1c are modulated by modulators 2a-2c and fed to light transmitters 3a-3c. The light transmitters 3a-3c convert the received video signal into an optical signal and the signal is sent. In this case, the modulation wave of the optical signal outputted from the light transmitters 3a-3c has different frequencies f1, f2, f3. On the other hand, the monitor center uses a light receiver 10 to receive the optical signal sent from each monitor location and converts it into an electric signal, a demodulator 11 converts the signal into a video signal and the signal is displayed on monitors 6a-6c. Then the monitor to each monitored location is conducted based on the video image displayed on the monitors 6a-6c.