PURPOSE: To decrease the number of demodulation circuits, to reduce the cost and to facilitate the expansion of a system by transmitting plural signals different in information quantity at the same transmission speed.
CONSTITUTION: A digital signal outputted from digital signal sources 10-12 is fed respectively to transmission speed conversion circuits 13-15 and each digital signal is supplied to time base multiplex circuits 16-18 by using the signal representing quantity of information supplied simultaneously. A framing code FC and a signals representing the quantity of information are added to each digital signal read at a prescribed speed for each time interval τ and the result is fed to optical modulation circuits 19-21, the intensity is modulated and the resulting signal is supplied to a multiplexer/demultiplexer 22, where the signals are multiplexed then the resulting signal is fed to an optical fiber cable 23. One optical demodulation circuit 27 in the reception section is enough for the system.
UCHIMURA KIYOSHI
NISHIOKA MINORU
