ANALOG PCM MULTIPLEXER, ADD-DROP CIRCUIT OF THE MULTIPLEXER, AND ELECTRIC SIGNAL MULTIPLEX CHANGEOVER METHOD FOR THE MULTIPLEXER

摘要

PROBLEM TO BE SOLVED: To allow the method to demultiplex a signal with wide frequency band such as a digital video signal from an optical signal during transmission or to multiplex the signal on the optical signal during the transmission. SOLUTION: A repeater 10 blocks passing of an electric signal with a designated frequency band in a main electric signal when an output control section 25 designates 'cut-off' of a desired frequency band, and multiplexes a frequency of a new electric signal on a designated frequency band in the main electric signal when the output control section 25 designates 'new signal multiplexing' of a desired frequency band. Furthermore, the repeater 10 passes the main electric signal as it is, converts the relayed main electric signal into an optical signal respectively and provides an output of the optical signal to an optical transmission line when the output control section 25 does not designate 'cut-off' or 'new signal multiplexing'.