Abstract

A communication system for carrying out communication between a plurality of stations through an electric power line operating in a commercial power frequency band. Spread spectrum modulation of an information signal, employing a pseudorandom code sequence is used at a transmitting station. Spread spectrum demodulation is carried out in a receiving station to reproduce the information signal. The modulated signal is spread over a wide frequency band different from the commercial frequency band. Each station may comprise both of a transmitter and a receiver, and may be specified by a an assigned destination address that also is transmitted. The destination station address may be indicated either by an address signal or by an additional pseudorandom code sequence peculiar to a destination station. Alternatively, polling operation is carried out through the electric power line by a polling station to select one of the stations. Preferably, another pseudorandom code sequence is superposed on the modulated signal so as to specify a synchronization signal and different from the pseudorandom code sequences conveying the information signal and/or the destination address.