Spread spectrum communications method and apparatus

摘要

A method and apparatus employing spread spectrum techniques in a wide bandwidth communications system is disclosed. A plurality of transmitting stations are each equipped to provide a transmission signal representing a pseudo-random coded, phase modulated, message signal. The transmission signal is directed through a bandwidth which encompasses otherwise dedicated, relatively narrow bandwidth repeater channels, employed in connection with a communications satellite, to a generally fixed receiver station. At the receiving station, the incoming signal is (a) code acquired and tracked, (b) carrier acquired and tracked, (c) phase locked to the receiver local oscillator and (d) coherently demodulated to extract the desired data. The receiving station advantageously employs plural receiving elements each having a pseudo-random sequence code matched filter which significantly reduces code acquisition time by obviating the necessity of exhaustively correlating the incoming signal with a replica of the pseudo-random code word at the receiver station.