Abstract: The data link includes a phase noise compensator to eliminate phase noise resulting from microwave frequency sources on a communications satellite. In addition, Fourier analyzers are utilized to determine the frequency of received signals having low carrier-to-noise density. The combination of the phase noise compensator and the Fourier analyzers permits data rates on the order of 50 to 400 bits per second to provide economically attractive communication links with aircraft over ocean areas.

Abstract: 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.