Abstract: A system for remotely accessing computer networks is provided in which a central hub is connected to a computer network. The central hub may then be connected to a plurality of remote sites through an earth-orbiting satellite. Users at multiple remote sites may be connected to the central hub simultaneously through frequency management techniques.

Abstract: An automatic frequency control system for use in satellite communications is provided that is pre-programmed with an initial acquisition Doppler offset frequency. The system includes a search mode for accurately determining the satellite's initial frequency translation error before the initiation of data transmission and also for determining the Doppler rate of change. The system further includes a tracking mode, in which the frequency variation is continuously monitored. Depending on the frequency characteristics of the transmission, the system is capable of re-entering the search mode to determine a new frequency translation error, if necessary.