Satellite communications system incorporating ground relay station through which messages between terminal stations are routed

A communication system in which communications between ground stations are relayed through an earth-orbiting satellite and a ground relay station, said system comprising

• a set of ground terminal stations linked to subscribers, each terminal station including
• a transmitter for transmitting outgoing messages independent of control from said ground relay station, and
• a receiver for receiving incoming messages,
• a satellite having a plurality of antennas, each of said antennas being arranged and designated for communication with a different group of said terminal stations,
• a ground relay station,
• means in said satellite for relaying to the ground relay station messages transmitted by said terminal stations,
• means in said ground relay station for processing the messages according to message destination relayed thereto and retransmitting the messages on different carrier frequencies according to the terminal station groups to which the messages are to be sent, and
• means in said satellite relay for sorting the transmissions from said ground relay station according to the carrier frequencies thereof and retransmitting them through the respective antennas according to the carrier frequencies so as to retransmit to each ground terminal station through the antenna designated for communication with that ground terminal station.