Satellite communication system with improved conference facility

Abstract

Abstract Gross, U.S. Pat. No. 3,842,350, teaches satellite communication system in which subscribers are connected to each other by appropriate assignment of two different transmitting frequencies to two parties, each being assigned a receiving frequency matching other's transmitting frequency. When third party (in commonest case, operator) must communicate with both subscribers, prior art requires operator to have as a minimum two receivers whose outputs are mixed to operator headset and two transmitters fed from operator microphone. One pair of operator transmitter and receiver communicates with one subscriber, the other pair communicates with other subscriber; but subscribers can not communicate with each other. This is somewhat inconvenient for operator intervention and, of course, intolerable if a conference connection is required. A conference facility may be provided by cross connecting the output of each receiver to its opposite transmitter via a conference bridge which also includes the operator headset and microphone. With such an arrangement, in the general case, intelligence from the first party passes up to the relay, down from the relay to the operator position, through the conference bridge, up to the relay from the operator position, and down to the second party. There are thus two up-and-down " hops" to the relay; these produce a delay which is subjectively very objectionable. This prior art method, whether or not a conference bridge is employed, also requires changing of frequency assignments each time the operator enters the conversation, which incurs some time delay. Present invention teaches provision of second receiver tuned to operator transmitting frequency, at both subscriber positions, the operator having only a single transmitter, but having two receivers tuned to the respective transmitting frequencies originally assigned to the subscribers for communication between them. Thus operator intervention does not interrupt conversation between subscribers, and time for necessary setting of receiver and transmitter frequencies is confined to those for operator communication. The basic principle may be expanded to generalized conference calls among any number of parties.

Inventors

• 👤 Edward W. Moll

Bibliographic Details