Domestic satellite communication system
First Claim
1. A domestic satellite communication system including a central earth station and a plurality of subscriber earth stations, means at said central earth station responsive to a demand for controlling a frequency assignment of voice communication satellite channels in response to an occurrence of a call which identifies a subscriber earth station-to-subscriber earth station call, a central switching system for carrying out voice switching operations, and each of said plurality of subscriber earth stations serving at least one voice communication terminal,each of said subscriber earth stations comprising:
- indication means for indicating that a call identified at said central earth station is for a subscriber earth station-to-subscriber earth station;
means for monitoring the continuity of a communication channel at said voice communication terminal; and
means for periodically transmitting an out-of-band signal in a voice communication satellite channel which is assigned by said central earth station while said monitoring means detects the continuity of a communication channel and said indication means indicates the subscriber earth station-to-subscriber earth station call,said central earth station comprising;
means for demodulating said out-of-band signal transmitted from said subscriber earth station;
means for receiving said out-of-band signal which has been demodulated by said demodulating means;
means for monitoring the continuity of a communication channel between said subscriber earth stations by periodically reading out the output of said receiving means; and
means for tuning the frequency of said demodulating means to coincide with a frequency assigned to said voice communication between said subscriber earth stations,whereby said subscriber earth station-to-subscriber earth station call is connected through one satellite link.
1 Assignment
0 Petitions
Accused Products
Abstract
A direct broadcast communication satellite system prevents over-charge for earth-subscriber to earth-subscriber toll calls via radio links to an earth station regardless of faults which may occur in satellite channels. A central earth station controls the frequency assignment of the radio link channels used for voice communication. Each of a plurality of subscriber earth stations has at least one voice communication terminal, with means for identifying a call destined for a subscriber at that earth station. The continuity of the channels involved in that call are monitored by periodically transmitting and receiving out-of-band signals on the assigned channel. It appears that there has been a loss of signal when the out-of-band signal does not appear, twice in succession. Then, the channel is released and the toll charges are terminated.
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Citations
11 Claims
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1. A domestic satellite communication system including a central earth station and a plurality of subscriber earth stations, means at said central earth station responsive to a demand for controlling a frequency assignment of voice communication satellite channels in response to an occurrence of a call which identifies a subscriber earth station-to-subscriber earth station call, a central switching system for carrying out voice switching operations, and each of said plurality of subscriber earth stations serving at least one voice communication terminal,
each of said subscriber earth stations comprising: -
indication means for indicating that a call identified at said central earth station is for a subscriber earth station-to-subscriber earth station;
means for monitoring the continuity of a communication channel at said voice communication terminal; and
means for periodically transmitting an out-of-band signal in a voice communication satellite channel which is assigned by said central earth station while said monitoring means detects the continuity of a communication channel and said indication means indicates the subscriber earth station-to-subscriber earth station call,said central earth station comprising; means for demodulating said out-of-band signal transmitted from said subscriber earth station;
means for receiving said out-of-band signal which has been demodulated by said demodulating means;
means for monitoring the continuity of a communication channel between said subscriber earth stations by periodically reading out the output of said receiving means; and
means for tuning the frequency of said demodulating means to coincide with a frequency assigned to said voice communication between said subscriber earth stations,whereby said subscriber earth station-to-subscriber earth station call is connected through one satellite link.
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- 2. A satellite communication system comprising a central earth station and a plurality of outlying earth stations mutually intercommunicating via a plurality of radio link channels extending between a satellite and said earth stations, means at said central earth station responsive to an occurrence of a call for controlling the assignment of channel frequencies to said call, means at each of the outlying stations for recognizing a call signal indicating that it is involved in the call for causing a recognized station to tune itself to a frequency assigned by the central earth station, means for periodically monitoring the continuity of an assigned channel by a use of an out-of-band signal frequency transmitted from the outlying earth station involved in said call, and means for terminating a call if said periodic monitoring indicates no out-of-band signal frequency during two successive monitoring periods.
Specification