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AssigneeNippon Electric Co., Ltd.
InventorsToshinori Hotta, Yukio Takimoto
Estimating the term…
On carrying out communication among a plurality of earth stations by the use of a satellite, super-frame time slots are specified on board the satellite at a super-frame period equal to a frame period multiplied by a predetermined natural number in order to synchronize the satellite and the earth stations with the super-frame time slots. The satellite informs each earth station of the super-frame time slots by generating super-frame bursts specifying the super-frame time slots. Alternatively, each earth station generates super-frame bursts to enter the super-frame time slots on the satellite. The satellite informs such earth station of the super-frame time slots by preventing the super-frame bursts from being returned to each station. At any rate, the satellite and each station change one on-line sequence of operation to the other in synchronism with a specified one of the super-frame time slots without any interruption of communication.
In a satellite communication method of carrying out communication among a plurality of terrestrial zones by the use of a satellite, each terrestrial zone comprising at least one earth station, said at least one earth station being for sending an up-link sequence of time division multiple access signals to said satellite and receiving a down-link sequence of time division multiple access signals from said satellite, one of the earth stations of said zones being for sending a format specifying signal and a format switching command to said satellite, said satellite comprising first memory means for memorizing a first switching format to produce a first sequence of switching signals, second memory means for memorizing a second switching format in response to said format specifying signal to produce a second sequence of switching signals, and means for generating frame pulses at a predetermined frame period, said method comprising the steps of selecting one of said first and said second sequences at a time in response to said frame pulses and said command, distributing the time division multiple access signals of each up-link sequence to the down-link sequences for the respective zones in compliance with the selected one of said first and said second sequences, and interspersing a plurality of down-link frame alignment bursts in each time division multiple access signal of each down-link sequence in synchronism with said frame pulses during distribution of said time division multiple access signals, said selecting, said distributing, and said interspersing steps being carried out on board said satellite, the improvement wherein:
In a circuit arrangement for use on board a satellite in carrying out communication among a plurality of terrestrial zones, each comprising at least one earth station, said at least one earth station being used for sending an up-link sequence of time division multiple access signals to said circuit arrangement and for receiving a down-link sequence of time division multiple access signals from said circuit arrangement, one of the earth stations of said zones being for sending a format specifying signal and a format switching command to said circuit arrangement, said circuit arrangement comprising first memory means for memorizing a first switching format to produce a first sequence of switching signals, second memory means responsive to said format specifying signal for memorizing a second switching format to produce a second sequence of switching signals, frame pulse generating means for generating frame pulses at a predetermined frame period, selecting means responsive to said frame pulses and said command for selecting one of said first and said second sequences at a time, and a switching matrix responsive to the selected one of said first and said second sequences for distributing the time division multiple access signals of each up-link sequence to the down-link sequences for the respective zones, said switching matrix being operatively coupled to said frame pulse generating means to intersperse a plurality of down-link frame alignment bursts in each time division multiple access signal of each down-link sequence in synchronism with said frame pulses, the improvement wherein:
A synchronization circuit for use in an earth station cooperating with a satellite, said satellite defining a plurality of frame time slots at a predetermined interval of time and a plurality of super-frame time slots at a super-frame period equal to said predetermined time interval multiplied by a predetermined natural number, said super-frame time slots synchronously alternating with said frame time slots at every super-frame period, said circuit being for putting said earth station into operation in synchronism with frame bursts arranged in said frame time slots by selectively sending a plurality of frame bursts at said predetermined time interval and by monitoring the frame bursts received through said satellite to compare the sent frame bursts and the received frame bursts, said satellite comprising means for specifying, for said earth station, said super-frame time slots substituted for said frame time slots at said super-frame period, said circuit being further for synchronizing said earth station with the specified super-frame time slots, the improvement wherein said circuit comprises:
Dependencies are inferred from the claim text.