Synchronizing burst transmission phase control system
First Claim
1. A synchronizing burst transmission phase control system for use in a satellite communication system based on a space division multiple access/satellite switching-time division multiple access (SDMA/SS-TDMA) scheme utilizing a plurality of spot beams corresponding to up and down links and having a communication satellite which switches line connections between said up and down links in a predetermined connection mode with a predetermined TDMA frame period, and produces a sync window and a plurality of data windows on the basis of a predetermined reference time in said satellite, and a plurality of earth stations intercommunicating via said satellite through a time division multiplexed connection, at least one of said plurality of earth stations being set as a reference station which establishes and maintains synchronization between earth stations corresponding to said plurality of spot beams, said reference station comprising:
- transmitting means for transmitting a predetermined synchronizing burst toward said satellite by taking the period corresponding to said TDMA frame as a reference;
receiving means for receiving the synchronizing burst transmitted by said transmitting means and returned from said satellite through said sync window;
first means responsive to the synchronizing burst received by said receiving means, for measuring a symbol length of a metric pattern which has passed through said synch window and is received correctly, and to compare the measured symbol length with a predetermined reference symbol length to thereby determine a transmission timing error;
second means responsive to an output of said first means for controlling a transmission timing of the synchronizing burst; and
third means for switching a symbol length of the metric pattern to be supervised in accordance with a synchronous state of said synchronizing burst.
1 Assignment
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Accused Products
Abstract
A synchronizing burst transmission phase control system is provided for a SDMA/SS-TDMA system. The synchronizing burst transmission control system is constituted by a transmission timing error difference measuring means including sync window forming means for limiting a TDMA frame, a comparator comparing measured symbol length with a predetermined reference symbol length for determining a transmission timing error; control means for controlling a transmission timing of a synchronizing burst signal; and switching means for switching a symbol length of a supervisory metric pattern in accordance with the synchronous state of the synchronizing burst signal.
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Citations
6 Claims
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1. A synchronizing burst transmission phase control system for use in a satellite communication system based on a space division multiple access/satellite switching-time division multiple access (SDMA/SS-TDMA) scheme utilizing a plurality of spot beams corresponding to up and down links and having a communication satellite which switches line connections between said up and down links in a predetermined connection mode with a predetermined TDMA frame period, and produces a sync window and a plurality of data windows on the basis of a predetermined reference time in said satellite, and a plurality of earth stations intercommunicating via said satellite through a time division multiplexed connection, at least one of said plurality of earth stations being set as a reference station which establishes and maintains synchronization between earth stations corresponding to said plurality of spot beams, said reference station comprising:
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transmitting means for transmitting a predetermined synchronizing burst toward said satellite by taking the period corresponding to said TDMA frame as a reference; receiving means for receiving the synchronizing burst transmitted by said transmitting means and returned from said satellite through said sync window; first means responsive to the synchronizing burst received by said receiving means, for measuring a symbol length of a metric pattern which has passed through said synch window and is received correctly, and to compare the measured symbol length with a predetermined reference symbol length to thereby determine a transmission timing error; second means responsive to an output of said first means for controlling a transmission timing of the synchronizing burst; and third means for switching a symbol length of the metric pattern to be supervised in accordance with a synchronous state of said synchronizing burst. - View Dependent Claims (2, 3)
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4. A synchronizing burst transmission phase control system for use in a satellite communication system based on a space division multiple access/satellite switching-time division multiple access (SDMA/SS-TDMA) scheme utilizing a plurality of spot beams corresponding to up and down links and having a communication satellite which switches line connections between said up and down links in a predetermined connection mode with a predetermined period which is referred as a TDMA frame, and produces a sync window and a plurality of data windows on the basis of a predetermined reference time in said satellite, and a plurality of earth stations intercommunicating via said satellite through time division multiplexed connection, at least one of said plurality of earth stations being set as a reference station which establishes and maintains synchronization between earth stations corresponding to said plurality of spot beams, said reference station comprising:
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transmitting means for transmitting a predetermined synchronizing burst signal toward said satellite by taking the period corresponding to said TDMA frame as a reference; receiving means for receiving the synchronizing burst signal transmitted by said transmitting means and returned from saaid satellite through the sync window; metric pattern memory means responsive to the predetermined synchronizing burst signal received by said receiving means for storing n, an integer larger than 1, metric patterns, each constituting a portion of said synchronizing burst signal; symbol weighting means for comparing said metric pattern read out from said memory means with a predetermined reference metric pattern for each symbol and extracting a predetermined weight coefficient for each symbol corresponding to the result of said comparison; weight coefficient integrating means for integrating n times said weight coefficient for each symbol; symbol threshold value judging means for extracting a predetermined K, an integer larger than 1, number of level identification signals related to a receiving threshold level for each symbol by comparing an integrated level of said weight coefficient integrating means with a predetermined reference level; and symbol timing judging means for measuring a symbol length of a metric pattern of a time region gated by said sync window by referring to said K-level identification signals for each symbol and forming a phase difference signal corresponding to a symbol length shift extracted by comparing said measured symbol length with a predetermined reference symbol length; control means for controlling a transmitting phase of said synchronizing burst signal according to said phase difference signal. - View Dependent Claims (5, 6)
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Specification