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Station relief arrangement for use in relieving operation of a reference station in a TDMA network without reduction of frame availability

  • US 4,688,216 A
  • Filed: 05/09/1985
  • Issued: 08/18/1987
  • Est. Priority Date: 05/10/1984
  • Status: Expired due to Term
First Claim
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1. A reference station relief arrangement for use in a predetermined one of a plurality of earth stations of a time division multiple access satellite communication network, each of said earth stations sending an up-link and receiving a down-link signal, each of said up-link and said down-link signals being divisible into a succession of multiframes which have a multiframe period and each of which is divisible into a particular frame and at least one remaining frame, said particular and said remaining frames having a common frame period, a preselected one of said earth stations being used as a primary reference station for producing first reference bursts at a first predetermined time instant in said particular frame and second reference bursts at second predetermined time instants which correspond to said first predetermined time instant in each remaining frame, said second reference bursts being discriminated from said first reference bursts by said earth stations, said first and said second reference bursts defining said multiframe and said particular and said remaining frames in the up-link signal sent by said primary reference station, each of said earth stations establishing and maintaining frame synchronization with reference to the first and the second reference bursts included in said down-link signal, placing a succession of synchronization bursts at a preassigned position at said multiframe period in the up-link signal sent thereby, and performing burst synchronization by detecting said synchronization bursts with reference to said first and said second reference bursts in the down-link signal received thereby;

  • wherein the improvement is such that said predetermined one of earth stations is used as a subsidiary reference station can relieve the operation of said primary reference station when said primary reference station becomes faulty, said improvement comprising;

    first means for producing at said multiframe period a particular one of said synchronization bursts that is specific to said subsidiary reference station and can be identified from the other synchronization bursts by said earth stations; and

    second means coupled to said first means for placing said particular one of the synchronization bursts at a third predetermined time instant within said particular synchronization burst in the up-link signal sent thereby while said first and said second reference bursts disappear in the down-link signal received thereby, said particular synchronization burst being kept during disappearance of said first and said second reference bursts to relieve said primary reference station.

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