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System for synchronizing digital bit stream for telecommunication system

  • US 4,789,895 A
  • Filed: 04/30/1987
  • Issued: 12/06/1988
  • Est. Priority Date: 04/30/1987
  • Status: Expired due to Term
First Claim
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1. A system for identifying the position, within a time window, of a flag bit included in a digital bit stream sent from a central facility to a terminal on lines of television frames, wherein each line starts with a horizontal sync pulse and a color burst, comprising:

  • a first data clock at the central facility for providing first data clock pulses synchronized with said color burst;

    means at said central facility for providing on one of said lines a digital data stream headed by said flag bit which is one of said clock pulses wide and is delayed by a first constant number of said clock pulses from the start of the horizontal sync pulse;

    a second data clock at said terminal for providing second data clock pulses synchronized with said color burst;

    means at said terminal for providing said time window delayed by a second constant number of said second clock pulses from the start of the horizontal sync pulse and bracketing said flag bit but not said horizontal sync pulse or said color burst;

    means at said terminal for providing a plurality of second data clock pulses during said time window; and

    means at said terminal for determining which of said plurality of second data clock pulses coincide in time with said flag bit to identify the position of the flag bit with respect to said plurality of second data clock pulses.

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