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

• Current Assignee: GTE Main Street Incorporated (Verizon Communications Inc.)
• Original Assignee: GTE Government Systems Corporation (General Dynamics Corporation)
• Inventors: Mustafa, Mehmet, Tweedy, Ernest P., Beriont, Walter J., Stoddard, James C.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Harvey, David E.
• Application Number:
  US07/044,387
• Time in Patent Office: 586 Days
• Field of Search: 358/148, 358/141, 358/142, 358/146, 358/147, 358/143, 358/145, 358/86, 358/83, 375/95, 375/111, 375/119
• US Class Current: 348/464
• CPC Class Codes: H04N 7/035 Circuits for the digital non-picture data signal, e.g. for slicing of the data signal, for regeneration of the data-clock signal, for error detection or correction of the data signal
• CPC Class Codes: H04N 7/088 the inserted signal being digital
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal

Abstract

A telecommunication system for synchronizing a digital bit stream sent from a central facility to a terminal on lines of television frames. Each active line starts with a horizontal sync pulse and a color burst. A first data clock at the central facility provides first data clock pulses synchronized with said color burst. A circuit at the central facility provides a flag bit one clock pulse wide delayed by a first constant number of clock pulses from the start of the line'"'"'s horizontal sync pulse. A second data clock at the terminal provides second data clock pulses synchronized with said color burst. A circuit at said terminal provides a time window delayed by a second constant number of clock pulses from the start of the line'"'"'s horizontal sync pulse so as to bracket said flag bit. A plurality of second data clock pulses occur during said time window. Circuits at the terminal determine which of said plurality of second data clock pulses coincide in time with said flag bit, thereby synchronizing said data stream with said second data clock.

Claims

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.

2. 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 active lines of television frames, wherein each active 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 digital data stream representing digital audio 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 line'"'"'s 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 lines 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 the plurality of second clock pulses.