Biphase digital television systems

• US 3,961,137 A
• Filed: 07/30/1974
• Issued: 06/01/1976
• Est. Priority Date: 07/30/1973
• Status: Expired due to Term

• Current Assignee: Independent Broadcasting Authority
• Original Assignee: Independent Broadcasting Authority
• Inventors: Hutt, Peter Richard, VON Cavallar, Gunter, Dodds, Philip John, Douglas, Brian Neil, Blake, Alan Ronald
• Primary Examiner(s): Libman, George H.
• Assistant Examiner(s): Martin, John C.
• Application Number:
  US05/493,111
• Time in Patent Office: 672 Days
• Field of Search: 178/68, 178/67, 178/69.5 R, 178/69.5 F, 178/69.5 TV, 178/DIG. 23, 178/5.6, 178/66 R, 178/DIG. 22, 178/6, 178/69.5 G, 325/38 A, 325/38 R, 325/30, 325/39, 325/141, 325/164, 307/269, 328/63, 328/134, 179/15 BS, 340/347 DD, 360/40
• US Class Current: 375/333
• CPC Class Codes: H03M 5/00 Conversion of the form of the representation of individual digits
• CPC Class Codes: H04N 7/0882 for the transmission of character code signals, e.g. for teletext circuits for the digital non-picture data signal H04N7/035

Abstract

Apparatus for processing groups of digital data for transmission comprises a run-in signal generator for providing at the output of the apparatus an output in which the groups of data are each preceded by a run-in signal, said apparatus being so constituted that the output is in the form of digital signals of the complemented type, and a start code generator operable to provide a start code with at least one break of complementation and arranged to insert a start code between each group and its preceding run-in signal.

The apparatus is especially suitable for the transmission of data intermittently, e.g. during periods of a television signal unoccupied by wide-band picture signals. Because of the complementation break, the start code cannot arise from a data combination. Good reliability of reception is achieved on channels susceptible to interference.

An apparatus for reception comprises a memory device controlled by a clock circuit responsive to the run-in signal, and means responsive to the start code to route the data for display purposes.

Claims

1. Apparatus for processing groups of binary digital information, each group consisting of a series of binary digits for transmission, which apparatus comprises a bi-phase generator for converting the digits of the groups to a bi-phase digital form in which each digit is represented by a transition from a first signal level to a second signal level and the digits of the group are accordingly all represented by signals of the first level complemented by signals of the second level, a start code generator operable to provide repeatedly a binary digital start code of said bi-phase digital form but with a break of said complementation, a run-in signal generator operable to provide a run-in signal and means for feeding trains of output signals to an output from the apparatus at spaced-apart intervals of time each train of output signals having a run-in signal from the run-in signal generator followed by a start code, from said start code generator, with said break of complementation and then by one of said groups in said bi-phase digital form.