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Method and apparatus for communication of video, audio, teletext, and data to groups of decoders in a communication system

  • US 4,866,770 A
  • Filed: 08/14/1986
  • Issued: 09/12/1989
  • Est. Priority Date: 07/08/1986
  • Status: Expired due to Term
First Claim
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1. A communication system for use by a broadcaster to allocate a predetermined combination of services selected from a plurality of more than two different services including at least video and audio services transmitted simultaneously on a single frequency tuned channel to selectable groups of a plurality of decoders, comprising:

  • a transmitter located at a first location, the transmitter transmitting on the single frequency tuned channel a multiplexed analog components (MAC) composite signal,said composite signal comprising the plurality of the more than two different services and control data,a plurality of decoders located at second locations, the plurality of decoders comprising a receiver for receiving the transmitted composite signal, and the plurality of decoders further comprising a separator for separator said composite signal into information signals,said composite signal being of a predetermined format, said format comprising a continuing sequence of fields, each field comprising a predetermined number of lines, a portion of each of said lines operating as a horizontal blanking interval, a portion of each field operating as a vertical blanking interval and remaining portions of each field comprising video information signals,said control data of said composite signal comprising system-wide control commands, group decoder control commands and individual decoder control commands, said transmitter transmitting and said decoders receiving said system-wide control commands and said group decoder control commands in a first predetermined set of lines said portion of each field operating as said vertical blanking interval and said individual decoder control commands in a second predetermined set of lines in said portion of each field operating as said vertical blanking interval, said individual decoder control commands transmitted in said first predetermined set of line by the transmitter and received by said decoders for assigning individual decoders to one or more groups of decoders,said individual decoders assigned to one or more groups of decoders comprising a memory to store said group assignment, said transmitter capable of subsequently transmitting said group decoder control commands for allocating at least one service package to selected groups of said groups of decoders according to previous group assignments stored in their memories,said decoders assigned to one or more groups of decoders and allocated at least one service regardless of whether any portion of the composite signal is encrypted with a key, each said service package comprising a predetermine combination of services selected from said plurality of more than two different services including at least video and audio services transmitted in said composite signal.

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