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Protected television signal distribution system

  • US 4,621,285 A
  • Filed: 12/10/1980
  • Issued: 11/04/1986
  • Est. Priority Date: 12/10/1980
  • Status: Expired due to Term
First Claim
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1. In combination in video distribution apparatus;

  • signal originating means including means for transmitting a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and means for transmitting a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval and a digital video tag interleaved with said horizontal synchronizing pulse timing information and at least one receiver coupled to said signal originating means for receiving said picture and sound carriers, each of said receivers including authorization register means, sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information and said digital video tag, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier during said vertical synchronizing interval, authorization comparator means connected to said digital video tag recovering means and said authorization register means for selectively permitting video reception, and means enabled by said authorization comparator means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information.

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