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Station signature system

  • US 4,647,974 A
  • Filed: 04/12/1985
  • Issued: 03/03/1987
  • Est. Priority Date: 04/12/1985
  • Status: Expired due to Term
First Claim
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1. A system for the automatic insertion of auxiliary video information into a network provided source television signal at a local station, said television signal including video signals representing program information occurring during horizontal trace intervals withing vertical trace intervals, said vertical trace intervals defining active picture intervals and associated vertical blanking intervals defining inactive picture intervals of respective field intervals, comprising:

  • means for selectively inserting a trigger signal into said active picture intervals of said source television signal by superimposing a carrier signal of a predetermined frequency on said video signals without disturbing said video signals substantially throughout said horizontal trace intervals but only during said vertical trace intervals, said carrier signal being of relatively low amplitude compared to said video signals so as to not produce visible artifacts which interfere with visible images produced in response to said video signals, said trigger signal indicating the desired timing of the insertion of said auxiliary video information;

    means for receiving said source television signal including said trigger signal at said local station;

    means coupled to said receiving means for providing a signal indicating the presence of said trigger signal in said received television signal, said means for generating said signal indicating the presence of said trigger signal including means for interrogating said received television signal during both of said vertical trace intervals and said vertical blanking intervals and generating said indicating signal if said carrier signal is present during said vertical trace intervals but a signal component having said predetermined frequency of said carrier signal is absent during said vertical blanking intervals;

    means coupled to said receiving means for generating an auxiliary video information signal which is synchronous with said received television signal; and

    switch means having signal inputs coupled to said receiving means and said auxiliary video information signal generating means and a control input coupled to said indicating signal generating means for providing at an output an output television signal including said auxiliary video information in response to said indicating signal.

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