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System and method for inserting and recovering an add-on data signal for transmission with a video signal

  • US 5,539,471 A
  • Filed: 05/03/1994
  • Issued: 07/23/1996
  • Est. Priority Date: 05/03/1994
  • Status: Expired due to Term
First Claim
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1. A system for transmitting a data signal with a video signal, comprising:

  • a first delay element receiving the data signal, the data signal being unrelated to the video signal, and producing a delayed data signal that is delayed a predetermined period of time from the data signal;

    a first adder element adding the data signal and said delayed data signal to produce a first filtered signal having a plurality of spectral peaks with a spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal;

    a modulator modulating a single unmodulated carder frequency with said first filtered signal to produce a modulated filtered signal, said carder frequency being selected to permit said first filtered signal to be inserted into said unused portion of the frequency spectrum of the video signal;

    a second adder element adding said modulated filtered signal and the video signal to produce a modified video signal containing said modulated filtered signal with said first filtered signal inserted into said unused portion of the frequency spectrum of the video signal;

    a transmitter transmitting said modified video signal;

    a receiver receiving said transmitted modified video signal and processing said modified video signal to regenerate the video signal;

    a separator circuit separating said modulated filtered signal from said transmitted modified video signal to reconstruct said first filtered signal; and

    an inverse filter processing said reconstructed first filtered signal to recover the data signal, whereby the data signal is transmitted with the video signal and subsequently separated from the data signal in said receiver.

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