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Traffic verification system

  • US 6,757,300 B1
  • Filed: 06/04/1999
  • Issued: 06/29/2004
  • Est. Priority Date: 06/04/1998
  • Status: Expired due to Fees
First Claim
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1. A method of inserting a data signal into an audio signal to provide a tagged signal, said method including the steps of:

  • A. removing a band of frequencies centred at a predetermined notch frequency from said audio signal;

    B. spectrally shaping said data signal such that it takes on the precise shape and magnitude of the envelope of the audio signal at said removed band of frequencies centred at said notch frequency; and

    C. inserting said shaped data signal into said audio signal within the removed band centred at said notch frequency.

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