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Modem in-band secondary channel via radial modulation

  • US 4,525,846 A
  • Filed: 12/27/1982
  • Issued: 06/25/1985
  • Est. Priority Date: 12/27/1982
  • Status: Expired due to Term
First Claim
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1. A method of transmitting a first and second input series of input bits simultaneously, over a single data channel comprising:

  • generating a series of symbols having a radial amplitude and corresponding to said first series of input bits;

    maintaining the radial amplitude of said symbols at a first level if said second input bits have a first value and alternating said radial amplitude between said first value and a second value for consecutive symbols when said second input bits have a second value;

    sending said symbols over said communication channel, to a receiver;

    detecting the radial amplitudes of the signals received by said receiver;

    correlating the radial amplitudes of a last preselected number of received signals to obtain a correlated value;

    comparing said correlated value to a threshold value; and

    generating a series of output bits having a first value if said correlated value is above said threshold value; and

    a second value if said correlated value is below said threshold value.

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