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Method and apparatus for demodulation of relative phase modulated binary data

  • US 4,007,330 A
  • Filed: 08/13/1975
  • Issued: 02/08/1977
  • Est. Priority Date: 08/13/1975
  • Status: Expired due to Term
First Claim
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1. In a communication system employing a carrier on which binary signals have been modulated by reversing the phase of the carrier 180°

  • for representation of one binary value and not reversing phase for representation of the other binary value, a method of demodulating binary digits modulated on said carrier comprisingconditioning the modulated carrier signal received in preparation for demodulation by phase comparison of each data bit period of said carrier with its succeeding data bit period,delaying the conditioned carrier signal for a plurality of distinct periods with at least one delay period less than the nominal period of a data bit modulated on said carrier, one delay period equal to said nominal data bit period, and one delay period greater than said nominal data bit period,phase comparing the conditioned carrier signal as delayed by said distinct periods in separate channels with the conditioned carrier signal undelayed, thereby demodulating said conditioned carrier signal with compensation for positive Doppler shift, no Doppler shift and negative Doppler shift, andselecting the channel producing a signal having the most detectable binary signals in a first group of a number, N, of successive data bit periods.

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