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Correlation system for pseudo-random noise signals

  • US 4,045,796 A
  • Filed: 11/12/1976
  • Issued: 08/30/1977
  • Est. Priority Date: 11/18/1974
  • Status: Expired due to Term
First Claim
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1. A system for correlation of a first coded digital signal having a clock frequency with an identical coded digital signal of unknown time delay which is bi-phase modulated on a suppressed carrier signal, without recovery of the suppressed carrier signal, comprising:

  • means for inverting alternate bits of the first coded digital signal for providing a PN* signal having a frequency component at one-half the clock frequency of the first coded signal;

    means for generating an estimated carrier signal;

    means for modulating said estimated carrier signal with said PN* signal;

    means for mixing said modulated signal with the identical coded signal of unknown time delay;

    means for squaring said mixed signal for providing a coded signal having a clock frequency equal to the clock frequency of the first coded signal; and

    means for controlling the phase of the first coded signal with said squared signal for correlating the first coded signal with the identical coded signal of unknown time delay.

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