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PN Lock indicator for dithered PN code tracking loop

  • US 4,279,018 A
  • Filed: 03/06/1979
  • Issued: 07/14/1981
  • Est. Priority Date: 03/06/1979
  • Status: Expired due to Term
First Claim
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1. In a PN code tracking loop for receiving a PN-spread IF signal, said loop having a dithered local PN code signal which is dithered ±

  • 1/2 code bit period at a predetermined rate controlled by a dither reference signal, and having a correlation in which said dithered local PN code is correlated with said PN-spread IF signal to control a local oscillator for synchronizing a PN code generator, a method for producing an indication of PN code tracking loop lock comprising the steps of delaying the dithered local PN code signal by a half code bit period, correlating the dithered and delayed PN code signal with said PN-spread IF signal to obtain a DC signal proportional to the correlation of the signals correlated, and phase detecting the DC signal with the dither reference signal to obtain an output signal the amplitude of which is proportional to the degree of correlation between said local PN code signal and said PN-spread IF signal independent of IF signal strength and independent of noise level.

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