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Doppler corrected spread spectrum matched filter

  • US 7,545,854 B1
  • Filed: 02/07/2000
  • Issued: 06/09/2009
  • Est. Priority Date: 09/01/1998
  • Status: Expired due to Fees
First Claim
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1. A system for processing communication data from a code signal input, the system comprising:

  • a signal sampler operable to receive signal data;

    a Doppler shift system operable to provide a Doppler shift correction value;

    a storage circuit configured to receive and store the signal data;

    a time domain signal processor comprising a complex mixer, coupled to the storage circuit and Doppler shift system, for mixing at least a portion of the signal data with the Doppler shift correction value, where the complex mixer is corrected for pure frequency shift independently from the signal sampler being corrected for both carrier and code Doppler shift;

    a complex product generation circuit, coupled to the complex mixer and the code signal input, for computing a complex product of the mixed portion of the signal data with a current code phase of a code signal received a the code signal input;

    a summing circuit coupled to the complex product generation circuit for summing the computed complex products as a current complex integration value;

    a square root circuit, coupled to the summing circuit, for computing a square root value of the sum of the squares of the current complex integration values, each square root value having a magnitude and an associated code phase; and

    an output processing circuit coupled to the square root circuit for processing a plurality of computed square root values, where the time domain signal processor is in signal communication with the signal sampler, the Doppler shift system and code signal input, the time domain signal processor operable to shift the signal data by the Doppler shift correction value and to determine a correlation between the shifted signal data and the code signal input where the code phase and the magnitude of the computed square root value having the largest magnitude indicates that correlation between the shifted signal data and the code signal and wherein the time domain processor is a matched filter processor.

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