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Global positioning system receiver digital processing technique

  • US 5,293,170 A
  • Filed: 04/06/1992
  • Issued: 03/08/1994
  • Est. Priority Date: 04/10/1991
  • Status: Expired due to Term
First Claim
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1. A system for processing L1 and L2 signals received from a satellite that include a unique frequency carrier with a known pseudo-random P-code and an unknown code modulated thereon, comprising:

  • means for generating replicas of the respective unique frequency carriers of the received L1 and L2 signals,means for generating a replica of the known pseudo-random P-code modulated on the received L1 and L2 signals,means receiving the L1 and L2 signals for demodulating the L1 and L2 signals with the replicas of their carriers provided by the carrier replica generating means and with the P-code replica provided by the P-code replica generating means, thereby producing demodulated L1 and L2 signals,means receiving the demodulated L1 and L2 signals for separately integrating them over time periods equal in length to a plurality of P-code cycles, thereby producing integrated demodulated L1 and L2 signals,means receiving the integrated demodulated L1 and L2 signals for correlating them with each other, thereby generating a correlation level, andmeans communicating with said carrier replica generating means and said P-code replica generating means for adjusting the phases of the carrier replicas and of the P-code replica relative to the incoming L1 and L2 signals in a manner to substantially maximize a measure of said correlation level,whereby useful phases of the carrier and P-code replicas are obtained.

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