• Patent Title: System and method for fast code phase and carrier frequency acquisition in GPS receiver
  • Application No.: US12395243
    Application Date: 2009-02-27
  • Publication No.: US08457177B2
    Publication Date: 2013-06-04
  • Inventor: Mark C. Sullivan
  • Applicant: Mark C. Sullivan
  • Applicant Address: US VA Herndon
  • Assignee: SkyBitz, Inc.
  • Current Assignee: SkyBitz, Inc.
  • Current Assignee Address: US VA Herndon
  • Agent Duane S. Kobayashi
  • Main IPC: H03D1/00
  • IPC: H03D1/00 H04B1/707
System and method for fast code phase and carrier frequency acquisition in GPS receiver
Abstract:
A GPS receiver acquires carrier frequency and Gold code phase using short segments of a received GPS signal. In one embodiment, a 1-ms segment of the GPS signal is transformed to the frequency domain. This is multiplied by a frequency representation of the Gold code. The resulting product is converted to the time domain, and a peak is detected. The location of the peak corresponds to the code phase. If no peak is located, the carrier frequency is changed. Full- and half-bin steps in carrier frequency are considered. Processing gain is achieved by using longer segments of the input signal, for example 4 or 16 ms and integrating 1-ms segments. Considerations are provided for compensating for the effects of a transition, should it occur in the short segment of the GPS signal being processed. Integrations can be performed using non-coherent and coherent techniques. Adjustments are made for non-integral millisecond segment lengths.
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