Journal of Astronautics ›› 2012, Vol. 33 ›› Issue (12): 1768-1773.doi: 10.3873/j.issn.1000-1328.2012.12.009

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Joint Code Phase Acquisition and Doppler Frequency Shift Estimation  for GPS Signals

LI Xiao jie, XU Lu ping, ZHENG Wen song   

  1. 1. School of Electronic Engineering Xidian University,Xi’an 710071,China;
     2. Xi’an Aerospace Propulsion Institute,Xi’an 710100,China
  • Received:2011-07-24 Revised:2012-05-25 Online:2012-12-15 Published:2012-12-18


The performance of PMF FFT code acquisition algorithm under different frequency offsets is analyzed in this paper. Focusing on the detection performance degradation under partial frequency offset caused by the low frequency estimation accuracy, an improved code phase and Doppler shift united acquisition method is proposed.First, a set of matched filter outputs are obtained based on the partial matching filter (PMF) algorithm; then a low complexity and high accuracy iterative frequency estimation algorithm is proposed by using the magnitude difference of the PMF FFT output, and the frequency offset estimation is used to compensate the PMF output, thus improving the accuracy of frequency estimation and signal detection probability at the same time.Simulation results show that the algorithm can effectively improve the frequency estimation accuracy and the detection probability, and has very low complexity.


Key words: Code acquisition, Frequency offset estimation, Fast Fourier Transform, Cramer Rao lower bound

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