Implementation and Testing of an Unaided Method for the Acquisition of Weak GPS C/A Code Signals

Gregory W. Heckler and James L. Garrison

Peer Reviewed

Abstract: Fast Modified Double Block Zero Padding (FM-DBZP) is presented as a method for unaided acquisition of weak GPS C/A signals. FM-DBZP uses frequency-domain techniques for coherent integration over integer multiples of the data bit period to perform a search in code delay, Doppler frequency, bit combination, and bit edge. The FFT operation count grows linearly with coherent integration time. The Zoom FFT (ZFFT) further reduces the multiplication count by 28% and the addition count by 37%. The coherent integration time is set to minimize the total computational cost, given a specified acquisition threshold. Successful acquisition, at a design C/N0 of 15 dB-Hz, is demonstrated using a GPS signal simulator. The signal is further attenuated until the algorithm failed to acquire a satellite with a success rate better than 50%. This occurs at a C/N0 of 12.5 dB-Hz.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 56, Number 4
Pages: 241 - 259
Cite this article: Heckler, Gregory W., Garrison, James L., "Implementation and Testing of an Unaided Method for the Acquisition of Weak GPS C/A Code Signals", NAVIGATION, Journal of The Institute of Navigation, Vol. 56, No. 4, Winter 2009-2010, pp. 241-259.
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