A New Comparison of Averaging Techniques Used for Weak GNSS Signal Acquisition with Application to GPS L5 Signals

H. Grant, D. Dodds

Abstract:	Acquisition of weak GNSS signals requires significant averaging. Several different averaging techniques are in use. Coherent averaging has the best performance but has limitations due to data modulation and frequency offset due primarily to Doppler shift. Other common techniques are power averaging and differential averaging [3]. These techniques have a higher tolerance to frequency offset and data modulation but have worse performance. Others have compared the averaging techniques as a function of the output signal to noise ratio [1]. The signal to noise ratio is not a good indication of the probability of detection as the distribution of signal and noise is significantly different for the three techniques. This paper compares the techniques by showing the averaging required for detection given an input signal to noise ratio. The advantage of this comparison is it gives the result in terms of the probabilities of false alarm and detection without further analysis. The analysis supporting the conclusions is shown. Simulation was used to verify the results. The results are displayed graphically. The paper shows how these results can be used to determine the averaging required for detection of week GPS L5 signals. The paper continues to describe methods for combined inphase and quadrature correlation of GPS L5 signals.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	2610 - 2616
Cite this article:	Grant, H., Dodds, D., "A New Comparison of Averaging Techniques Used for Weak GNSS Signal Acquisition with Application to GPS L5 Signals," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 2610-2616.
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