Assessment and Handling of CA Code Self-Interference During Weak GPS Signal Acquisition

Y.T.J. Morton, J.B.Y. Tsui, D.M. Lin, L.L. Liou, M.M. Miller, Q. Zhou, M.P. French, J. Schamus

Abstract:	This paper presents an analysis of GPS CA code self-interference, its impact on the acquisition of weak GPS signals when coexisting with strong GPS signals, and the means to mitigate the interference to allow successful acquisition of the weak GPS signals using software GPS receivers. Current software GPS receivers are capable of acquiring and tracking satellite signals with C/N0 as low as 24 dB without aid and without extensive computing time. To achieve this level of sensitivity, there cannot be substantial interference from other satellites with strong signal levels. In practice, however, the weak signals may coexist with much stronger signals from other satellites. This may happen when only a limited area of the sky is exposed to a receiver, such as in the case of navigating in city canyons or under a forest canopy. The presence of the strong signals may produce higher cross-correlations between the strong signals and a weak signal, resulting in complete loss or false acquisition of weak signals which may be necessary in determining the user position. This paper presents method and software algorithms that have been developed to successfully remove the strong satellite signals from the GPS receiver input. The resulting net signal can then be used to acquire the weak signals. Experiments using both simulation and hardware simulator data show that with the removal of strong satellite signals from the input, it is possible to acquire the weak satellite signals at C/N0=24 dB-Hz level.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	646 - 653
Cite this article:	Morton, Y.T.J., Tsui, J.B.Y., Lin, D.M., Liou, L.L., Miller, M.M., Zhou, Q., French, M.P., Schamus, J., "Assessment and Handling of CA Code Self-Interference During Weak GPS Signal Acquisition," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 646-653.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In