A Simple Approach to Obtain the CA Code Spectral Separation Coefficient

S. Raghavan, T. Powell

Abstract:	Spectral lines of the Global Positioning System (GPS) coarse acquisition (CA) codes play an important role in the amount of Code Division Multiple Access (CDMA) noise generated, which degrades the available effective carrier-to-noise density ratio (C/N0)effective to a GPS receiver. (C/N0)effective is a key metric widely used to characterize the impact of various interference sources because by knowing the available (C/N0)effective, we can predict the performance of the GPS receivers in terms of code acquisition, carrier loss of lock, and data bit error rates. Most analysis performed several years ago ignored the spectral line effects altogether, claiming that any significant effect is of short duration and limited geographical extent. But with the growing number of Global Navigation Satellite Systems (GNSSs) in the Radio Navigation Satellite System (RNSS) band, there has been a renewed interest in accounting for all the interference sources accurately in the intersystem and intrasystem Radio Frequency Compatibility (RFC) studies. Since CA code intrasystem interference is a significant contributor to (C/N0)effective, many studies done in the past couple of years have focused on CA code spectral line issues. Quasi-analytical models of the correlator output, simulation models of GPS satellite constellation and the receivers, and limited laboratory measurements were employed in the studies. Each one of these methods is very computationally intensive and time consuming. In this paper we provide a much simpler way to obtain the CA code spectral separation coefficient (CASSC), which is a key component required to calculate the CA code intrasystem interference and the (C/N0)effective.
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:	86 - 94
Cite this article:	Raghavan, S., Powell, T., "A Simple Approach to Obtain the CA Code Spectral Separation Coefficient," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 86-94.
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