Tight Integration of a GPS Adaptive Array with a Software-Defined Receiver

Sai K. Kalyanaraman and Michael S. Braasch

Abstract:	The effect of adaptive array processing on the code and carrier phase of the spread spectrum signal is a function of the signal operating environment and the nature of the adaptive processing mechanism. Spatial adaptive processing (SAP) utilizes its degrees of freedom to form spatial nulls towards interference sources and Space-Time Adaptive Processing (STAP) proves effective against both wide and narrow band interferers by forming more precise spatio- temporal nulls. The effects of adaptive array processing on the GPS signal could vary from ranging errors to loss of phase lock due to distortions imposed on the GPS signal. A significant portion of the work published to date has been appliqués which attempt to minimize the impact of the interferer on the desired signal and, to a lesser extent, minimize distortion of the desired signal. Previous work published by the authors [1] has been directed at carrier phase compensation applied at the tracking loop level in the base-band receiver module to alleviate the effects of phase distortions imposed on the GPS signal as a function of adaptive array processing. Previous work by other researchers [2] has suggested the possibility of utilizing a matched filter-like mechanism for code phase compensation in the base-band GPS receiver processing. With the advent of software GPS receivers, it is now possible to implement the aforementioned compensation mechanism in conjunction with null/beam steering base-band modules which are integrated with the GPS receiver processing. This paper describes the results of a project to implement and evaluate the performance of the integrated adaptive antenna/GPS software receiver system.
Published in:	Proceedings of the 2007 National Technical Meeting of The Institute of Navigation January 22 - 24, 2007 The Catamaran Resort Hotel San Diego, CA
Pages:	657 - 668
Cite this article:	Kalyanaraman, Sai K., Braasch, Michael S., "Tight Integration of a GPS Adaptive Array with a Software-Defined Receiver," Proceedings of the 2007 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2007, pp. 657-668.
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