Effect of Linear Time-Invariant Distortions on RNSS Code Tracking Accuracy

John W. Betz

Abstract:	Imperfections associated with the space vehicle transmitter hardware, the channel, and receiver hardware can distort a GPS signal. An important class of imperfections can be modeled as linear time-invariant (LTI) systems, and thus represented by a magnitude response and phase response in the frequency domain. This paper introduces a parametric mathematical model to describe the effect of LTI distortions on an RNSS signal's correlation function. It also introduces quantitative measures of a correlation function's "goodness" for code tracking. These measures of "goodness" are independent of the mechanism that introduces the distortion. It relates levels of imperfection in the LTI system to the resulting distortion of the signal's correlation function, indicating how the quality of the signal changes with different types and degrees of distortion. Rules of thumb are provided to predict how different imperfections, ranging from filters on the space vehicle to dispersive effects in the channel to receiver antennas, affect performance of receivers for different specific modulations. Specific results are shown for different modulations for RNSS ranging signals.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	1636 - 1647
Cite this article:	Betz, John W., "Effect of Linear Time-Invariant Distortions on RNSS Code Tracking Accuracy," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 1636-1647.
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