Effect of Narrow Correlator Spacing on Code Tracking Accuracy

John W. Betz and Paul B. Fine

Abstract:	A generalized theory for predicting code tracking accuracy has recently been developed. This theory shows that commonly used expressions for code tracking accuracy may not apply when the receiver front-end bandwidth is limited, indicates the conditions under which the commonly used expressions may not apply, and provides a new analytical expression that applies over a wide range of conditions. In addition, a new closed-form approximation is provided. When the receiver front-end bandwidth is limited, code tracking accuracy is shown to depend on this bandwidth as well as the early-late spacing. In addition, the new theory shows that, for a fixed front-end bandwidth, code tracking error does not increase as the early-late spacing becomes very small; instead the error approaches a constant value as the spacing is decreased further. This is important for C/A code receiver design, where it has been thought that using very narrow correlator tap spacing for multipath mitigation would degrade code tracking performance in noise. This paper confirms this new theory using measurements made using laboratory equipment implementing a real-time code tracking loop. Theoretical and experimental results are presented and compared for various situations representing C/A code tracking, and also representing tracking of the proposed new civilian signal on L5. The experimental results confirm the new theoretical predictions.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	716 - 723
Cite this article:	Betz, John W., Fine, Paul B., "Effect of Narrow Correlator Spacing on Code Tracking Accuracy," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 716-723.
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