A Design Technique to Remove the Correlation Ambiguity in Binary Offset Carrier (BOC) Spread Spectrum Signals

Phillip W. Ward

Abstract:	As is well known, the correlation envelope of current GPS spread spectrum signals (C/A-code and P(Y)-code) is approximately a triangle whose (rounded) peak amplitude corresponds to perfect correlation of the GPS receiver's replica code with the incoming code. The extremities of the base of this triangle are approximately zero amplitude and these correspond to a plus or minus 1- chip offset of the replica code with respect to the incoming code (where the replica code becomes effectively uncorrelated with the incoming code). The modernized military (M-code) signal is a binary offset carrier (BOC) spread spectrum signal. The normal correlation envelope for this signal is a set of tapered triangles with both positive and negative peaks. Only the central positive peak corresponds to perfect correlation of the GPS receiver's replica M-code with the incoming code. The BOC signals in space provide numerous benefits, but they create a new problem for both signal acquisition and tracking. Each of the multiple correlation peaks corresponds to signal detection during the acquisition process and to a stable code loop state during the tracking process. Only the central peak is the correct state. In other words, the result of correlation with the BOC spread spectrum signals is ambiguous. The Galileo navigation satellite system also plans to use BOC spread spectrum signals. This paper describes a simple replica code design technique that totally removes the BOC ambiguity. The same design technique can be applied to the receiver acquisition and tracking processes alike. Also described are several novel code loop tracking techniques that utilize the advantages of this new design technique.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	886 - 896
Cite this article:	Ward, Phillip W., "A Design Technique to Remove the Correlation Ambiguity in Binary Offset Carrier (BOC) Spread Spectrum Signals," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 886-896.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In