A Comparison of the Loss of Lock Threshold of BOC and NRZ Signals For First Order Code Tracking Loops

J.K. Holmes, S. Raghavan

Abstract:	When selecting signal waveforms for GPS, Galileo or other navigational systems there are a number of important parameters that have to be considered. For example the rms tracking error is one important consideration, as well as the ease to acquire the signal both in jamming and in white Gaussian noise. One of these parameters, the mean time to loss of code loop lock is an important parameter that has not been addressed in the literature for signals other than non-return to zero (NRZ), and is evaluated here both theoretically and by simulation to determine which waveforms, from the class of NRZ and the binary offset carrier (BOC), have the lowest threshold to loss of lock. It is known that for comparable chip rates of a BOC signal, when the Gabor bandwidth is higher, then the tracking performance in the above threshold condition is better than for N Z waveforms However, the code acquisition is more complicated due to the correlation sidebands of the BOC signals. What is not known is whether the loss of lock point is higher or lower for BOC signals when compared to a NRZ signal of comparable chip rate. The purpose of this paper is to address theoretically and by simulation the comparative mean time to lose lock for the optimum spacing BOC waveform and various early late correlator spacings for NRZ waveforms considered in GPS and Galileo.
Published in:	Proceedings of the 2003 National Technical Meeting of The Institute of Navigation January 22 - 24, 2003 Disneyland Paradise Pier Hotel Anaheim, CA
Pages:	649 - 656
Cite this article:	Holmes, J.K., Raghavan, S., "A Comparison of the Loss of Lock Threshold of BOC and NRZ Signals For First Order Code Tracking Loops," Proceedings of the 2003 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2003, pp. 649-656.
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