Impact of Transmitter and Receiver Filtering on the Code-tracking Performance of GPS Modernization Signals

P. A. Dafesh and A. S. Parker

Abstract:	The GPS modernization program is considering a number of new signal options for both the military and civilian signals. Some of the key constraints effecting the implementation of these signals involve the impact of transmitter and receiver filters on the ranging performance of GPS modernization signals. Although the impact of filtering on GPS signals has been considered in prior works, a thorough simulation of these effects has not yet been completed. This paper describes the effect of transmitter and receiver filtering on the code-tracking performance of GPS ranging signals. The objectives of the work are to understand the performance variation of GPS military (M) signal options as compared to the performance of the Precision- (P) code signal, with and without transmitter and receiver filtering. The results were obtained using a simulation constructed in the Signal Processing Worksystem (SPW) environment to simulate the code-tracking performance of these signals when being tracked by a receiver delay-locked loop (DLL). Data describing pseudorange error and discriminator gain are presented as a function of filter width for the P- and the M-code signal options. The work illustrates that the ranging degradation predicted by implementation (power) loss is inadequate to explain the ranging performance of P-and M-Code signals for moderate filtering. It is found that the band-limiting loss is mitigated during state 3 ranging by an enhancement in discriminator slope and a reduction in correlated noise power with moderate channel filtering. This effect is further explained by simulations of the DLL discriminator slope S-curve slope with filtering, for P- and M-code signals.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	521 - 527
Cite this article:	Dafesh, P. A., Parker, A. S., "Impact of Transmitter and Receiver Filtering on the Code-tracking Performance of GPS Modernization Signals," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 521-527.
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