Acquisition And Tracking Performance Of NRZ And Square Wave Modulated Symbols For Use In GPS

Jack K. Holmes, Srini H. Raghavan, Steve Lazar

Abstract:	Square wave modulation schemes are being considered for modulating either a new military or civil signal at L2 in order to implement frequency reuse of the GPS band. For a new military signal (the Manchester code of Tricode Hexaphase) the use of square wave modulation will allow the simultaneous modulation of the existing P(Y)-code in phase quadrature with a combination of the existing C/A code at and a new military signal spectrally isolated from the C/A code that is predominantly in the center of the band. For a new civil signal (split spectrum C/A code) the use of square wave modulation will allow the simultaneous transmission of the P(Y) code in quadrature with anew civil signal spectrally isolated horn most of the P(Y) code signal energy in the center of the band. Regardless of whether square modulation is used for a new military or civil signal, this technique allows for reuse of the GPS band by adding a balanced code as opposed to the non-return-to-zero formatted codes that comprise the current C/A and P(Y) codes. In this paper a generalized equation for the linearized tracking error variance is developed to characterize the tracking performance of square modulated symbols. This equation is applied to Manchester coded and split spectrum C/A code symbols. The complexity of the acquisition algorithm and the power loss associated are affected by the multiple minor correlation peaks which are present with the major correlation peak. In this paper the results of the acquisition performance analysis is presented and compared with the performance of an NIL? formatted signal and shown that the required increase in the signal power for a Manchester coded signal over an NRZ signal to maintain same acquisition time is less than 1.4 dB when comparing Manchester symbols and NRZ Symbols at the same chip rate.
Published in:	Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998) June 1 - 3, 1998 The Adams Mark Hotel Denver, CO
Pages:	611 - 626
Cite this article:	Holmes, Jack K., Raghavan, Srini H., Lazar, Steve, "Acquisition And Tracking Performance Of NRZ And Square Wave Modulated Symbols For Use In GPS," Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998), Denver, CO, June 1998, pp. 611-626.
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