Simulation and Hardware Demonstration of New L2 Civilian GPS Ranging Codes

P. A. Dafesh, R.T. Bow, M. D. Partridge, and T. Fan

Abstract:	An essential part of the civilian GPS modernization effort has been to provide a second civilian signal on the L2 GPS carrier, in addition to the Course Acquisition (C/A) signal currently on the L1 frequency. Initially, the modernization program planned to implement the GPS C/A signal on the GPS L2 carrier. Subsequently, alternate recommendations have been made to replace the C/A code on the L2 carrier with civilian (C) codes having better correlation properties than the C/A code. Codes that have been considered for use on L2 include one of the L5 codes or the time division multiplexed (TDM) combination of two new codes (with all code options chipped at the C/A rate). The TDM codes include a civil-moderate (CM) and civil-long (CL) ranging code that are significantly longer than the C/A code to improve the correlation and spectral properties as compared to C/A code. The code provides an L5-like signal structure, well in advance of the L5 signal implementation. In order to verify the performance of the proposed codes, a simulation and hardware proof-of-concept implementation was constructed. The work was conducted using The Aerospace Corporation's flexible GPS (FlexGPS) system simulation and hardware brassboard that has previously been used to verify the performance and implementation of proposed Military GPS modernization signals. This paper describes the results of Aerospace's constellation-level GPS performance simulation of the CM and CL codes, and the first hardware proof-of-concept demonstration of the L2 C TDM signal. The work demonstrates theoretically expected benefits of the codes and verifies the ability to independently track either of the L2 CM or CL codes. Details of the receiver tracking loop design for the TDM codes will also be presented.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	925 - 930
Cite this article:	Dafesh, P. A., Bow, R.T., Partridge, M. D., Fan, T., "Simulation and Hardware Demonstration of New L2 Civilian GPS Ranging Codes," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 925-930.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In