Performance Tests of a 12-Channel Real-Time GPS L1 Software Receiver

B.M. Ledvina, A.P. Cerruti, M.L. Psiaki, S.P. Powell, P.M. Kintner

Abstract:	A 12-channel real-time GPS software receiver has been tested in order to determine its accuracy and tracking performance under dynamic conditions. The motivation for this work is to demonstrate that this receiver's performance is equivalent to a hardware receiver despite the fact that it implements all of its base-band mixing, correlation, and accumulation operations in software in a general-purpose PC. Such receivers offer an attractive route to the development of products that exploit new signals that will be available in the future such as the L2 civilian signal and Galileo signals. A software receiver can be developed to track such signals without the need to develop a new hardware correlator chip. All that needs to be done is to adjust the parameters of the RF front-end to receive the new carrier frequencies and upgrade software to calculate correlations using the new spread-spectrum codes. The real-time software receiver is reviewed, and its operation is compared to that of receivers which use hardware correlators. Also discussed is an upgrade to the original implementation that uses processor-specific x86 assembly code (MMX). This upgrade provides a 25% increases in processing speed. Another aspect that is discussed is the use of 1-bit RF front end data and the related speedup. The software receiver is tested under static and dynamic conditions and is compared to a hardware receiver in terms of its tracking stability and the accuracy of its observables. The dynamic test conditions include a rocket scenario that is generated using a GPS signal simulator and road vehicle motion that is tested using car-mounted receivers.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	679 - 688
Cite this article:	Ledvina, B.M., Cerruti, A.P., Psiaki, M.L., Powell, S.P., Kintner, P.M., "Performance Tests of a 12-Channel Real-Time GPS L1 Software Receiver," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 679-688.
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