A Real-Time Software Receiver for the GPS and Galileo L1 Signals

B.M. Ledvina, M.L. Psiaki, T.E. Humphreys, S.P. Powell, P.M. Kintner Jr.

Abstract:	A real-time interoperable GPS and Galileo L1 software receiver has been developed and tested. The receiver has 12 channels for tracking GPS satellites and 12 channels for tracking Galileo satellites. The receiver consists of a GPS L1 RF front end, data parallelizing and acquistion hardware, and software routines running on a 3.4-GHz Pentium processor. The software is composed of bt-wise parallel correslation routines, code and carrier tracking loops, data demodulation routines, and navigation solution code. The main contributions of this work are the demonstration of a GPS S1 C/A code RF front end being used with the Galileo L1 binary-offset-carrier (1,1) (BOC(1,1)) signals and the demonstration of an interoperable GPS and Galileo real-time software receiver. This RF front end uses a commercial off-the-shelf (COTS) GPS RF front end desighned for the L1 C/A code signal. To accommodate the Galileo L1-B BOC (1,1) signal, modifications to the delay-locked-loop (DLL) were required. The downside to the approach is that this particular RF front end induces a 4.6 dB loss in carrier-to noise in the Galileo signals, because of the narrow filtering intended for the narrower GPS L1 C/A code signal. The successful live tracking of GPS and the feasibility of using RF front ends designed for the GPS L1 C/A code signals in interoperable GPS and Galileo receivers or Galileo receivers. The GPS and Galileo L1 software receiver tracks 24 channels in real time. It requires 46% of the processing capabilities of a 3.4 GHZ Intel Pentium 4 PC.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2321 - 2333
Cite this article:	Ledvina, B.M., Psiaki, M.L., Humphreys, T.E., Powell, S.P., Kintner, P.M., Jr., "A Real-Time Software Receiver for the GPS and Galileo L1 Signals," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2321-2333.
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