Development of Software Based GPS L1 IF Signal Simulator for GEO Satellite Environments

G. Kim, D. Han, C. Kim, C. Kee

Abstract:	Software based GPS L1 IF signal simulator for Geostationary (GEO) satellite environment was developed and tested in this paper. The developed GPS L1 IF signal simulator consists of two parts: one is pseudo range and Doppler generation, and the other is modulation for pseudo range and Doppler into Intermediate Frequency (IF) signal. The pseudo range was calculated using relative distance between the GPS satellite and the GEO satellite, ionosphere delay, GPS satellite clock bias, receiver clock bias, and Gaussian noise. The Doppler was calculated using relative velocity of the GEO satellite and the GPS satellite, change rate of ionosphere delay, GPS satellite clock drift, receiver clock drift, and Gaussian noise. The calculated pseudo range and Doppler were modulated into the IF signal. The procedure of IF signal modulation can be summarized as: carrier generation, C/A code modulation, data bit modulation, frame bit modulation, and signal sampling. We used IF instead L1 frequency when generating carrier, because we assumed that the received signal had down converted in the RF front before sampled in the receiver. The C/A code was generated using gold code of each GPS PRN. The generated C/A code and carrier were modulated using BPSK method. And then, data bits are modulated in the C/A code modulated signals, the data bits are come from GPS broadcast navigation data. The preamble of data frame is synchronized to signal transmitting and receiving time. Finally, Gaussian noise was added the modulated signal to obtain desired SNR value. With this simulated.
Published in:	Proceedings of the ION 2013 Pacific PNT Meeting April 23 - 25, 2013 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	1074 - 1080
Cite this article:	Kim, G., Han, D., Kim, C., Kee, C., "Development of Software Based GPS L1 IF Signal Simulator for GEO Satellite Environments," Proceedings of the ION 2013 Pacific PNT Meeting, Honolulu, Hawaii, April 2013, pp. 1074-1080.
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