Test Results From A Direct L-Band Digitizing GPS/Glonass Receiver

Joe Caschera, Mike Stockmaster, James Tsui, Michael S. Braasch and Dennis M. Akos

Abstract:	In the generation since GPS was first envisioned, positioning accuracies have decreased from tens of meters to centimeters. With the advent of the full complement of Glonass satellites, precise positioning capability is available on a virtually continuous basis. Current receiver architectures, however, still limit the full potential of the system. Non-linearities and temperature and age-based effects which plague analog hardware represent significant sources of error in ultra-high precision applications. The concept of the ‘software radio’ provides the mechanism by which these problems can be solved. Ideally, a software- radio GNSS receiver would consist of an antenna, pre-amp, A/D converter and a microprocessor. This would represent the absolute minimum set of analog components. The presence of unwanted out-of-band signals requires the addition of filter networks. Clever application of bandpass sampling, however, allows one to use a single sampling rate (at L-band), and simultaneously process multi-band signals (e.g., GPS and Glonass, GPS Ll and L2, etc). This paper presents test results of a prototype GPYGlonass software radio. A state-of-the-art analog-to-digital converter is used to capture the signals directly at L-band. Temporary hardware limitations restrict the results to a post-processing demonstration of signal acquisition. However, the architecture for a realtime high-precision receiver (currently under development) will also be described.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	537 - 542
Cite this article:	Caschera, Joe, Stockmaster, Mike, Tsui, James, Braasch, Michael S., Akos, Dennis M., "Test Results From A Direct L-Band Digitizing GPS/Glonass Receiver," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 537-542.
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