Signal Generation, Verification, and Interaction Analysis of Legacy and Modernized GNSS Systems

B. Goodrich, B. Gonzales, L.H. Hughes, R. Weaver, B. Deary

Abstract:	Development and support of the different GPS modernization programs have presented new challenges. In answer to these challenges, new technologies and improvements in existing technologies have provided new tools in the development of wireless communication and navigation systems. Preserving the integrity of the legacy GPS, and measuring the performance of legacy and modernized signals in the presence of the different power modes of the modernized GPS, in addition to answering question about system interaction issues related to the developing Galileo system, has given rise to the need for simulating many different types of signal which include both the legacy signals and the proposed and future signals. Many of the interaction questions are related to selection of appropriate modulation schemes, and different methods have been used to analyze how the different signals will interact. Computer simulation provides a large part of the analysis. As a confirmation of the computer models, real simulation of the proposed signals and analysis of the interaction of these signals with each other and the legacy signals also needs to be performed. This paper is concerned with this real simulation and the resulting project which consists of a set of general purpose signal generation devices which can produce existing and proposed signals at any stage from data and code up to RF. These generation tools are coupled with a set of data capture and analysis tools including a configurable Software Receiver to do non real-time analysis of captured data. These data capture tools can be used to capture both the laboratory simulated signals as well as real signals, when coupled to the appropriate antenna. This captured data is also exceptionally valuable for algorithm development and regression testing. Experiences with DSP and FPGA designs, used in creating codes and modulation schemes along with the test equipment used to create and receive the signals will be discussed. Design of a general purpose receiver front-end will be presented, and finally our experiences with software receiver models and large data set handling will be reviewed.
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:	1494 - 1501
Cite this article:	Goodrich, B., Gonzales, B., Hughes, L.H., Weaver, R., Deary, B., "Signal Generation, Verification, and Interaction Analysis of Legacy and Modernized GNSS Systems," 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. 1494-1501.
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