Characterization of Signal Deformations for GPS and WAAS Satellites

G. Wong, R.E. Phelts, T. Walter, P. Enge

Abstract:	Signal deformations are caused by imperfections or faults in the signal generating hardware onboard the satellites. Left uncorrected, these can lead to range errors. Thus they need to be measured and understood so their effects on user position accuracy and integrity can be better quantified. Past attempts have been made to characterize these distortions. This involved the collection and analysis of real data from twenty-four then-current, nominally healthy GPS satellites. An update for the previous results is presented in this paper. This paper sets out to answer the following questions: 1. What is the current signal deformation behavior of the entire set of GPS and WAAS satellite signals? 2. Have there been any degradation/ changes in the characteristic parameters of the older GPS satellite signals (Block IIA, Block IIR) due to the passage of time? 3. What is the signal deformation behavior of the satellites which had not been launched at the time of the previous study – subsequent Block IIR, Block IIR-M, Block IIF? How do they compare with that of previous satellites? 4. Are our current definitions of signal deformation still meaningful and applicable to the new satellite signals, in particular the new Block IIF-L5 in-phase and quadrature signals? To obtain the raw data necessary to obtain signal deformation measurements, high-resolution raw baseband satellite signals were collected for the entire set of GPS and WAAS satellite signals (both L1 and, where applicable, L5 frequencies). This was done over a continuous 24-hour period, something which had not been done previously in open literature. The data was collected using SRI’s 46 meter dish antenna, and involved 6 people in planning and operations.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	3143 - 3151
Cite this article:	Wong, G., Phelts, R.E., Walter, T., Enge, P., "Characterization of Signal Deformations for GPS and WAAS Satellites," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 3143-3151.
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