Performance Analysis of Geodetic-Grade GPS Receivers Based on Zero Base-Line Measurements

G.E. Vázquez

Abstract:	The primary motivation behind this paper is to present the performance analysis based on the stochastic properties of the GPS observables for geodetic-grade GPS receivers. For this purpose, single-difference residuals (SD-residuals) derived from zero baseline measurements are analyzed. Traditionally, when GPS data is processed, the structure of a variance-covariance matrix (v-c matrix) is assumed diagonal considering all one-way carrier phases or all pseudo-ranges having the same variance, and being statistically independent. However, correlation among the different types of GPS observables might exists, and a study was done in order to verify this hypothesis. Thus, correlation measures such as normalized autocorrelation and cross-correlation coefficient are thoroughly examined, as well as the spectral analysis (i.e. power spectral density), all derived from the SD-residuals. Results from the performance analysis indicate that the noise characteristics for the eight types of geodetic-grade GPS receivers analyzed here are receiver-specific, and the correlation among the different types of GPS observables exist, and it varies between the receivers. In addition, some preliminary results of a practical study performed on the Co-Op tracking loops of the Topcon/JPS Legacy GPS receiver are presented. Tracking results are improved in terms of noise reduction when narrowing the bandwidth of individual PLL (within 3-5 Hz) and the bandwidth of common PLL (within 15-25 Hz) in urban environment and under medium dynamics of the receiver mounted on a moving vehicle (i.e. 35 miles per hour in city roads and 55-65 miles per hour in highway). The tracking options studied have an impact on tracking the apparent dynamics of each satellite, on the receiver itself, and the internal oscillator using the entire satellite constellation.
Published in:	Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003) June 23 - 25, 2003 Hyatt Regency Hotel Albuquerque, NM
Pages:	188 - 199
Cite this article:	Vázquez, G.E., "Performance Analysis of Geodetic-Grade GPS Receivers Based on Zero Base-Line Measurements," Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003), Albuquerque, NM, June 2003, pp. 188-199.
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