Some theoretical and practical aspects of geodetic positioning using carrier phase difference observations of GPS satellites

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During the summer of 1983, the Earth Physics Branch of the federal Department of Energy, Mines and Resources conducted the first test in Canada of the Macrometer V-100 GPS receiver. Two receivers were used to determine the vector baselines between six points in the Ottawa area. The data obtained were processed by the Earth Physics Branch using software developed by Macrometrics Inc., the manufacturer of the Macrometer, and independently, at the University of New Brunswick (UNB). The impetus for the UNB analysis was two-fold: (1) to corroborate the results obtained by the Earth Physics Branch, and (2) to develop an independent Canadian capability to process Macrometer (and other types of) GPS observations. In this paper we describe the UNB analysis. A computer software package was developed to process doubly-differenced phases from single or multiple observing sessions with the capability of estimating both receiver coordinates and satellite orbits. Out software yielded baseline components agreeing with the mean of those obtained with Macrometrics' software to about 1 ppm. The corresponding agreement with terrestrial measurements is of the same order for longitude and latitude and, as may be expected, somewhat worse for the height (2 ppm to 20 ppm). The software is also capable of directly yielding a network solution by processing all observation sessions on all baseline simultaneously. The network solution is significantly stronger than the solution based on single baseline processing.