Geodetic Baseline GPS Processing by a Simple Sequential Technique

M. Vermeer, M. Väisänen

Abstract:	We describe a simple sequential algorithm for static geodetic GPS baseline processing by double differences. The objective of the vecsol software, an open-source geodetic vector processing package built upon the GPStk library, is to provide an open source, cross-platform utility for geodetic- precision adjustment of inter-station vectors, useable also by non-scientists. For writing such a software, the existence of the GPStk package is of tremendous value. Vecsol works in a sequential processing mode, iteratively improving the solution while every time processing the original GPS observations one epoch at a time. It takes as input both code and carrier phase observations in RINEX format, and attempts to resolve ambiguities by several methods. Statistical testing is done primarily on the triple-difference level. One may use either broadcast or precise ephemeris, and output are both a weighted average solution based on L1 and L2 – preferable over short baselines – , and a ionosphere-free solution. The reference satellite for constructing double differences is chosen “on the fly”, i.e., suboptimally, and will be switched more often that would be necessary in a batch solution. We mitigate this by a postprocessing “adjustment by condition equations” step. We now have well-working, though still slightly immature, geodetic GPS processing software, which is available on the source code level, freely user-modifiable and crossplatform. Especially in academic education, the usefulness of this approach must be obvious, as our own experience already indicates.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2877 - 2882
Cite this article:	Vermeer, M., Väisänen, M., "Geodetic Baseline GPS Processing by a Simple Sequential Technique," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2877-2882.
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