An Efficient Algorithm for Batch Estimation of Non-Dynamic Parameters of Double-Differenced GPS Phase Measurement

H. Rim, B. Schutz, and B. Tapley

Abstract:	The dual frequency GPS phase measurement is commonly used for the high precision GPS geodetic applications. Processing this particular data type involves solving several non-dynamic parameters, such as the ambiguity parameters and the tropospheric parameters. The total number of these measurement parameters to be estimated grows as the number of GPS satellites and ground stations increases, or as the arc length becomes longer, which in turn, requires allocation of large amounts of computer memory. These parameters have special characteristics in their correlation relation with each other. The parameters adjacent in time are highly correlated, while parameters separated in time are not. This special correlation property allows the correlation between time- separated parameters to be ignored, thereby reducing the parameter set which must be in the memory at any given time. Also, the size of the parameter set which will reside in the memory does not depend on the arc length. Two different types of GPS tracking data have been processed using this approximation to demonstrate significant reduction on computer memory usage and computation time without losing the accuracy level for other geodetic parameters. One is the data set from IGS campaign, the other is the data set from Topex/Poseidon (Topex). The memory requirement reduced by 23% for IGS data and 46% for the Topex data to process one day worth of these data. CPU time also reduced by 26% on Cray J90/16, and by 38% on HP 735/125 workstation for IGS data, while 32% and 64% reduction in CPU time demonstrated for Topex data on Cray J90/16 and HP 735/125, respectively.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	63 - 71
Cite this article:	Rim, H., Schutz, B., Tapley, B., "An Efficient Algorithm for Batch Estimation of Non-Dynamic Parameters of Double-Differenced GPS Phase Measurement," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 63-71.
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