Integrated Use of GPS and GLONASS: Transformation Between WGS 84 and PZ-90

P. N. Misra, R. I. Abbot, and E. M. Gaposcbkin

Abstract:	GPS and GLONASS employ different geocentric Cartesian coordinate frames to express the positions of their satellites and, therefore, of their users. GPS uses WGS 84; GLONASS, PZ-90. The current difficulty in estimating a transformation between the two coordinate frames is largely due to the dearth of GLONASS receivers. A transformation has been estimated using an approach which sidesteps this difficulty. The approach consists of relating orbital positions of two GLONASS satellites expressed in the two coordinate frames. The main advantage is that the satellite positions in PZ-90 are easy to obtain: they are broadcast by the satellites. The corresponding positions in WGS 84 are obtained by fitting orbits to satellite tracking data obtained from a global network of laser tracking stations and radar systems. The orbital positions expressed in PZ-90 and WGS 84 are related via a seven-parameter transformation accounting for displacement of the origin, rotation of the axes, and a scale factor. The difference between the coordinates of points on earth in WGS 84 and PZ-90 has been found to be less than 15 m (average: 5 m). The two coordinate frames are brought substantially into coincidence by a small rotation (0.4”) of the z-axis of either. An additional improvement, though only slight, is obtained by displacing the origin by 2.5 m along the y-axis of WGS 84.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	307 - 314
Cite this article:	Misra, P. N., Abbot, R. I., Gaposcbkin, E. M., "Integrated Use of GPS and GLONASS: Transformation Between WGS 84 and PZ-90," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 307-314.
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