Solution of Timing Errors for AGPS

Éamonn P. Glennon and Roderick C. Bryant

Abstract:	AGPS navigation solutions differ from normal GPS navigation solutions due to the use of ambiguous codephases rather than full time-of-transmits for each GPS satellite observation. As such, it is necessary to reconstruct the full time-of-transmit using a-priori knowledge such as a position estimate within 150 km of the true position and an estimate of the time-of-receipt. Unfortunately errors can arise if the initial time-of-receipt used to construct the time-of-transmit observations is in error. This paper describes a number of algorithms used to solve this problem, as well as describing failures that were experienced when the algorithms were applied to real-life situations. These failures led to the definition of a special dT-DOP metric, similar to the standard DOP metrics used for normal GPS solutions, which was then used to successfully predict such errors.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	136 - 141
Cite this article:	Glennon, Éamonn P., Bryant, Roderick C., "Solution of Timing Errors for AGPS," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 136-141.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In