Real-Time Centimeter-Accuracy GPS: Initializing While in Motion (Warm Start Versus Cold Start)

Benjamin W. Remondi

Abstract:	The initialization of real-time centimeter-accuracy GPS (i.e., based on carrier phases) can be performed while in motion. The goal of the initialization procedure is to determine the doubie- difference carrier phase integer ambiguities. It has previously been demonstrated that this can be accomplished with as few as five satellites and with a single frequency C/A code receiver. Moreover, it has been demonstrated that the process benefits substantially from a sixth satellite and L2 carrier phases (even if obtained by codeless means). Here I report the benefit, to the initialization procedure, of additional knowledge or constraints. As an example, I show the speedup (meaning fewer epochs, not computational speed) of the initialization procedure and increased reliability using a priori knowledge of the average ellipsoidal height of the antenna phase center on a marine platform. As another example, I show the benefit of prior knowledge of one or two double-difference integer biases either alone or coupled with a priori knowledge of the ellipsoidal height of the antenna phase center.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	1053 - 1061
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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