Simultaneous position estimation & ambiguity resolution (SPEAR) for high-integrity carrier-phase navigation with robustness to tracking loss

This paper introduces a GNSS processing algorithm called simultaneous position estimation and ambiguity resolution (SPEAR), with the goal of delivering high-accuracy, high-integrity navigation with robustness to carrier-tracking interruptions. The algorithm operates by continuously applying integer constraints to estimate the navigation solution recursively as a histogram of possible state values. The proposed approach is distinctive in that it decomposes the carrier-wave measurement into two components: an apparent integer difference, used for Bayesian prediction, and a fractional phase, used for Bayesian correction. The algorithm has potential application for high-accuracy, high-integrity safety of life operations near buildings or other obstructions of the sky, as may occur during aircraft surface movement or automobile navigation in urban canyons.