On-the-Fly Ambiguity Resolution for Precise Differential Positioning

Abstract

On-the-fly (OTF) carrier phase ambiguity resolution allows precise differential positioning. This paper describes a technique developed for real-tune Ol% ambiguity determination. Single- and dual-frequency formulations are presented for position determination on distances of up to several tens of km. Several marine and land-based experiments were performed in order to investigate the performance of the algorithm. Marine positioning from multiple reference sites and repeated positioning in case of land experiments show position agreement in the centimeter range. The convergence time is analyzed with respect to the number of visible satellites, satellite geometry and baseline length. The technique for ambiguity resolution is based on Sequential Square Root Information Filtering. This technique allows to determine the sum of squares residual error, which is used for ambiguity search, in a sequential way without reprocessing previous measurement data with the updated state. The approach is therefore well suited for real-time applications. The paper shows the remarkable speed of the developed algorithm which is not tied to the use of the P-code.