Determination of high-precision trajectories without fixing integer ambiguities

The processing of kinematic GPS phase measurements calls for suitable methods to deal with the carrier-phase ambiguities. Resolving the integer ambiguities `on the fly´ is the key to centimetre navigation. Specialized search strategies are used to select the correct combination of integer ambiguities. These techniques are successful provided that non-biased measurements are available. The influence of systematic biases-such as ionosphere and multipath-can be minimized by applying certain restrictions (e.g., the maximum length of a baseline). Such restrictions may, however, reduce the number of potential applications. This paper presents an alternative approach. Although this approach cannot match ambiguity resolution `on the fly´ in terms of absolute position, it produces very high relative-position results (centimetre accuracy) within the trajectory itself. High-accuracy results are also achievable when ambiguity resolution is impossible e.g., at distances over 20 kilometres. Based upon the results of our tests, the paper discusses the limitations of ambiguity resolution `on the fly´ and the circumstances under which it might be preferable to choose alternative techniques-such as the one proposed in this paper-in order to obtain reliable, high-accuracy results