Spatially convergent GPS kinematic positioning

Abstract.It is a known fact that obtaining accurate GPS carrier-phase measurements involves fixed, unknown whole-cycle ambiguity parameters. As the use of cosine functions to eliminate any double-difference integer ambiguities causes spatial ambiguity problems, both reasonably approximated positions and wavelength-dependent convergence ranges are of the utmost importance. Differential GPS-based position solutions are first smoothed to create a polynomial trajectory, leading to less variable position approximations. Long-wavelength wide-lane phase combinations will then be utilized to facilitate convergent GPS positioning, on a stage-by-stage basis. Although double-difference ionospheric path delays are often interpreted as nuisance parameters, they can be obtained when the respective cosines of the original L1 and L2 carrier phases undergo a simultaneous least-squares estimation. In particular, quadratic forms of the estimated phase residuals will be linked with hypothesis testing to allow for a meaningful statistical inference. Some low-dynamics experiments are then performed to prove the feasibility of the proposed hierarchical positioning concept.