Automated cycle-slip correction of dual-frequency kinematic GPS data

In order to attain high precision positioning and navigation results with GPS, cycle slips must be correctly repaired at the data preprocessing stage. A slip of only a few cycles can bias measurements enough to make centimetre-level positioning or navigation difficult. Over the past decade a number of methods have been developed to detect and repair cycle slips. The majority of approaches involve forming cycle-slip-sensitive linear combinations of the available observables. Algorithms have been designed to detect, determine, and repair these cycle slips by fitting functions to the linear combinations and observing differences between the functions and the data combinations. These methods invariably require user intervention for problematic cycle slips in portions of data, tuning of input parameters to data, or introduction of additional carrier-phase ambiguity-resolution parameters in the main data processing where pre-processing cycle- slip determination has failed. A method has been developed from various existing techniques, that provides fully automatic cycle-slip correction at the data preprocessing stage. The algorithms utilise two dual frequency, double-difference carrier phase and pseudorange geometry-free linear combinations. These combinations are filtered to allow for high-resolution cycle-slip detection, and are then compared with least-squares-fitted Chebyshev polynomials for cycle-slip determination. Results indicate that single-cycle slips can be reliably detected for receivers in varied environments, and that these slips can be repaired correctly.