Abstract:The ability of polynomial fitting for detecting and correcting cycle slips is strongly affected by the errors of the carrier phase observations and the intervals of the observation data. The observation data being divided into several pieces will improve the results, however, the efficiency will be decreased.A method for combining epochdifferenced with robust estimation to improve the method of polynomial fitting is proposed. The numerical experiment is performed by using the real data of GPS /GLONASS. The results indicate that the method of robust polynomial fitting is more rigorous in theory and more powerful in practice for detecting and correcting cycle slips comparing with the normal polynomial fitting method.