Cycle slip detection and repair with triple frequency combination method

As the application field of GNSS (Global Navigation Satellite System) is expanding, users have increasing demand of real-time positioning accuracy. The modernization of the global positioning system and the development of BDS (BeiDou Navigation Satellite System) will lead to a more high-accuracy on-the-fly positioning system. Unlike GPS, BDS is consists of MEO, GEO and IGSO satellites. The presence of the S band provided by RDSS from GEO satellites has introduced more degrees of freedom for observation data combination. We establish geometric-free and ionosphere-free linear combinations of BDS observations on the three of B1-B2-B3-S band with the aim to enhance the sensibility of detecting and repair cycle slips in real time. The small cycle slips can be magnified by the linear combinations. Therefore, the three combination cycle slips are detected. Once the combination cycle slips have been detected, the real cycle slips on each frequency can be estimated using the combination coefficients and the jumps can be fixed. These combinations are defined with the aims of long wavelength and weakening geometric and ionosphere errors. In this paper, some principles are established to appraise the performance of these combinations in order to obtain the optimal combinations. A combination method to detect and repair the small cycle slips for triple frequency of BDS is proposed. Some simulations based on real collection data have been carried out and the results have showed the proposed method is able to detect and repair both big and small cycle slips (even smaller than 1 cycle) on each carriers.