Real-Time Detection and Repair of Cycle Slips in Triple-Frequency BDS Measurements

To improve the effectiveness and reliability of cycle slips detection and repair, a real-time algorithm to detect, determine, and validate the cycle slips for triple-frequency BDS is proposed in this study, in which the geometry-free (GF) combination noise residual method and the GF code and phase combination method are utilized. At first, the optimal BDS triple-frequency GF phase combinations are selected. Then the GF code and phase combination method are used to detect all the cycle slips. After the cycle slips are detected, an effective simple round method using the optimal triple-frequency GF code and phase combinations is applied to calculate the cycle slips. The workflow of entire algorithm for cycle slips detection and repair is also designed. Finally, a BDS triple-frequency test is performed to test the proposed algorithm. Results show that the successive mixed small and big cycle slips can be detected and repaired effectively in real time. The 5-min signal unlock time and 1 small cycle slips can be also detected and corrected.