Non-difference FCB estimation and the application  in fixed fuzziness of PPP

The ambiguity fixing technology can significantly improve the accuracy and convergence speed of precise point positioning (PPP), which is a research hotspot in the field of satellite navigation and positioning at home and abroad. In this paper, the receiver and satellite FCB are separated by the least square method, and the integer characteristic of non-difference ambiguity is restored. The obtained satellite-end FCB can be provided to the user to realize precise single-point positioning with fixed non-difference ambiguity. The experiment of zero-difference FCB estimation is implemented with the observations from IGS tracking stations worldwide. The result shows that wide-lane FCBs are stable and its variations in a week are within 0.1 cycle, but the variation of narrow-lane FCBs in a day is large. The estimated FCBs are used for the PPP experiment with ambiguity resolution. The position accuracy in E, N and U directions are 0.7 cm, 0.8 cm and 2.1 cm respectively. Compared with the floating-point PPP, the position accuracy in E, N and U directions are increased by 68％, 51％ and 37％ respectively, which verifies the performance of estimated FCBs for the ambiguity fixed PPP.