INS-Aided Single-Frequency Cycle-Slip Detection for Real-Time Kinematic GNSS

GNSS ambiguity fixed solution can greatly improve the accuracy of GNSS/INS integrated system. But it is difficult to achieve perfect real-time dynamic single frequency cycle-slip detection merely by GNSS observations especially in complex environment. Inertial assisted cycle-slip detection terms (DTs) based on station-satellite double-differences and satellite single-difference observations are derived. The error characteristic of the DT is analyzed emphatically. The DT error is affected by the drift of INS error. In addition, the magnitude of the influence on different satellites is related to the angle between its station-satellite vector and that that vector of the reference satellite. Thus, it is important to select reference satellite. It is proposed that two group of DTs can be used together by selecting two different reference satellites. The threshold of detection is estimated in a sliding window, where the DTs, whose INS error is submerged in GNSS error, are removed in order to reflect INS error. The method of threshold estimating has stronger self-adaptability.