Novel Adaptive GPS Cycle Slip Detection Method Based on TDCP Measurements in Urban Environments*

Abstract

On account of high accuracy of carrier phase and difficulty of real-time solution for integer ambiguity, GPS/INS integrated navigation based on time differenced carrier phase (TDCP) is used to estimate vehicles position. However, in urban environments, blocking of satellite signals would affect signal reception and lead to cycle slips frequent occurrence on carrier phase. Because TDCP could be affected by cycle slip easily, cycle slip detection and correction work need to be done. High-order difference cycle slip detection method is considered to have advantages, eliminating outliers simply and effectively. However, there would be misjudgement for cycle slip when vehicle is in motion if a constant threshold is adopted. Thus, this paper proposes a kinematic characteristics separation algorithm from observation to provide an adaptive detection threshold for high-order difference method, which adjusts cycle slip identification to dynamic situation of vehicles with high reliability. Validity of the algorithm are verified by road tests. Experimental results show that cycle slip detection method with adaptive threshold performs effectively, and accuracy of vehicle positioning under urban environment is guaranteed.