A Optimal Method to Detect Cycle Slip in Real Time for GPS Medium-long Baseline Network RTK

Errors correlations with distance make it difficult to resolve real-time ambiguity in GPS medium-long baseline network RTK. So, how to detect and recover cycle slip is a key technology. And we develop a method to resolve this problem. In this paper, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive 'relative' ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have 'slipped' when loss-of-lock occurred).First getting linear combinations of triple-differenced (TD) between carrier L1 and L2 by wide lane and free ionosphere, regarding reference coordinates as a prior information, and using selecting weight fitting to get float resolution of TD ambiguity, then search cycle slip(TD integer ambiguity) using LAMBDA method. Detecting the cycle slips of several baselines whose length from a few kilometers to one thousand kilometers using method in this paper in real time, we get results which are consistent with those from professional software in long time and success rate is 100 percent.