A New Algorithm of Detecting and Correction Cycle Slips in Dual-Frequency GPS

Detecting and reconstruction the cycle slip are very important in GPS carrier phase time transfer (GPS CPTT). Many kinds of algorithms have been developed in the past several years especially using GIPSY OASIS software developed by JPL (Jet Propulsion Laboratory) for estimating ambiguity resolution and solving cycle slip problem. NTSC has installed one geodetic like dual frequency Ashtech Z12T receiver for GPS CPTT investigation. The GPS carrier phase time transfer data have been obtained using this receiver at NTSC (National time service center, Chinese Academy of Sciences). In this paper, a new algorithm of TWO STEP method for detecting outliers and cycle slips in dual-frequency GPS is presented. Firstly, using Kalman filter in the model of the 3rd order polynomial for a larger cycle slips, such as larger than 2cycles. Secondly, estimating and reconstruction small cycle slips(less than 1) by using Daubechies wavelet. The details of algorithm are given in section 2. The processing result using the algorithm is presented in section 3. It is applicable to the carrier phase measurement with one sample per 30 second. The calculated results using data of GPS on NTSC show that the algorithm is so efficiency that it can accurately find the small cycle slip less than one cycle.