A New Cycle-Slip Detection Algorithm for Network RTK Using Optimal Dual-Frequency Carrier-Phase Combinations

Many strategies for treating dual-frequency cycle slip have been studied over the years; however, the conventional method using the Melbourne-Wubbena (MW) combination is vulnerable to pseudorange multipath effects. In this paper, we propose a new detection algorithm of dual-frequency cycle slip using only carrier-phase stationary observations for the network real-time kinematic (RTK) system which generates high-precision corrections for user. Two independent and complementary carrierphase combinations, called the ionospheric negative (IN) and ionospheric positive (IP) combinations in this paper, are employed for avoiding insensitive pairs. They can successfully detect all of the cycle slips since two L1/L2 combinations combine cycle slips with opposite signs for uniquely detecting insensitive pairs. We verified that the actual error distributions under severe ionospheric storm of these monitoring values can be sufficiently bounded by the normal Gaussian distribution from a theoretical analysis. Consequently, we demonstrated that the proposed method ensures high-integrity performance with a probability of missed detection of 7.5 × 10?9 .under a desired false-alarm probability of 10?5 . In addition, the IN and IP combination shows the best detection performance than the other linear combinations such as ionosphere-free, wide-lane, and narrow-lane. Through an algorithm verification test using actual data collected under a severe ionospheric storm, we confirmed that all artificially inserted cycle slips are successfully detected. In conclusion, the proposed method is confirmed to be effective for handling dual-frequency cycle slips for network RTK system.