Real-Time Cycle Slip Detection and Repair Algorithm for SBAS Airborne Receiver

摘要

SBAS improves performance of GNSS by providing timely corrections and integrity monitoring to meet the requirement for civil aviation. Single frequency SBAS augments GPS L1 signal, such as WAAS and EGNOS, providing APV-I service. Receiver uses GIVD to correct ionosphere delay, in which way the impact of ionosphere storm cannot be eliminated. Thus, SBAS performance is limited. Dual frequency SBAS receiver directly mitigates ionosphere delay. However, receiver will suffer considerably larger noise, proposing a higher demand for carrier smoothing techniques. Cycle slip is frequent in airborne receiver's carrier measurement, which makes smoothed measurement pulsing, thereby reducing the positioning accuracy. This paper presents a real-time cycle slip detection and repair method, including chi-square detection algorithm and sequence-sum repair algorithm based on the statistical property of fourth order differential of carrier measurement, and its repair error variance. According to the measured data analysis, the algorithm shows good performance in cycle slip detection and repair and is sufficient for carrier smoothing techniques for SBAS airborne receiver.