Cit-Based Correction Algorithm For The Ionospheric Delay In Wide Area Augmentation System

Ionospheric delay is one of the most important error sources in satellite navigation and positioning, many methods were adopted to mitigate the ionospheric delay for high precision navigation applications, such as local area differential GPS, wide area differential GPS, wide area augmentation differential GPS and Wide Area Augmentation System (WAAS). A new algorithm based on Computerized Ionospheric Tomography (CIT) for ionospheric delay correction in WAAS was proposed in this paper. The error of ionospheric delay can be corrected by the orthogonal combination of model-based function and Truncated Singular Value Decomposition (TSVD) for single frequency user in WAAS. The simulation results of 23 wide-area reference stations and 10 user stations in China show that the precision of ionospheric delay correction based on traditional grid-based algorithm and CIT-based algorithm have evident correlation with solar activities, local time and magnetic latitude as well. However, the performance of CIT-based algorithm is much better than that of grid-based algorithm. Both the mean error and standard deviation of CIT-based algorithm are far less than grid-based algorithm.