Code and carrier divergence technique to detect ionosphere anomalies

A single and dual frequency smoothing techniques implemented to detect ionosphere anomalies for GBAS system (ground based augmentation system) were discuss in this paper. As a dominant threat for using differential navigation satellites systems in landing applications an ionosphere storm is considered. To detect these occurrences the number of algorithms is developed. Some of them are addressed to meet the integrity requirements of CAT III landing and base on the multi frequency GPS techniques. Depending on the combination of frequency used during code and carrier phase measurements the smoothed pseudorange achieves a different level of accuracy. From this reason the most popular algorithms e.g. the divergence free and ionosphere free smoothing algorithms are analyzed and compared. In the article the works realized in the Institute of Radioelectronics connected with GBAS application are presented, too. The investigations were conducted by using actually GPS signals and signals from GNSS simulator. The self prepared software was used to analyze the results.