Automatic data-quality monitoring for continuous GPS tracking stations in Taiwan

Taiwan has more than 300 Global Positioning System (GPS) tracking stations maintained by the Ministry of the Interior (MOI), Academia Sinica, the Central Weather Bureau and the Central Geological Survey. In the future, GPS tracking stations may replace the GPS control points after being given a legal status. Hence, the data quality of the tracking stations is an increasingly significant factor. This study considers the feasibility of establishing a system for monitoring GPS receivers. This investigation employs many data-quality indices and examines the relationship of these indices and the positioning precision. The frequency stability of the GPS receiver is the most important index; the cycle slip is the second index and the multipath is the third index. An auto-analytical system for analysing GPS data quality and monitoring the MOI's tracking stations can quickly find and resolve problems, or changes in station environment, to maintain high data quality for the tracking stations.