Add to ORKGfrom the Universität Hannover. He has worked in the field of GPS since 1983. In 1990 he founded the company Geo++®, which develops satellite navigation and positioning software and systems. Among these are the post−processing system GEONAP and the real−time system GNSMART. Andreas Bagge got his Dipl.−Ing. in Geodesy from the Universität Hannover. Since 1986 he works in the field of GPS, first at the Universität Hannover, and now for several years at Geo++®. Dr. Martin Schmitz received his degrees in Geodesy from the Universität Hannover. He has been working in the field of GPS for the industry and as a research fellow at the Universität Hannover since 1991. All authors are currently employed at Geo++®. They ar