Communication Options for Network RTK / SAPOS ® Realization

Abstract- Real-Time Kinematic (RTK) service providers compute RTK corrections based on the observations of networks of GNSS (Global Navigation Satellite Systems like GPS or GLON-ASS) reference stations with station distances of about 50 to 80 kilometres. This correction data enables Network RTK users to position themselves with centimetre accuracy in real-time using a single GNSS-receiver. The selection of appropriate communication channels for the distribution of Network RTK corrections is the key to a successful positioning service. The German Satellite Positioning Service SAPOS was one of the first RTK-services using the Network RTK ap-proach. More than 250 reference stations are deployed nationwide. Presently, SAPOS Network RTK corrections are mainly received by mobile phone (GSM). 1 Network RTK Real-Time Kinematic (RTK) positioning with centimetre accuracy requires the re-ception of GNSS code and carrier phase correction data. Observations or observa-tion corrections of a single reference station are transmitted for single-base RTK. In the case of Network RTK the observations of several reference stations are usually pre-processed in a central computing facility and network corrections are then made available to the user. The crucial part of the pre-processing consists of the resolution of the carrier phase ambiguities in the network data [1]