System Architecture for Server-Based Network-RTK using Multiple GNSS

Improved accuracy and reliability of the real-time user coordinates is expected if GNSS data is processed using the network-RTK technique. Some implementations of conventional network-RTK, e.g. Virtual Reference Station (VRS) techniques, require bi-directional communications via GSM/GPRS since the network server transmits network-corrections to a user, while the user receiver is required to transmit its (approximate) coordinate information to the server. The data transmission from the user is kept to a minimum because the server needs the user’s coordinate information only for “initialization” or “handover”. On the other hand, a server-based network-RTK requires raw measurements from the rover/user receiver in order to compute the rover’s coordinates. There are several commercially available networkRTK systems, however server-based techniques are relatively new in GNSS surveying. In GNSS geodesy, server-based network processing has always been the norm, though rarely in real-time. With the move of the IGS towards a “real-time future”, the distinctions between server-based network-RTK implementations for survey users and for geodesy will be blurred.