How It Works

The Network
GPS observation data from fixed reference stations (CORS) distributed throughout the network area are continuously streamed to a central server running Trimble GPSNet™ and RTKNet™ software.

Error Correction
The network processor checks the integrity of all GPS observables and then computes the ionospheric, tropospheric, and ephemeris errors for each reference station position. These calculations result in an error model for the network so that the error at any given position within the network can be estimated.

Virtual Reference Station
When the survey begins, the rover provides its approximate position to the central server via cellular modem. The central server consults its error model and generates a “virtual reference station” for that individual rover. The server outputs standard format correction messages (CMR+ or RTCM) as if they were coming from the virtual reference station and transmits them via cellular modem to the rover.

User Requirements

• MWRTK User service agreement (user name and password)
• Rover or other GPS device that supports NTRIP (Networked Transport of RTCM via Internet Protocol) and the VRS broadcast format
• An Internet Data capable cell phone or modem