GMV, a supplier of satellite control centers, has added precise-point-positioning capability to its new web-based global navigation satellite system (GNSS) analysis program called magicGNSS. magicGNSS, is a web-based, user-friendly program that allows users to perform a wide range of calculations and analyses related to GNSS and its augmentation systems. With magicGNSS, users can: Use current or past data from a predefined set of GPS core stations; Upload station data in order to analyze GNSS performance for the user’s specific case study or situation; Process any available data to generate precise orbits, clocks, troposphere and station coordinates; and produce comprehensive PDF reports.
The Orbit Determination & Time Synchronization (ODTS) module was the first available in the suite. ODTS is an algorithm that processes measurements generated by a network of GPS stations worldwide distributed, providing precise satellite orbit and clock estimations and predictions, as well as other outputs (station coordinates, troposphere parameters, etc). Past and current data from a set of core stations from the International GNSS Service (IGS) is available for the user on the magicGNSS server, and the possibility also exists to upload and process RINEX observation files from any user station. A recently added module called COMP allows comparing orbits and clocks from ODTS with IGS ultra-rapid, rapid and final products.
The newest version incorporates the Precise-Point-Positioning (PPP) algorithm. PPP is a relatively new technique for decimeter and sub-decimeter error in positioning, and sub-nanosecond error in timing, using a stand-alone user receiver and precise GPS orbit and clock products calculated beforehand. The user receiver can be fixed to the ground (static PPP) or can be a roving receiver (dynamic or kinematic PPP). PPP is different from other precise-positioning approaches like Real Time Kinematics (RTK) in that no ‘base station’ or surrounding stations are needed. The only observation data that must be processed is the user receiver data itself, thus reducing the bandwidth and calculation power needed for the service. Another advantage is that since the GPS orbit and clock products are by nature global, the PPP solutions are also global, i.e., the PPP approach works for a receiver located anywhere on or above the Earth surface, and the resulting PPP solution (coordinates) are referred to a well-known terrestrial reference frame.
magicGNSS is for anyone interested in processing data from high-grade dual-frequency static receivers for high-precision applications. The outputs from PPP are mainly antenna coordinates, tropospheric delay at the user’s zenith, and receiver clock. Examples of PPP applications are station displacement and tectonic plate motion monitoring at sub-centimeter level, weather forecast from dense GPS receiver networks, and synchronization of remote atomic clocks (via GPS) at sub-nanosecond level.
