Abstract
This case study aims to investigate the effect of different Multi-GNSS EXperiment (MGEX) precise products provided by International GNSS Service (IGS) Analysis Centers (ACs) on post-processing kinematic Precise Point Positioning (PPP) accuracy performance with different satellite system combinations in a dynamic environment. Within this frame, a test was carried out in a lake and kinematic data were collected over 6 h at 1 Hz rate from the available Global Navigation Satellite System (GNSS) constellations with the geodetic-grade receiver fixed on a marine vehicle for bathymetric mapping. PPP-derived coordinates were determined by a commercial GNSS post-processing software with different processing approaches as GPS (Global Positioning System)-only, GPS+GLObal’naya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), GPS+GLONASS+European Global Navigation Satellite System (Galileo), GPS+GLONASS+Chinese Global Navigation Satellite System (BeiDou), and GPS+GLONASS+Galileo+BeiDou. The PPP coordinates were then compared to the reference coordinates obtained from the post-processed carrier phase-based differential kinematic solutions. In general, the results showed that the kinematic multi-constellation GNSS PPP technique could provide positioning accuracy from cm to decimeter level as depending on the collected data constellations and used precise products in the processing. Among all solutions, the GPS+GLONASS+Galileo+BeiDou combination with German Research Centre for Geosciences (GFZ)’s precise products presented the best multi-GNSS PPP performance, rather than the other combinations and quad-constellation alternatives using different precise products. In this study, the test procedure and the obtained results are given in detail.
Highlights
In recent years, the world of satellite-based positioning has experienced dramatic changes
A vessel equipped with Trimble R10 multi-frequency multi-constellation Global Navigation Satellite System (GNSS) receivers with compact antenna was used. 440-channels R10 receivers are capable of simultaneously tracking GPS, GLObal’naya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), Galileo, BDS, QZSS, and NavIC (IRNSS)
In order to achieve this purpose, a nearby single reference station with precisely known ITRF coordinates was used and the coordinates of each measurement epoch were obtained with the Post-12 of Processed Kinematic (PPK) (Post-Processed Kinematic) differential method using GrafNav Software by applying “Both” processing strategy
Summary
The world of satellite-based positioning has experienced dramatic changes. A few decades ago, it was necessary to make carrier-phase based measurements with at least two geodetic-types of Global Navigation Satellite System (GNSS) receivers (one as a rover and at least one for the base) for achieving high accuracy positioning. Nowadays, new methods and techniques using a single GNSS receiver have been developed to make it possible to determine the positions accurately without using data from any reference station. Precise Point Positioning (PPP), as one of the most common and successfully used methods, allows positioning with centimeter to decimeter (dm) level accuracy in static and kinematic applications by using a single GNSS receiver after convergence. Convergence (initialization time) is inevitable due to the phase ambiguity solution required to achieve a highly accurate position. Convergence is a problem only in real-time PPP applications or where only one-way (forward or backward) post-processed PPP is applied
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