The effectiveness of a multiple-frequency global navigation satellite system (GNSS)on multipath mitigation

Abstract

[Abstract]: Positioning technology is progressing at a rapid pace. One of the latest developments is the availability of Global Navigation Satellite System (GNSS) receivers. RTK (Real Time Kinematic) GNSS receivers have the potential to increase satellite coverage and improve satellite geometry with the additional available satellites from the GLONASS constellation. This will prove beneficial to users who work in difficult operating environments such as open pit mines or urban canyons. This research is interested in the effect of difficult operating environments (i.e. obstructed satellite window and high multipath presence) on the RTK GNSS receiver’s ability to operate. This research project has tested and compared the performance of an RTK GNSS receiver to a RTK GPS (Global Positioning System) receiver. The antenna was setup in a difficult operating environment where there was a multipath presence, and almost half of the satellite window was blocked. An analysis of the results allowed conclusions to be made about the compatibility of the combined GNSS satellite positioning frequencies of GPS and GLONASS satellites in a difficult operating environment, and about the effectiveness of a multiple frequency GNSS to mitigate multipath compared to a receiver observing solely GPS satellites. From the results of the tests, it was found that the GNSS receiver has a superior ability to mitigate errors associated with multipath. This was demonstrated as the GNSS receiver had 7% less outlying observations than the GPS receiver in a high multipath environment. The GNSS receiver also had 33 more initialisations and a decreased time to first fix (TTFF) of 17 seconds. The results indicated that the GNSS receiver’s accuracy and precision was comparable to the GPS receiver. This research shows that users who work in difficult operating environment (i.e. obstructed satellite window, high multipath) will benefit from the advantages of an RTK GNSS receiver which include; increased satellite coverage, improved TTFF and increased initialisation reliability.