Development of a trajectory constrained rotating arm rig for testing GNSS kinematic positioning

The positioning quality of static global navigation satellite system (GNSS) positioning can be assessed and monitored with a known reference point. However, quality assessment of real kinematic data is difficult because the true position of a moving antenna at a specific time is usually unknown. A rotating arm rig with one end hosting a prism or a GNSS antenna is proposed. With a prism mounted on the rig and by measuring the prism at more than three positions with a total station, the true circular trajectory can be mathematically determined and served as the reference in kinematic GNSS positioning testing. The RMS errors of estimated trajectory in Easting, Northing, and vertical components are 0.29 mm, 0.30 mm, and 0.41 mm, respectively. Six test cases are performed in different environments with the rotating arm rig placed near to a wall, near to a building and in an open clear area. The results show that in kinematic conditions GNSS double differenced carrier phase residuals are from 2.5 mm to 4 mm, and carrier phase multipath errors of relative positioning are from few millimeters up to 4 cm with resolved ambiguity. The test also show that the positioning quality can be improved with a higher sampling rate (10 Hz) and using full GNSS consultations, but less affected by changing speed of rig rotation. These tests demonstrate that the proposed rig can be used for validation and performance assessment in GNSS research.