A Multipath Error Mitigation Method for GNSS Kinematic Single Epoch Positioning by Fusing Track Inspection Information

  Objectives  With the rapid development of China's high-speed rail technology, the external geometric parameters rapid extraction of high-speed railway is a new research topic. GNSS kinematic positioning has broad application prospects, but its accuracy is difficult to meet the requirements of track detection. Multipath effect is one of the main factors affecting the accuracy of GNSS kinematic positioning. At present, most of the existing multipath error reduction methods are suitable for static measurement, but there is no effective method to reduce the kinematic multipath error.

  Methods  The GNSS observation data are solved by using the traditional algorithm and the geometric information of track inspection as constraints, and then compared the measurement results affected by multipath with the accurate information of track inspection. Meanwhile, wavelet multi-scale analytical method is applied to separating the multipath error from the noise in the coordinate residual sequence, and the clean coordinate series is obtained.

  Results  The accuracy of the double difference model can be improved by about 19% in the east-west direction, 20% in the south-north direction and 18% in the elevation direction based on the constrained adjustment with the track longitudinal level. Reducing and eliminating the multipath effect and noise in the coordinate domain by wavelet multi-scale decomposition algorithm, the accuracy is improved about 19%-21% in the east-west direction, 15%-18% in the south-north direction, and 9%-20% in the elevation direction. The combination of track longitudinal level constraint adjustment and wavelet filtering can improve the positioning accuracy by 35% in the east-west direction, 31% in the south-north direction and 25% in the elevation direction.

  Conclusions  The multipath error and observation noise can be effectively extracted by combining track inspection information with GNSS data, the multipath error in coordinate domain can be further weakened by wavelet correlation analysis, and the accuracy of GNSS kinematic positioning can be improved to meet the requirements of high-speed track measurement.