Extracting relevant patterns from GNSS observations to mitigate multipath in RTK deformation monitoring

Abstract Employing high precise positioning ability, the Global Navigation Satellite Systems (GNSS) could accurately capture subtle deformations in bridges, supplying critical data for structural health monitoring. However, GNSS antennas placed on bridges often encounter multipath interference generated by bridge deck and water surface reflections, compromising the quality of observation data and positioning accuracy. Through the analysis of GNSS data collected from an operational bridge, we discovered a strong correlation between pseudorange multipath and carrier multipath components. Subsequently, through a series of steps including phase adjustment, decorrelation, and resolution, we successfully mitigated the multipath within residuals, and then reconstructed the corrected residuals into displacements; in addition, the method does not require advance deployment of GNSS equipment to collect calibration information. In terms of positioning results, this method improves by 69.8% compared to the original kinematic resolution and by 32% compared to the least squares method. The residuals of each satellite are reduced by 33.2% compared to kinematic resolution, effectively weakening the multipath interference in carrier phase observations and significantly improving positioning accuracy.