复杂环境下GNSS滑坡监测多路径效应分析及处理方法

Multipath Effect Analysis and Processing Method of GNSS Landslide Monitoring Under Complicated Environment

GNSS-RTK技术用于地形地貌、植被环境较为复杂区域监测形变时,因反射引发的多路径效应会对形变监测结果产生较大影响,严重制约该技术应用于高精度滑坡监测。针对复杂环境下GNSS滑坡监测多路径效应,通过采集秦巴山区监测环境与黄土监测环境下GNSS滑坡形变监测数据,对不同环境的可视卫星观测范围、信噪比及多路径效应序列进行详细分析,并利用恒星日滤波法对多路径效应序列进行修正,验证复杂环境下削弱多路径效应的方法和精度。结果表明:受监测地形影响,多路径效应与低高度角相关关系减弱,采用单一截止高度角削弱多路径效应的方法不适用;复杂环境引起的多路径效应可达2m,其定位精度无法满足形变监测要求;通过小波去噪,对定位结果采用恒星日滤波法提取误差趋势项,并用于相邻两天的定位误差实时修正,发现采用恒星日滤波法进行多路径效应修正后使定位残差提高至毫米级,东、北和高程3个方向精度分别提高84.38%、72.88%、64.84%。

GNSS-RTK technology has been widely used in deformation monitoring.However,the multipath effect has a great impact on deformation monitoring under complicated environment,which seriously restricts the application in high-precision landslide monitoring.In order to eliminate the multipath effect of GNSS landslide monitoring under complicated environment,the GNSS landslide deformation monitoring data under Qinba mountain area and loess monitoring environments were collected to analyze the range of visible satellite,SNR and multipath effect sequences,and the sidereal filtering method was used to correct the multipath effect sequences,and to verify the method and accuracy for weakening the multipath effect under complicated environment.The results show that because of the terrain,the correlation between multipatheffect and elevation is weakened,and the single cutoff elevation is not fine to weaken the multipath effect;the multipath effect under complicated environment is up to 2 m,which can not meet the requirements of deformation monitoring;based on wavelet denoising,the error trend terms are extracted from positioning results by sidereal filtering method,and are used to correct the positioning error of two continuous days in real time;the positioning residual errors are promoted to millimeter-level,and the accuracies in east,north and elevation directions increase by 84.38%,72.88% and 64.84%,respectively.