Stability And Automation Of GPS/BDS Deformation Monitoring Datum

The principle of GNSS deformation monitoring is to obtain the coordinates of the monitoring station relative to the reference station by solving the baseline between each monitoring station and the reference station.The change of the coordinates of the monitoring point reflects the deformation of the object.However,the reference station may be unstable.The displacement of the reference station causes the difference of its coordinates to be mixed into the coordinates of the monitoring station,thus affecting the deformation value of the monitoring point.At present,post-processing is used in stability monitoring of reference stations,and the monitoring results lag behind in time and the data processing is complex.In this context,this paper proposes to monitor the stability of the reference station with a long baseline or an extraterritorial benchmark,build a reference benchmark with IGS or other CORS stations,and automatically resolve the long baseline between the CORS station and the reference station to obtain the coordinate time series of the reference station.The monitoring results and coordinate time series of different periods were analyzed to identify the unstable reference points.Moreover,the original deformation monitoring system is upgraded and optimized,so that the system can carry out high-precision deformation monitoring and ensure the stability of the whole monitoring net.The improved system can be used for engineering deformation monitoring and geological disaster monitoring.The main research contents of this paper are as follows:1.This paper expounds the theory of GNSS baseline calculation and stability monitoring of reference station,analyzes the error influencing factors and treatment strategies of long baseline calculation.2.Research and development of wide range and high precision Beidou /GNSS benchmark stability automatic monitoring and analysis software(BSMA).On the basis of the original deformation monitoring software,a long baseline calculation module,a precise ephemeris module and an automatic file download module are added to realize the post-mortem and realtime calculation of reference station coordinates.It can process mixed data of popular GNSS receivers,and can process L1,L2 GPS,and B1,B2 signals of BDS.The displacement calculation of 200 km between the regional CORS station and the reference station is realized.3.The stability,reliability and accuracy of the software are analyzed by using BSMA to process the actual data.The post-processing model was used to calculate the different data in the coastal zone,the seismic fault zone and the mountain plateau region respectively,which verified that the software could stably monitor the stability of the long baseline reference station.Using CORS net of SWJTU to test the real-time operation of the software,the results show that the software can automatically monitor.BSMA and GAMIT were used to process the data with a span of two years,and the comparison and analysis showed that the displacement trend of BSMA and GAMIT was highly consistent.The results of datum stability analysis show that there is no obvious local non-tectonic movement trend except P300 station.4.The effect of multipath effect on dynamic monitoring was analyzed.The method of multi-antenna is proposed to correct the original dynamic positioning coordinate sequence by using linear interpolated multi-path,and the accuracy can be improved by up to 50% in the environment of strong multi-path effect.