Study On Selection Of Permanent Scatterers Of Ground-based Synthetic Aperture Radar And Atmospheric Influence Of Deformation Detection

Various geological disasters that caused by surface deformation not only threaten seriously people’s lives and property,but also brought great economic losses to the country.Effects from natural environment changes and human activities cause the surface instability and deformation,which threaten the safety of artificial buildings,dam reservoirs and other facilities.Therefore,it is necessary to carry out fast,high-precision and real-time deformation monitoring and analyze its mechanism,so that we can make early warning for these risks.Traditional deformation measurements is mature and more accurate,but the observation point is sparse and it’s difficult to provide a large area of surface continuous displacement information,spending a lot of manpower and resources,and threatening safety of the observer.In recent years,the newly developed ground-based synthetic aperture radar(SAR)interferometry not only has the advantages of observing all-weather,all-day and so on,but also can obtain high spatial and temporal resolution and high-precision SAR images.In addition,it is flexible to sele ct position of the instrument,so it has a broad application prospects in the field of displacement monitoring.Based on the study of the basic principle of GB-In SAR in this article,the series experiment of deformation monitoring is carried out.The main researches are as follows:Firstly,the deformation monitoring reliability of Fast GB-SAR is studied.Monitor the reflector that through adjusting percentage to control the deformation at the same time with the Fast GBSAR and the total station.The results show that the Fast GBSAR monitoring results coincide with the total station results.Secondly,a improved method of SAR PS point selection based on average coherence coefficient,amplitude difference index,estimated SNR and displacement precision index is proposed,which effectively improves the quality of selected PS points.Through field verification,compared and analyzed the selected PS results of amplitude difference index threshold method,average coherence coefficient method and the improved method,the results show that the quality of PS obtained by the improved PS method are better than single threshold method(amplitude difference threshold method or average coherence coefficient method).Finally,setting atmospheric correction model with select ed PS points and atmospheric correction tests are introduced.The PS is extracted in the test of Yuehu bridge and small slope by using the improved PS method.The PSC is extracted from selected PS in the Yuehu bridge experiment,which is used to correct at mospheric phase.By comparing the nine PS points before and after atmospheric correction,it demonstrates that the atmospheric correction method with the global PSC point has been improved accuracy of results in the experiment.In the small slope test,the atmospheric correction network was constructed by manually selected PS.By comparing 9 extracted points of the time series deformation maps of before and after atmospheric correction,the results show that it is improved accuracy of measurement results effectively to use the atmospheric correction network.