Study Of The Key Technology Of Micro-Displacement Monitoring System

Micro-displacement monitoring has great significance for the safety monitoring of large buildings and natural geological disasters, such as landslides. Compared with traditional measurement method, the Interferometry Synthetic Aperture Radar(InSAR) has unique advantages of low-cost, high-precision, all-weather and continuous real-time remote monitoring. Ground-based Differential Interferometry SAR(D-InSAR) has extensive application prospects in local area deformation monitoring. This thesis mainly focuses on three key technologies applied in Ground-based D-InSAR including the Synthetic Aperture technology, the Differential Interferometry technology and the broadband Linear Frequency Modulated Continuous Wave(LFMCW) technology. Furthermore, this thesis emphasizes on the systematic design of the Ground-based D-InSAR.Firstly, according to the micro-displacement characteristics of the local target area, the observation model of Ground-based D-InSAR monitoring system is researched and built in this thesis. This thesis derived the process of deformation measurement, and detailedly analyzes the factors which could affect the measurements, including coherent source and true value calculating error.Secondly, to improve the range resolution of Ground-based D-InSAR system, the broadband LFMCW technology is studied.In this thesis, we have studied and deduced the improved Frequency Scaling(FS) imaging algorithm that uses the transmit signal as reference signal in Ground-based D-InSAR system which adopts the broadband LFMCW institutionThen, according to the method of micro-displacement detection, we have researched image measurement, interference fringes and image noise filtering method to improve the precision. And it focused on the phase unwrapping algorithm, simulated Branch-cut method, Quality-guide algorithm and Least-square method, and comparedthe running time and accuracy of these algorithms. This paper selected the Branch-cut method as the main solution of the phase unwrapping algorithm.Finally, on the basis of theoretical research results, we have designed a scheme of Ground-based D-InSAR monitoring system which based on broadband LFMCW signal. The monitoring range of this system is from 100 m to 4000 m, whose working frequency is 10 GHz, and FM bandwidth is 500 MHz. In this design, signal processing board uses single-chip AD9240 to perform 5 MHz high precision sampling, and uses single-chip Xilinx-XC7VX690T-FPGA to perform high-speed imaging. The function block diagram of this board and signal processing preceduce are given in this thesis. The MATLAB simulation results verify that the parameter settings and system design are correct and measurement accuracy is 1mm. The system has the characteristics of high resolution, low power consumption, low cost and high realizability.