The Key Technology Of Microwave Radar With Transponder In Multi-point Synchronous Measurement Of Large-scale Structural Deformation Monitoring

Large-scale infrastructure such as bridges and elevated structures are important facilities that guarantee the country’s economic development and the normal life of the people.Their stable operation is related to the safety of everyone’s property and life.The structural deterioration of large structures during long-term service can be most intuitively reflected through deformation.Among various non-contact deformation monitoring methods,radar has the characteristics of all-weather,high-precision,and high-speed measurement.The active different-frequency reflection microwave radar system based on the improved Doppler radar has been able to achieve sub-millimeter single-point measurement at a distance of hundreds of meters,but to realize its engineering application,it needs to study its multi-point technology and multi-point accuracy,further improve the measurement distance,and complete the corresponding software development.Therefore,this article mainly completes the following content.(1)According to the principle of three-dimensional deformation measurement of structure,a mathematical model of one-dimensional displacement deformation and three-dimensional deformation measurement is established;starting from the principle of Doppler radar measurement,the relationship between one-dimensional displacement measurement and phase difference change of active inter-frequency microwave radar is derived,And proposed two phase difference demodulation schemes.(2)In response to the multi-point measurement requirements of active inter-frequency radars,a radar system multi-reflector signal multiplexing scheme is proposed,completed the structural design of the multi-point active different-frequency reflection radar system,and proposed and deduced the principle of the phase difference demodulation technology based on the Fourier transform of the multi-point radar system.(3)Analyze the factors affecting the displacement measurement accuracy of the active inter-frequency radar at multiple measuring points,and derive the analytical expressions of each accuracy influencing parameter in detail,and combine the key parameters to carry out the accuracy simulation of the multiple measuring points to prove its high-precision multiple measuring points Measurement capabilities.(4)In view of the limited measurement distance of the existing radar prototype,the reasons for the limitation of the measurement distance in the two channels of the radar system are analyzed in detail,and the performance requirements of key components affecting the measurement distance of the system are proposed,and the device selection and experiment are completed.It is verified that the signal transmission of 5.8G channel 2km meets the system design requirements.(5)According to the Fourier transform phase difference demodulation principle of multi-measurement points,a multi-measurement radar displacement demodulation unit based on Labview was developed,and the displacement demodulation simulation experiment of the program was completed.