| In China,landslide accidents cause huge economic losses and heavy casualties every year,so it is urgent to carry out real-time monitoring and early warning of slope deformation by effective technical means.In view of the problems of slow scanning speed,poor ability of penetrating vegetation,difficult deployment and installation of the existing ground-based interferometric synthetic aperture radar,In this thesis,the key technology research and prototype design are carried out for the RF front end of L-band FMCW radar,which also lays the corresponding foundation for further research on the ground-based interferometric synthetic aperture radar.Firstly,the principle of frequency modulated continuous wave radar is analyzed,the characteristics and performance of different frequency synthesis methods are compared and analyzed,and the phase-locked loop frequency synthesis scheme is determined.The working principle of phase-locked loop is discussed,the design of loop filter is emphatically expounded,and the influence of the parameters of loop filter on the system performance is simulated.The design of the frequency source circuit is completed,and the STM32 is selected to configure the AD4159 PLL chip to generate an FMCW signal with a central frequency of 1.3GHz and a bandwidth of 300 MHz.Secondly,the characteristics of the two receiver structures are compared and analyzed.The zero IF structure is adopted,and the appropriate chip is selected according to the requirements of the design requirements.The simulation evaluation of the designed receiver link is conducted by using ADS software.The circuit diagram of the receiver and PCB hardware is presented.Finally,the experimental verification of the designed L band RF front end is carried out,including frequency sweep signal generation and transceiver test.The RF signal and LO signal output with center frequency of 1.3GHz and bandwidth of300 MHz are realized.The coaxial cable is directly connected to the transceiver channel to simulate the radar working scene.The experimental results show that the designed circuit achieves the expected goal. |
