High Speed FPGA Implementation Of Active Jamming Countermeasure For Missile Borne Radar

This thesis focuses on the active interference countermeasure system of missile borne radar,and completes the FPGA implementation of the short time Fourier transform.Based on the implementation plan,the interference recognition experiment of the active interference signal is completed.We have studied the active interference countermeasure strategy of missile borne radar based on radio frequency cover and frequency decoy,and completed simulation and FPGA implementation verification.The main work and contributions of this article are as follows:1.The design scheme of the active jamming and countermeasure system for missile borne radar was studied.Based on the types of active jamming and the expected functions of the jamming and countermeasure system,the architecture of the jamming and countermeasure system in this thesis was presented,and the design principle of the system,corresponding FPGA design scheme,and system functions were explained.2.Based on the principle of the Short Time Fourier Transform and the expected performance of the interference countermeasure system,the FPGA implementation of the Short Time Fourier Transform was completed.The implementation scheme adopts the Fourier transform of stream mode and 75% data overlap rate,and selects Hanning window as the window function to ensure that the running speed and time-frequency resolution of the module meet the performance requirements of the system.Based on the FPGA implementation of the short time Fourier transform,interference recognition experiments were conducted on the active interference signal of the missile borne radar.By analyzing the time-frequency characteristic maps of the measured interference signal and other experimental results,the feasibility of using the short time Fourier transform FPGA to achieve the interference signal recognition function was demonstrated.3.Based on the principles of radio frequency shielding technology,interference countermeasures against speed dense false target interference and intermittent sampling and forwarding interference were studied.Under the working mechanism of sampling and forwarding,the interception stage and interference forwarding stage of the jammer cannot work simultaneously.In response to this weakness,a radio frequency cover interference countermeasure strategy suitable for sampling and forwarding type interference and false target type interference is proposed.Based on the countermeasure strategy,the timing of radar signal transmission is designed,and the implementation verification of the radio frequency cover interference countermeasure strategy is completed.4.Based on the characteristics of inter pulse frequency agility signals,a frequency induced interference countermeasure strategy was studied to address the weak point of time delay in the frequency band switching of jammers.By designing the radar signal transmission timing corresponding to the interference countermeasure strategy,simulating and implementing it with FPGA,the feasibility of frequency induced interference countermeasure strategy against range false target interference was verified.