System Design Of Frequency Sweeping Radar For Low Slow And Small Target Detection

Nowadays,the low-altitude area is facing openness.Under the situation that gliders,paramotors,especially drones and UAVs are used more widely,it is more urgent to have a complete monitoring system to deal with low-altitude,low-speed and small cross section targets.Therefore,development of a general-purpose radar that has small size,light weight,high reliability,low price,small area blind zone,high range resolution and good anti-interference performance is imminent.Starting from the previous individual soldier detection equipment,this paper designs and implements a radar system capable of detecting and tracking low and slow targets.It is introduced from the aspects of system design,algorithm flow simulation,hardware implementation and system test analysis.Based on the performance goal,the overall scheme of the system is designed.The system is mainly comprised of antenna and radio frequency front-end,signal processor,and the PC software.the radar is designed to be pulsed radar,the antenna operation mode is frequency sweep,the azimuth scanning range is 90°.The structure of RF front-end module and the signal processing board is also introduced.Secondly,radar model of MATLAB has been established according to the previous mentioned radar parameters.The signal processing flow of the system is simulated,including mid-band pass sampling,digital down conversion,pulse compression,moving target detection,constant false alarm,dot formation and target tracking.The simulation results are discussed.Thirdly,The hardware implementation of the system in the field programmable gate array(FPGA)is introduced.Mainly includes clock domain division in FPGA,band pass sampling,digital down conversion and logic implementation of pulse compression algorithm and interface design of Gigabit Ethernet.Finally,the performance of the whole system is analyzed,including the dynamic range,leakage and coherence of the RF front-end.The detection capability of the system is analyzed according to the measured performance of the RF front-end.The monitoring and tracking for a real flight test using DJI drone is mentioned in the final section,in both open area and urban background.Small size of target and weak echo signal results in many false alarms in complex background.Therefore,a method to improve the probability of false alarm is proposed at the end.