Research On Key Technology Of UAV-based Millimeter Wave Broadband Obstacle Avoidance Radar Based On FPGA

In recent years,the UAV technology has broad prospects and has been widely used in military and civil fields.UAVs often need to perform tasks in the complex environment.In order to protect the UAV when performing the task,the obstacle avoidance radar is needed to give early warnings and make the UAV to avoid obstacles.This paper is based on the power line obstacle avoidance research which is taken charge of Shandong State Grid Power Research Institute,and the obstacle avoidance radar of UAV is analyzed.The main works in this paper has been done as follows:At the part of the transmitter,a VCO open loop linear correction method based on FPGA is proposed for the generation of linear frequency modulation continuous wave(LFMCW).The D/A chip which is controlled by FPGA adjusts the VCO's open-loop wide-band linearity correction.At the same time,the VCO can generate the LFMCW with arbitrary width by controlling the clock of the FPGA.The process of designing the power divider,frequency multiplier and power amplifier by using ADS is described specifically.At the part of the receiver,the receiving scheme and the design of low noise,mixer and intermediate frequency filtering amplifier circuit are introduced.The intermediate frequency filter can not only filter the clutter and noise,but also realize the function of the equalizer.It can avoid the saturation problem of the amplifier circuit due to the large echo power of the near distance target.At the part of the signal processing,the radar distance detection algorithm is implemented by the FPGA.The schematic and PCB file is designed by the Altium.The plate making,welding and testing are finished,then the correctness and reliability of the program are verified by the plate.Finally,the test datum of the inner field and outer field show that the millimeter-wave obstacle avoidance radar system meets the requirements of UAV obstacle avoidance power line.At the end of 2016,this system has been passed the technical test of Shandong State Grid Electric Power Research Institute.