RF Circuit Module And Algorithm Design For The Altimeter Of UAV

As an altimeter of unmanned aerial vehicle,it is necessary to detect the target with the nearest distance below the uav.The purpose is to measure the distance,speed and direction of the target below the UAV.Therefore,millimeter wave radar is selected because of the advantages of long distance,all-weather used and low cost.Firstly,this thesis analyzes the requirements of the RF circuit.Then according to the requirements of the RF antenna and RF circuit simulation design,it makes its performance meet the design goal through the optimization of the simulation software.Finally,the real performance of the antenna is tested in a microwave an-echoic chamber.Based on the demand analysis of radar signal processing algorithm,the overall algorithm structure of the system is designed.In order to get the information of target object,this thesis carries on a series of processing to radar signal.Firstly,a low-pass FIR filter is designed with matlab to filter high-frequency interference signals.Then the algorithm combining FFT and chirp-z is designed to realize the accurate recognition of target signal frequency.At last,the CA-Cfar algorithm is designed to eliminate the environmental interference signals,and the false alarm and missing alarm are eliminated by the combination of amplitude maximum similarity method and variable modulation signal frequency method.In this thesis,the software structure of the system is designed by modular method.Through the test of single target and two targets,the result shows that the radar signal processing algorithm designed in this thesis can accurately identify the information of speed and distance of the target.