Multi-point Interferometric Measurement Technology Of AgileDARN High Frequency Radar Antenna Array

The ionosphere is the space environment which is more than 60 kilometers above the earth's surface,and is the most active area of human being.With the progress of science and technology,more and more scientific research activities are affected by the ionosphere.Therefore,ionospheric sounding-work has been the focus of scientific research,especially in the middle and high latitudes.From the beginning in the middle of 80's,with the development of high-frequency radar which detect ionospheric in the middle and high latitudes in the world,the Super Dual Auroral Radar Network(SuperDARN)has been set up.The SuperDARN has become an important tool for studying the ionospheric activity in the polar region due to its wide geographical coverage and high precision continuous measurement.China's high latitude ionospheric exploration activities started relatively late,the South Pole high-frequency radar of the zhongshan station,which was completed in 2010,joined the SuperDARN radar network,and made a number of important breakthroughs.In order to meet the need of the high latitude ionosphere detection within the territory of China,in support of the ziwu project phase two,the National Space Science Center of CAS is developing a sensitive dual-auroral HF radar,The radar uses the full digital phased array technology to realize the arbitrary scanning of the radar-beam in the field of view,which breaks through the limitation of the fixed beam and the fixed beam interval of the traditional SuperDARN radar.The elevation information can be used to determine the height of the target,which is a necessary parameter to detect the ionospheric irregularities and convection.In the world,the acquisition of elevation information is an important and difficult research topic in the field of ionospheric sounding.The SuperDARN radar uses the mature single baseline measurement algorithm and other models to obtain elevation information,but it is always accompanied by the 2? aliasing effect.A new generation of TIGER-3 radar introduced the idea of multi-baseline to eliminate the 2? aliasing effect,so as to obtain the elevation information accurately,however,the antenna array has the disadvantages of large area and low gain,and is not suitable for the traditional high frequency radar.However,the full digital phased array technology of AgileDARN radar provides a possibility for the balance of various factors and the accurate elevation information.The purpose of this thesis is to research and design the elevation measurement system of Agile DARN radar system: Design and analysis the elevation measurement algorithm and Build the software platform of FPGA system for AgileDARN radar.laying the foundation for the follow-up.The main work of this thesis is as follows:(1)The development of SuperDARN radar at home and abroad is analyzed,and the most commonly used elevation measurement techniques in the world,such as the single-baseline measurement algorithm and the algorithm of the double-interference subarray measurement technology,are analyzed.At the same time,the influence factors,accuracy,advantages and disadvantages of the algorithm are analyzed and studied in detail.(2)Deep understanding and analysis of the AgileDARN radar system and the digital phased array technology.Based on the AgileDARN radar system,design elevation measurement algorithm,and analysis the accuracy of the measurement algorithm,finally,gives the algorithm model.(3)Based on the design requirement of the elevation measurement algorithm,the FPGA software platform of radar digital system is designed and implemented in detail,and the logic function of each module is verified by ISim and Modelsim simulation software.At the same time,we develop the FPGA software program of multi-baseline data,and get the complete software platform.(4)The algorithm model is built in MATLAB to verify the validity of the algorithm,and preparation of high frequency radar elevation measuring instrument software for using in the future.In this thesis,the radar test system is used to verify the function of the FPGA software platform,and the whole working link of the radar digital system is verified,which lays a solid foundation for the following work.