Research On Signal Detection And Direction Finding Technology In Endangered Birds Monitoring System

Radio telemetry is an important means of monitoring endangered birds.Signal detection technology and passive direction finding technology are the basis for realizing radio telemetry.Through radio telemetry,high-precision azimuth information can be obtained in a small area in real time,which is of great significance for studying the movement laws of endangered birds and establishing an information database of the living environment of endangered birds.At present,commonly used technologies such as bird encircling technology,microwave radar technology and satellite tracking technology generally suffer from deficiencies such as high labor intensity,high cost,and delayed data collection.In order to obtain real-time location information of endangered birds in a small area,this paper studies signal detection technology and passive direction finding technology.The main contents of this paper are as follows:1)Mainly study the signal detection algorithm.The cyclostationary feature detection,energy detection and matched filter are studied,and the working principle of each algorithm is explained.The matched filter algorithm is analyzed through simulation experiments.The advantage of the matched filter is that while maximizing the received signal-to-noise ratio,it can complete synchronization in a short time and increase the signal processing gain.2)Mainly study the commonly used passive direction finding algorithms.First of all,it studies the amplitude-comparison direction finding algorithm,analyzes and introduces its working principle,and analyzes the factors that affect the performance of the amplitude-comparison direction finding algorithm through simulation.Then,the interferometer direction finding algorithm is studied,the working principles of the phase interferometer and the related interferometer direction finding algorithm are analyzed and introduced,and the factors affecting the performance of the related interferometer direction finding algorithm are analyzed through simulation.Finally,the direction finding algorithm for multiple signal classification is studied,its working principle is analyzed,and the algorithm performance under multiple parameters is studied through simulation,and the advantages and disadvantages of the algorithm are analyzed.3)In order to overcome the shortcomings of the amplitude ratio direction finding algorithm and the multiple signal classification direction finding algorithm and retain the advantages of the two,a fast and high-precision direction finding method is proposed.This method mixes the amplitude ratio direction finding algorithm with the multiple signal classification algorithm,and takes advantage of the simple structure and high real-time characteristics of the amplitude ratio direction finding algorithm to solve the problem of long time-consuming spectral peak search and excessive resource consumption of the multiple signal classification algorithm.Through comparative analysis,the fast and high-precision direction finding method consumes more than 80% less time than the multiple signal classification algorithm,and at the same time,it has the same accuracy as the multiple signal classification algorithm.4)Based on the theoretical basis of the amplitude ratio direction finding algorithm,design and implement the endangered bird direction finding subsystem.First,according to the signal source parameters and the principle of the amplitude ratio direction finding algorithm,a high-gain directional antenna is selected and the antenna pattern is measured.Then,design the antenna array base according to the antenna pattern.Finally,the ZC702 development kit based on the Zynq-7000 series AP-SoC is used as the direction-finding subsystem signal processing platform;the FMCOMMS5 evaluation board based on the radio frequency transceiver AD9361 is used as the direction-finding subsystem receiver.According to the system design requirements,the hardware system architecture combining the ZC702 development kit and the FMCOMMS5 evaluation board was determined.Using the concept of software and hardware collaborative development,the system was designed to realize the required main functional modules.5)Conduct field tests on the prototype of the passive direction finding system at the test site of Sichuan Skyeye Technology Co.,Ltd.In order to protect the ecological environment and reduce the impact of field tests on the lives of endangered birds,the DJI Spirit 4A quadrotor UAV image transmission signal is used as the signal source to test the key performance indicators of the system and record the experimental data.