Based On Multi-Baseline Interferometer Two-Dimensional Direction Finding Algorithm Research And Implementation

Radio direction finding is a traditional field with a history of more than one hundred years.Early applications were in sea and air navigation systems.It was also an important tool for electronic intelligence acquisition and was used to detect submarines as early as World War II.In addition,a lot of help has been provided in search and rescue operations,live wildlife tracking and other aspects.Therefore,it is necessary to continuously study the radio direction finding technology.Radio direction finding is a process of using instruments to determine the direction of incoming radio waves according to the propagation characteristics of electromagnetic waves.Common radio direction finding methods include specific amplitude direction finding,specific phase direction finding and space spectrum estimation.Among them,the direction finding technology using interferometer phase ratio has high Angle measurement accuracy and simple equipment,which is suitable for a variety of passive direction finding systems and scenes.In view of the complexity of testing methods in actual direction finding,phase compensation table or Angle compensation table under each frequency needs to be recorded,and the testing requirements are harsh.In the face of this shortcoming,a hardware implementation scheme of improved direction finding algorithm of correlation interferometer is proposed in this thesis,and its implementation and testing are carried out.In this thesis,the wideband interferometer direction finding system is taken as the research object,the complex core algorithm of this direction finding system is studied in detail,and it is deeply explored and analyzed.The main work contents are as follows:Firstly,the radio direction finding system is briefly introduced in this thesis.Then,the basic principle of interferometer direction finding and its error analysis are introduced in detail.In view of the problem of phase ambiguity in direction finding,two common methods of multi-baseline interferometer direction finding are described: correlation interferometer and phase interferometer.Secondly,this thesis improves the direction finding algorithm of phase interferometer and related interferometer respectively,and presents and introduces it.Software implementation and simulation of phase interferometer are carried out on MATLAB platform to preliminarily verify the feasibility and design rationality of the algorithm.Secondly,experiments are used to analyze the number of sampling points,signal-to-noise ratio and incoming wave frequency.The influence of incoming wave direction Angle and pitch Angle on the accuracy and error of the system direction finding is pointed out.The existing problems of phase interferometer testing are pointed out.The algorithm of correlation interferometer is improved on the correlation function,which reduces the number of Angle samples required by the sample base and guarantees the accuracy of direction finding.Finally,the ability of the algorithm to calculate the frequency and direction of pulse modulated wave is increased.Then,the wideband related interferometer direction finding system designed in this thesis is elaborated.The wideband related interferometer direction finding system can be divided into broadband antenna module,RF front-end processing module,IF sampling processing module,and signal understanding and calculation software module,which are respectively responsible for completing the conversion from RF signal reception to IF,analog signal to digital signal.Fast Fourier transform processing and each channel frequency and phase solution,incoming wave signal azimuth Angle and pitch Angle data display.Finally,the wideband correlation interferometer direction finding system designed by this pair is tested in the field.By comparing the simulation results with the software results,the hardware system index requirements are proved,and the feasibility of the algorithm is verified.