Research On Technology Of Calibration Of Interferometer Direction Finding

As modern high-tech countermeasures become more and more abundant,controlling and using the electromagnetic spectrum is an important area in which various camps are competing for development.As an important method of passive Direction Finding,Interferometer Direction Finding is widely used on various platforms such as ground,airborne,and shipborne.It can quickly obtain non-cooperative electromagnetic wave parameters and bearing.Calibration technology has become an indispensable technology for accurate interferometer direction finding because of channel phase error and other reasons.In this thesis,the following analysis and research are carried out on the calibration technology of Interferometer Direction Finding:One is to study the related theory of Interferometer Direction Finding.It summarizes the common structure of the interferometer direction-finding system,and derives the angle calculation methods of the one-dimensional single-baseline Interferometer Direction Finding System and the two-dimensional circular array Interferometer Direction Finding System.The analog extraction method and digital extraction method of phase difference extraction in the Interferometer Direction Finding System are analyzed.At the same time,the angle and phase ambiguity problems that may occur in the direction-finding are analyzed.The second is to analyze the sources of direction-finding errors that may occur during the direction-finding process of the Interferometer.The conclusion is that the Direction Finding error mainly consists of frequency measuring error,antenna phase center error and phase difference error.Among them,the error analysis was carried out separately according to different frequency measurement methods;the analysis of the phase difference error generated by different subsystems.The third is to calibrate and simulate Direction Finding Errors.The analysis of Antenna Phase Center Calibration and channel calibration is carried out.The Antenna Phase Center Calibration is divided into microwave darkroom method and external field calibration method according to different sites;channel calibration mainly includes external signal source method,filter calibration method and automatic calibration method.In order to improve the calibration efficiency of the Interferometer Direction Finding system and adapt to the calibration requirements in different environments,an adaptive real-time calibration method is proposed.Finally,the MATLAB simulation was performed using the adaptive real-time calibration method.From the simulation results,it can be seen that the adaptive real-time calibration can solve the Direction Finding errors caused by the Direction Finding Errors of the Interferometer.