Key Technologies Of Spatial Monitoring Based On Passive Direction Finding Of External Radiation Source

With the rapid development of former science and technology,new technologies have been continuously applied to military affairs at home and abroad.Various stealth fighter jets,bombers,ultra-low altitude aircraft,and various types of UAVs have been widely used,challenging the traditional active detection mode.A new theory of direction finding for external radiation sources has been proposed and continuously developed.This article mainly studies and improves the direction finding algorithm in the external radiation source direction finding system,so that the external radiation source direction finding system can monitor fixed airspace through external broadcast signals and other non cooperative signals,and adapt to direction finding work under different functional requirements.In practical applications,multiple DF base stations can be deployed to monitor fixed airspace through collaborative work between multiple base stations.The specific content is as follows:Firstly,this paper introduces the basic composition of passive direction finding systems for external radiation sources,models the receiving array antennas and signal sources under study,introduces spatial spectrum direction finding systems and compressed sensing theory,laying a foundation for theoretical research in the following article.Secondly,in the passive direction finding environment for external radiation sources,the signals received by the array antenna are mostly small signal to noise ratio coherent signals superimposed with multiple Gaussian noises.The traditional MUSIC algorithm has poor estimation performance for such signals.Therefore,a fusion MMUSIC-Like algorithm is proposed,which can perform high-precision direction finding for small signal to noise ratio coherent signal sources and can suppress the interference of multiple Gaussian noises,The requirement of high-precision direction finding for external radiation source direction finding systems is realized.Then,in scenarios where there is a high demand for the response speed of the direction finding system,according to the compressed sensing direction finding theory.An improved OMP direction finding algorithm is proposed,which improves the OMP direction finding algorithm through dictionary optimization to achieve fast and accurate direction finding for coherent signal sources under low signal-to-noise ratio conditions,meeting the requirements of high-speed direction finding for external radiation source systems.Finally,this article uses GNU Radio as a software simulation platform to build an external radiation source simulation direction finding system,which includes four modules: signal generation,antenna array,algorithm processing,and result display.By loading the proposed fusion MMUSIC-Like algorithm and improved OMP direction finding algorithm on it,we verify the direction finding performance of the algorithm in the external radiation source passive direction finding environment.Perform direction finding on broadcast signals within the range of 50 MHz to 110 MHz,with an angle error of less than 1 degree and analyze the results.