Research On Super-resolution Electromagnetic Imaging Positioning Algorithm For Passive Intermodulation In Complex Environment

With the more intensive use of the communication spectrum,the gradual application of high-power transmitters and receivers requiring higher sensitivity,and the increasing integration of high-power devices,passive intermodulation has gradually become impossible in the field of wireless communication.Neglected interference sources are being paid more and more attention by people in the field.Although there are passive intermodulation detection technologies such as passive intermodulation testers,there are still relatively few studies on air interface passive intermodulation positioning methods that have complex internal electromagnetic environments,cannot be easily disassembled,and require short test time,especially There are still deficiencies in the imaging and positioning of passive intermodulation by means of electromagnetic imaging.Facing the above problems in the existing research,this paper conducts research on the superresolution electromagnetic imaging positioning algorithm of passive intermodulation in complex environments.Firstly,the background and significance of passive intermodulation electromagnetic imaging positioning work are introduced,and the domestic and foreign research history and recent research status of electromagnetic imaging methods based on compressive sensing are introduced,and the effectiveness of compressive sensing algorithms in the field of electromagnetic imaging is explained..The basic theory of compressive sensing electromagnetic imaging algorithm is deduced and summarized.Starting from the basic signal model,the mathematical model of compressed sensing,the construction of transmission matrix and the reconstruction of sparse signals are deduced,which provides theoretical support for the electromagnetic imaging of passive intermodulation by compressed sensing algorithm.At the same time,the commonly used reconstruction algorithms and performance analysis evaluation indicators are introduced to facilitate the comparison between different results.Secondly,for the problem of locating multiple passive intermodulation with a small number of antennas,an electromagnetic imaging method based on frequency expansion compressed sensing is proposed,which proves the feasibility of the method theoretically and has been verified by numerical simulation.Aiming at the localization problem of using a small number of antennas for multiple passive intermodulations and when passive intermodulations are submerged by sidelobes,an electromagnetic imaging method based on coprime array synchronous imaging compressed sensing is proposed.Firstly,the basic theory of coprime array is introduced,and then the transmission matrix screening method and fuzzy synchronization principle used in this method are introduced,which realizes the high-precision positioning of multiple passive intermodulation,and the existence of submerged passive intermodulation successful positioning.Finally,an electromagnetic imaging method based on compressive sensing based on the local sliding polynomial noise reduction algorithm is proposed,which solves the problem of accurate super-resolution positioning of passive intermodulation in the environment of extremely low signal-to-noise ratio.The algorithm principle and implementation process of the local sliding polynomial noise reduction algorithm are introduced.Through the electromagnetic imaging experimental system built,the highprecision positioning of passive intermodulation under the condition of extremely low signal-to-noise ratio is realized,and super-resolution imaging of multiple passive intermodulations can still be performed.