Research On The Imaging Mechanism And Key Techniques Of Cognitive Through-the-wall Radar

In this paper,the imaging mechanism and other key technologies of cognitive through-the-wall radar are studied by using the information sensing technology in cognitive radar,supplemented by waveform optimization technology.The multi-input and multi-output(MIMO)wall imaging radar is used as the platform.The main work and innovation points are as follows:In the aspect of electromagnetic environment information perception technology,an on-line estimation method of Radio Frequency Interfence(RFI)based on minimum statistics is proposed,which can improve the accuracy of electromagnetic environment information.And in order to reduce the damage of RFI suppression to the target behind the wall,a new RFI suppression method based on iterative sparse reconstruction is proposed,which has better ability of weak target protection compared with the existing reconstruction class method.In the aspect of background environment information perception technology,an extended target enhancement imaging method based on power spectral coherence factor is proposed,which effectively improves the problem of high grating lobe level in traditional building structure imaging.And in order to further improve the imaging performance of building structure,a sparse imaging method of building structure based on coherent factor enhancement is proposed in this paper.Compared with the traditional sparse imaging method,the method in this paper has better reconstruction stability and convergence speed.In the aspect of target information perception,this paper first analyzes the influence of the human moving target behind the wall on the traditional radar imaging method,obtains the distribution information of the maximum allowable speed of the target,and puts forward the background information assistant interpretation method based on Spatial Doppler processing and 3-D constant false alarm detection for the ghost clutter problem.Then the negative influence of traditional waveform optimization method on through-the-wall imaging is analyzed,and on this basis,a double constrained waveform optimization method considering the performance limitation of emission energy and signal one-dimensional impulse response is put forward.This paper also analyzes the relationship between the moving target imaging problem in MIMO radar and the problem of Focus Before Detection(FBD)in traditional radar signal processing,and puts forward a multi-pulse combined imaging method for MIMO radar with multi-pulse sliding range-velocity projection technology as the core.All the above methods are effectively verified by simulations or measured data.