Research On Coherent DOA Estimation Algorithm In Complex Electromagnetic Environment

In the modern information war,the face of battlefield electromagnetic factors of land,sea and air,electricity,five integrated battlespace.The struggle between the two sides of the information countermeasure,high density,high strength,multi-frequent electromagnetic wavestransmitted by many kinds of weapons and equipment,and background noise make the electromagnetic environment of battlefield extremely complex.The Existing DOA estimation methods when applied to DOA estimation under complicated electromagnetic environment due to multiple source,low SNR and coherent interference makes the algorithm performance serious decline.In this paper,we mainly focus on the case of coherent signals,angle closecausethe problem of the serious decline of DOA estimationalgorithm error and resolution performance,the main research contents of this paper are summarized as follows:(1)By analysis of traditional space smooth coherence technology solutions,the method at the expense of the number of arrays to achieve the purpose of coherent solution.For a given array,reduce the array aperture means lower resolution coherent spatial smoothing solution algorithm performance.Aiming at this problem,this paper proposes an improved spatial smoothing algorithm.By constructing a matrix,the number of smooth subarrays is equal to the number of elements in the original array.And then forward-back spatial smoothing,equivalent to increase the number of elements,improved algorithm performance,computer simulation verifies the effectiveness of the algorithm.(2)Aiming at the problem that the traditional MUSIC algorithm has the problem of angle-ambiguity because of the limitation of the resolution of the algorithm,when it is estimated the multiple targets have close angles.Introducing of vector polarization factors effectively solve the problem,however,this caused large computational complexity.In this paper,a new dimension reduction MUSIC algorithm is proposed for estimationjoint angle and polarization parameters with pre-estimation.Firstly,according to the established vector electromagnetic arraydata receiving model,reducing the search range viapre-estimation,then by using the constraint condition of the polarization matrix,the angle and polarization parameters are estimated,separately.This method reduces dimension processingand the amount of computation.The simulation results show that the algorithm is of good performance.(3)In recent years,the vector polarization array is used to solve the problem of coherent DOA estimation,the high dimensional matrix operateslarge computational complexity.In this paper,a two-dimensional DOA estimation algorithm based on the correlation PARAFAC model decomposition algorithm is implemented for a polarization sensitive vector L-shaped array.The algorithm makes use of the PARAFAC model decompositionwith good performance of without fuzzy identification model parameters.Due to the PARAFAC algorithm is a three-dimensional matrix decomposition algorithm,it contains the parameters of the spatial domain,the polarization domain and the time domain.In the case that the signalsare coherent and the space angleclosed,the signals can be well resolved.In the end,theperformance of the algorithm is analyzed by comparing with the Cramér–Rao bound.