Research On High Resolution Direction Finding Algorithm For Wideband Radiation Sources

Direction of arrival is an important research content in array signal processing,and plays an important role in many fields such as electronic reconnaissance,biomedicine,and wireless communication.After many scholars' efforts,the narrow-band high-resolution direction finding algorithm has been basically mature and already widely used in the military field.Compared with the narrow-band signal,the wide-band signal has gained a lot of attention because of its unique advantages such as carrying large information and strong antiinterference ability.Therefore,it is of great significance to study the high-resolution direction finding algorithm of wide-band signal.The main research work and achievements of this thesis include:The first part of the thesis introduces the relevant theory of DOA estimation and the classical non-coherent signal subspace algorithm ISM.Firstly,the assumptions of the physical environment and the concept of broadband signals are explained.On this basis,the frequency domain model of broadband signals is studied and analyzed.Secondly,the factors affecting DOA estimation and the problems in DOA estimation of wideband signals are described.Finally,the classical non-coherent signal subspace algorithm is theoretically analyzed,and the performance of the algorithm is verified by simulation.In the second part,the ISM algorithm is computationally intensive and cannot solve the coherent signal source.The coherent signal subspace algorithm CSM is introduced.Firstly,the principle of CSM algorithm is studied and analyzed.The classical RSS algorithm of this kind of algorithm is taken as an example to study the construction method of focusing matrix.Secondly,considering that the CSM algorithm generally needs to reconstruct the iterative estimation of the focus matrix based on the searched peak results when improving the estimation performance,there is still a problem of large computational complexity.Therefore,this paper proposes a wide-band signal DOA estimation method based on realvalued matrix.The proposed algorithm uses the imaginary part of the covariance matrix to construct a real-valued matrix,which can not only reduce the search space,but also reduce the computational complexity.Finally,the algorithm is verified by simulation performance.In the third part,the problem of low resolution and poor precision of CSM algorithm in complex electromagnetic environment is studied.The DOA estimation method based on sparse reconstruction is studied and analyzed.Firstly,the rationality and sparse reconstruction model of sparse reconstruction algorithm applied to DOA estimation are studied.Secondly,the classical convex optimization algorithm L1-SVD is introduced to solve the direction of arrival of the signal under sparse representation,and the L1-SVD-focus algorithm combined with the focus idea is analyzed in the background of wideband chirp signal.Finally,for the shortcomings of the L1-SVD algorithm,the number of known sources is needed in the process,and the L1-SRACV algorithm is introduced.In the background of wideband chirp signal,a wideband DOA estimation method based on covariance matrix sparse representation is proposed.This method uses the transformation matrix to reduce the dimension of each column of the covariance matrix,avoiding the influence of noise power,and has no need to estimate the source.The advantages of the number and noise power are verified by simulation to verify the performance of the relevant algorithm.