Research On Two-dimensional DOA Estimation Algorithm

The main purpose of array signal processing is to master the basic theory and method of acquisition and processing of space incident signal.The DOA estimation is a major branch of array signal processing.It is developing rapidly and widely used in civil and military applications.Such as beamforming algorithms,signal subspace-based algorithm,maximum likelihood estimation algorithm and so on.In the actual space electromagnetic environment,with the existence of multipath propagation and the electronic interference,the signals from different paths are often coherent or highly correlated.In such a case,leading to the conventional DOA algorithms cannot track the true subspaces.Therefore,in the coherent source conditions,obtaining accurate parameter estimation has become an important research topic.At present,The common preprocessing approaches for coherent or highly correlated sources are the spatial smoothing(SS).The main is to solve the problem of the rank loss of the covariance matrix by finding the mean of the covariance matrix of each subarray.They decorrelates the signals,however,with a reduced effective aperture of the array.In response to this problem,a preprocessing method,called temporal smoothing(TS)technique,was recently presented for the decorrelation purpose in moving source scenario,without reducing the resolution of the array.The traditional DOA estimation algorithm basically uses the second-order cumulants,ie,the autocorrelation matrix.The non-Gaussian signals are included in the higher-order cumulants matrix,and the higher-order cumulants have important properties of array expansion.In this paper,a temporal smoothing(TS)and fourth-order cumulants joint estimation algorithm based on L-type array is proposed.Then,the new algorithm and the classical MUSIC algorithm are simulated and analyzed by statistical experiment,which verifies the advantages of high accuracy and good performance.From the actual situation,conformal array antennas(CAA)promising applications in a variety of fields.Conformal array antennas(CAA)can save space,weight and can effectively reduce the air resistance,and is very conducive to the military in the concealed design.However,the conformal array antenna(CAA)is very complex.It is special array form and complex electromagnetic field characteristics.It also has a serious cross-polarization effect.In this paper,establishing a cone-shaped conformal array model and analyzing its polarization.We derive the polarized steering vector and the airspace steering vector of the conformal array.This paper also introduces the application of ESPRIT algorithm in conformal array.For the coherent source conditions,Spatial smoothing(SS)algorithm reducing the resolution of the array.And so we propose the temporal smoothing and fourth-order cumulants joint algorithm based on conformal array.Since the new algorithm combines the temporal smoothing algorithm,it doesn't reduce the resolution of the array.The new algorithm also combines high order cumulants with array expansion performance.Finally,we have done a number of statistical experiments to verify the superiority of the algorithm.