High Resolution DOA Estimation Technique For Array Coherent Signals

Aiming at high resolution DOA estimation techniques for array coherent signals,different decorrelation methods for narrowband signals and focusing matrices for wideband signals were studied,as well as some new wideband focusing methods.The main research content and innovation points in this paper are as follows:A DOA estimation method for narrowband coherent signals was studied.Due to the big estimation error under low SNR,a data processing method was designed.Taking advantage of the mean of enough simulation results,the final results matched the conditions were selected,and the precision of DOA estimation was improved.Based on the DOA estimation method using one snapshot,a new method using one snapshot which is independent of the correlation and snapshot is proposed.Moreover,due to the poor performance under low SNR,a cumulating method was proposed using the periodicity of transmitted signals and simulation results indicated that the proposed method could provide better DOA estimation performance under low SNR.A construction method for focusing matrixes was studied in which a preliminary estimate of the DOA was necessary or not.Effects on the DOA estimation performance from different focusing matrixes were analyzed.A discrete array manifold wideband focusing method was proposed.It didn't require a preliminary estimate of the DOA and avoided the calculation of Bessel function in the array manifold interpolation method,which decreases the complexity of computation effectively.The simulation results were presented,which indicated the proposed method was effective.Spatial resample methods and spatial-temporal DFT projection methods which don't need focusing matrices were studied.The idea of data reconstruction was transplanted into wideband MVDR algorithm,and the simulation results showed that data reconstruction methods could provide lower SNR threshold of resolution and lower root mean square error than FFT interpolation method for MVDR algorithm.An improved spatial-temporal DFT projection method was proposed.By increasing sampling frequency appropriately,the performance of DOA estimation can be improved.Using esprit-like algorithm,the real-time is good.Simulation results indicated that spatial-temporal DFT projection method could give better DOA estimation performance than FFT interpolation method.DOA estimation methods using Bayesian Focusing for Coherent Wideband signals were studied.A new Bayesian unitary Focusing method was proposed,whose weighted function was be adjustable adaptively according to the preliminary DOAs and preliminary beamwidth.Simulation results indicated that the proposed method could reduce the computation of preliminary estimate of the DOA and it had better performance than Rotate Signal Subspace(RSS)method.