Research On Improved Coherent Signal DOA Estimation Algorithm And FPGA Verificatio

With the rapid development of smart antenna technology,the algorithms in the field of array signal processing are becoming more and more mature,especially the subspace class-based DOA estimation algorithms.Subspace class DOA estimation algorithms mainly include two types: one is Multiple Signal Classification(MUSIC)algorithm which applies the orthogonal property of signal subspace and noise subspace,and the other is Estimating Signal Parameter via Rotational Invariance Techniques(ESPRIT)which applies the rotational invariance property of signal subspace.In this paper,we focus on these two types of algorithms.Since the existing subspace algorithms cannot estimate the DOA accurately when the incident signal is a coherent source,this paper makes relevant improvements and verifies them by using Field-Programmable Gate Array(FPGA).The main research contents and results are as follows:(1)Introduce the array signal model for DOA estimation,and on this basis,analyze and explain the mathematical model of uniform line array,the mathematical model of signal and noise,and the knowledge of linear algebra involved in the paper,so as to lay the theoretical foundation for the later research.(2)To study a coherent source DOA estimation algorithm based on MUSIC algorithm.To address the problem that the estimation performance of the MUSIC algorithm decreases rapidly when the incidence angles of the sources are relatively close,the received signal data covariance matrix is reconstructed and the rank of this matrix is restored to full rank,thus improving the estimation performance of the algorithm.Since the MUSIC algorithm cannot locate the angle of coherent sources,the traditional spatial smoothing algorithm is then investigated.The covariance matrix of the spatial smoothing technique is optimized in order to more fully exploit the subarray autocorrelation and intercorrelation information and thus improve the decoherence capability of the algorithm.Finally,the improved MUSIC algorithm and the optimized spatial smoothing algorithm are combined and used to solve the problem of DOA estimation of coherent signals with small angular intervals.(3)A coherent signal DOA estimation algorithm based on the TLS-ESPRIT algorithm is investigated.Due to the influence of noise,the existing coherent signal DOA estimation algorithm has a significant decrease in accuracy when the measurement environment is not ideal.To solve this problem,the smoothed array covariance matrix is reconstructed based on the property of strong correlation between signals and weak correlation between noises,and then the angular information of the signals is determined using the TLS-ESPRIT algorithm.Through simulation modeling,it is found that the method in this paper has high resolution and accuracy under the conditions of low signal-to-noise ratio,small signal source incidence interval and small number of samples.(4)To study the FPGA verification of coherent signal spatial spectrum estimation based on MUSIC algorithm under uniform line array.The hardware system module is mainly composed of three parts: signal covariance matrix construction,eigenvalue decomposition and spectral peak search.Through the hardware modules such as multipliers,registers and address generators inside the FPGA,the system framework is designed and the simulation results of each module are shown by Modelsim,and then compared with the Simulation data of MATLAB,it shows the correctness and engineering value of FPGA design.