| Beamforming(BF)and Direction of Arrival(DOA)estimation are two important parts in array signal processing,and how to utilize limited resources to improve their effectiveness has always been a focus of research in the field.Vector coprime array(VCA)has gained widespread attention and research due to its advantages of large array aperture,high degree of freedom,and low demand for the number of elements,providing new ideas for array placement and signal processing.However,the sparse nature of the coprime array not only gains the advantage of larger array aperture,but also brings about gate lobe interference and high sidelobe problems.The effect is poor in the case of multiple targets,so it can be solved from two directions:improving beam effect and using high-resolution algorithms.However,the virtual array domain where the high-resolution algorithm is located also has the defect of insufficient information utilization.This article focuses on these problems by suppressing coherent multi target gate lobes Research is being conducted on improving the high-resolution spectral estimation performance of coprime matrices and optimizing the arrangement of vector coprime matrices.The main work of this article is as follows:(1)The structural characteristics and performance of vector coprime array,vector coprime array signal model and basic signal processing methods are studied,and the advantages of conventional beamforming,product method and minimum method of the coprime array are analyzed and verified,which can obtain larger array aperture under the same number of array elements while using fewer array elements under the same array length.These conclusions are verified by using experimental data validation.(2)The derivation proves that the gate lobes of the coprime array can only appear in coherent multi target situations at special angles,while the gate lobes can be suppressed by the coprime array in independent multi signal and non-special angle situations.The least squares virtual array element interpolation is proposed to be applied to vector coprime matrices to suppress gate lobes.In response to the difficulties in matrix inversion and the high computational complexity of broadband targets in this method,diagonal loading virtual source interpolation and time delay summation virtual source interpolation methods are further proposed.Through theoretical derivation,simulation verification,and experimental data,it has been proven that the new method can effectively suppress gate lobes and improve the resolution of multiple targets.The paper also analyzed the effects of phase and target intensity on the resolution of vector coprime array multiple targets.(3)Derive the differential structure of the coprime array and construct a virtual domain signal.In response to the problem of insufficient utilization of virtual domain information and waste of degrees of freedom,spatial smoothing algorithms and matrix reconstruction algorithms are applied to vector coprime matrices to improve the effective size of the virtual array,better utilize the information received by the coprime array in the signal,and address the problem of "holes" in the virtual array,propose Nuclear Norm Minimization(NNM)optimization The Atomic Norm Minimization(ANM)optimization algorithm is applied to vector coprime matrices,improving their degrees of freedom and multi-objective resolution.After algorithm comparison and performance analysis,it has been proven that the method has obvious advantages in terms of angle resolution and degree of freedom.(4)An improved arrangement method of mutual prime array is proposed,which embeds a special uniform array into a nested mutual prime array structure.The structure is compared with extended mutual prime array and subarray compressed mutual prime array in multiobjective gate lobe suppression and high-resolution spectrum estimation.Performance analysis shows that the improved mutual prime array structure can effectively improve angle resolution and noise resistance. |
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