| With the development of digital technology,the digital array radar system has been widely concerned.Digital array radar can use digital multi-beam forming technology at both the transmitting end and the receiving end,and can realize multi-target detection in complex target environment.Taking the digital array radar system of moving platform as the research background,this thesis studies the simultaneous digital multi-beam forming of transmitting and receiving,and the space-time clutter suppression technology and angle measurement technology in the receiving signal processing technology.Firstly,the overall framework of the digital array radar system is introduced as a whole,then the array signal model is established,and finally the main modules of the radar system are studied and analyzed.Its main work and contributions are:(1)The simultaneous digital multi-beamforming algorithm for calculating the weight vector using digital matching method,orthogonal projection method and constant modulus shaping algorithm based on convex relaxation is studied.Then,the memoryless power amplifier behavior model is modeled,and the influence of the nonlinear characteristics of the power amplifier at the transmitting end on the simultaneous multibeamforming of transmission is further analyzed,and the advantages and disadvantages of the three beamforming algorithms are compared and analyzed.(2)The space-time processing and clutter suppression technology under the framework of digital multi-beam are studied.Digital multi-beam array radar has a high degree of freedom and a large amount of data,which requires high real-time processing of received signals;in order to achieve clutter suppression and target detection in the context of motion platform applications,efficient space-time adaptive processing(STAP)is required algorithm.In this thesis,a dimensionality reduction STAP processing architecture and processing flow under simultaneous multi-beam are proposed.Through modeling and simulation,the clutter suppression performance of different space-time processing algorithms is analyzed,and the effects of target angle spacing and signal correlation on processing performance are discussed.(3)A target angle measurement algorithm based on compressed sensing is studied.The target angle measurement of the digital multi-beam array radar of the moving platform faces problems such as large number of array element channels,few available data samples,and simultaneous multi-target scenarios.The traditional single-pulse angle measurement technology is not applicable.In order to improve the real-time processing,A small sample,low-complexity super-resolution goniometric algorithm must be used.Aiming at the shortcomings of subspace-based super-resolution algorithms and the problem that some current one-dimensional algorithms are directly extended to twodimensional DOA estimation,there is a large amount of calculation.Two methods based on compressed sensing are proposed to reduce the dimension of dictionary matrix by separating array manifold matrix.It is a kind of two-dimensional DOA estimation algorithm,which has low computational complexity and decoherence ability,and can solve the problem of out-of-grid DOA estimation,and can accurately estimate the incoming wave direction in the scene with low signal-to-noise ratio or few snapshots.Besides,a two-dimensional DOA estimation algorithm based on L1 norm regularization of dynamic parameters is improved to solve the lattice mismatch problem. |
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