| Airborne radar has a wide observation range.When airborne radar detects or identifies marine targets,it will receive a large number of strong sea clutter echoes from different directions,affecting the detection accuracy of the radar.Sea clutter is different from ground clutter.Because of its volatility,it is necessary to focus on the time-varying and scattering characteristics of sea clutter,establish a precise echo model and effectively simulate the data of sea clutter,which can provide a favorable basis for the optimization of clutter suppression algorithm and target detection algorithm,radar system design and marine environment monitoring.The more precise of the sea clutter echo model is,the more data and calculation of clutter simulation,which cannot meet the real-time and accuracy requirements of the airborne radar sea clutter simulation method.With the development of GPU technology,the parallel computing feature of GPU can be applied to the field of radar systems to improve simulation performance.In view of the above problems,the research content of this thesis are as follows:(1)On the basis of systematic combing of sea clutter modeling and simulation and CPU + GPU heterogeneous technology,we found that the traditional sea clutter model is inaccurate and it is difficult to simulate real clutter data.In order to address this problem,a precise space-time echo model of airborne multi-channel radar sea clutter in time domain and frequency domain is established based on the LFM signal as the transmit signal,according to the time-varying and scattering characteristics of sea clutter and radar equation.Then we carry out specific derivation and simulation analysis of the planar phased array antenna model,the classic Morchin,TSC and dual-scale average backscattering coefficient models with different polarizations included in the model.Finally,the Gaussian power spectrum model of the airborne radar sea clutter is derived in detail from the mechanism of sea waves and aircraft movement,which provides theoretical support for the simulation of sea clutter time-correlation characteristics.(2)According to the model of sea clutter,a specific clutter simulation method is given.First,the simulation methods of instantaneous scattering coefficient of sea clutter and internal disturbance of clutter under different adaptability conditions are given,and the applicability of the method is verified through simulation experiments.Then,the overall scheme of sea clutter simulation for airborne multi-channel radar under CPU is designed,and specific simulation steps and procedures are given.Finally,the simulated sea clutter data is processed and its characteristics are analyzed,including range-Doppler,space-time spectrum,characteristic spectrum distribution,inter-channel interference and SCNR loss after adaptive processing.The effectiveness of the modeling and simulation method is demonstrated by the experimental results of the first and third level sea conditions.(3)To address the problem of the traditional sea clutter simulation method with large amount of calculation and long simulation time that is difficult to meet the real-time performance of the new radar system,we develop a fast simulation method of airborne multi-channel radar sea clutter under the CPU + GPU architecture.Firstly,the GPU architecture and CUDA programming foundation are briefly introduced.Secondly,the thesis analyzes the parallelism of the sea clutter simulation algorithm of the airborne multi-channel radar,gives the memory allocation and scene block design,and designs the sea clutter parallel scheme under the CPU + GPU architecture.Then,the programming ideas and implementation process of each module are described in detail,and the fast simulation system software of airborne multi-channel radar sea clutter under the CPU + GPU architecture is developed.Finally,the simulation results are compared and analyzed on the two platforms under the CPU serial and CPU + GPU heterogeneous parallel,and the time-consuming and acceleration ratios in different scenarios are calculated.When the range unit is 2400,the pulse number is 300 and the number of channels is 4,the acceleration ratio can reach 459 times,which demonstrates the feasibility of the fast simulation method of sea clutter. |
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