基于发射和接收优化设计的认知雷达动目标检测技术研究
发布时间：2018-10-05 14:25
【摘要】：认知雷达(Cognitve Radar,CR)是一种新型的雷达体制,具有学习、理解和推断环境的能力,具备接收机向发射机的持续信息反馈和波形自适应发射能力。自适应发射机,自适应接收机与目标环境构成了认知雷达的动态系统结构。本文首先对认知雷达的知识辅助模块进行了研究,研究了海杂波的幅度分布模型和多普勒谱模型;接着将认知雷达的体制与动目标检测(Moving Target Detecting,MTD)和空时自适应处理(Space-time adaptive processing,STAP)相结合,针对认知MTD和STAP雷达中发射和接收优化问题,提出了认知发射和认知接收的优化设计算法;最后通过仿真验证,自适应发射和自适应接收能有效改善接收信号的信杂噪比(Signal to Clutter and Noise Ratio,SCNR),提高动目标检测性能。本文完成的主要工作如下:(1)详细分析了海杂波的幅度分布模型和多普勒谱模型,利用IPIX雷达实测海杂波数据对幅度分布和多普勒特性进行了分析,并且分别对低、高海况数据的幅度分布和多普勒谱模型进行拟合仿真,作为后续认知雷达动目标检测的杂波环境模型。(2)以SCNR为优化设计准则,建立了基于慢时间域脉冲编码的MTD雷达信号模型,针对此模型进行了一系列的简化处理,得到锥约束下的二次型规划(Cone Constrained Quadratic Programming,CCQP)问题;提出了基于简约梯度法(Simplified Gradient Method,SGM)求解脉间编码的算法;最后,与已有的重新设置参数的凸优化算法(Convexification via Reparametrization,CoRe)和直接码设计的循环算法(Cyclic Algorithm for Direct Code Design,CADCODE)进行对比,计算机仿真结果表明:慢时间域编码优化能够有效改善回波的SCNR为3dB左右,且该算法具有运算量小和实时性能好的特点。(3)建立了认知接收MTD滤波组的信号模型,并采用Lagrange对偶算法求解。将认知接收MTD滤波组与已有的两种自适应MTD滤波器组做对比,仿真结果表明:认知接收MTD滤波组具有凹口深,旁瓣低的特点;用IPIX真实海杂波数据来设计认知接收MTD滤波器组,高于传统加窗的FFT滤波器组输出SCNR为10dB左右,对海杂波具有显著的抑制效果。(4)建立了STAP脉间编码信号模型,在选定目标空时多普勒平面区间,提出了一种基于辅助变量和交替方向的方法结合的脉间编码的优化设计算法。实验结果显示了平行于杂波脊附近的检测器输出SCNR有一定的改善,有利于慢速目标的检测。同时建立了认知STAP接收滤波器的模型,并采用Lagrange对偶算法求解。仿真结果表明:输出信号的SCNR高于传统自适应滤波器的输出,同时认知接收滤波器的输出旁瓣功率低于自适应滤波器,旁瓣抑制性能较好。
[Abstract]:Cognitive radar (Cognitve Radar,CR) is a new radar system, which has the ability of learning, understanding and inferring environment, continuous information feedback from receiver to transmitter and waveform adaptive transmitting ability. Adaptive transmitter, adaptive receiver and target environment constitute the dynamic system structure of cognitive radar. In this paper, the knowledge assistant module of cognitive radar is studied firstly, the amplitude distribution model and Doppler spectrum model of sea clutter are studied, then the system of cognitive radar is combined with moving target detection (Moving Target Detecting,MTD) and space-time adaptive processing (Space-time adaptive processing,STAP). Aiming at the problem of transmitting and receiving optimization in cognitive MTD and STAP radar, an optimal design algorithm of cognitive transmitter and receiver is proposed. Adaptive transmission and adaptive reception can effectively improve the signal-to-noise ratio (Signal to Clutter and Noise Ratio,SCNR) of the received signal and improve the performance of moving target detection. The main work of this paper is as follows: (1) the amplitude distribution model and Doppler spectrum model of sea clutter are analyzed in detail. The amplitude distribution and Doppler characteristics are analyzed by using the measured sea clutter data of IPIX radar. The amplitude distribution of high sea condition data and Doppler spectrum model are simulated as the clutter environment model for moving target detection of cognitive radar. (2) based on SCNR, a MTD radar signal model based on slow time domain pulse coding is established. For this model, a series of simplified processing is carried out, and the quadratic programming (Cone Constrained Quadratic Programming,CCQP problem with conical constraints is obtained. An algorithm based on reduced gradient method (Simplified Gradient Method,SGM) is proposed to solve the inter-pulse coding problem. Compared with the existing convex optimization algorithm (Convexification via Reparametrization,CoRe) and the direct code design (Cyclic Algorithm for Direct Code Design,CADCODE) algorithm, the computer simulation results show that the slow time domain coding optimization can effectively improve the echo SCNR about 3dB. The algorithm has the advantages of small computation and good real-time performance. (3) the signal model of cognitive received MTD filter group is established and solved by Lagrange dual algorithm. Comparing the cognitive receiving MTD filter group with the two existing adaptive MTD filter banks, the simulation results show that the cognitive receiving MTD filter group has the characteristics of deep notch and low sidelobe, and the IPIX real sea clutter data is used to design the cognitive received MTD filter bank. Compared with the traditional windowed FFT filter bank, the output SCNR of the FFT filter bank is about 10dB, which has a remarkable suppression effect on the sea clutter. (4) the STAP inter-pulse coded signal model is established, and the selected target space-time Doppler plane is selected. An optimal design algorithm for interpulse coding based on the combination of auxiliary variables and alternate directions is proposed. The experimental results show that the output SCNR of the detector, which is parallel to the clutter ridge, is improved to some extent, which is beneficial to the detection of slow targets. At the same time, the model of cognitive STAP receiver filter is established and solved by Lagrange dual algorithm. The simulation results show that the output SCNR of the output signal is higher than that of the conventional adaptive filter, and the output sidelobe power of the cognitive receiver filter is lower than that of the adaptive filter, and the sidelobe suppression performance is better.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.51
[Abstract]:Cognitive radar (Cognitve Radar,CR) is a new radar system, which has the ability of learning, understanding and inferring environment, continuous information feedback from receiver to transmitter and waveform adaptive transmitting ability. Adaptive transmitter, adaptive receiver and target environment constitute the dynamic system structure of cognitive radar. In this paper, the knowledge assistant module of cognitive radar is studied firstly, the amplitude distribution model and Doppler spectrum model of sea clutter are studied, then the system of cognitive radar is combined with moving target detection (Moving Target Detecting,MTD) and space-time adaptive processing (Space-time adaptive processing,STAP). Aiming at the problem of transmitting and receiving optimization in cognitive MTD and STAP radar, an optimal design algorithm of cognitive transmitter and receiver is proposed. Adaptive transmission and adaptive reception can effectively improve the signal-to-noise ratio (Signal to Clutter and Noise Ratio,SCNR) of the received signal and improve the performance of moving target detection. The main work of this paper is as follows: (1) the amplitude distribution model and Doppler spectrum model of sea clutter are analyzed in detail. The amplitude distribution and Doppler characteristics are analyzed by using the measured sea clutter data of IPIX radar. The amplitude distribution of high sea condition data and Doppler spectrum model are simulated as the clutter environment model for moving target detection of cognitive radar. (2) based on SCNR, a MTD radar signal model based on slow time domain pulse coding is established. For this model, a series of simplified processing is carried out, and the quadratic programming (Cone Constrained Quadratic Programming,CCQP problem with conical constraints is obtained. An algorithm based on reduced gradient method (Simplified Gradient Method,SGM) is proposed to solve the inter-pulse coding problem. Compared with the existing convex optimization algorithm (Convexification via Reparametrization,CoRe) and the direct code design (Cyclic Algorithm for Direct Code Design,CADCODE) algorithm, the computer simulation results show that the slow time domain coding optimization can effectively improve the echo SCNR about 3dB. The algorithm has the advantages of small computation and good real-time performance. (3) the signal model of cognitive received MTD filter group is established and solved by Lagrange dual algorithm. Comparing the cognitive receiving MTD filter group with the two existing adaptive MTD filter banks, the simulation results show that the cognitive receiving MTD filter group has the characteristics of deep notch and low sidelobe, and the IPIX real sea clutter data is used to design the cognitive received MTD filter bank. Compared with the traditional windowed FFT filter bank, the output SCNR of the FFT filter bank is about 10dB, which has a remarkable suppression effect on the sea clutter. (4) the STAP inter-pulse coded signal model is established, and the selected target space-time Doppler plane is selected. An optimal design algorithm for interpulse coding based on the combination of auxiliary variables and alternate directions is proposed. The experimental results show that the output SCNR of the detector, which is parallel to the clutter ridge, is improved to some extent, which is beneficial to the detection of slow targets. At the same time, the model of cognitive STAP receiver filter is established and solved by Lagrange dual algorithm. The simulation results show that the output SCNR of the output signal is higher than that of the conventional adaptive filter, and the output sidelobe power of the cognitive receiver filter is lower than that of the adaptive filter, and the sidelobe suppression performance is better.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.51
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