【作者】 黄亮；

【导师】 刘皓春；

【作者基本信息】 武汉理工大学 ， 电路与系统， 2014， 硕士

【摘要】 随着信息科学的不断发展，雷达的工作电磁环境越来越差。在恶劣的电磁环境中，有源干扰是雷达难以对付的一种干扰，该干扰信号通过雷达天线的旁瓣进入到雷达系统，从而对雷达的性能产生影响，并且难以抑制。在对抗有源干扰的方法中，自适应旁瓣对消技术是抑制有源干扰的非常有效的技术之一，且在雷达领域应用比较广泛。该技术主要采用空间滤波技术，通过辅助通道在干扰方向形成波束图的零点，从而实现对干扰信号的抑制。本文以自适应旁瓣对消技术为研究对象，针对旁瓣区域的两个干扰信号，采用四个辅助天线，通过自适应算法计算辅助通道权系数，使得辅助通道与权值的加权和正好与主通道的干扰相互抵消，对消比达到15dB以上。自适应旁瓣对消系统包括辅助通道模块、数字信号处理模块、幅相加权模块和主通道对消模块等。辅助通道模块实现对辅助通道天线接收的信号进行处理，如滤波、低噪声放大、混频、数模转换等。数字信号处理模块采用FPGA作为硬件平台，实现数字下变频、通道校正、干扰检测和干扰抑制等功能。数字下变频实现中频数字信号转换成基带数字信号；通道校正实现对辅助通道与主通道的幅相一致性进行校正；干扰检测通过对辅助通道的采样判断是否存在干扰信号；干扰抑制实现存在干扰的时候通过闭环LMS算法计算辅助通道的加权系数，并提供给幅相加权模块。幅相加权模块是将干扰抑制模块计算出的辅助通道加权系数转换成辅助通道的幅度和相位控制字，实现辅助通道的幅度和相位加权求和。主通道对消模块实现主通道信号与辅助通道幅相加权和进行对消达到抑制干扰信号的目的。本文主要完成FPGA数字信号处理模块的功能设计，并对各模块进行时序仿真，通过Matlab对自适应旁瓣对消算法的性能进行仿真分析。仿真结果表明，该自适应旁瓣对消算法对抗有源干扰的有较好的抑制能力，针对旁瓣区域的两个干扰信号，对消比达均到15dB以上，满足设计要求。更多还原

【Abstract】 With the development of information technology, the electromagneticenvironment radar system work in is getting worse. Active jamming is the mostdifficult for radar system to barrage, because jamming can enter radar system throughantenna side-lobes, which have an severe influence on the performance of radarsystem, and any method can dispose it. Adaptive side-lobe cancellation technology isone of the most effective ways to suppress active interference, which are widely usedin satellite, radar and other areas. It suppress the interference signal by forming Beampattern zero point in interference direction through auxiliary passages, which usingspatial filtering techniques.The paper based on a phased array radar and make the adaptive side-lobecancellation system as research object, discussed a number of issues about the designand engineering implementation of adaptive side-lobe cancellation system. Theadaptive side-lobe cancellation system need to reach cancellation ratio at15dB whentwo strong interference signals enter from antenna side-lobes. The system of side-lobecancellation consist of the auxiliary channel module, digital signal processing module,amplitude and phase weighting module and the main channel cancellation module.The function of auxiliary channel module is to receive and process the signal fromauxiliary channel antenna, such as low pass filtering, low noise amplification,frequency mixing, digital to analog conversion. The digital signal processing moduleselect FPGA as the hardware platform, and complete the function of IQ quadraturedown conversion, signal channel correction, interference detection and interferencesuppression. The main function of IQ quadrature down conversion is to convertdigital signal into a baseband digital signal; Channel Calibration main achievement ofthe amplitude and phase consistency correction of auxiliary channel; Interferencedetection main achieve the goal of detecting the auxiliary channels to see whether itcontain interference signals; interference suppression achieve the goal of calculatingthe weighting coefficients via the auxiliary channel LMS algorithm. Amplitude andphase weighting module achieve the goal of convert weighting coefficients intoamplitude and phase control words, and implement the weighted sum of theauxiliary channel amplitude and phase. The main channel module achieve thefunction of cancelling interference signals from the main channel through theweighted sum of the auxiliary channel amplitude and phase. The paper mainly complete the digital signal processing module functionaldesign based on FPGA, and then simulate the adaptive side-lobe cancellation systemusing Matlab to analyze the performance of the adaptive side-lobe cancellation system.Simulation results show that the adaptive side-lobe cancellation system perform wellin suppress active interference. It can suppress two strong active interference, andcancel ratio can reach15dB, and it can meet the design requirements.更多还原