【作者】 刘磊；

【导师】 刘兴钊；

【作者基本信息】 上海交通大学 ， 信息与通信工程， 2019， 博士

【摘要】 随着雷达系统在分辨率、带宽和通道数目上的不断提高,其对数据处理能力和处理速度等方面提出了更高的要求。面对海量且高速的数据处理需求,数字信号处理技术已经或即将暴露其在运算速度和功耗等方面的局限性。在此背景下,光电协同信息处理技术被开发用于雷达信号处理。光电协同信息处理技术采用空间光学信息处理方法完成海量数据的复杂数学运算,采用电子技术完成逻辑运算和时序控制等。由于具有高速并行处理能力和高密度数据承载能力,该技术具备为雷达系统提供海量数据处理和实时处理的潜力。而且该技术主要依靠无源的光学元件,因此功耗低、抗电磁干扰能力强。本文围绕光电协同雷达信号处理进行深入的研究。首先,开展了高速空间光调制技术的研究,并提出了一种基于数字微镜器件(Digital Micromirror Device,DMD)的空间光幅度相位联合调制方法(JAPC方法)。空间光调制技术是实现光电协同信号处理的必需技术。该方法的实现依靠一个离轴的4-f光学系统和一套基于混合整数规划的DMD编码求解算法。求解算法充分考虑了调制结果中所有像素之间的相互影响,因此该方法具有比传统调制方法更高的调制精度。而且,由于采用了高数据刷新率的DMD,JAPC方法具有高速调制的独特优势。另外,JAPC方法能够同时且独立地对空间光束的幅度和相位进行调制。因此,利用该方法可以完成将任意复信号加载到激光光束上。其次,开展了相控阵雷达信号的光电协同波束形成研究,提出了一种用于接收端的实时光电协同波束形成(OPBF)系统。面对海量相控阵雷达数据处理的需求,如大型相控阵、多波束的情况,该系统能够有效解决实时波束形成处理的问题。该系统是将雷达数据和加权系数调制到激光光束上,并在光域上完成对雷达数据的加权、求和运算,从而获得波束形成结果。所有通道的雷达数据被并行处理且并行形成多波束。由于高速并行的处理特点,与DBF系统相比,OPBF系统在海量数据的处理速度上有显著的优势。而且,阵元数目和波束数目的增多并不会影响该系统的处理速度。另外,该系统面对窄带或者宽带雷达信号均可精确快速地形成波束。同时,开展了合成孔径雷达信号的光电协同成像处理研究,提出了一种适用于高分辨率合成孔径雷达(Synthetic Aperture Radar,SAR)信号的实时光电协同成像系统。该系统利用空间光调制器将SAR回波数据调制到激光光束上,调制后的激光光束通过透镜成像系统聚焦成SAR图像。该系统具有在线实时成像处理的独特优势。同时,在子孔径结构的帮助下,该系统能够通过多个子孔径光电协同处理模块并行地对海量SAR数据进行处理。因此,该系统能够高速处理高分辨率的SAR信号并实时生成全分辨率的SAR图像。而且,基于子孔径结构,该系统可支持的数据处理规模易于扩展。最后,开展了雷达组网中的光电协同编解码研究,提出了一种基于涡旋光束的高维度光电协同编解码方法。在雷达组网中,通信是桥梁。该方法能够有效解决高速、大容量的自由空间通信问题,适用于大规模雷达组网中的通信系统。在该方法中,采用基于DMD的算法生成涡旋光束以用于编码信息。信息的解码利用干涉图来高效率的实现,避免了其他常用的基于相位匹配原理的解码方法所需的严格对准。该方法能够实现高维度编码,如64进制编码。编码维度的提升和高速DMD的使用使得所提出的方法比其他常用通信技术具有更高的数据传输率。另外,通过引入阵列涡旋光束,该方法实现了多个信息的同时传输,从而进一步提升了该方法的数据传输率,使其适用于高速大容量的通信系统。更多还原

【Abstract】 The increasement of resolution,bandwidth and the number of channels has led to a higher demand on data processing capacity and speed.For the demand of massive and high-speed data processing,digital processing technology has or will soon expose limitations in computing speed and power consumption.On this background,optronic processing has been developed for radar signal processing.The technology utilizes spatial optical information processing to complete the complex mathematical computing of massive data and applies electronic processing to complete logic operations and sequential control.Owing to high-speed parallel processing and high-density data carrying capacity,this technology has the potential to provide massive data processing and real-time processing for radar systems.Moreover,the processing mainly relies on passive optical components with low power consumption and anti-electromagnetic interference capacity.In this paper,optronic radar signal processing is thoroughly studied.Firstly,the research on high-speed spatial light modulation is carried out,and a novel joint amplitude and phase control(JAPC)method of spatial light using a digital micromirror device(DMD)is proposed.This technology is indispensable for the realization of optronic processing.An off-axis 4f-configuration and a DMD pattern formation algorithm based on mixed integer programming are required for the implementation of the proposed method.As the correlations among all pixels in the modulation result is fully considered,the proposed method has higher modulation precision compared with conventional methods.JAPC method has a superior performance in modulation speed by using a high-speed DMD.It also has the capability of independently and simultaneously controlling amplitude and phase of laser beams,which makes it possible to encode arbitrary complex signal onto laser beams.Then,the research on optronic beamforming of phased array radar signals is carried out,and a real-time optronic beamforming(OPBF)system on receive is proposed.The system is suitable for real-time processing of massive phased array radar data,such as large phased array and multiple beams.In this system,radar raw data and weighting coefficients are both encoded on the laser beams.Radar data is then weighted and summed in the optical domain to obtain the beamforming result.And radar data of all channels are processed in parallel and multiple beams are generated concurrently.Due to the high-speed parallel processing characteristics,compared with DBF,OPBF has a significant advantage in processing speed for massive data.Moreover,the processing speed will not be affected by the increase in the number of array elements and forming beams.Additionally,OPBF system is suitable for narrowband beamforming as well as wideband beamforming.Next,the research on optronic processing of synthetic aperture radar signals is carried out,and a real-time optronic high-resolution synthetic aperture radar(SAR)imaging system is proposed.In this scheme,SAR raw data is encoded on the laser beams,and the modulated laser beams pass through a lens system to form a SAR image.The system has a superior performance of real-time imaging.With the help of subaperture architecture,the proposed system enables optically processing large-scale SAR data in parallel by multiple optical subaperture processing modules.Therefore,the system is able to process high-resolution SAR signals and generate full-resolution SAR image in real time.Moreover,owing to the subaperture structure,the data scale is easy to expand.Finally,the research on optronic encoding in netted radar system is carried out,and a high-dimensional optronic encoding scheme using vortex beam is proposed.Communication is a bridge in netted radar system.The proposed scheme can effectively perform large-capacity and high-speed free-space communication,which is suitable for large-scale netted radar system.In this scheme,an algorithm with a DMD is employed to generate vortex beams that can be used for encoding.Interference is introduced to efficiently decode data information,which avoids stringent alignment required by other phase distribution based decoding technologies.This scheme enables high-dimensional encoding,such as 64-ary encoding.Owing to enhancement of encoding dimension and employment of high-speed DMDs,the proposed scheme enjoys a higher transfer rate exceeding other communication technologies.In addition,the transfer rate can be further improved by introducing vortex arrays,which makes the scheme suitable for high-speed large-capacity communication.更多还原