【作者】 邹博；

【导师】 梁甸农；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2011， 博士

【摘要】 共置天线多发多收(Multiple Input Multiple Output,MIMO)雷达综合利用多相位中心和多频资源,获得更大的虚拟孔径和更高的系统自由度,在地面运动目标指示(Ground Moving Target Indication,GMTI)、参数估计等方面表现出明显优势。通过对MIMO雷达接收回波的多通道、多维联合处理,有利于获得更强的抑制杂波和抗干扰能力,能够解决传统雷达GMTI存在的慢速运动目标检测困难、最小可检测速度(Minimum Detectable Velocity,MDV)和测速范围之间相互制约、盲速目标无法检测等难题,提高目标检测和参数估计性能。本文以共置天线MIMO雷达GMTI为研究对象。在研究确定频分正交信号满足MIMO-GMTI雷达指标要求的基础上,围绕机载PD体制MIMO-GMTI中的空-时-频自适应处理(Space-Time-Frequency Adaptive Processing,STFAP)及其降维方法、基于STFAP的多频融合检测和参数估计、以及星载SAR体制MIMO-GMTI中的多频顺轨干涉(Along Track Interferometry,ATI)信号模型、多频联合检测性能分析和解测速模糊等关键问题开展研究。主要工作安排如下:第二章研究MIMO-GMTI雷达正交信号设计。基于两类正交信号——同频编码正交信号和频分正交信号,首先针对MIMO雷达发射分集的特点,提出综合积分旁瓣比(Integrated Sidelobe Ratio,ISLR)的指标定义,将综合ISLR定义为自相关旁瓣能量和所有正交信号互相关能量之和与脉压函数主瓣内的积分能量的比值;然后,从理论上证明同频编码正交信号的综合ISLR接近0dB,无法满足MIMO-GMTI雷达系统需求,而频分正交信号的互相关能量近似为0,几乎不会对综合ISLR产生影响;最后,基于两类正交信号的杂波和成像仿真进一步验证理论分析结果,从而选择频分正交信号作为MIMO-GMTI雷达系统的发射信号。第三章建立了基于频分信号的MIMO雷达STFAP信号模型。首先,在分析杂波特性的基础上,阐述STAP抑制杂波的基本原理;然后,研究杂波抑制性能的评价准则,包括:输出信号杂波噪声比(Signal to Clutter plus Noise Ratio,SCNR)、恒虚警检测概率、MDV和最大无模糊速度等;最后,在分析频分正交信号解盲速原理的基础上,建立STFAP信号模型。基于STFAP的杂波抑制性能仿真结果验证了MIMO雷达在提高杂波抑制性能、缓解MDV和盲速相互制约、增加可测速范围和提高GMTI性能等方面具有优势。第四章研究基于STFAP的MIMO雷达SCAN-GMTI技术。首先,在仿真分析不同方位角杂波特性基本一致的基础上,采用STFAP技术实现SCAN-GMTI杂波抑制;针对STFAP运算量较大的缺点,建立了STFAP降维处理的统一框架,提出时空级联STFAP降维方法和STFAP M-Capon降维方法,结合实际工程应用指出基于子阵级的STFAP 3-Capon法更具有实际意义,为解决STFAP降维问题提供了思路;最后,研究MIMO雷达多频融合检测和参数估计问题,提出了基于STFAP的多频融合检测方法,推导了基于STFAP的运动目标参数估计的CRB,仿真结果验证了MIMO雷达STFAP提高目标检测和估计性能的优势。第五章基于星载SAR系统,重点研究单基线两发两收SAR-ATI信号处理方法。首先,从ATI工作原理和信号模型出发,论证两发两收SAR-ATI联合检测和估计的可行性,推导不同载频杂波和目标ATI干涉相位相加后的统计分布;然后,以相位检测子分布为出发点,分析了两发两收SAR-ATI联合检测性能和相位-幅度二级检测性能,提出先融合后检测的方法改善MDV,先检测后融合的方法改善盲速,并通过信号处理仿真实验验证了双频ATI联合检测改善盲速和MDV的优势;最后,研究双频解测速模糊方法,根据干涉相位所处区间不同,分三种情况对模糊数分别进行求解,通过不同情况示例分析,验证了解模糊方法的有效性。将多频与多基线技术相结合,本章研究成果可推广至任意多发多收GMTI系统。更多还原

【Abstract】 MIMO radar with co-located antennas, which utilizes the techniques of multi-channel and multi-frequency, and provides larger virtual aperture and more system freedoms, has evident advantages in GMTI and parameter estimation. Through the multi-channel and multi-dimensional joint processing of the received echoes, MIMO radar is able to provide more capability in clutter suppression and interference rejection, and solving the GMTI problems in traditional radar, such as slowly moving target detection, the restriction between MDV and velocity range, blind velocity target detection, and so on, which can improve the performance of target detection and parameter estimation.This paper takes GMTI in MIMO radar with co-located antennas as the research object. On the basis of studying and determining the orthogonal signal form suitable to MIMO-GMTI radar, the following issues are studied in the paper: the key problems in MIMO-GMTI of airborne PD system, such as Space-Time-Frequency Adaptive Processing (STFAP), reduced dimension STFAP, multi-frequency fusion detection and parameter estimation based on STFAP, and the key problems in MIMO-GMTI of spaceborne SAR system, such as multi-frequency ATI signal model, performance analysis of multi-frequency combined detection and a deblurring method of velocity measurement. The detailed work of this paper is as follows:Orthogonal signal design for MIMO-GMTI radar is studied in chapter 2. Based on two types of orthogonal signals-orthogonal coding signals with the same frequency band and orthogonal frequency division signals, firstly, the definition of the synthetic ISLR index is proposed according to the transmission diversity characteristic of MIMO radar, which is defined as the ratio of the sum of the integrated energy of all autocorrelation side lobes and all the cross-correlation energy to the integrated energy of the main lobe in the pulse compression function. Secondly, it is theoretically demonstrated that the synthetic ISLR of orthogonal coding signals with the same frequency band is close to 0dB, which can not satisfy the demand of MIMO-GMTI radar system, whereas the cross-correlation energy of orthogonal frequency division signals is nearly 0, which hardly affects the synthetic ISLR. Finally, the results of clutter and imaging simulation using two types of orthogonal signals verify the validity of the theoretical conclusions. Therefore, the orthogonal frequency division signals are selected as the trasmitted signals for MIMO-GMTI radar.The STFAP signal model of MIMO radar is established in chapter 3. Firstly, on the basis of clutter characteristics analysis, the basic principles of suppressing clutter through STAP are described. Secondly, the evaluation criteria for the performance of clutter suppression is studied, including output SCNR, CFAR detection probability, MDV, maximum unambiguous velocity, and so on. Finally, the simulation results of clutter suppression through STFAP demonstrate that MIMO radar is effective in improving the performance of clutter suppression, MDV, blind velocity, velocity range and GMTI.The technique of SCAN-GMTI in MIMO radar based on STFAP is studied in chapter 4. Firstly, on the basis of simulation analysis of clutter characteriscs for each azimuth viewing direction, STFAP technique is adopted to achieve clutter suppression for SCAN-GMTI. Secondly, the unified framework of reduced dimension STFAP is established. The time-space cascade reduced dimension STFAP and the STFAP M-Capon reduced dimension method are proposed. It is presented that the STFAP 3-Capon method based on subarrays has practical meaning for engineering application, which provide some suggestions for implementation of reduced dimension STFAP. Finally, multi-frequency fusion detection and parameter estimation for MIMO radar is studied. The method of multi-frequency fusion detection is proposed based on STFAP. The CRB for moving target parameter estimation is deduced based on STFAP. Simulation results demonstrate that MIMO radar STFAP has evident advantages in improving the performance of target detection and parameter estimation.Based on spaceborne SAR system, the single-baseline signal processing of dual-frequency SAR-ATI with two transmit antennas and two receive antennas is studied in chapter 5. Firstly, according to the working principle and signal model of ATI, the feasibility of combined detection and estimation for dual-frequency SAR-ATI is demonstrated, the statistical distribution of summation of dual-frequency ATI phases for clutter and target is deduced. Secondly, Starting with the distribution of ATI phase, the performance of combined detection and two-step detection with phase and amplitude for dual-frequency SAR-ATI are analyzed, the method of fusion detection is proposed to improve MDV, and the method of detection and fusion is proposed to improve blind velocity, simulation results demonstrate that the combined detection for dual-frequency ATI is effective in improving MDV and blind velocity. Finally, a deblurring method of velocity measurement with dual-frequency is studied. According to different interferometric phase values, three situations are considered to deblur velocity measurement, and the validity of the method is validated through example analysis. Combining the technique of multi-frequency with the technique of multi-baseline, the research findings of this paper can be extended to any MIMO-GMTI system.更多还原