【作者】 赵建宏；

【导师】 杨建宇；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2008， 博士

【摘要】 低空、超低空飞行目标难以检测和跟踪,是雷达面临的四大威胁之一。研究低空目标的检测与跟踪,对于反低空突防具有重要意义,但至今未能有效解决。宽带雷达优点突出,并且可提高低空目标的检测与跟踪性能。但宽带信号检测理论还没建立起来,现有研究成果的检测性能有待提高,而且尚未开展脉间存在越距离单元走动的动目标检测研究。本文基于总装基金项目,由低空问题的研究引出宽带雷达信号检测理论研究。主要内容为:1.研究了低空目标检测与跟踪的两种新技术。在分析低空探测难点问题的基础上,提出采用频率分集加权积累检测技术对抗多径效应,使低空检测性能有显著提高。同时,提出并验证了一种采用宽频带扫频测量低空目标高度的新方法。2.研究了宽带雷达的回波特性。通过实测数据研究了机载宽带雷达的目标回波特性。从杂波生成机理的角度,研究了机载宽带雷达杂波单元构成的时变性和非平稳性。探讨了宽带杂波的幅度分布模型、功率谱模型及统计特性的研究方法,分析了最新的试验研究成果。3.研究了宽带雷达的检测性能。分析了信号带宽与检测单元的信号、杂波及噪声功率的关系。研究了宽带雷达与窄带雷达目标回波的能量分布函数,在此基础上,基于匹配滤波器,分析了宽带雷达相比窄带雷达在检测性能上的优势。4.研究了宽带雷达的单脉冲检测。提出了宽带目标回波的单次脉冲检测结构,分析了M/N检测器、模平方积累检测器等经典方法的应用。提出了宽带LFM信号的Radon-Wigner变换方法,该方法产生的衍生散射点可提供检测增益。研究了基于空域散射密度假设的SSD-GLRT检测方法。基于宽带单脉冲回波是随机幅度-相位-时延脉冲串的假设,提出了改进RPPT检测方法。提出基于散射点加窗的GLRT检测方法,检测性能相对最优。最后,推导了散射点RCS服从指数分布的扩展目标最优检测方法,该理论成果验证了基于散射点加窗的GLRT检测方法的良好性能。5.研究了宽带雷达的多次脉冲检测。宽带雷达动目标回波的脉间越距离单元走动使得经典MTD方法的应用条件不再成立,宽带MTD需对齐多脉冲回波的各周期多普勒距离单元轨迹后再做MTD。本文提出基于快时间频域对齐的MTD方法,增加较小的运算量,实现了宽带MTD,但存在信噪比要求。研究了基于Coherent-Radon变换的宽带MTD方法,这是对齐多普勒距离轨迹的最优方法,但运算量大。基于目标先验多普勒分析,进一步提出基于局域Coherent-Radon变换的宽带MTD方法,它是Coherent-Radon变换方法的快速方法,在增加较小运算量的条件下实现了宽带目标的相干积累检测。更多还原

【Abstract】 Low-altitude flying targets are difficult to detect and track, and this is one of the four great threats propelling radar development. Research on detecting and tracking of low-altitude targets is of great significance to counter low-altitude air defence penetration, but up to now, this problem has not been effectively resolved.Wideband radar holds many merits, and it can enhance the low-altitude targets detecting and tracking performance. Wideband radar detection theory is still not built up, the performance of current wideband detection strategies needs to be improved, and scholars still pay no attention to moving target detection with echoes migration through resolution cells during CPI. Based on the support of the General Armament Department fund project, this dissertation formulates our study from low-altitude problem to wideband radar detection theory.The main results are as follows:1. Two new technologies for low-altitutde detection and tracking are investigated. Based on the analysis of difficult problems of low-altitude detection, we put forward frequency diversity weighting accumulation detection technology to resist multipath effect, and the detection performance is improved significantly. And then, we propose and testify a new low-angle altitude measurement method using wideband frequency scan.2. Echo characteristics of wideband radar are studied. Using the field sampled data, we study the characteristics of airborne wideband radar target echoes. From the angle of clutter generation mechanism, we also research on the time-variant and nonstationary properties of clutter cells. In this part, the amplitude distribution model, power spectrum model and statistical characteristic research methods for the wideband radar clutter are also been discussed. At last, the novel test research results are presented.3. Detection performance of wideband radar is researched on. The relationship between signal bandwidth and target echo power, clutter echo power and noise power has been analysed. Target echo energy distribution functions for wideband radar and narrowband radar are researched. And from this foundation, based on the matched filter, we compared the wideband radar detector with the narrowband radar detector, and discussed the performance improvement of the wideband radar detector.4. Wideband single pulse detectors are studied in detail. Single pulse detection structure for wideband radar is presented. The appication of the conventional detectors, such as M/N detector and norm square accumulated detector, is discussed. For wideband LFM signal, we put forward the Radon-Wigner transformation method. The derivative scattering points produced by this method can provide detection gain. SSD-GLRT detector based on the spatially scattering density assumption is researched on. And then, based on the assumption that wideband single pulse echo is a pulse train with the random amplitude-phase-time delay, we propose the modified RPPT detection method. Scattering-points windowed GLRT detection method is also proposed, and its performance is optimum relatively. At last, the optimum detection strategy for exponential distributed scattering-points of extended target is deduced out. This optimum strategy testifies the better performance of scattering-points windowed GLRT detector.5. Wideband multiple pulses detectors are studied in detail. The moving target echoes of wideband radar maybe migrate through range resolution cells bewteen two pulses duing one CPI. This makes the condition of conventional MTD can not still exist. Wideband MTD should be implemented after aligning the different periodic range cell trace of the dopper signal. Wideband MTD based on fast-time frequency domain alignment is proposed. By the cost of less computational burden increments, this method can implement wideband MTD, but SNR condition is needed. Wideband MTD based on Coherent-Radon transformation is researched on. This method is optimum for range-cell trace alignment of doppler signal, but its computational cost is too high. Based on the prior target doppler analysis, wideband MTD based on local Coherent-Radon transformation is then put forward. This is a fast computation method of the Coherent-Radon transformation method. It can implement coherent accumulation detector for the wideband target with less computational burden increments.更多还原