目标雷达隐身性能测试技术研究

本文简述了表征目标对雷达波散射能力的特征量--目标雷达截面积,讨论了大型目标雷达隐身性能(后向散射)的室外场测量方法、室外场测量环境要求等,给出了电磁理论在地面环境研究的结果,论述了室外场测量环境要求和采取的主要技术措施.重点论述了目标雷达隐身测量系统的组成、测量原理、成像方法等.     

雷达目标模拟器校准技术研究

文章论述了雷达目标模拟器主要参数的校准方法。用数字存储示波器的时间差测量功能完成距离模拟参数校准;用数字存储示波器的分段采集功能,通过测量模拟目标的距离变化率完成速度模拟参数校准;用频谱分析仪的频谱峰值功率测量功能完成幅度模拟参数校准;用数字存储示波器的信号采集功能采集线性调频信号,复Morlet小波变换分析线性度,完成线性调频信号线性度的校准。并根据以上校准方法建立了一套半自动雷达目标模拟器校准装置。     

雷达参数自动测试系统中的目标回波信号模拟器的设计

本文介绍了一种用于校准雷达测距准确度的目标回波信号模拟器。详细设计了具有延时准确度高的固定目标、移动目标的回波信号的延时电路，以及单片机Ｉｎｔｅｌ８０３１与模拟器的接口电路。它可用于雷达参数自动测试系统作为程控信号源，也可以独立作为雷达测距准确度校准等的精密延时信号源。     

扫描器运动多参数测试技术研究

新型图像扫描器具有较高的响应频率，可以实现高速扫描。在研究扫描器运动参数分离的基础上，利用对称放置的半导体位置探测器建立了扫描器的多运动参数测试系统，提出了光电二维位置传感器的非线性修正和补充方法，实现了四路模拟信号的DMA传送，提高了测试的速度和精度，实现扫描器在高频运动时的多运动参数测试。     

雷达技术状态测试系统方案探讨

针对目前雷达计量测试状况,通过对几种雷达测试系统方案的对比,提出了最佳的方案,组成了雷达自动测试系统。测试结果表明,本系统实现了对不同用途不同体制雷达技术指标的自动准确测试,并能对雷达故障进行准确分析与定位,在雷达的研制、生产、使用及维修过程中有很强的实用性。     

集成电路测试系统时间参数测试能力比对

本文结合集成电路测试系统时间参数测试能力比对,对比对过程中所采用的标准和测试方法、被测件的制备及其稳定性考核、比对实施方案的制定、比对结果的评价方法等关键内容进行了详细描述,为集成电路测试系统时间参数的量值溯源提供了一种有效的方法。     

高分辨率雷达目标特性和杂波模型研究

在宽带高分辨率雷达中,距离分辨率远小于目标尺寸,目标回波是各散射中心分布函数的径向投影与发射信号作用的结果。目标的一维距离像反映了目标强散射中心在径向距离轴上的投影分布,它是目标特征的体现。本文主要研究高分辨雷达的目标特性和杂波模型并进行仿真。     

一种通过相续雷达成像构建目标三维像的算法

逆合成孔径雷达(ISAR)作为成像雷达技术之一,它是应用雷达波束对基于遥感目标的二维像进行观测.ISAR对相继像的观察就类似于采用摄像机捕捉移动的画面.在光学成像的领域里,将图像而成的二维速度变换称为"光速流"或者是"速度场".当摄像机与目标之间的相对运动是已知的时候,那么基于速度场的以相继运动图像来估计目标的三维形态是合理的.     

地面目标多谱测试及隐身效能评估现状与展望

随着隐身技术的应用以及多模探测技术的发展,单一频段的光电对抗已经不能满足日益复杂的现代战争需求,隐身、探测、识别与跟踪等技术都必须基于多谱测试技术的发展。本文以地面武器装备的威胁分析入手,以应用最为广泛的雷达、红外目标特性测试为例分析了多谱测试及后期数据融合处理技术的发展现状,并提出了发展建议。     

高加速飞行体多环境动态参数测试技术研究

本文探讨高加速飞行体多环境动态参数测试的问题，结合一个具体的实例，介绍其特点及难点，传感器的选用原则，电路结构设计的特点，如何根据飞行体的冲击响应及测试装置的冲击响应从测试数据中提取需要的动态参数，以及关于电池选择和电源处理等问题。     

Hybrid interference suppression for multistatic radar

The accurate estimation of a monostatic radar range profile is considered when in the presence of multistatic radar interference for which the illuminating waveforms are assumed known. In an effort to approach the ideal interference-free performance, the range?domain `beamforming? properties of the recently developed multistatic adaptive pulse compression (MAPC) algorithm is herein combined with the well-known CLEAN algorithm which operates on an interference-subtraction basis. Two versions of this hybridised methodology are presented and compared. To ascertain relative sensitivity, both the mean-squared error and the probability of detection are examined as a function of SNR when in the presence of multistatic interference. It is demonstrated that the respective merits of MAPC and CLEAN can be used to offset the limitations of the other and thereby combine to provide significant additional sensitivity improvement.     

Design and evaluation of a low-cost multistatic netted radar system

This paper reports on the design and initial evaluation of a low-cost multistatic radar system that exploits digital components. The system is based on a commercial-off-the-shelf and open architecture approach, using a direct digital synthesiser, a field programmable gate array and a digital signal processor as core components. Instrument function testing, calibration and the results of the initial field tests are reported. Some of the first multistatic experimental results are reported and demonstrate a number of aspects of the performance of such a configuration. The advantages and limitations of a low-cost digital radar design are discussed and further system development possibilities outlined. This system will enable the collection of a wide range of novel multistatic data and has the potential to demonstrate a number of new radar applications.     

Feature-based human motion parameter estimation with radar

Radar can be an extremely useful sensing technique to observe persons. It perceives persons behind walls or at great distances and in situations where persons have no or poor visibility. Human motion modulates the radar signal which can be observed in the spectrogram of the received signal. Extraction of these movements enables the animation of a person in virtual reality. The authors focus on a fast feature-based approach to estimate human motion features for real-time applications. The human walking model of Boulic is used, which describe the human motion with three parameters. Personification information is obtained by estimating the individual leg and torso parameters. These motion parameters can be estimated from the temporal maximum, minimum and centre velocity of the human motion distribution. Three methods are presented to extract these velocities. Additionally, we extract an independent human motion repetition frequency estimate based on velocity slices in the spectrogram. Kalman filters smooth the parameters and estimate the global Boulic parameters. These estimated parameters are input to the human model of Boulic which forms the basis for animation. The methods are applied to real radar measurements. The animated person generated with the extracted parameters provides a realistic look-alike of the real motion of the person.     

Automatic target recognition using multi-diversity radar

The information content of radar target signatures is a key aspect for automatic target recognition. The role of high-range resolution is investigated as a function of the illuminating wavelength. The classification performance is evaluated using (i) full-scale 2D inverse synthetic aperture radar images obtained from a stepped-frequency chirp modulation radar system and (ii) the corresponding sub-spectra of the target reflectivity function forming lower resolution images at differing centre frequencies. The classification performance as given by different combinations of RF frequencies are also evaluated and compared with the coherent reconstruction from the full bandwidth. Finally, the classification results are also computed using multiple aspects to sense the target. In this way, classification performance as function of diversity space is examined.     

Measurements of radar wave speeds in polar glaciers using a down-hole radar target technique

A new technique for measuring the speed of radar waves in polar ice sheets was developed to investigate a previously reported disagreement between the permittivities of laboratory and glacier ice. The technique involves lowering a cylindrical radar target to several carefully measured depths in a borehole and measuring the travel time of a radar wave transmitted from a surface radar unit to the target in the borehole. The experiment was performed at Dome C, East Antarctica, and Dye-3, Greenland, and useable data were collected for target depths between 200 and 800 m. After computing the range to the target along a straight ray path and after correcting the travel time for delays in the radar receiver, the velocities determined from these experiments were found to be in good agreement with the velocities predicted by Robin's empirical formula. The apparent discrepancy between the permittivity of glacier ice, as measured using the radar wide-angle reflection method, and laboratory ice now seems to be due in large part to signal delay in the radar receiver that was ignored in earlier experiments.     

Trends in radar absorbing materials technology

The research in the area of Radar Absorbing Materials (RAMs) has been actively pursued for at least four decades. Although resonant RAMs were originally designed by transmission line approach, and the broad band RAMs were obtained by multilayering, the quest for ultrawide band performance has led to novel approaches such as chirality and even exploring biochemical products. It is observed that radome materials are frequently used as RAMs. The understanding of the underlying principles of electromagnetic analysis and design, fabrication and the trends in RAMs reviewed in this paper could lead to indigenisation, and even pioneering next generation of RAM technology.     

Ultra-wideband radar noise reduction for target classification

The authors describe a calibration procedure for ultra-wideband (UWB) radar systems in order to measure the frequency-dependent transfer function or radar cross-section, respectively, of objects with a high computational efficiency. The benefit of using UWB pulses is that only one measurement is required for covering several GHz. However, the signal processing steps contain a deconvolution operation producing spike artefacts. They were successfully removed by the calculation of frequency-dependent signal-to-noise ratio and a following Wiener filtering. The proposed method was verified by some elementary targets of which the size of the objects were determined.     

带干扰雷达型目标模拟器校准方法

为解决雷达型目标模拟器中干扰信号参数的校准难题,提出一种基于软件无线电思想的校准方法,通过对目标模拟器输出的回波信号下变频,并进行数字化处理,匹配预设的干扰信号模型,解算出干扰信号参数,实现带干扰雷达型目标模拟器的校准。研建雷达型目标模拟器校准系统,对某型目标模拟器进行校准,并对校准结果进行不确定度评定。校准结果表明:干扰信号参数误差3%以内,拖引速度不确定度1 m/s,拖引加速度不确定度0.2 m/s~2,干扰信号捕获、拖引、保持与关机时间的不确定度为0.01 s,校准结果证明该方法可以应用于带干扰雷达型目标模拟器的校准。     

Nonlinear techniques in optical synthetic aperture radar image generation and target recognition

One of the most successful optical signal-processing applications to date has been the use of optical processors to convert synthetic aperture radar (SAR) data into images of the radar reflectivity of the ground. We have demonstrated real-time input to a high-space-bandwidth optical SAR imagegeneration system by using a dynamic organic holographic recording medium and SAR phase-history data. Real-time speckle reduction in optically processed SAR imagery has been accomplished by the use of multilook averaging to achieve nonlinear modulus-squared accumulation of subaperture images. We designed and assembled an all-optical system that accomplished real-time target recognition in SAR imagery. This system employed a simple square-law nonlinearity in the form of an optically addressed spatial light modulator at the SAR image plane to remove the effects of speckle phase profiles returned from complex SAR targets. The detection stage enabled the creation of an optical SAR automatic target recognition system as a nonlinear cascade of an optical SAR image generator and an optical correlator.