一种基于IPC的多区域网络视频监控系统设计

针对多区域网络监控的应用需求,设计了一套基于IPC的网络化视频监控系统。该系统采用基于视频分析的运动目标侦测,基于双码流的图片、视频传输与存储,以及优先级和多通道的IPC与图片服务器交互等关键技术。由此,实现了多区域全时段的标清视频监控,实时运动检测报警与连续高清图片抓拍取证功能。该系统设计兼容现有的软硬件系统平台,并具有较高性价比。     

基于运动补偿的双通道星载SAR动目标检测方法

分析常规的双通道星载合成孔径雷达-偏移相位中心天线(SAR-DPCA)技术检测运动目标的方法,建立了斜距平面坐标系来描述星载合成孔径雷达回波多普勒特性,说明了这种常规动目标检测方法在星载情况下的不足。针对这种情况,提出基于运动平台补偿的双通道星载SAR-DPCA动目标检测方法。该方法通过相位补偿,消除了星地相对径向运动对双通道DPCA杂波对消效果的影响,改善了双通道星载SAR-DPCA系统的动目标估计性能。     

Run-Time Integration of Reconfigurable Video Processing Systems

Embedded systems in field-programmable gate arrays (FPGAs) can be customized and adaptive if assembled from modular components at run time. This paper examines realizing run-time system assembly by extension of platform-based design. Two major challenges are addressed in this paper. First, the design of a reconfigurable platform architecture suitable for run-time system assembly is described. Different systems are constructed by integrating the platform architecture with different modular components, which employ the communication infrastructure supplied by the platform in order to interact. Second, where on-chip communications channels use shared media, we propose techniques for modeling the intermodule communication behavior based on statistical time-division multiplexing. The proposed techniques enable system designers to guarantee that logical communication requirements between the adjunct modules can be satisfied by the infrastructure. An in-depth analysis is presented and then verified with cycle-accurate simulations for an example reconfigurable platform for real-time video applications.     

动平台雷达组网系统探测效能评估与仿真

利用不同平台雷达进行动态组网为系统效能实时评估带来了难度。为了正确实时描述系统探测效能,建立了雷达组网系统探测动态效能模型,并选取了探测范围、发现概率和探测精度等主要指标来评估系统的探测效能,同时设计开发了仿真软件,为雷达合理部署和平台运动路线优化提供决策依据。仿真结果表明平台雷达组网效能评估仿真系统具有较好的实用性。     

Space-time adaptive processing for manoeuvring airborne radar

Space-time adaptive processing (STAP) techniques provide simultaneous rejection of jamming and clutter in airborne radar. The greatest benefits over conventional MTI (moving target indication) approaches are in terms of a capability to detect slow-moving targets which possess the same Doppler frequency as mainlobe clutter returns. This paper examines the effects of platform manoeuvre on STAP clutter and jamming rejection performance for a forward-facing array (i.e. where the array is orientated transversally to the direction of travel). It is shown that STAP slow-target detection performance is not sensitive to the radar platform orientation. It is also demonstrated that, under conditions of manoeuvre, STAP can provide better jammer rejection performance than architectures which cascade conventional clutter filtering and spatial adaptive beamforming     

周视IRST系统运动目标检测算法的硬件实现

针对当前周视IRST系统中对运动目标检测的需求,综合考虑系统硬件成本和系统实时处理能力需求,研究了基于帧间差分法的运动目标检测算法,并基于FPGA+DSP硬件处理平台,进行了算法的硬件实现与优化,实验结果表明,该信号处理系统检测性能优异,满足目前IRST系统中对运动目标检测的应用需求。     

Application of feature extraction methods for landmine detection using the Wichmann/Niitek ground-penetrating radar

Ground-penetrating radar (GPR) has been proposed as an alternative to classical electromagnetic induction techniques for the landmine detection problem. The Wichmann/Niitek system provides a good platform for novel GPR-based antitank mine detection and classification algorithm development due to its extremely high SNR. When the GPR sensor is mounted on a moving vehicle, the target signatures are hyperbolas in a time-domain data record. The goal of this work is to extract useful features that exploit this knowledge in order to improve target detection. The algorithms can be divided into two steps: feature extraction and classification. Preprocessing is also considered to remove both stationary effects and nonstationary drift of the data and to improve the contrast of the desired hyperbolas. The algorithm is evaluated using real data over primarily plastic antitank mines collected with a fielded GPR sensor at a government test site.     

星上运动目标识别的若干关键问题

未来战争,敌我双方的战争机器将向机动性、隐蔽性方向发展。许多武器系统本身就是运动目标,如航母战斗群、弹道导弹、巡航导弹,远程战斗轰炸机等。因此,空间卫星侦察系统的星上运动目标检测和识别就是迫在眉睫的课题。文中探讨了与此课题相关的若干关键技术问题,并给出了一个检测弹道导弹运动目标的方法和模拟结果。     

基于联合像素特征对消动目标检测方法

提出了基于三通道联合像素的最小功率特征对消的方法来检测SAR图像中的地面运动目标。文中的方法不要求多天线间距、载机速度、脉冲重复频率满足特定的条件,它通过构造三通道联合像素矢量来产生协方差矩阵,然后对协方差矩阵进行特征分解,选取噪声的特征向量来构成噪声子空间,最后利用噪声子空间来抑制地面杂波,从而检测出地面慢速运动目标;同时还分析了针对实测数据中存在系统误差的情况下选取不同的特征向量分别构成的噪声子空间对于该方法的运动目标检测性能的影响。实测数据处理结果验证了该方法的有效性。     

基于嵌入式视频监控的人脸检测系统设计

针对视频监控系统智能化的要求,提出了一种基于嵌入式视频监控的人脸检测设计方案。采用在ARM-Linux操作平台上建立Servfox流媒体服务器,实现USB摄像头的视频采集和传输。在客户端首先采用帧间差分更新背景模型的改进算法获取运动目标,减少视频中运动目标对背景模型的影响,且为人脸目标的检测缩小了范围。在运动目标区域内,通过Ada-Boost人脸检测算法,最终获得人脸位置。结果表明,系统对人脸检测效果良好,准确率可达95.2%,检测时间22～27 ms/frame,满足视频监控的实时性要求。     

A novel hardware/software embedded system based on automatic censored target detection for radar systems

This paper presents a practical design exploration for a new application related to real-time, high-resolution target detection for radar systems. In this paper, an embedded architecture that combines the hardware and software components in a single platform is experienced using a field programmable gate array FPGA-based PC-board. The detection process utilises three techniques: namely, automatic censored ordered statistics detection (ACOSD), cell averaging (CA) and ordered statistics (OS) CFAR techniques, all of which operate in parallel to increase the accuracy of the detection and to reduce the false-alarm rate for both homogeneous and non-homogeneous environments. A prototype of the embedded system detector has been implemented for homogeneous and non-homogeneous environments on Stratix IV FPGA Board. The prototype operates at 200 MHz and performs real-time target detection with an execution delay of 0.27 μs, which is less than the critical time (0.5 μs) for high-resolution detection.     

天基微弱运动点目标检测研究综述

近几十年来,针对复杂背景下红外图像序列的天基微弱 运动点目标探测问题备受关注。该问题对于空间监视系 统、预警系统以及导弹跟踪系统等而言十分重要。受各方面的影 响,天基微弱点目标检测、跟踪和识别研究仍然面临着很多挑 战。仪器抖动和平台运动均会造成目标定位偏差。受制于观测距 离和天基成像环境,目标往往会淹没在背景杂波或噪声之中。因此,如 何在低信杂噪比的情况下快速、准确地探测和识别运动点目 标,并满足检测率和虚警率指标,是相关领域亟待解决的问题。 对近年来国内外相关领域的研究进行了分类和总结,以期在此基 础上寻求新的探索和发现。     

基于帧间差分法和VIBE算法的运动目标检测

针对运动目标在视频序列检测时易受各种因素干扰的问题,采用TI公司的TMS320DM6446作为系统图像处理器,提出了一种基于帧间差分法和VIBE算法相结合的运动物体检测方法,并在DM6446硬件平台上实现。实验表明,在室内场景背景下,系统在满足实时性情况下能够克服光线变化等因素的干扰,准确地检测出运动目标,现场试验取得了良好的效果。     

一种基于多级维纳滤波的多通道SAR动目标检测算法

该文针对机载多通道SAR-GMTI系统及实测数据,提出一种新的地面慢动目标检测算法。新算法利用多级维纳滤波器实现多通道SAR系统杂波抑制,同时结合对角加载技术和非均匀检测器,进一步改善SAR系统在非均匀环境下的动目标检测性能。实测数据实验结果表明：与常规的自适应检测方法相比,新算法能够明显提高系统对杂波的抑制能力及非均匀环境下系统的动目标检测性能。     

便携式战场侦察雷达系统设计

便携式战场侦察雷达已被世界各国广泛应用于战场情报侦察、边境和敏感区域监视等任务中,其主要用途是对指定地区的活动目标进行探测.本文介绍一种便携式战场侦察雷达系统设计思路及关键技术,并对关键技术的解决措施进行分析.     

Monocular precrash vehicle detection: features and classifiers.

Robust and reliable vehicle detection from images acquired by a moving vehicle (i.e., on-road vehicle detection) is an important problem with applications to driver assistance systems and autonomous, self-guided vehicles. The focus of this work is on the issues of feature extraction and classification for rear-view vehicle detection. Specifically, by treating the problem of vehicle detection as a two-class classification problem, we have investigated several different feature extraction methods such as principal component analysis, wavelets, and Gabor filters. To evaluate the extracted features, we have experimented with two popular classifiers, neural networks and support vector machines (SVMs). Based on our evaluation results, we have developed an on-board real-time monocular vehicle detection system that is capable of acquiring grey-scale images, using Ford's proprietary low-light camera, achieving an average detection rate of 10 Hz. Our vehicle detection algorithm consists of two main steps: a multiscale driven hypothesis generation step and an appearance-based hypothesis verification step. During the hypothesis generation step, image locations where vehicles might be present are extracted. This step uses multiscale techniques not only to speed up detection, but also to improve system robustness. The appearance-based hypothesis verification step verifies the hypotheses using Gabor features and SVMs. The system has been tested in Ford's concept vehicle under different traffic conditions (e.g., structured highway, complex urban streets, and varying weather conditions), illustrating good performance.     

Moving target detection in foliage using along track monopulsesynthetic aperture radar imaging

This paper presents a method for detecting moving targets embedded in foliage from the monostatic and bistatic synthetic aperture radar (SAR) data obtained via two airborne radars. The two radars, which are mounted on the same aircraft, have different coordinates in the along track (cross-range) domain. However, unlike the interferometric SAR systems used for topographic mapping, the two radars possess a common range and altitude (i.e., slant range). The resultant monopulse SAR images are used to construct difference and interferometric images for moving target detection. It is shown that the signatures of the stationary targets are weakened in these images. Methods for estimating a moving target's motion parameters are discussed. Results for an ultrawideband UHF SAR system are presented.     

Background and foreground modeling using nonparametric kernel density estimation for visual surveillance

Automatic understanding of events happening at a site is the ultimate goal for many visual surveillance systems. Higher level understanding of events requires that certain lower level computer vision tasks be performed. These may include detection of unusual motion, tracking targets, labeling body parts, and understanding the interactions between people. To achieve many of these tasks, it is necessary to build representations of the appearance of objects in the scene. This paper focuses on two issues related to this problem. First, we construct a statistical representation of the scene background that supports sensitive detection of moving objects in the scene, but is robust to clutter arising out of natural scene variations. Second, we build statistical representations of the foreground regions (moving objects) that support their tracking and support occlusion reasoning. The probability density functions (pdfs) associated with the background and foreground are likely to vary from image to image and will not in general have a known parametric form. We accordingly utilize general nonparametric kernel density estimation techniques for building these statistical representations of the background and the foreground. These techniques estimate the pdf directly from the data without any assumptions about the underlying distributions. Example results from applications are presented.     

基于OpenCV的运动目标跟踪系统研究

本文分析比较了传统运动目标检测的3种主要方法：背景图像差分法、时态差分法和光流法,在此基础上给出了一种背景图像预测算法,大大减少了因为背景变化而产生的目标检测误差。本文基于OpenCV设计出改进的运动目标检测与跟踪算法,实现了运动目标的跟踪,并在VC＋＋编译环境下,利用USB摄像头作为视频采集器,通过观察实验结果可以看出,本文的运动目标检测算法能够正确地检测出视频图像中的运动目标,而且在检测性能上优于普通的自适应背景差分法。     

Electrical signal processing techniques in long-haul fiber-opticsystems

The potential for electrical signal processing to mitigate the effect of intersymbol interference in long-haul fiber-optic systems is discussed. Intersymbol interference can severely degrade performance and consequently limit both the maximum distance and data rate of the system. Several techniques for reducing intersymbol interference in single-mode fiber systems with single-frequency lasers are presented, and those techniques which are appropriate at high data rates in direct coherent detection systems are identified. The performances of linear equalization (tapped delay lines), nonlinear cancellation (variable threshold detection), maximum-likelihood detection, coding, and multilevel signaling are analyzed. The results for a simulated binary 8-Gb/s system show that simple techniques can be used to reduce intersymbol interference substantially, thereby increasing the system margin by several decibels. A six-tap linear equalizer increases the dispersion-limited distance (due to chromatic or polarization dispersion) by 20% (or reduces the optical power penalty by as much as a factor of two) in direct detection systems, even when the distortion is nonlinear. A nonlinear cancellation technique (adjusting the decision threshold in the detector based on previously detected bits) can more than double the dispersion-limited distance and/or data rate