Radio-Holographic Object Imaging Technology Based on Forward Scattering Phenomena for Security Sensor Networks

保护本土领土、离岸和海外资产以及相关的国家经济和政治利益是英国和国际社会的重要战略优先事项。过去几年的全球经济和政治危机加深了这一挑战，英国目睹了它的后果，导致非法移民入境增加，海盗行为以及对商业和国家资产的威胁。犯罪分子可以迅速获得技术进步，因此需要灵活的对抗措施，包括开发可部署的传感器网络，重新使用现有的多模式操作通信技术，以及先进的信号处理，以应对现代挑战。这需要有针对性地研发高性能、经济高效的电子安全（ESS）系统，包括实际实施和开发高效的数字信号处理算法。ESS是世界上最大的（而且还在不断增长的）市场之一，每年价值约620亿美元，英国公司基本上参与了这个行业的高科技终端。ESS市场的一个重要部分涉及到周界/边界保护解决方案，提供态势感知，重要的是，在复杂环境条件下，基于可靠的全天候、白天和夜间操作，实时识别和识别入侵者。没有单一的解决方案，因此一般的方法是使用所有可用的技术和系统，它们可以通过提供额外的信息或数据融合来相互补充。广泛用于监视，电光或毫米波实时成像系统在没有视线和传播介质透明度差的情况下效率不高：墙壁，树叶，雾，烟，雪等。相反，频率较低的无线电信号可以穿透这些障碍物，这就是为什么所有的远程监视和安全任务都委托给雷达的原因。传统雷达对目标的反射信号进行处理时，将目标视为一组亮点，由于目标是由许多散射体组成的，它们在振幅上闪烁，并随向角的变化而改变位置。因此，即使在高性能雷达中，自动目标识别仍然是最困难的任务。同时，由于缺乏可靠的目标分类功能，几乎所有广域监视雷达的价值都大大降低。该项目解决了一个重要的应用领域——低可观测性或所谓的“困难”目标成像，即低成本可部署射频（RF）前向散射（FS）周界防护雷达网络。该雷达已被证明具有良好的探测能力和目标参数估计能力。这种雷达网络高度受欢迎的识别能力将首次结合目标阴影轮廓重建（TSPR）技术和MIMO方法。这种新型成像方法将基于反衍射问题的精确解，通过分布式射频传感器网络重构目标轮廓，该网络配置为多层射频发射器和接收器链。每一对分离的发射器和接收器形成一个“电子围栏”的一部分，因此每次越过基线都被实时记录和处理。多层配置将提供同一目标的多个基线交叉，从而允许多视角图像，因此非相干MIMO将被用于增强成像能力。研究了相干同步虚拟MIMO阵列形成改进的多视角目标形状轮廓的能力。重建的目标轮廓将为目标自动识别（ATR）提供基础。FS传感器所采用的目标成像技术，将有助于实施全功能的雷达系统，以保护和监视周边环境。

Protection of homeland territory, offshore and overseas assets and related national economic and political interests are strategically important priorities for the UK and the world community. Worldwide economical and political crisis over the last few years has deepened this challenge and the UK witnesses the consequences of it, resulting in increased illegal immigration entries, piracy, and threats to commercial and national assets. Technological advances become quickly available to criminals so that flexibility of contra-measures, including development of deployable sensor networks, re-use of existing communication technologies with multi-mode operation, advanced signal processing is required to tackle the modern challenges. This requires targeted R&D of high-performance cost-effective electronic security (ESS) systems, including practical implementation and development of efficient digital signal processing algorithms. ESS is one of the world's largest (and growing) markets worth about $62 bn a year with UK companies fundamentally involved at the hi-tech end of this industry. An essential segment of the ESS market relates to perimeter/border protection solutions to provide situational awareness and, importantly, real-time recognition and identification of intruders, based on reliable all weather, day and night operation in complex environmental conditions. There is no single solution, so that general approach is to use all technologies and systems available, which can complement each other by providing additional information or data fusion. Widely used for surveillance, electro-optical or mm wave real time imaging systems are not efficient in the absence of line-of-sight and poor transparency of propagation media: walls, foliage, fog, smoke, snow, etc. In contrast, relatively low frequency radio signals penetrate such obstacles and this is the reason why all long-range surveillance and security missions are entrusted to radars. In traditional radar which process the reflections from the target, a target is viewed as a set of bright points, scintillating in amplitude and changing position with aspect angle, as it is composed of many scatterers. Thus even in high performance radar, automatic target recognition remains the most difficult task. At the same time the value of virtually all wide area surveillance radar is substantially reduced by the absence of reliable target classification functionality.This project addresses an important application area - that of low observable or, so-called 'difficult' target imaging in low-cost deployable radio frequency (RF) forward scatter (FS) perimeter protection radar networks. This radar has already proven its excellent detection and target parameter estimation ability. The highly sought-after recognition capability for such a radar network will be provided by combining, for the first time, the Target Shadow Profile Reconstruction (TSPR) technique with MIMO approaches. The novel imaging approach will be based on accurate solution of inverse diffraction problem to reconstruct the target silhouette by a network of distributed RF sensors, configured as a multi-tier chain of RF transmitters and receivers. Each pair of separated transmitter and receiver forms a section of an 'electronic fence', so that each crossing of the baseline is registered and processed in real time. A multi-tier configuration will provide crossings of multiple baselines by the same target allowing multi-perspective images, so that non-coherent MIMO will be exploited for enhanced imaging capability. Coherent synchronized virtual MIMO array will be also investigated on its ability to form an improved multi-perspective target shape outline. The reconstructed target profiles will be a base for the automatic target recognition (ATR).The introduction of target imaging by FS sensors will facilitate implementation of the fully functional radar system for perimeter protection and surveillance.