Real-Time Wind Estimation and Tracking with Transponder Downlinked Airspeed and Heading Data

The use of magnetic heading and true air speed measurements made on board civil airplanes to assist in radar tracking is described. The data are telemetered via the air-ground data link of the mode S radar system. A new filter, similar to the first-order Kalman filter, is developed using velocity measurements to bias its prediction equations. This filter follows satisfactorily maneuvers, and estimates, in real time, the wind in the vicinity of the airplane. Finally a scheme is described to remove false data due to data-link corruption.     

EBAA：An efficient broadcast authentication scheme for ADS-B communication based on IBS-MR

Automatic dependent surveillance-broadcast （ADS-B） systems can broadcast satellitebased aircraft position, identification, etc., periodically, and are now on track to replace radar to become the backbone of next-generation air traffic management （ATM） systems. However, ADS-B systems suffer severe cyber-security problems due to the broadcast-type data link and the lack of designed-in security measures. Especially, since ADS-B messages are unauthenticated, it is easy to insert fake aircraft into a system via spoofing or insertion of false messages. Unfortu- nately, the authentication for ADS-B messages has not yet been well studied. In this paper, based on identity-based signature with message recovery （IBS-MR）, an efficient broadcast authentication scheme for ADS-B messages is proposed. The security analysis demonstrates that the scheme can achieve authenticity and integrity of ADS-B broadcast messages, as well as adaptive evolution of broadcasters＇ private keys. The performance evaluation shows that the scheme is computationally efficient for typical avionics devices with limited resources. Furthermore, the scheme achieves low communication overhead since broadcast messages can be recovered from signatures, and thus it is suitable for low-bandwidth ADS-B data link.     

Bayesian and Dempster-Shafer target identification for radarsurveillance

This paper considers the problem of target track identification in a radar surveillance system. To build a target identifier alongside a tracker, four features which are available for real-time processing in an air surveillance system are used here: target identity (TID) from a friend-and-foe identification (IFF) system, elevation measurement from the radar, target speed, and acceleration estimated by a tracker. These four features are combined to classify air targets into five different air target categories: friendly commercial, friendly military, hostile commercial (or unknown airline), hostile military, and false targets (clutter). Two popular statistic-based techniques, namely, the Bayesian and Dempster-Shafer methods, are applied to develop radar target identification algorithms for our application. Real-life as well as simulated air surveillance radar data are used to evaluate the practicality and effectiveness of this track identification approach in a radar surveillance system     

扫描模式航管监视雷达风电场杂波检测与抑制

近年来,全球风力发电装机容量呈指数增长。研究表明,风轮机对其附近的航管(ATC)监视雷达会产生严重影响。风轮机杂波的有效检测及抑制,对于保证空中交通安全具有重要意义。首先提出了基于回波谱宽特征的航管监视雷达的风轮机杂波检测方法。针对扫描模式下航管监视雷达频谱分辨率较低的问题,将基于自回归(AR)模型的超分辨率方法和质量中心的概念应用于雷达回波的快速谱宽和谱中心估计算法中,提高谱宽估计的精度。其次针对扫描模式下的风轮机回波数据不是一个完整周期数据的问题,基于缺省数据幅度和相位估计(GAPES)算法实现了扫描模式下风轮机雷达回波缺省数据的估计,而后利用风轮机杂波的周期性抑制风轮机杂波。该算法实现了风轮机杂波的有效检测和抑制,并且其不受限于风轮机与飞机目标在同一个距离单元的情况。仿真结果验证了所提方法的有效性。     

Wingtip generated wake vortices as radar target

Previous radar wake vortex detection experiments have resulted in measured beam averaged values of radar reflectivity from wake vortices in clear air. We have employed average wind and thermodynamic variable output from a two dimensional wake vortex model in clear air and fog to predict radar reflectivity in a wake vortex on a one meter grid. The results agree well, compared to data in the literature. In the clear air case, scales of turbulence were analyzed at each grid point to determine the appropriate maximum radar frequency for detection, initial wake structure, transport, and vortex persistence are related to atmospheric winds, atmospheric stability, and generating aircraft characteristics     

机载多目标跟踪系统模型和运动补偿

研究多目标跟踪技术在机载雷达应用中的特殊问题——坐标系的选择、载机运动的稳定与补偿。建立了数学模型 ,进行了仿真研究。研究结果表明 :载机运动的稳定与补偿是机载多目标跟踪中必须重视的问题 ,并得出基于 NED和 RHV的组合坐标系下的模型 ,在机载应用中有很好的性能。优点是易于解耦、避免了非线性、降低了计算量、且有较高的精度     

Knowledge-based system for multi-target tracking in a littoral environment

The paper addresses how to efficiently exploit the knowledge-base (KB), e.g. environmental maps and characteristics of the targets, in order to gain improved performance in the tracking of multiple targets via measurements provided by a ship-borne radar operating in a littoral environment. In this scenario, the nonhomogeneity of the surveillance region makes the conventional tracking systems (not using the KB) very sensitive to false alarms and/or missed detections. It is demonstrated that an effective use of the KB can be exploited at various levels of the tracking algorithms so as to significantly reduce the number of false alarms, missed detections, and false tracks and improve true target track life. The KB is exploited at two different levels. First, some key parameters of the tracking system are made dependent upon the track location, e.g., sea, land, coast, meteo zones (i.e., zones affected by meteorological phenomena) etc. Second, modifications are introduced to cope with a priori identified regions nit hi high clutter density (e.g. littoral areas, roads, meteo zones etc.). To evaluate the behavior of the proposed knowledge-based tracking systems, extensive results are presented using both simulated and real radar data     

利用信号特征的风电场对二次雷达影响评估

研究表明风力发电场可能会影响航管雷达系统,导致其工作性能下降,因此准确评估风电场对航管雷达的影响具有重要意义。利用二次雷达信号特征给出了一种风电场对二次雷达影响的评估方法。首先根据二次雷达信号特征从风电场反射信号干扰方面分析了风电场对航管二次雷达可能产生的影响．然后阐述了以反射信号的时延来划分风电场影响区域的评估方法。最后通过在DEM（digital elevation model数字高程模型）数据上的仿真实验来验证本文评估方法。     

Rotating Blades Radio Interference in a Helicopter-Borne CW Doppler Radar

Radio interference generated in a helicopter-borne continuous wave (CW) Doppler radar system due to the rotating blades is analyzed. This problem has been previously treated for the case of pulse Doppler radar systems with very narrow (near zero) beamwidth. In this case the strong interference component returning directly from the blades (with no ground reflection) need not be considered as it reaches the receiver when it is still blinded. In the case of a CW Doppler radar, however, this interference component must be included. Numerical calculations show that the total blade interference power level, dominated by the direct component, is higher than that of the direct ground clutter in the radar clutter region. It decreases approximately as (f - fo)-4 in the radar clear region. It stays, however, well above the thermal noise level which might cause false alarm and degrade the radar performance.     

两种空管自动化系统中管制员可靠性研究

介绍了人的可靠性评估的发展,进而提出了雷神雷达系统和欧洲猫雷达系统两种空管自动化系统下的管制员可靠性研究方法和数据采集的形式,通过对采集样本数据的分析,计算出管制员从雷神雷达系统过渡到欧洲猫雷达系统可靠性的评估结果,进一步指出提高管制员可靠性的改进措施.     

Synchronization improvements using traceability in spread spectrumsignal design

Synchronization improvements using traceability information found in the narrowband auto-ambiguity function (NB AAF) are demonstrated. This new auto-ambiguity function property, traceability, is the key to defining a signal design approach for solving the synchronization problems in spread spectrum system such as communication systems, radar networks, and sonar systems. This work defines the property and introduces a new tracing synchronization scheme that significantly reduces initial synchronization time and the number of false synchronization events     

超视距空战的威胁估计

针对现有超视距空战威胁估计模型的不足,提出了一种新的基于模糊逻辑的超视距空战威胁估计模型。该模型以机载中远程空空导弹攻击区、雷达搜索区性能参数以及双方战术几何关系、相对运动趋势作为评估对象进行模糊化,设计了角度优势、距离优势推理模块,并以二者的加权和作为当前空战态势的优势指数。模型较为全面反应了空战态势与参战飞机的作战能力,可为超视距多机协同攻击多目标空战时的目标分配、战术选择提供参考。仿真结果验证了模型的有效性。     

基于高空风修正的四维航迹优化算法

航迹预测是基于航空器航迹运行的核心技术,也是空中交通流量管理的基础技术。结合航空器飞行速度数据与航段飞行时间数据,分析高空风对航空器飞行时间的影响。基于GRIB2格式风数据,建立高空风修正模型,提出一种四维航迹优化算法进行航迹预测。利用中南区域实际航班飞行数据进行算例仿真,并与实际雷达飞行数据进行对比。对比结果表明,预测飞行时间总误差分别减少了7%和16.4%,从而验证了模型的有效性与正确性。     

末制导雷达虚警概率检验方法

针对只有10^-8～10^-9量级的末制导雷达虚警概率难以检验的问题,研究虚警概率与发现概率、虚警时间的关系,论证了将虚警概率转化为虚警时间的检验方法,利用定时截尾统计检验理论,研究了不同鉴别比、不同试验时间、不同接收故障数时研制方与使用方的风险,提出了新型末制导雷达虚警概率的检验方法,解决了该项指标检验的难题。     

CFAR behavior of adaptive detectors: an experimental analysis

We conduct an experimental analysis for assessing the constant false alarm rate (CFAR) behavior of four coherent adaptive radar detectors in the presence of experimentally measured clutter data. To this end we exploit several data files containing both land, lake, and mixed land and sea clutter, collected by two radar systems (the MIT Lincoln Laboratory Phase-One radar and the McMaster IPIX radar) at different polarizations, range resolutions, and frequency bands. The results show that all the receivers, in the presence of real data, don't respect their nominal probability of false alarm (P/sub fa/), namely they exhibit a false alarm rate higher than the value preassigned at the design stage. Nevertheless one of them, the recursive persymmetric adaptive normalized matched filter (RP-ANMF) is very robust, in the sense that it presents an acceptable displacement from the nominal P/sub fa/, in correspondence of all the analyzed scenarios.     

Reacting to new air defence threats: a netcentric approach to the Hungarian air defence system augmented by VHF radars

Different types of distributed radar systems and data fusion centers are increasingly used by surface-based air defense systems. Besides the well-established airborne threats, new platforms for air surveillance and attacking devices have appeared and recognized air picture (RAP) production needs to be revised and modified following the events of September 11, 2001. From a military operational and logistic support point of view, it is well-known that not only the long range radars currently in operation, but also the recently procured radars, degrade in performance rapidly and their maintenance costs are high. Using the possibilities offered by emerging technical developments, the problem is to upgrade sensors and existing infrastructure in a way that exploits the information gathered optimally. It is the opinion of this author that one of the most promising approaches to emphasis net-centricity is the use of radar-triangle netcentric structures augmented by netted VHF radars to solve these tasks in a cost-effective manner. This work introduces an analysis of a solution that fully integrates newly required capabilities into the current long range radar net and infrastructure, keeping research and development (R&D) and maintenance at a low cost.     

Optimal polarimetric detection of radar target in a slowlyfluctuating environment of clutter

It is shown that in a situation where a radar target is distant enough from the radar and is included in a natural or artificial clutter environment in such a manner that the conventional detection methods fail, it is possible to improve the radar detection performance by using appropriate signal processing on two orthogonal polarization states. A CFAR (constant false alarm rate) polarimetric detection system based on the study of the polarization difference between clutter and target is proposed. Since the polarization state of the clutter echoes fluctuates slowly from cell to cell, an autoregressive model can be applied to the components of the polarization vector to predict the detection thresholds needed to follow the polarization state variation. The detection thresholds are determined to maintain a false alarm probability equal to 10^-6. The presence of a target registers as a significant variation of the estimation error of the polarization vector. Results obtained from measurements of simple and canonical targets with artificial clutter are presented, and these results validate the principle of polarimetric detection     

Prescreening during image formation for ultrawideband radar

Standard radar image formation techniques waste computational resources by full resolving all areas of the scene, even regions of benign clutter. We introduce a multiscale prescreener algorithm that runs as part of the image formation processing step for ultrawideband (UWB) synthetic aperture radar (SAR) systems. The prescreener processes intermediate radar data generated by a quadtree backprojection image former. As the quadtree algorithm iterates, it is resolving increasingly finer subpatches of the scene. After each quadtree stage, the prescreener makes an estimate of the signal-to-background ratio of each subpatch and applies a constant false alarm rate (CFAR) detector to decide which ones might contain a target of interest. Whenever the prescreener determines that a subpatch is not near a detection, it cues the image former to terminate further processing of that subpatch. Using a small database of UWB radar field data, we demonstrate that the prescreener is able to decrease the overall computational load of the image formation process. We also show that the new multiscale prescreener method produces fewer false alarms than the conventional two-parameter CFAR prescreener applied to the completely formed image     

Summary of recent Australian radar developments

Over the last 30 years there has been a growing Australian capability in very long-range radar systems, especially over the horizon radar (OTHR) and a related technology, surface wave radar (SWR). Both operate in the high frequency (HF) band between 3 and 30 MegaHertz (MHz), which are wavelengths between 100 and 10 metres, respectively. Based on current evidence, it appears that Australia may have found the tools with which to conduct efficient long-range surface and air surveillance more effectively than by the single use of traditional surveillance forces. Given increasing success and refinement of these technologies, one can see that the SWR systems in particular could, in addition, satisfy a number of potential export requirements and earn useful export credits.