Spectral Analysis and Subtraction of Noise in Radar Signals

A new method of maximum entropy spectral estimation called the revised maximum entropy method (MEM) is formulated and is applied to the spectral analysis of the echo signals from atmospheric turbulence observed by an incoherent scatter radar. The revised MEM is shown free from many demerits of the other methods for spectral analysis. Further it makes it possible to subtract the white noise usually contained in the data during the processing. Some examples of spectral estimation are shown for the actual radar signals and the simulated data. Another application of the revised MEM is the subtraction of the clutter component which is difficult to do by linear filtering. The method is successfully applied to several data abounding with the clutter to obtain the spectra of the echo signals with less clutter distortion.     

基于贡献度模型方法对空中交通管制中心系统的效能评估

 空中交通管制(ATC)中心系统的效能变化,直接影响到管制员的工作负荷和管制中心所辖空域的交通容量,是ATC系统的关键运行指标。基于系统行为表现的效能概念框架,采用系统效能分析的贡献度模型方法,对ATC中心系统的运行环境和工作过程进行了建模分析,构建了一个由9个外部环境变量和50个内部单元变量构成的ATC中心系统行为关系模型。通过采集系统专家和管制人员对外部信息贡献度和内部功能关键度的等级判断,计算生成了反映系统内外因素变化对系统效能影响的系统效能贡献度模型,并利用该模型对一个实际运行的ATC中心系统进行了效能分析评估,初步揭示了ATC中心系统效能变化的特点和规律。评估结果与运行专家对系统效能的经验判断具有较高的吻合度,验证了所创建的ATC中心系统效能贡献度模型及其分析方法的合理性。     

空管模拟机的IBM ViaVoice技术实现研究

阐述了空管模拟机自动机长席位的实现方法。通过对语音识别技术的研究,在引进IBMViaVoice语音识别系统的基础上,根据空管模拟机的功能需求,通过对其主控软件的改进,使语音识别技术与管制训练控制系统有机结合,实现了自动机长席位对非特定管制学员、连续管制指令语言的识别和仿真模拟雷达显示控制。     

空中交通管理系统安全绩效评估模型研究

客观准确的安全绩效评估,可以反映出空中交通管制系统运行的安全状况,并识别出安全管理存在的薄弱环节.从管制员、空中交通管制设备、环境、管理四方面找出影响系统安全运行的过程性指标,将过程性指标与结果性指标相结合构建空中交通管制系统安全绩效评估指标体系;在模糊物元分析法的基础上,对隶属度函数的确定方法进行改进,建立基于改进的模糊物元分析法的空中交通管制系统安全绩效评估模型;利用该模型对某空中交通管制单位的安全绩效进行评估,评估结果能够反映出该单位的安全状况,并指出应当改进的环节.结果表明:本模型可以对空中交通管制系统的安全绩效作出综合评判,并可以对空中交通管制系统的安全性进行量化描述.     

BL分析下的管制员差错本体建模研究

为分析识别空中交通管制任务中管制差错问题,结合BL(body loop,BL)压力产生模型研究管制员压力来源.提出领域本体的建模流程,确立推理模型的内部逻辑关系,构建管制差错领域本体模型.采用FaCT++推理机针对实际案例进行语义推理,从而识别管制差错类型,提出了基于本体的管制差错专家系统的系统框架.结果验证了构建推理模型的有效性和合理性.     

An experiment with an S-band radar using pulse compression andrange sidelobe suppression for meteorological measurements

A major technology barrier to the application of pulse compression for the meteorological functions required by a next generation ATC radar is range/time sidelobes which mask and corrupt observations of weak phenomena occurring near areas of strong extended meteorological scatterers. Techniques for suppressing range sidelobes are well known but without prior knowledge of the scattering medium's velocity distribution their performance degrades rapidly in the presence of Doppler. Recent investigations have presented a “doppler tolerant” range sidelobe suppression technique. The thrust of the work described herein is the extension of previous simulations to actual transmitted dispersed/coded waveforms using the S-band surveillance radar located at Rome Laboratory Surveillance Facility. The objectives of the experiment are: 1) to extend the verification of the simulation of the Doppler tolerant technique; and 2) to demonstrate that the radar transmitter, waveform generator, and receiver imperfections do not significantly degrade resolution, performance or reliability of meteorological spectral moment estimates     

A model of air traffic controllers' conflict detection and conflict resolution

A model of the mental activities of en route controllers in air traffic control (ATC) is outlined. As an example of the psychological research rendering the basis for this model, the methods and results of an experiment with experienced controllers is sketched which is concerned with conflict detection in ATC. Further, a procedure for conflict resolution is described, supplementing the general model. This procedure is designed to be transformed into a computer based assisting system in ATC. Problems and functions of operator models in the development of new technologies in air traffic management are discussed.     

基于嵌入式仿真的雷达训练系统设计

介绍了嵌入式仿真技术及其发展,将嵌入式仿真与雷达模拟训练相结合,构成了能够嵌入到机械扫描雷达实装的模拟训练系统。描述了对嵌入式仿真训练系统的结构组成以及部分模块的功能,研究了模拟雷达视频回波数据的方法和模型,包括目标回波、地物杂波、海杂波、气象杂波、有源干扰和接收机内部噪声,利用数学模型计算回波的强度、方位、距离等特性,调制实际录取的回波数据,生成与态势设置参数相应的模拟回波数据,能够对信号处理操作和抗干扰操作做出响应。通过对视频回波进行仿真,由终端显示画面可知模拟的回波数据具有较高的逼真度,经测试模拟视频回波能够被雷达显控终端识别。     

转子支承不对中故障建模与机理分析

针对工程实际所出现的不对中现象,建立了一个转子支承不对中故障的通用模型。将任意形式的联轴器在径向刚度和角向刚度等效的前提下简化为1个等效模型,该模型与实际的总体径向刚度和角向刚度等效,依据实际联轴器刚度计算得到等效模型参数;根据等效联轴器模型推导出转子系统由于连接对角向位置的不均匀、连接刚度的差异性和非线性等不确定性因素所产生的不对中激励力,基于此建立含转子支承不对中故障的转子-支承耦合动力学模型。通过故障仿真分析得到转子支承不对中故障激励下的振动特征,通过数值仿真验证了平行不对中和角度不对中故障的2倍频和4倍频现象,以及由于角度不对中产生的1倍频轴向振动现象。利用含套齿联轴器的3支点转子故障模拟试验器进行了特征转速下多种不对中工况的振动响应试验,通过比较仿真结果的精度达到85%以上,表明所提出的转子支承不对中故障通用模型的正确有效性。     

民航空管专业学生心理健康指导研究

通过对中国民航空管不安全事件的统计特征分析,以及对空管人员执业素质要求的分析,探讨了影响中国民航空管人员执业素质的基本心理要素,并结合空管专业学生的实际情况,根据空管职业对从业人员心理品质的要求,探索对空管专业学生进行心理健康指导的途径与方法.     

Canonical transform for tracking with kinematic models

A canonical transform is presented that converts a coupled or uncoupled kinematic model for target tracking into a decoupled dimensionless canonical form. The coupling is due to non-zero off-diagonal terms in the covariance matrices of the process noise and/or the measurement noise, which can be used to model the coupling of motion and/or measurement between coordinates. The decoupled dimensionless canonical form is obtained by simultaneously diagonalizing the noise covariance matrices, followed by a spatial-temporal normalization procedure. This canonical form is independent of the physical specifications of an actual system. Each subsystem corresponding to a canonical coordinate is characterized by its process noise standard deviation, called the maneuver index as a generalization of the tracking index for target tracking, which characterizes completely the performance of a steady-state Kalman filter. A number of applications of this canonical form are discussed. The usefulness of the canonical transform is illustrated via an example of performance analysis of maneuvering target tracking in an air traffic control (ATC) system.     

Doppler-Tolerant Classification of Distributed Targets -- A Bionic Sonar

Sonar echo analysis that is not affected by relative motion between target, transmitter, and receiver is discussed. Motion-tolerant measurement and recognition of range-distributed targets involves: 1) a determination of the effects of range rate upon echoes from non-planar reflectors and 2) the derivation of a signal, filter bank, and target parameterization scheme that is insensitive to those effects. The appropriate system is derived, simulated with a computer, and tested with actual echoes from various targets. The system's signals and filters are very similar to those found in biological sonars.     

Preoperational testing of data link-based air traffic managementsystems in Magadan, far East Russia

The Global Positioning System (GPS) has been used in many ways which were unimagined by its original planners and implementers. This paper discusses one such application; the surveillance of commercial aircraft in a developing airspace environment. GPS provides system users with the ability to determine their own position with an accuracy, reliability and cost that is unprecedented. Voice procedures augmented by radar have been the primary tools for air traffic surveillance since the end of World War II. But for some countries the equipage of aircraft with GPS and a data link capable of carrying position reports to the ATC authorities is providing a viable alternative to long-range secondary radar systems. In the summer and fail of 1995, ARINC installed and demonstrated equipment in Magadan, Russia which permits air traffic controllers of MagadanAeroControl to monitor GPS position reports generated by aircraft as far away as Canada and the South Pacific. The position reports were displayed against maps and flight tracks. This equipment has clearly demonstrated an alternative technology for the upgrading of the ATC system in Siberia and other remote areas     

空管飞行冲突分析与模拟系统设计实现

随着民用航空的发展，空中交通流量加大，飞行冲突增加，空中交通管制部门的工作难度提高。目前国内还没有一套便捷的系统用于对空管飞行冲突进行分析，仍采用人工方式评估，效率较低。介绍了一套基于普通计算机的飞行冲突评估系统，重点介绍对雷达信息的转存和处理，及对冲突目标的分析和模拟，实现利用计算机的精确、高效特性解决管制工作中遇到的分析、评估和培训问题。     

Application of Ground/Air Data Link to General Aviation Operations

The Federal Aviation Administration (FAA) is currently upgrading secondary surveillance radars with systems which will have an integral data link capability, the Mode Select (Mode S) beacon system. These new systems will allow two-way data communications between ground systems (e.g., weather databases and Air Traffic Control (ATC) systems) and aircraft that are equipped with data link compatible Mode S transponders and suitable display and input devices. Initial data link services include both weather information and ATC advisories. The MITRE Corporation* is developing an in-house capability to perform end-to-end operational evaluation of data link services. Initially, a low-cost, portable pilot position man-machine interface is being developed for use in general aviation operations. The objective is to explore operational issues in laboratory and limited flight test environments, and to demonstrate these services on a data link I/O device, a laptop portable personal computer (PC) with touch panel. A group of pilots will bench test the interface design, and the results will be incorporated into the design used in flight testing. This paper describes the project's objectives and results to date, including implementation details and pilot test results.     

机场管制系统运行的危险源识别研究

风险管理对于机场管制系统运行的安全具有重要作用,危险源识别是风险管理的关键环节,所以需要研究机场管制系统运行中的危险源识别问题。利用过程方法的思想,考虑机场管制系统的运行过程构造出机场管制过程中的危险源集合,根据机场管制的特点对作业条件危险性评价法(LEC法)进行了改进,并结合灰色关联分析法和离差最大化法建立了危险源的危险程度评估模型。算例中,对机场管制过程危险源的危险程度进行了验证分析,表明了方法的可行性和有效性。     

基于BDI模型的管制员Agent行为建模研究

针对空中交通仿真系统中的管制员Agent建模问题，通过分析管制操作行为特点，采用BDI结构，建立了基于决策树模型的管制规则知识库，设计了慎思型管制员Agent。基于Jadex平台，构建了管制员Agent模型，将由JADE平台建立的航空器Agent和模拟空管自动化系统Agent与Jadex平台建立的管制员Agent进行通信与协调，通过仿真系统构建仿真场景并验证管制员Agent的BDI推理过程，实现了对管制员的日常指挥行为的模拟。实验结果表明，所构建的管制员Agent模型可以顺利进行推理过程并对飞行冲突进行探测与解脱。     

民航ATC系统中交通信息的数据融合

民航空中交通管理系统的核心是交通信息处理，随着我国民航建设事业的发展，各地区的网络的互联，雷达信息源的分布数量的增加，自动相关监视技术的逐步应用，传统的交通信息处理模式技术已经不再适应新的形势的需要，根据民航空中交通管理系统的特点，对交通数据融合在民航空中交通管制系统（ＡＴＣ）中的一些应用前景作了一些探讨。     

Analysis of CA-CFAR processors for linear-law detection

A method for evaluating the performance of cell-averaging constant false alarm rate (CA-CFAR) processors which use the amplitude of echo signals rather than their squared amplitude is presented. Results for the case of Rayleigh clutter/noise statistics are given. Detection probabilities are evaluated for the case of a Rayleigh fluctuating target embedded in Rayleigh clutter/noise for linear-law CA-CFAR processors. These results are observed to be practically identical to those of square-law CA-CFAR processors for which analytical expressions are readily available. These observations are verified using Monte Carlo simulations. The same conclusion is reached in the case of a nonfluctuating target embedded in Rayleigh clutter/noise for which only simulation results are presented     

Ocean Tides in GRACE Monthly Averaged Gravity Fields

The GRACE mission will map the Earth's gravity fields and its variations with unprecedented accuracy during its 5-year lifetime. Unless ocean tide signals and their load upon the solid earth are removed from the GRACE data, their long period aliases obscure more subtle climate signals which GRACE aims at. In this analysis the results of Knudsen and Andersen (2002) have been verified using actual post-launch orbit parameter of the GRACE mission. The current ocean tide models are not accurate enough to correct GRACE data at harmonic degrees lower than 47. The accumulated tidal errors may affect the GRACE data up to harmonic degree 60. A study of the revised alias frequencies confirm that the ocean tide errors will not cancel in the GRACE monthly averaged temporal gravity fields. The S₂ and the K₂ terms have alias frequencies much longer than 30 days, so they remain almost unreduced in the monthly averages. Those results have been verified using a simulated 30 days GRACE orbit. The results show that the magnitudes of the monthly averaged values are slightly higher than the previous values. This may be caused by insufficient sampling to fully resolve and reduce the tidal signals at short wavelengths and close to the poles. This revised version was published online in August 2006 with corrections to the Cover Date.