Proposed UWB radar terminology

The term ultra-wideband (UWB) [which was formally defined by DARPA in 1990], for classifying an emerging technology in the field of radar and radio communications is synonymous with the following terms: baseband; video pulse; nonsinusoidal; carrierfree (carrierless); impulse; time-domain; super-resolution; ultra-high resolution; stealthy; spread spectrum; Rayleigh spectrum. The paper lists the terminologies that may be used for the emerging technology of UWB radar.     

Software approach to access UWB interference on GPS receivers

Ever since the FCC approved the use of UWB devices in commercial and federal bands, various agencies whose operations and/or products rely on the integrity of signals within certain "restricted" radio frequency bands have voiced concerns over the potential impact of the UWB interference. GPS signals are among these "restricted" bands. Several groups in the GPS community have conducted experimental studies concerning the impact of UWB interference on the performance of various grades of commercial and aviation GPS receivers. In this paper, we present a software approach to simulate and evaluate UWB interference on GPS receivers. The software approach provides greater flexibility in the design of testing scenarios, such as the inclusion of a large number of aggregated UWB devices, the generation of new UWB signals and modulation schemes, and the possibility of extending the study to new GPS signals. The paper discusses a general framework for developing algorithms to evaluate UWB and GPS interference under a wide variety of hardware and software conditions. This framework consists of three classes of components: input, processing, and analysis. The input components are responsible for the generation of UWB signal waveforms and modulation schemes, and GPS signals. The processing components include a simulated model of GPS RF front end and software implementation of GPS processing blocks, such as acquisition, tracking, and post-processing. The analysis components focus on the study of specific receiver processing component outputs. Both real and simulated UWB signals can be used in the study. The real UWB signals are primarily used to validate the simulation procedure, whereas the simulated UWB signals are used to allow the immediate incorporation of new UWB waveforms and modulations in the evaluations. This paper presents details of the software components developed and the preliminary results achieved     

UWB radars in medicine

Applied research on biomedical applications of UWB radar is targeted to the identification of the possible new devices made possible by the technology, to the design and development of those devices, and to the clinical testing of the systems obtained. Applications can be divided into two main sectors according to the frequency range used. For the conventional UWB radar microwave region: cardiac biomechanics assessment; chest movements assessment OSA (obstructive sleep apnoea) monitors; soft-tissue biomechanics research; heart imaging ("Holter type" echocardiography); chest imaging. Together with systems for: cardiac monitoring; respiratory monitoring; SIDS (sudden infant death syndrome) monitor; vocal tract studying. If an IR laser diode is used as the antenna, a more common radar is obtained (actually a hybrid between a narrow band and a wide band radar) which emits a short packet of electromagnetic waves whose echoes are sampled using conventional UWB receiver equipped with a PIN photodiode. Possibilities include: non-invasive biochemical study of soft tissues, non-invasive study of metabolic processes, and IR spectral imaging     

NETEX UWB test results

The goal of the Defense Advanced Research Projects Agency's (DARPA) Networking in Extreme Environments (NETEX) program is to create a wireless networking technology for the military user that enables robust connectivity in harsh environments and support its integration into new and emerging sensor and communication systems. Phase 1, resulted in a thorough understanding of the effects of ultra wide band (UWB) system operation on existing military spectrum users based on modeling, simulation, and measurements. In order to accomplish this task, the DARPA Advanced Technology Office (ATO) procured a set of UWB emitters and broadband antennas to use as interference sources and contracted with the Naval Air Warfare Center Aircraft Division (NAWC AD) Electromagnetic Environmental Effects (E/sup 3/) Division to provide candidate victim systems from the existing (legacy) US naval aircraft and shipboard inventory for testing. Testing was conducted on seventeen legacy systems during October 2002 through March 2003. The purpose of this paper is to provide a brief overview of the results of these tests. This paper will provide a brief discussion of the UWB emissions as described by the US Federal Communications Commission (FCC) and describe the generic UWB emitter used for these tests. It will then provide a discussion of the results as they apply to the purpose of the NETEX program.     

UWB与GNSS结合的室内外一体化定位系统设计

针对电力北斗安全应用、自动驾驶导航等应用场景对室内外一体化无缝定位的迫切需求,设计了一种将UWB与GNSS结合的一体化无缝定位系统.通过将UWB标签与小型化GNSS模块集成到手持智能设备上形成一体化定位终端,服务器软件对卫导结果与超宽带定位结果进行融合,输出连续定位结果.实验结果表明,该系统可以实现人员的室内外一体化无缝定位,室内环境下的静态定位精度小于10cm,该系统已应用于大型发电厂和变电站的人员安全防护管理项目.     

Short-distance ultra wideband radars

The possibility of ultrawideband (UWB) radar usage in various fields for remote measuring the object's motion at short distance is considered. Application of UWB radar in medicine for remote measuring of patient's heart activity and respiration is shown. The measuring method is described and practical results of tests are cited. The opportunity of radar application in other areas is described.     

顾及空间分布和NLOS的UWB室内可信定位方法

针对现行室内可信定位存在的三维定位精度低与结果可信度难以定量评估的难点,提出了一种可信超宽带(UWB)室内定位模型。该方法采用无迹卡尔曼滤波和IGG-III抗差理论模型,解决了UWB定位中的非线性化和非视距误差问题;同时,为提高该方法定位结果的可信度,进一步构建了一种兼顾UWB基站空间分布和非视距误差的可信精度评估模型。与现有模型相比,提出的方案可有效实现基于UWB的室内高精度可信定位。仿真和实测数据结果表明：1)与传统最小二乘结果相比,该方法可提高30%～40%的UWB定位精度;2)引入IGG-III抗差模型可提高11%的定位精度;3)非线性化误差对UWB定位精度的影响不尽相同,约为22%～50%;4)提出的可信度评估模型可实时准确评估UWB定位精度。     

Ultrawideband microwave-radar conceptual design

This paper outlines the special considerations that characterize the design of an UWB radar for the detection of low-altitude missiles over the sea. It discusses the factors which enter into the choice of frequency, and the selection of the transmitter, antenna, and receiver. Reviewed are signal processing issues concerning detection of UWB signals in noise and clutter, nondoppler MTI based on the pulse-to-pulse change in range due to target motion, measurement of target height based on multipath time delay, and target recognition. As the investigation progressed, the authors became disappointed with the available UWB technology, but encouraged about the potential advantages of UWB for this application. The chief limitation of UWB radar that must be overcome before applications are viable is its poor electromagnetic compatibility (EMC)     

Estimating the Doppler centroid of SAR data

After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ΔE estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found that the nonlinear SDE algorithm, which estimates the Doppler-shift on the basis of data signs alone, gives superior performance     

基于超宽带和航位推算的室内机器人UKF定位算法

超宽带是一种传输速率快、功耗低的新型无线通信技术,可提供亚米级定位精度,近年来超宽带定位在机器人领域的应用日益广泛。在超宽带信号有效区域边缘或信号受到遮挡时,超宽带定位精度急剧下降。为此提出了一种基于超宽带定位和航位推算的UKF组合定位方法,可有效克服上述问题,从而为室内机器人定位提供一种稳定可靠的解决方案。     

非视距误差神经网络改正的超宽带定位模型研究

非视距环境是造成超宽带定位系统精度下降的主要原因。由于非视距环境的测距精度下降难以通过常规计算方法建立改正模型,提出了一种基于反向传播算法的神经网络改正的超宽带稳健定位模型。该方法通过反向传播神经网络的自适应学习方法建立了一种超宽带非视距误差改正的稳健定位模型,实现了在非视距环境下超宽带定位精度的提升。首先采集非视距环境下超宽带测距值,提取超宽带在非视距环境下的坐标序列,计算得到误差序列,然后通过反向传播神经网络建立误差改正模型预测得到标签的误差改正值,最后使用超宽带Kalman滤波定位模型进行超宽带定位,从而消除非视距环境对定位精度的影响。通过对比实验分析,本模型较多项式拟合模型超宽带测距精度提高46.8%,定位精度提高43.4%;较多面函数拟合模型超宽带测距精度提高28.2%,定位精度提高26.2%。实验结果表明,反向传播算法的神经网络对超宽带非视距定位模型的误差改正有很好的效果,对超宽带定位精度的改正效果显著。     

脉冲超宽带信号测量性能分析

超宽带技术是一项新兴的无线通信技术,具有极其广阔的发展前景,但目前仅用于室内短距离通信,少见用于航天测控系统。为了将超宽带技术应用于测控系统中,以模糊函数为工具,对脉冲超宽带信号的测量性能进行分析。首先推导矩形脉冲串信号和载波调制矩形脉冲串信号的模糊函数,并对其模糊特性进行仿真分析。在此基础上,主要针对用于测控系统的伪码调制脉冲超宽带信号,利用其模糊函数分析其测距测速性能。结果表明:该超宽带信号具有良好的测距测速性能,其最大无模糊距离为1个伪码周期,最大无模糊多普勒频率为脉冲重复频率的倒数;单脉冲宽度越窄,其测距性能越好而测速性能越差。     

Programmable ultrawideband signal generator for electromagnetic susceptibility testing

Under Phase I of the Defense Advanced Research Projects Agency (DARPA) Networking in Extreme Environments (NETEX) initiative, Multispectral Solutions, Inc. (MSSI) was tasked with the development of a general-purpose, ultrawideband hardware simulator capable of reproducing a wide variety of ultrawideband (UWB) waveforms. The simulator, with UWB outputs from baseband through millimeter wave, was to be used for the purpose of electromagnetic susceptibility testing of legacy military radio, radar, and positioning systems. The ultimate goal of this portion of the Phase I program was the quantitative determination of those UWB parameters (e.g., frequency, power, pulse rate, pulse shape, dithering, etc.) which had the least impact on the operational performance of legacy designs. This describes the development of the MSSI NETEX UWB simulator (BFP1000).     

Ultra-wideband impulse radar-an overview of the principles

Over the past decade, extensive research work has been carried out to develop the ultra-wideband (UWB) technology for radar applications, and to resolve the practical challenges in implementing an efficient UWB radar system. In this paper, we present an overview of the basic principles of UWB impulse radar. The focus is on the principles of UWB signal generation, impulse radiation, waveform design, pulse compression, range-velocity resolution (ambiguity function), array beamforming, and radar-target signature     

密林环境空地协同GNSS/UWB快速高精度定位技术

针对密林中卫星信号遮挡难以实现快速高精度定位的问题,提出了一种密林环境空地协同全球卫星导航系统/超宽带(GNSS/UWB)高精度定位方法。该方法综合考虑无人机平台在空旷环境快速运动与超宽带的强穿透性测量等特征,通过无人机携带GNSS/UWB集成化载荷,以移动单基站模拟多基站,配合密林中UWB标签组网测距,完成密林中UWB标签定位。对基站布设方案展开研究,为密林环境下空地协同GNSS/UWB快速高精度定位技术应用提供基站布设指导和依据,并且利用密林环境下实测测距实验+仿真定位实验对提出的方法进行验证。结果表明,所述方法可有效实现密林环境下的快速高精度定位,精度达到分米级,并且通过优选基站布设网型、范围及高度可有效提高定位精度,为密林环境下快速高精度定位方法提供了理论支撑。     

基于TOF的UWB可移动基站快速自定位算法

针对运动场中超宽带(UWB)可移动基站的位置获取需要人工测量、定位不方便的问题,提出了基于飞行时间(TOF)的UWB可移动基站快速自定位方法.首先根据基站布局情况确定局部坐标系,建立基于UWB基站间相互测距信息的各基站坐标方程,采用最小二乘法对各基站的坐标进行解算,进而分析其定位误差.最后通过实验验证了算法的可行性和稳定性.实验结果表明,可移动基站平均定位精度在0.05m以内.相对于传统的人工测量方式,基站自定位可有效节省基站布设时间,减少工作量.     

脉冲超宽带通信与测距技术初步研究

相对于连续波窄带技术,脉冲超宽带技术在短距离通信及高精度测距方面具有一定优势.为了向未来航天应用提供新的技术支持,对脉冲超宽带通信及测距技术进行了初步研究.描述了系统的收发单元及天线单元,同时给出了各单元的测试结果.脉冲超宽带通信、测距实验表明,系统成功实现了短距离高速通信和高精度测距.在10 m范围内通信码速率为100 Mbit/s,定位精度为厘米量级.     

超宽带无线电技术及其进展

介绍了超宽带(UWB)无线电技术的原理、结构、特点,及其在军事领域应用的进展情况,具体介绍了几种UWB通信和UWB雷达的系统构成及其主要技术参数。     

Assessment of ultra-wideband (UWB) technology

A summary report on a view of the state of the art and the potential performance benefits and limitations of UWB technology, with particular emphasis on radar applications, is presented. This review was carried out at the request of the Defense Advanced Research Projects Agency (DARPA) and the Office of the Secretary of Defense. The focus is on issues pertinent to impulse radar. Recommendations are made for future US Dept. of Defense investments in UWB radar related studies and analyses     

基于MEMS/UWB组合的室内定位方法

在深入研究超宽带（UWB）与车载低成本MEMS的定位原理和算法的基础上,提出了采用UWB辅助MEMS定位的算法,以抑制MEMS的发散并提高定位精度。设计了两者的融合定位算法,完成了基于MEMS/UWB的室内定位技术研究。最终试验运动253.4m,MEMS定位误差小于0.61m,MEMS/UWB融合定位误差小于0.07m。试验结果表明,MEMS/UWB算法与单独的MEMS定位算法相比,有效地提高了定位精度与定位稳定性。