探讨UWB技术用于cbtc列车定位系统的可能性（简述uwb技术的基本思想）

 

原标题：探讨UWB技术用于cbtc列车定位系统的可能性

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Moreto the Story — UWB Systems

UWB相关历史介绍

目录

1 、国外UWB技术厂家介绍

2 、专家的问答交流部分

3 、UWB-RTLS 技术要点

1 、国外UWB技术厂家介绍

Thereare now three competing UWB real-time locating systems (RTLS) using time-of-flight (ToF) technology — PulsON, Swarm Bee, and Decawave.

现在有三种竞争性的UWB 实时定位系统（RTLS）产品，PulsON 、Swarm Bee和Decave。使用的是飞行时间（ ToF）技术。

Arelated technology is TDoA (time difference of arrival). Beginning with LORAN in the early 1940s, TDoA was known as multilateration. Both ToF and TDoA technologies have various application-specific pros/cons.

相关的UWB定位技术有TDoA （到达时间差）。从20世纪40年代初的罗兰开始，TDoA被称为多点定位。ToF和TDoA技术都有各种特定应用场景。

Overthe past 3-5 years, Metrom and Protran have introduced roadway worker protection (RWP) schemes in the North American market using UWB-RTLS ToF technology.

在过去的2013-2015 年间， Metrom和Protran在北美市场使用UWB-RTLS ToF技术引入了轨道工人保护（ RWP）方案。

Metromis systems integrator selling the PulsON system produced by Time Domain (Huntsville, AL). In addition with RWP, Metrom is also selling RTLS for detecting train location and speed in connection with vaguely-defined HX and PTC concepts.

Metrom 是一家系统集成商，提供TimeDomain生产的PulsON系统。除了轨道工人保护方案， Metrolm还提供RTLS（用于确定列车的位置和速度）。

Protran/Harscois another systems integrator selling the Swarm Bee UWB-RTLS platform produced by Nanotron Technologies (Berlin, Germany).

Protran/Harsco 是另一家系统集成商，提供NanotronTechnologies生产的Swarm Bee UWB-RTLS平台。

TheDecawave (Dublin, Ireland) DW1000 is a similar UWB-RTLS technology, but has not yet appeared in rail applications. Sewio (Brno, Czech Republic), eliko (Tallin, Estonia) are based on Decawave and aimed at factory automatic applications, hospital equipment tracking, etc. CenTrak (Newtown PA) is a 900 MHz RTLS for hospital staff, patient, and asset tracking.

Decave DW1000 是一种类似的UWB-RTLS技术，但尚未出现在铁路应用中。Sewio、eliko基于Decave，旨在实现工厂自动化应用、医院设备跟踪等。CenTrak是一款900 MHz RTLS，用于医院员工、患者和资产设备跟踪。

2 、专家的问答交流部分

Q.How long has this been going on?

A.UWB-RTLS technologies have been commercialized only within the last 2-5 years.

问：UWB-RTLS技术何时开始应用的？

A.UWB-RTLS 技术仅在过去2013-2016年内实现了商业化。

Q.Who else knows about this?

A.The premier application of UWB-RTLS is indoor and aerial drone displays. Factory automation and hospital asset tracking are rapidly expanding markets.

问： UWB还有其他应用？

A.UWB-RTLS 的首要应用是室内定位。工厂自动化和医院资产跟踪应用场景正在迅速扩大。

Q.What is the maximum operable range of UWB-RTLS?

A.Competing vendors claim 800-2500 feet.

问：UWB-RTLS 的最大覆盖范围是多少？

A. 竞争对手声称有240-750米。

Q.Why not use inertial measurement instead of suffering the vagaries of receiving or transmitting RF signals?

A.IMUs drift over time; the best only drift at a slower rate. As you’ve already learned from your study of inertial navigation, railroad vehicles are constrained to just two of the six axes. With an IMU, everything is relative to a initial position. Error is cumulative over time.

问：为什么不使用惯导，替代接收 /发送射频信号的技术方式？

A.IMU会随时间漂移；低速下的漂移较小。正如在惯性导航研究中已经了解到的，铁路车辆仅限于六个轴中的两根轴可用于安装 IMU。有了 IMU，一切都是相对于初始位置的。误差是随时间累积的。

Q.What else can UWB-RTLS do?

A.Each system can exchange user data among peers and act as a short-range radar system.

问：UWB-RTLS 还能做什么？

A. 可以在列车之间直接交换用户数据，并充当短程雷达系统。

Q.Does UWB-RTLS have any fail safe properties?

A.No.

问：UWB-RTLS 有任何故障导向安全属性吗？

答：没有。

Q.Would UWB-RTLS be useful as a CBTC or station stopping localization subsystem?

A.Yes. UWB-RTLS is, in fact, little more than a hot-rod RFID system. Unlike the MATRA, Amtech, or Eurobalise tag/reader systems, accurate UWB-RTLS localization and direction info is continuously available to the train while standing or moving within 100m or so from the tag. Using a UWB-RTLS in a station stopping feedback loop is especially interesting when compared to contemporary marker coil or loop transposition counting techniques. Until now, radar or lidar seemed to be the next step forward, but UWB-RTLS looks attractive.

问：UWB-RTLS 作为CBTC或车站停止定位子系统是否有用？

答：是的。事实上，UWB-RTLS 是一个“ 特殊”RFID 系统。与MATRA、Amtech或Eurobalise标签/读取器系统不同，在距离标签100米左右的范围内站立或移动时，列车可连续获得准确的UWB-RTLS定位和方向信息。与标记线圈或环路换位计数技术相比，在车站定位停车中，使用UWB-RTLS 尤其有效。直到现在，雷达或激光雷达似乎是发展方向，但 UWB-RTLS看起来很有吸引力。

Q.Could dynamic UWB tags be used as a non-contact tripstop system similar to PZB/Indusi, ZST-90, ZUB-n, TPWS, or Westcab?

A.As in the preceding, the advantages of UWB-RTLS are the ability to communicate and accurately determine position while in close proximity to the tag. With a conventional RFID tag, the longitudinal coupling range as never more than a few feet. Further, a conventional RFID tag that is continuously ‘illuminated’ by the stationary carborne reader on a stopped train poses various problems including the increased likelihood of cross-reading by trains on adjacent tracks. The ranging function of UWB-RTLS provides directionality information that would otherwise require multiple RFID tags.

问：UWB天线是否可以用作类似于 PZB/Indusi、ZST-90、ZUB-n、TPWS或Westcab的非接触式系统？

A. 如前所述，UWB-RTLS的优点是能够在接近标签时进行通信并准确确定列车位置。对于传统的 RFID标签，纵向耦合范围不超过几英尺。此外，传统的RFID标签被停下来的列车上的固定车载读取器连续“激活” ，这会带来各种问题，包括相邻轨道上列车交叉读取的可能性增加。UWB-RTLS的测距功能提供计算列车方向功能。而传统的应答器需要 2个以上RFID标签。

Q.UWB for communications?

A.Unavoidable multipathing causes notoriously poor propagation of VHF and UHF signals in subway and mine tunnels. In some instances, a pair of otherwise healthy 5-watt walkie-talkies will not reliably communicate over a line-of-sight range of just 100-200 feet. Similar propagation problems develop inside the hulls of ships.

Leakycoax (Radiax) cable is the only practical means of ensuring 100% coverage in tunnels and ships, however, leaky coax has bandwidth limitations which dictate unduly large diameters at higher frequencies. Bidirectional diplexing and amplification along the line is problematic, limiting leaky coax segments to 2000 feet or less. Lack of space for leaky coax transceiver equipment is a special problem in under-river tubes. NYCT’s tunnels are now rigged with multiple leaky coaxes for competing cell service providers and NYCT’s RTO 161 MHz and 478 MHz police radio systems.

Basebandpulse modulation (UWB) offers some theoretical advantage over frequency- or time-division carrier modulation, however, UWB will not be a panacea in underground wireless communications. Leaky coax is incompatible with UWB due to its wavefront retarding propagation characteristic. OTOH, UWB pulse modulation can be carried directly to/from outlying transceivers over long lengths of fiber. Read more: Canarsie radio (2003).

Q.UWB 用于通信？

A. 不可避免的多路径会导致地铁和矿山隧道中VHF和UHF信号传播不良。在某些情况下，一对健康的5瓦对讲机在100-200英尺的视距范围内无法可靠地通信。类似的传播问题在船体内部也存在。

泄漏同轴电缆是确保隧道和船舶 100%覆盖的唯一实用方法，然而，泄漏同轴电缆具有带宽限制，导致在较高频率下直径过大。沿线的双向双工和放大是有问题的，将泄漏的同轴电缆段限制在2000英尺或以下。缺少泄漏同轴收发器设备的空间是海底管道中的一个特殊问题。NYCT的隧道现在配备了多个泄漏同轴电缆，用于竞争手机服务提供商和NYCT的RTO 161 MHz和478 MHz警用无线电系统。

与频分或时分载波调制相比，基带脉冲调制（UWB ）提供了一些理论上的优势。然而， UWB并不是地下无线通信中的灵丹妙药。泄漏同轴电缆由于其波前延迟传播特性而与UWB不兼容。OTOH、UWB脉冲调制可以通过长光纤直接传送到外围收发器。

Q.UWB is WiFi, right?

A.Yes/no. Some versions of UWB utilize WiFi’s 2.4 or 5 GHz ISM bands, but modulation characteristics, packet structure, and message protocols are entirely different. Per FCC definition, UWB is any system with a bandwidth of 500 MHz or more. Within North America, PulsON and Swarm Bee operate at a center frequency of 2.44 GHz. All are unlicensed FCC Part 15 devices, meaning that they must not interfere with anything else, and users have no right to complain about disruptive interference from elsewhere.

问：UWB 是WiFi，对吧？

A. 是/否。某些版本的UWB利用WiFi的2.4或5GHzISM频带，但调制特性、分组结构和消息协议完全不同。根据FCC的定义，UWB是带宽为500MHz或更高的任何系统。在北美，PulsON和Swarm Bee的中心频率为2.44 GHz。所有这些都是未经许可的FCC第15部分设备，这意味着它们不得干扰任何其他设备，用户无权投诉来自其他地方的干扰。

Q.Radar?

A.In addition to their function as an RTLS, UWB tags can measure time-of-flight of pulses reflected by nearby objects, both moving and stationary, even when there are no other tags within view. Using this data, UWB-RTLS can serve as a field disturbance detector. 10 GHz field disturbance detectors have been used 25+ years to detect people approaching/passing through a doorway. Keep in mind that radars, lidars, photoelectric beams, etc., cannot distinguish trains from other objects in the efficient, reliably way of olde-fashioned track circuits.

Q.UWB 是雷达？

答：除了作为RTLS 的功能外，UWB标签可以测量附近物体反射的脉冲的飞行时间，无论是移动的还是静止的，即使视野中没有其他标签。利用这些数据，UWB-RTLS可以用作障碍物检测。 10GHz场干扰检测器已经使用了25年以上，用于检测接近/通过门口的人。请记住，雷达、激光雷达、等无法高效、可靠地将火车与其他异物区分。

Q.Why not use olde-fashioned GPS?

A.Consider aerial drone navigation — GPS would work, but a separate communication network is required. Available space and lift capacity are scarce on small drones, thus an RTLS system which combines localization and communication in one transceiver/antenna package is a clear winner.

问：为什么不考虑GPS ？

答：考虑无人机的导航-GPS 可以工作，但还需要单独的通信网络。因此，将定位和通信结合在一起的 RTLS系统显然是赢家。

Keypoints to understanding UWB-RTLS technology:

3 、UWB-RTLS 技术要点

Theterm UWB refers only to the mode of RF transmission (baseband pulse modulation). UWB-RTLS is a three-dimensional localization system designed to a substitute for GPS and GNSS in short-range, indoor, or underground applications where satellite-based localization is not feasible.

术语UWB 仅指RF传输模式（基带脉冲调制）。UWB-RTLS是一种三维定位系统，设计用于在基于卫星的定位不可行的短程、室内或地下应用中，替代 GPS、GNSS 。

Youalready understand how RFID transponders [tags] generate modulated backscatter of the interrogator’s CW carrier to transmit data from the tag to interrogator. Now imagine Amtech/Transcore RFID tags with two-way data transmission capability.

您已经了解了RFID 应答器[标签]如何生成询问器CW载波的调制反向散射，以将数据从标签传输到询问器。现在想象一下具有双向数据传输能力的Amtech/Transcore RFID标签。

Forconvenience, we’ll use the term ‘tag’ to describe RTLS transceivers which interact in a peer-to-peer ‘swarm’ (constellation).

为了方便起见，我们将使用术语 “标签”来描述在点对点交互中的RTLS 收发器。

AllRTLS tags employ identical hardware but may differ in operating mode. Some may be in fixed locations, serving as ‘anchors’ while others are mobile.

所有RTLS 标签使用相同的硬件，但操作模式可能不同。有些可能位于固定位置，充当“锚”，而另一些则是移动的，则是 “天线”。

Aswith RFID tags, the maximum range of RF coupling is limited by FCC restrictions for maximum RF output power and antenna configuration (effective radiated power, ERP). Metrom claims its maximum range is 1200-2500 feet; Protran claims 800-1200 feet. Sales lit doesn’t discuss factors which affect range. Attempts to increase range would be counterproductive in several ways, e.g. unnecessarily increasing the number of tags within the swarm; decreasing location accuracy due to multipathing; decreasing data communications throughput due to longer time-of-flight between successive pulses.

与RFID 标签一样，RF耦合的最大范围受到FCC对最大RF输出功率和天线配置（有效辐射功率，ERP）的限制。Metrom声称其最大射程为365-762米； Protran声称有244-365米。增加范围的尝试会在几个方面产生反作用，例如不必要地增加群内的标签数量；由于多路径而降低定位精度；由于连续脉冲之间的飞行时间更长，数据通信吞吐量降低。

Eachtag has a unique ID code.

每个锚（ UWB轨旁设备）都有一个唯一的ID 代码。

Eachtag has ranging capability, to measure round-trip, time-of-flight for individual pulses or data packets sent to/from a specific tag within a ‘swarm’ of tags.

每个标签都具有测距能力，可以测量往返于标签群中特定天线的单个脉冲或数据包的飞行时间。

Tominimize non-productive message collisions among peers, pulse and packet transmissions are dynamically varied in time and rate.

为了最小化点对点之间的非生产性消息冲突，脉冲和分组传输在时间和速率上动态变化。

Whereone tag is mobile and others in the swarm are fixed, the mobile tag can readily determine its position and velocity relative to the fixed tags.

车上的天线是移动的，而群中的轨旁标签是固定的。移动天线可以容易地确定其相对于固定标签的位置和速度。

Afixed [anchor] tag can determine the location and speed of mobile tags.

标签可以确定移动标签的位置和速度。

Athree-dimensional position estimate requires the mobile tag to have a minimum of three other tags in view. Just like GPS, there is an angular geometric dilution of precision factor that affects accuracy.

三维位置估计要求移动标签至少具有三个其他标签。与GPS 一样，不同角度的信号也会影响精度。

Accurateranging between tags requires line-of-sight coupling. Multipathing errors are minimized using pulse modulation.

标签之间的精确测距需要视线耦合。使用脉冲调制使多径误差最小化。

Optionalaccelerometers and rate gyros within the tag are used to improve range/position estimates for fast moving objects such as aerial drones.

可选配加速计和速率陀螺仪用于提高列车的距离/ 位置估计。

翻译不妥之处，请谅解。

原文作者：Has-Been翻译：徐纪康

素材来源： 粉丝 徐纪康 供稿

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