经济学人221:可见光通信 与光共舞

 　　Science and technology

　　科学技术

　　Visible-light communication

　　可见光通信

　　Tripping the light fantastic

　　与光共舞

　　A fast and cheap optical version of Wi-Fi is coming

　　一个高速而廉价的光学Wi-Fi即将问世

　　AMONG the many new gadgets¹ unveiled at the recent Consumer Electronics Show in Las Vegas was a pair of smartphones able to exchange data using light.

　　最近，在拉斯维加斯国际消费电子展上首次展出的电子产品中，有一对能利用光交换数据的智能手机。

　　These phones, as yet only prototypes from Casio, a Japanese firm, transmit digital signals by varying the intensity² of the light given off from their screens.

　　目前，这两部不过是日本卡西欧公司的样机，它们能通过改变自身屏幕的光强来传传输数字信号。

　　The flickering⁴ is so slight that it is imperceptible to the human eye, but the camera on another phone can detect it at a distance of up to ten metres.

　　这样的闪光很微弱，人眼无法感知，但另一部手机的摄像头能够在十米的范围内检测得到。

　　In an age of Wi-Fi and Bluetooth, flashing lights might seem like going back to sending messages with an Aldis lamp.

　　在这个Wi-Fi和蓝牙横行的时代里，使用闪光可能有点像回到用奥尔迪斯手提信号灯发送信息的年代。

　　In fact, they are the beginning of a fast and cheap wireless⁵-communication system that some have labelled Li-Fi.

　　事实上，它们正是有人称之为Li-Fi的高速、廉价的无线通讯系统的鼻祖。

　　The data being exchanged by Casio’s phones were trifles:

　　两部卡西欧手机交换的数据量非常小：

　　message balloons to be added to pictures on social-networking sites.

　　不过是添加在社交网站图片中的虚拟对话框。

　　But the firm sees bigger applications, such as pointing a smartphone at an illuminated⁶ shop sign to read information being transmitted by the light:

　　但卡西欧公司发现这项技术有更大的应用前景，比如将智能手机对准发光的商店招牌读取通过灯光传送的信息：

　　opening times, for example, or the latest bargains.

　　如营业时间或最新优惠。

　　Yet that is still only a flicker³ of what is possible.

　　但是，这项技术可能有万千功能，以上不过是冰山一角。

　　Last October a number of companies and industry groups formed the Li-Fi Consortium, to promote high-speed optical wireless systems.

　　去年十月，多家公司及实业集团共同成立了Li-Fi联盟，以推广高速无线光学通信系统。

　　The idea is that light can help with a looming⁷ capacity problem.

　　他们的想法是可见光通信将有助于解决即将来临的数据传输瓶颈问题。

　　As radio-based wireless becomes ubiquitous, more and more devices transmitting more and more data are able to connect to the internet, either through the mobile-phone network or through Wi-Fi.

　　随着无线电通讯的普及，越来越多的数据传输量越来越大的设备能够通过移动网络或Wi-Fi与互联网连接。

　　But there is only a limited amount of radio spectrum⁸ available.

　　但可用于通信的无线电频段是有限的。

　　Using light offers the possibility of breaking out of this conundrum⁹ by exploiting a completely different part of the electromagnetic spectrum, one that is already ubiquitous because it is used for another purpose: illumination.

　　运用一个完全不同的电磁波段—可见光，就有可能解决这个难题；这个波段其实早已相当常用，因为它有另一个作用：照明。

　　Lighten the darkness

　　照亮黑暗

　　To turn a light into a Li-Fi router involves modulating¹⁰ its output, to carry a message, and linking it with a network cable to a modem¹¹ that is connected to a telephone or cable-broadband service, just like a Wi-Fi router.

　　要将一个可见光源变成能够携带信息的Li-Fi路由器，需要调制其光强以及用网线将其与一个调制解调器连接，一如Wi-Fi路由器。

　　Incandescent¹² light bulbs and fluorescent¹³ tubes are not really suitable for modulation¹⁴,

　　白炽灯和日光灯的光其实并不适合调制，

　　but they are yesterday’s lighting¹⁵ technology.

　　不过它们已是旧式的照明技术了。

　　Tomorrow’s is the light-emitting diode.

　　新式的照明技术是发光二极管，

　　LEDs are rapidly replacing bulbs and tubes because they are more efficient.

　　LED正凭借其更高的能量利用率迅速取代电灯泡和灯管。

　　And because they are semiconductor¹⁶ devices, tinkering with their electronics to produce the flickering signals required for data transmission is pretty straightforward¹⁷, according to Gordon Povey,

　　歌登·波文在英国爱丁堡大学与哈拉尔德?哈斯及其同事一起研究光通信；他说，因为LED是半导体器件，

　　who is working on light communication with Harald Haas and his colleagues at the University of Edinburgh, in Britain.

　　调整一下其电路就能很轻易地产生传输数据所需的闪光信号。

　　The rate of data transfer is also good. Dr Povey’s group is already up to 130 megabits a second over a distance of about two metres, using standard LEDs.

　　用可见光传输数据的速度也相当可观。波文博士的研究小组已能利用标准LED在约两米内以最高每秒130兆位的速度传输数据。

　　Dr Povey, who is also the boss of VLC, a firm set up to commercialise the technology, thinks such devices should be able to reach 1 gigabit per second, and do so over greater range.

　　同时也是VLC公司的老板的波文博士认为这种器件应能达到每秒1千兆比特的传输速度，且传输距离可以更远。

　　Specially¹⁸ constructed LEDs would be even faster.

　　采用特制LED所达到的速度将会更高。

　　The Li-Fi consortium reckons more than 10 Gbps is possible.

　　Li-Fi联盟估计传输速度可能达到10 Gbps以上。

　　In theory, that would allow a high-definition film to be downloaded in 30 seconds.

　　理论上，这个速度意味着不到30秒就能下载一部高清电影。

　　Dr Povey believes that adapting existing LEDs to work with the sensors¹⁹ and light sources—cameras, ambient-light detectors²⁰, screens, flashbulbs, torches and so on.

　　波文博士认为，改造现在的LED使之适应智能手机及类似设备上已有的感应器及光源，如摄像头、环境光感应器、屏幕、闪光灯泡、手电筒等，

　　already found in smartphones and similar devices will be the fastest way to bring Li-Fi to market.

　　是将Li-Fi推向市场最快的方法。

　　VLC has already produced a smartphone app which allows low-speed data transmission between a pair of iPhones.

　　VLC已设计了一款智能手机软件，两部iPhone能用此软件以低速传输数据。

　　It has also made an experimental optical transceiver that plugs into a laptop to receive and send light signals.

　　该公司也制造了一台用作试验的光收发器，可插入笔记本电脑以收发光信号。

　　Later this year it will bring out Li-Fi products for firms installing LED-lighting systems.

　　今年再过不久，VLC将面向安装了LED照明系统的企业推出Li-Fi产品。

　　There are limitations to using light, of course.

　　当然，利用可见光通信也存在局限性。

　　Unlike radio, light waves will not penetrate²¹ walls.

　　可见光不同于无线电波，无法穿透墙壁。

　　Yet for secure applications that could be a bonus.

　　但对于安全应用而言这可能是个意外的优点。

　　And light bulbs—some 14 billion of them around the world—are almost everywhere and often on.

　　而全球大约共有一百四十亿个灯泡，它们几乎随处可见，而且经常亮着。

　　As they are gradually replaced by LEDs, every home, office, public building and even streetlight could become a Li-Fi hotspot.

　　随着电灯泡逐渐被LED所取代，每家每户、办公室、公共建筑物、甚至路灯都可能成为一个Li-Fi热点。

　　Having a line-of-sight connection with the LED in question would undoubtedly²² improve the signal,

　　若你正在使用的LED光源处于视线范围内，信号强度无疑会有所增加，

　　but light reflected from walls or ceilings might often be enough.

　　不过仅靠墙壁或天花板的反射光可能往往也足够了。

　　In any case, having a good line of sight helps Wi-Fi as well.

　　同样，不论如何，若在视线之内有Wi-Fi信号源，信号当然也会更强。

　　And spotting a nearby light in order to sit next to it is certainly easier than finding the location of a Wi-Fi router.

　　而在身边找一个光源就近使用之当然要比寻找Wi-Fi路由器来得容易。

　　Communication, though, is a two-way street.

　　不过通信是双向的。

　　That means the LEDs involved in Li-Fi would need photodetectors to receive data.

　　这意味着Li-Fi中的LED需要有光电探测器来接收数据。

　　Some LED systems have such sensors already.

　　一些LED系统已经配备这种探测器了。

　　But even if LEDs are not modified Dr Povey reckons hybrid²³ systems are possible:

　　但即使不对LED进行改造，波文博士认为混合系统也可能行得通：

　　data could be downloaded using light but uploaded using radio.

　　通过光下载数据，而上传数据则使用无线电波。

　　In an office, for example, an LED-powered desk lamp could work as a Li-Fi router, able to link up with any networked device placed on the desk.

　　例如在一个办公室里，一盏LED台灯也可以是一个Li-Fi路由器，它能连接桌上任何一个已经联网的设备。

　　A big advantage of light is that it can be used in areas which contain sensitive equipment that radio signals might interfere²⁴ with, such as aircraft and operating theatres.

　　可见光通信的一大好处在于：它在装有可能会受无线电信号干扰的敏感设备的场所能派上用场，如飞机上及手术室内。

　　LEDs in the ceiling of an airliner²⁵ would not only allow internet access but could also transmit films on demand to individual seats, removing the need for lots of expensive and heavy cabling, thus saving airlines fuel.

　　将LED安装在大型客机的舱顶，不仅能提供网络服务，还能将旅客点播的电影传送至他们的座位上，这样就不必安装许多昂贵而又笨重的线缆，如此一来也会节省燃油。

　　That alone could be enough to, as it were, make this idea fly.

　　光是这一点，似乎就足以令这项技术腾飞。

　　1.fantastic a.极好的；巨大的；奇异的

　　We watched a fantastic play yesterday evening.

　　昨天晚上我们看了一场非常精彩的演出。

　　2.imperceptible a.感觉不到的；细微的

　　The pulse is almost imperceptible.

　　脉搏几乎摸不清。

　　3.communication n.交流；通讯；传达

　　Most important of all, computers create wide communication around the world.

　　最重要的是,计算机在世界范围内建立了广泛的交流。

　　4.application n.应用；申请；专心

　　I didn't receive an acknowledgement of my application.

　　对我的申请,我还没有收到复信告知收悉。

　　5.flicker v.闪动；闪烁；摇动

　　She is read by the flicker light of the candle.

　　她借著闪烁的烛光读书。

1 gadgets   

n.小机械，小器具（ gadget的名词复数 ）

参考例句：

• Certainly. The idea is not to have a house full of gadgets. 当然。设想是房屋不再充满小配件。 来自超越目标英语 第4册
• This meant more gadgets and more experiments. 这意味着要设计出更多的装置，做更多的实验。 来自英汉非文学 - 科学史

2 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

3 flicker   

vi./n.闪烁，摇曳，闪现

参考例句：

• There was a flicker of lights coming from the abandoned house.这所废弃的房屋中有灯光闪烁。
• At first,the flame may be a small flicker,barely shining.开始时，光辉可能是微弱地忽隐忽现，几乎并不灿烂。

4 flickering   

adj.闪烁的，摇曳的，一闪一闪的

参考例句：

• The crisp autumn wind is flickering away. 清爽的秋风正在吹拂。
• The lights keep flickering. 灯光忽明忽暗。

5 wireless   

adj.无线的；n.无线电

参考例句：

• There are a lot of wireless links in a radio.收音机里有许多无线电线路。
• Wireless messages tell us that the ship was sinking.无线电报告知我们那艘船正在下沉。

6 illuminated   

adj.被照明的；受启迪的

参考例句：

• Floodlights illuminated the stadium. 泛光灯照亮了体育场。
• the illuminated city at night 夜幕中万家灯火的城市

7 looming   

n.上现蜃景（光通过低层大气发生异常折射形成的一种海市蜃楼）v.隐约出现，阴森地逼近( loom的现在分词 )；隐约出现，阴森地逼近

参考例句：

• The foothills were looming ahead through the haze. 丘陵地带透过薄雾朦胧地出现在眼前。 来自《简明英汉词典》
• Then they looked up. Looming above them was Mount Proteome. 接着他们往上看，在其上隐约看到的是蛋白质组山。 来自英汉非文学 - 生命科学 - 回顾与展望

8 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

9 conundrum   

n.谜语；难题

参考例句：

• Let me give you some history about a conundrum.让我给你们一些关于谜题的历史。
• Scientists had focused on two explanations to solve this conundrum.科学家已锁定两种解释来解开这个难题。

10 modulating   

调整( modulate的现在分词 )； （对波幅、频率的）调制； 转调； 调整或改变（嗓音）的音调

参考例句：

• In his horn solo,he kept modulating from key to key. 他在喇叭独奏时不断地变调。
• Water vapour and clouds are the primary variables modulating direct solar absorption. 水汽和云是调节直接太阳吸收的主要要素。

11 modem   

n.调制解调器

参考例句：

• Does your computer have a modem?你的电脑有调制解调器吗？
• Provides a connection to your computer via a modem.通过调制解调器连接到计算机上。

12 incandescent   

adj.遇热发光的， 白炽的，感情强烈的

参考例句：

• The incandescent lamp we use in daily life was invented by Edison.我们日常生活中用的白炽灯，是爱迪生发明的。
• The incandescent quality of his words illuminated the courage of his countrymen.他炽热的语言点燃了他本国同胞的勇气。

13 fluorescent   

adj.荧光的，发出荧光的

参考例句：

• They observed the deflections of the particles by allowing them to fall on a fluorescent screen.他们让粒子落在荧光屏上以观察他们的偏移。
• This fluorescent lighting certainly gives the food a peculiar color.这萤光灯当然增添了食物特别的色彩。

14 modulation   

n.调制

参考例句：

• The soft modulation of her voice soothed the infant. 她柔和的声调使婴儿安静了。
• Frequency modulation does not allow static to creep in. 频率调制不允许静电干扰混入。

15 lighting   

n.照明，光线的明暗，舞台灯光

参考例句：

• The gas lamp gradually lost ground to electric lighting.煤气灯逐渐为电灯所代替。
• The lighting in that restaurant is soft and romantic.那个餐馆照明柔和而且浪漫。

16 semiconductor   

n.半导体

参考例句：

• In the beginning,engineers hoped to use semiconductor lasers.在开始时，工程师们希望能够利用半导体激光器。
• The main agent of the company brand semiconductor sales.本公司主要代理各品牌半导体销售。

17 straightforward   

adj.正直的，坦率的；易懂的，简单的

参考例句：

• A straightforward talk is better than a flowery speech.巧言不如直说。
• I must insist on your giving me a straightforward answer.我一定要你给我一个直截了当的回答。

18 specially   

adv.特定地；特殊地；明确地

参考例句：

• They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。
• The machine was designed specially for demolishing old buildings.这种机器是专为拆毁旧楼房而设计的。

19 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

20 detectors   

探测器( detector的名词复数 )

参考例句：

• The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。
• This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者，这是令人兴奋的美酒。 来自英汉非文学 - 科技

21 penetrate   

v.透(渗)入；刺入，刺穿；洞察，了解

参考例句：

• Western ideas penetrate slowly through the East.西方观念逐渐传入东方。
• The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。

22 undoubtedly   

adv.确实地，无疑地

参考例句：

• It is undoubtedly she who has said that.这话明明是她说的。
• He is undoubtedly the pride of China.毫无疑问他是中国的骄傲。

23 hybrid   

n.(动，植）杂种，混合物

参考例句：

• That is a hybrid perpetual rose.那是一株杂交的四季开花的蔷薇。
• The hybrid was tall,handsome,and intelligent.那混血儿高大、英俊、又聪明。

24 interfere   

v.(in)干涉，干预；(with)妨碍，打扰

参考例句：

• If we interfere, it may do more harm than good.如果我们干预的话，可能弊多利少。
• When others interfere in the affair,it always makes troubles. 别人一卷入这一事件，棘手的事情就来了。

25 airliner   

n.客机，班机

参考例句：

• The pilot landed the airliner safely.驾驶员使客机安全着陆。
• The passengers were shepherded across the tarmac to the airliner.旅客们被引导走过跑道去上飞机。