Unit 5 Wireless Communications
Wireless communications systems include cellular telephones, pagers, radio telegraphs, satellite telephones, laptop computers, personal digital assistants, shortwave radios, and two-way radios. Do you know anything about the brief history of mobile phones? (1973-) Mobile phone is one of the most essential things of people. It takes much convince for people. The technology of mobile phone is increase rapidly everyday. Form 1st generation up to now, people want to build up a mobile 1G (First Generation) is the name given to the first generation of mobile telephone networks. These systems used analogue circuit-switched technology, with FDMA (Frequency Division Multiple Access), and worked mainly in the 800-900 MHz frequency bands. The networks had a low traffic capacity, unreliable handover, poor voice quality, and poor security. 第一代手机(1G)模拟移动电话在 70 年代末诞生了. 模拟移动电话系统主要采用模拟和频分多址(FDMA)技术. AMPS(北美蜂窝系统),NMT(北欧移动电话)和 TACS(全向通信系统)是主要的模 拟标准.(大哥大 模拟制式 信号不好,安全性也差 容易盗打 收费还贵) 只能进行语音通信,收讯效果和保密性不足,无线带宽利用也不充分. 第一代无线网络技术的最大成就是去掉了将电话连接到网络的用户线, 用户可以 在任何地方无线接收和拨打电话. 2G - Second Generation mobile telephone networks were the logical next stage in the development of wireless systems after 1G, and they introduced for the first time a mobile phone system that used purely digital technology. The demands placed on the networks, particularly in the densely populated areas within cities, meant that increasingly sophisticated methods had to be employed to handle the large number of calls, and so avoid the risks of interference and dropped calls at handoffs. Although many of the principles involved in a 1G system also apply to 2G - they both use the same cell structure - there are also differences in the way that the signals are handled, and the 1G networks are not capable of providing the more advanced features of the 2G systems, such as caller identity and text messaging.
第二代 (2G) 目前全球使用最广泛的手机是 GSM 手机,CDMA 手机和小灵通(PHS)手机,这些都称为第 二代手机(2G). 第二代系统引入了数码无线电技术,它提供更高的网络容量,改善了语音质量和保密性,还 引入了无缝的国际漫游. 第二代系统除了可以进行语音通信以外,还可以收发短信(短消息,SMS),彩信(MMS, 多媒体简讯),WAP 等.
如今全世界第二代手机的市场标注,包括 GSM,D-AMPS,PDC 和 IS-95CDMA 等.
3G - Third Generation mobile telephone networks are the latest stage in the development of wireless communications technology. Significant features of 3G systems are that they support much higher data transmission rates and offer increased capacity, which makes them suitable for high-speed data applications as well as for the traditional voice calls. In fact, 3G systems are designed to process data, and since voice signals are converted to digital data, this results in speech being dealt with in much the same way as any other form of data. Third Generation systems use packet-switching technology, which is more efficient and faster than the traditional circuit-switched systems, but they do require a somewhat different infrastructure to the 2G systems. 用于第三代移动通信系统(3G)的手机也已经研制出来了,但是由于相关网络 没有普及,并未得到广泛的应用.第三代手机的开始的目标之一是开发一种可以 全球通用的无线通讯系统,但是实际最终的结果是出现了多种不同的制式,主要 有 CDMA2000,WCDMA 和 TD-SCDMA 在竞争.这些新的制式都基于 CDMA (码分多址)技术,在带宽利用和数据通信方面都有进一步发展.
Background Information and Language Points

  1. Teachers struggle to stop smoking, too. You hang in there. (Para.
  2) hang in there: 再等等;坚持一下 Hang in there old buddy; the worst is yet to come. 坚持下去,老兄,更困难的还在后头呢!
  2. Technology revolutions come in two flavors: jarringly fast and imperceptibly slow. (Para.
  4) 科技革命常呈现出两种特色:或是惊人地迅速,或是难以察觉地迟缓.
  3. As our phones get smarter, smaller and faster and enable users to connect at high speeds to the Internet, an obvious question arises: Is the mobile handset turning into the next computer? (Para.
  5) 随着电话变得越来越智能,小巧,快捷,并且能够让用户高速地连接到互联网, 一个显而易见的问题就出现了:移动手持设备将成为下一代计算机吗?
  4. Tweak the questions, though, to ask whether mobile phones will ever eclipse, or replace, the PC, and the issue suddenly becomes controversial. (Para.
  6) 不过,把上面的问题换个角度来问,即手机是否会使个人电脑黯然失色或将其取 而代之,人们立即会觉得这个问题值得商榷.
  5. PC proponents say phones are too small and connect too sluggishly to the Internet to become effective at tasks now performed on the luxuriously large screens and keyboards of today's computer. (Para.
  7) 个人电脑的支持者说手机的尺寸太小,联网速度太慢,干活效率太低,无法同目
  6. PalmOne is among the firms racing to trot out the full featured computerlike phones that the industry dubs smartphones. (Para.
  7) 许多公司正竞相开发具有全电脑功能的手机??业界称之为"智能手机" , PalmOne 是其中的一家.
  7. Hawkins's newest product, the sleek, pocket-size Treo 600, has a tiny keyboard, a built-in digital camera and slots for added memory. (Para.
  7) PalmOne 的最新产品 Treo 600 外形纤巧, 带有微型键盘, 内置数码相机以及附加 储存卡插槽.
  8. Motorola's upcoming MPx has a nifty "dual hinge" design: the handset opens in one direction and looks like a regular phone, but is also flips open along another axis and looks like an e-mail device, with the expanded phone keypad serving as a small qwerty keyboard. (Para.
  7) 摩托罗拉即将推出的 MPx 则拥有一个绝妙的"双铰式"设计:从一个铰轴上打 开这款手机,它看上去就是一部普通的手机;但是从另一面铰轴上打开,它看上 去就像是专门发送电子邮件的设备, 这时手机的袖珍键盘扩展成为一个小型传统 布局的键盘.
  9. There are also smartphones on the way with video cameras, GPS antennas and access to local Wi-Fi hotspots, the superfast wireless networks often found in offices, airports and cafes. (Para.
  7) 还有一些正在开发中的智能手机,它们将带有摄像头,GPS 天线以及本地 Wi-Fi (一种常常能在办公室, 机场和咖啡馆找到的超高速无限网络) 热点链接的入口.
  10. Mobile-phone watchers say that handsets in the next years will pack a gigabyte or more of flash memory, turning the phone into a huge photo album or music player and giving stand alone iPods a run for their money. (Para.
  10) 手机观察家表示在未来几年里,手机所拥有的闪存内容将达到或超过 1G,使其 变成巨大的电子相册或者是音乐播放器, 能和独立的各种数字音乐播放器一争高 低.
  11. With this capability, phones will soon be able to provide precise driving directions, serve up discounts for stores as you walk by them and expand dating services. (Para.
  10) 有了这项功能,手机很快就能提供精确的行车向导,播报路过店铺的打折信息, 并拓展约会服务.
  12. Yet mobile-phone innovators are working to solve that tricky problem, too. Scientists are continuing decades of research into speech-recognition systems and have recently introduced the technology into PDAs. (Para.
  13) 然而,手机创新者也正着手解决这个棘手的问题.科学家在语音识别系统方面的 研究已经持续了几十年,而且最近已将该技术引入 PDA 中.

  13. Cell phones aren't likely to take the fastest road to this bright future. Innovation in the mobile industry is full of zigzags and wrong turns, often because no single company completely controls the device in your pocket. (Para.
  14) 手机不太可能沿着最快的道路驶向自己光明的未来. 这个行业里的创新充满了曲 折和失误,其原因是常常由于没有任何一家公司能完全控制这一产品.
  14. The uncoordinated, noncommercial programming that led to the quick evolution of the Internet hasn't taken hold in the world of mobile phones. (Para.
  14) 各自为政,非商业化的程序开发引发了互联网的快速演变,但在手机世界里,这 并不适用.
Exercises (P. 1
Blank Filling
  1. multimedia
  2. revolutionize
  3. access
  4. streaming
  5. device Cloze 1-5 BABDB 6-10 CBDAC Translation Practice (P.1
  53) II. Word and Phrase Translation A.
  1. 现有的技术
  2. 语音命令
  3. 蜂窝网络
  4. 附加存储卡用槽
  5. 具有电脑功能 B.
  1. flash memory
  2. mobile-phone watchers
  3. projection keyboard
  4. defenders of the PC
  5. speech-recognition system
  6. instantaneous
  7. connected
  8. model
  9. operators
  10. facilities 11-15 DBADB 16-20 ABDAC

  6. 内置式数码相机
  7. 建立临时办公室
  8. 文字处理能力
  9. 标准键盘
  10. 定位服务
  6. "dual hinge" design
  7. the touch-tone pad
  8. a phone guy
  9. the luxuriously large screen
  10. smartphones


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