1、专 业 英 语,Specialized English,第一部分 专业英语基础知识,长句的翻译： 英语：习惯于用长句表达复杂的感念 汉语：常使用若干短句并列表达思想 长句在科技英语中出现得极为频繁，原因有三方面： 修饰语过多 并列成分多 语言结构层次多,Specialized English for Communication Engineering,翻译长句时： 不要因为句子太长而产生畏惧心理，无论是多么复杂的句子，都是由一些基本的成分组成的 弄清英语原文的句法结构，找出整个句子的中心内容及其各层意思 分析几层意思之间的逻辑关系，按汉语的表达发式正确译出原文的意思，不必拘泥于原文的形式。,S
2、pecialized English for Communication Engineering,分析长句的结构： 找出全句的主语、谓语和宾语，整体把握句子的结构； 找出句中从句的引导词，分析从句的功能；分析词、短语和从句之间的关系； 注意分析插入语等成分； 分析句子中是否有固定词组或固定搭配。,Specialized English for Communication Engineering,常用方法： 顺译法:基本按照英语的语序，把英语长句拆分为汉语中的短句，不必打乱原文的顺序。 倒译法：若英语长句的表达顺序与汉语的表达顺序相反，在翻译时就得用倒译法。 分译法：将繁杂的长句子拆分开翻译。可
3、以适当地增译或者省译某些词语。 综合译法,Unit 6：,第二部分 通信技术,Evolution of Lightwave Systems,光波系统的发展,Specialized English for Communication Engineering,NEW WORDS AND PHRASES,evolution n. 进展, 发展, 演变, 进化 dispersion n. 色散 drawback n. 缺点, 缺陷, 瑕疵, 障碍 sensitivity n. 灵敏度, 灵敏性 magnitude n. 量级,大小, 数量, 巨大, 广大, counteract vt. 抵消, 中和
4、nonlinearity n. 非线性 soliton n. 孤立子, 孤波 maturity n. 成热, 完备,Specialized English for Communication Engineering,The enormous progress over the 25-year period extending from 1975 to 2000 can be grouped into several distinct generations. extend from . to .:从延续（一直）到 从1975年一直到2000年这25年期间的巨大发展可以划分为不同的几代。,TEX
5、T,Specialized English for Communication Engineering,In every generation, BL increases initially but then begins to saturate as the technology matures. initially:最初, 开头 saturate:饱和 BL：比特率和距离的乘积。表示传输容量。 在每一代（光波系统）中，BL最初总是增加的，但是随着技术的成熟，BL就开始饱和。,Specialized English for Communication Engineering,The larg
6、er repeater spacing compared with 1-km spacing of coaxial systems was an important motivation for system designers because it decreased the installation and maintenance costs associated with each repeater. repeater spacing :中继距离； repeater:中继器 coaxial systems:同轴（电缆）系统 motivation :动力，动力与同轴系统1km的中继距离相比
7、，这种更大的中继距离对系统设计者来说是一种很重要的动力，因为这降低了每一个中继器的安装和维护费用。,Specialized English for Communication Engineering,However, the introduction of third-generation lightwave systems operating at 1.55 m was considerably delayed by a large fiber dispersion near 1.55 m. 然而，1.55 m附近大的光纤色散，严重的推迟了工作在该波段的第三代光波系统的引入。,Special
8、ized English for Communication Engineering,Conventional InGaAsP semiconductor lasers could not be used because of pulse spreading occurring as a result of simultaneous oscillation of several longitudinal modes. semiconductor lasers：半导体激光器 pulse spreading ：脉冲展宽 longitudinal modes ：纵模 由于多纵同时模震荡导致的脉冲展宽
9、，使得传统的InGaAsP半导体激光器不能使用。,Specialized English for Communication Engineering,The dispersion problem can be overcome either by using dispersion-shifted fibers designed to have minimum dispersion near 1.55 m or by limiting the laser spectrum to a single longitudinal mode. dispersion-shifted fibers：色散位移光
10、纤 spectrum ：光谱 通过使用在1.55 m 附近色散最小的色散位移光纤，或者将激光器的光谱限制为单纵模， 来解决色散问题。,Specialized English for Communication Engineering,The repeater spacing can be increased by making use of a homodyne or heterodyne detection scheme because its use improves receiver sensitivity. repeater spacing:中继距离 homodyne：零差的； hom
11、odyne detection：零差检测 heterodyne：外差的； heterodyne detection：外差检测 sensitivity：灵敏度通过零差或外差检测可以增加中继距离，因为使用这种检测方法提高了接收机的灵敏度。,Specialized English for Communication Engineering,Coherent systems were under development worldwide during the 1980s, and their potential benefits were demonstrated in many system ex
12、periments. coherent systems：相干系统 potential benefits：潜在的优点 demonstrate：表明，证实80年代，相干系统在世界范围内得到了发展，许多系统实验都证实了该系统潜在的优点。,Specialized English for Communication Engineering,The fourth generation of lightwave systems makes use of optical amplification for increasing the repeater spacing and of wavelength-di
13、vision multiplexing (WDM) for increasing the bit rate。 wavelength-division multiplexing：波分复用 第四代光波系统利用光放大器来增加中继距离；利用波分复用来增加比特率。,Specialized English for Communication Engineering,In most WDM systems, fiber losses are compensated periodically using erbium-doped fiber amplifiers spaced 60-80 km apart.
14、compensate：补偿 erbium-doped fiber amplifiers：掺铒光纤放大器 在大多数的WDM系统中，都是用间距为60-80 km的掺铒光纤放大器来周期性的补偿光纤损耗。,Specialized English for Communication Engineering,By 1996, not only transmission over 11,300 km at a bit rate of 5 Gb/s had been demonstrated by using actual submarine cables, but commercial transatlan
15、tic and transpacific cable systems also became available . submarine cables：海底光缆 transatlantic：穿越大西洋的 transpacific：穿越太平洋的到1996年，不仅可以用实际的海底光缆以5 Gb/s的速率传播11,300 km，而且穿越大西洋和太平洋的光缆系统也开始商用。,Specialized English for Communication Engineering,Several WDM systems were deployed across the Atlantic and Pacific
16、 oceans during 1998-2001 in response to the Internet-induced increase in the data traffic; they have increased the total capacity by orders of magnitudes. in response to：响应, 适应 data traffic：数据通信 orders of magnitudes：数量级 1998-2001年间，配置了一些穿越大西洋和太平洋的WDM系统，以适应因特网所导致的数据通信的增长。这些系统将总容量增加了几个数量级。,Specialized
17、 English for Communication Engineering,extend：扩充, 延伸, 伸展, 扩大 simultaneously：同时地 conventional wavelength window ：传统的波长窗口 respectively：分别地, 各个地 Raman amplification technique：拉曼放大技术,Specialized English for Communication Engineering,An interesting approach is based on the concept of optical solitons-pul
18、se that preserve their shape during propagation in a lossless fiber by counteracting the effect of dispersion through the fiber nonlinearity. optical solitons-pulse：光孤子脉冲 counteract：抵消, 中和, 阻碍 nonlinearity：非线性 一种引起注意的方法是基于光孤子脉冲这个概念的，这种脉冲在无损光纤中传播时，通过光纤的非线性效应抵消色散效应，从而保持脉冲形状（不变）。,Specialized English fo
19、r Communication Engineering,Although the basic idea was proposed as early as 1973, it was only in 1988 that a laboratory experiment demonstrated the feasibility of data transmission over 4000 km by compensating the fiber loss through Raman amplification. compensating:补偿 Raman amplification:拉曼放大 it was only in 1988 that为强调句型 虽然早在1973年就提出了这种基本思想，但直到1988年在实验室中进行的一次试验才证明，通过拉曼放大来补偿光纤损耗，使数据传输4000 km成为可能,小 结,长句的翻译 Evolution of Lightwave Systems,
