资源描述:
《翻译练习参考译文》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、Exercise1Fiber-opticlineswillformmostofthebackboneoftheinformationhighway,justastheydoforthephonesystemtoday.Fiber-opticcableismadeoflong,thinkstrandsofglassratherthanwire,andittransmitsinformationintheformofdigitizedpulsesoflaserlightratherthanthera
2、diowavesusedbycoaxialcable.Becauselightpulseshaveshorterwavelengthsthanradiowaves,engineerscancrammuchmoredataintofiber-opticlinesthanintootherkindsofcablesandwires.Asinglefiber,forexample,canhandleamind-boggling5,000videosignalsormorethan500,000voic
3、econversationssimultaneously.Thishugecapacityallowsittotransmitallsignalsdigitally.Sonoiseorstaticeasilycanbefilteredout.Finally,becauseglassisaninherentlymoreefficientmediumfortransmittinginformationthanothermaterials,afiber-opticlinecantransmitasig
4、nalthousandsofmileswithoutmuch“signalloss”.Fiber-opticcable,simplyput,isthemethodofchoicefortransmittingmassivequantitiesofinformationoverlongdistances.Anotherkeyis“digitalcompression”–avarietyofmethodsforreducingtheamountofdigitalcode(streamsofonesa
5、ndzeros)neededtorepresentapieceofinformation–whetheritisadocument,astillpicture,amovieorasound.Digitalcompressionismostcriticalfortransmittingvideo,becausedigitizedvideoconsumesenormousamountsofspace.Justfoursecondsofadigitizedfilm,forexample,wouldco
6、mpletelyfilla100-megabyteharddrive.Afeaturefilmoftypicallength,ifuncompressed,wouldoccupymorethan350ordinarycompactdiscs.Compressiontechniquesachievetheirginsbyrecordingonlythechangesfromoneframetothenext.Thebackgroundimageinamoviescene,forexample,ty
7、picallydoesnotchangemuchfromoneframetoanother.Inadigitalcompressionscheme,thebackgroundwouldberecordedonlyonce;afterthat,onlytheactors’movementswouldbecaptured.Oneresultismorechoices–hundredsofchannelscomingthroughyourcableTVlineinsteadofdozens.Digit
8、alcompressionalsomakesiteasiertopiggybackdataontomediathatwerenotdesignedwithdatainmind:inparticular,phonelines.译文:光纤电缆构成了今日电话系统的主干线,同样,它也将构成未来信息公路的主干线。光纤电缆的制造材料是细长的玻璃丝而不是金属导线,它的信息传输方式是激光数字脉冲而不是同轴电缆使用的无线电波。由于光脉冲的波长比无线电波的波长短,因而工程师可以输入光纤电缆的信息量之大令其它类型的电