电子通讯的发展英语ppt课件.ppt

电子通信的发展 Thedevelopmentoftheelectroniccommunications theagesofE communication inancienttime Inancienttimes ChinausedrummingTransferinformationfirstinthelateprimitivesociety NeatandheavydrumssayingtheintentoftheEmergencyandrhythmwhenthetwoarmiesatwar The flamesofwar isamethodofcommunicationinancientChinausedtopassthefrontiermilitaryintelligence beganintheShangandZhou untiltheMingandQingDynasties Frontiermilitaryfortortheheightofthehubofeverycertaindistancefrombuildingsahighplatform China srecordedhistory carrierpigeonismainlyusedforthepurposeofmilitarycommunications Peopletiedthetroopmovementsoftheinstrumentwiththepigeon wireless satellite microwave internet 光纤通信技术opticalfibercommunications 多媒体通信Computercommunication Mobilesatellitecommunication 卫星移动通信 Theuseofsatellitetranspondersignalcanalsobemobilecommunication mobilecommunicationcanbeusedforthefixedsatellite andonthehandheldterminal usingaloworbitsatelliteconstellationisadvantageoustothe 利用卫星转发信号也可实现移动通信 对于车载移动通信可采用赤道固定卫星 而对手持终端 采用中低轨道的多颗星座卫星较为有利 Tiangong 1 Chinese 天宫一号 isaChinesespacelaboratorymodule anexperimentaltestbedtodemonstratetherendezvousanddockingcapabilitiesneededtosupportaspacestationcomplex LaunchedunmannedaboardaLongMarch2F Grocket 1 on29September2011 itispartoftheTiangongprogram whichaimstoplacealarger modularstationintoorbitby2020 3Gisamobilemultimediacommunicationsystem providesservicesincludingvoice fax data multimediaentertainmentandglobalseamlessroaming 3G是移动多媒体通信系统 提供的业务包括语音 传真 数据 多媒体娱乐和全球无缝漫游等 3Gtechnologywith2MBPSstandarduserrate highspeedmobiletoprovide144KBPSrate 3G技术提供2MBPS标准用户速率 高速移动下提供144KBPS速率 NowdaystherearesomemobilephoneswithitsownCPU RAM ROMandDiskjustlikeaPC wecallthemsamrtphones Mostsmartphoneshaveboth2Gand3Gfunctions Thecharacteristicsof3Garevideocalls highspeedinternetandhighcharge 4Gisthetruemeaningofthemobilecommunicationsystem userrate20MBPS 4Gsupportsinteractivemultimediaservice highqualityimages the3DanimationandbroadbandInternetaccess broadbandisthelargecapacityhigh speedcellularsystem 4G是真正意义的高速移动通信系统 用户速率20MBPS 4G支持交互多媒体业务 高质量影像 3D动画和宽带互联网接入 是宽带大容量的高速蜂窝系统 Maybemanystudentsinourclassisusing3GPhone comunicatewithme MarsroverCuriosityblastsoffNASA sCuriosityrover rocketedtowardMarsonNovember26 2011onasearchforevidencethattheredpl