资源描述:
《码分多址通信系统、扩频通信外文翻译——通信毕业设计》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、毕业设计英文翻译专业电子信息工程班级2010级学生姓名学号课题码分多址通信系统的建模、仿真和设计——初始化模块、基站接收模块指导教师译文原文1.1Thebasicconceptofspread-spectrumcommunicationSpreadspectrumcommunication’sbasiccharacteristics,isusedtotransmitinformationtothesignalbandwidth(W)isfargreaterthanpracticalrequiredminimum(effective)bandwidth(),astheradioo
2、fprocessinggain.Aswewellknow,theordinaryAM,FM,orpulsecodemodulation,GPvalueintheareamorethan10times,collectively,the“narrow-bandcommunication”,andspread-spectrumcommunicationGPvaluesashundredoreventhousandsoftimes,canbecalled“broadbandcommunication”.Duetothespread-spectrumsignal,itisverylowp
3、owertransmitters,transmissionspacemostlydrownedinthenoise,itisdifficulttointerceptedbytheotherreceiver,onlyspreadingcodeswiththesame(orrandomPNcode)receiver,Gaincanbedealtwith,anddespreadingresumetheoriginalsignal.1.2Thetechnologysuperiorityofspread-spectrumcommunication.Stronganti-interfere
4、nce,biterrorrateislow.Asnotedabove,thespreadspectrumcommunicationsystemduetotheexpansionofthetransmittersignalspectrum,thereceiverdespreadingreductionsignalproducedspreadinggain,therebygreatlyenhancingitsinterferencetolerance.Underthespreadinggain,orevennegativeinthesignal-to-noiseratiocondi
5、tions,canalsosignalfromthenoisedrownedoutExtraction,inthecurrentbusinesscommunicationssystems,spreadspectrumcommunicationssystems,spreadspectrumcommunicationisonlyabletoworkinanegativesignal-to-noiseratioundertheconditionsofcommunication.Anti-multi-pathinterferencecapability,increasetherelia
6、bilityofsystem.Spread-spectrumsystemsasusedinthePNhasagoodcorrelation,correlationisveryweak.Differentpathstothetransmissionsignalcaneasilybeseparatedandmayintimeandre-alignmentphase,formationofseveralsuperimposedsignalpower,therebyimprovingthesystem’sperformancetoreceiveincreasedreliabilityo
7、fthesystem.Easytousethesamefrequency,improvingthewirelessspectrumutilization.Wirelessspectrumisveryvaluable,althoughlong-wavemicrowavehavetobeexploited,andstillcannotmeettheneedsofcommunity.Tothisend,countriesaroundtheworldaredesignedspectrummanage