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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
2、(effective)bandwidth(),astheradioofprocessinggain.Aswewellknow,theordinaryAM,FM,orpulsecodemodulation,GPvalueintheareamorethan10times,collectively,the“narrow-bandcommunication”,andspread-spectrumcommunicationGPvaluesashundredoreventhousandsoftimes,canbecalle
3、d“broadbandcommunication”.Duetothespread-spectrumsignal,itisverylowpowertransmitters,transmissionspacemostlydrownedinthenoise,itisdifficulttointerceptedbytheotherreceiver,onlyspreadingcodeswiththesame(orrandomPNcode)receiver,Gaincanbedealtwith,anddespreading
4、resumetheoriginalsignal.1.2Thetechnologysuperiorityofspread-spectrumcommunication.Stronganti-interference,biterrorrateislow.Asnotedabove,thespreadspectrumcommunicationsystemduetotheexpansionofthetransmittersignalspectrum,thereceiverdespreadingreductionsignal
5、producedspreadinggain,therebygreatlyenhancingitsinterferencetolerance.Underthespreadinggain,orevennegativeinthesignal-to-noiseratioconditions,canalsosignalfromthenoisedrownedoutExtraction,inthecurrentbusinesscommunicationssystems,spreadspectrumcommunications
6、systems,spreadspectrumcommunicationisonlyabletoworkinanegativesignal-to-noiseratioundertheconditionsofcommunication.Anti-multi-pathinterferencecapability,increasethereliabilityofsystem.Spread-spectrumsystemsasusedinthePNhasagoodcorrelation,correlationisveryw
7、eak.Differentpathstothetransmissionsignalcaneasilybeseparatedandmayintimeandre-alignmentphase,formationofseveralsuperimposedsignalpower,therebyimprovingthesystem’sperformancetoreceiveincreasedreliabilityofthesystem.Easytousethesamefrequency,improvingthewirel
8、essspectrumutilization.Wirelessspectrumisveryvaluable,althoughlong-wavemicrowavehavetobeexploited,andstillcannotmeettheneedsofcommunity.Tothisend,countriesaroundtheworldaredesignedspectrummanage
