通信毕设中英文文献翻译.doc

通信毕设中英文文献翻译.doc

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英文文献

TheApplicationofonepointMultipleAccessSpreadSpectrumCommunicationSystem

LiuJiangang,NanyangCity,HenanProvinceElectricPowerIndustryBureau

【ABSTRACT】SpreadSpectrumDigitalMicrowavecommunicationasacommunication,becausetheirexcellentperformancehavebeenwidelyused.ThearticleinNanyangCityPowerIndustryBureauonepointMultipleAccessSpreadSpectrumCommunicationSystemasanexample.briefedthespreadspectrumcommunications,thebasicconceptandcharacteristicsofthepowersystemcommunicationapplications

.KEYWORDS：

onepointmultipleaccess;Spread-spectrumcommunication;Attenuation

NanyangCityintheoutskirtsofCentralcloth35to11kvsubstationfarmterminals,theiroperationmanagementrightsbelongtotheCouncilEast,RuralPowerCompanywest（theeasternsuburbofagriculturalmanagementcompanies--four,thewesternsuburbsofRuralPowerCompanyManagement7）,SchedulingofthevariousstationsofthemeansofcommunicationtotheoriginalM-150radioandtelephoneposts.2002Withthetransformationofruralnetwork,theremotestationequipmentintooperationandcommunicationchannelstoputahigherdemand.AsPUCDispatchCommunicationBuildingtotheeastandwestoffarmers--thedifferencebetweenacompanylinkedtofiber,Therefore,if11substationsandtheestablishmentofatransferLinkBuildinglinksPointmaybethedataandvoiceweresenttotworuralpowercompaniesdispatchroom,RuralNetworkschedulingfortheimplementationofautomationtocreatethenecessaryconditions.

Giventhestatusandpowergridsubstationlevel,nature,takingintoaccountthecarrierandoptical-fibercommunicationstoconductmultipleforwarding,increasingtheinstabilityfactor,consideringthecostandconditionsoftheurbanconstruction,Finallydecidedtoadoptwirelessspread-spectrumtechnologytoestablishthat11farmterminalsubstationcommunicationsystem.Thispaperdescribesthespreadspectrumtechnologyandthecurrentsystemofthebuilding.

1.Thebasicconceptofspread-spectrumcommunication.

SpreadSpectrumCommunication'sbasiccharacteristics,isusedtotransmitinformationtothesignalbandwidth（W）isfargreaterthanthepracticalinformationrequiredminimum（effective）bandwidth（△F）,astheratioofprocessinggainGP.

GP=W/△F

Asweallknow,theordinaryAM,FM,orpulsecodemodulationcommunications,GPvaluesintheareamorethan10times,collectively,the"narrow-bandcommunication",andspread-spectrumcommunicationsGPvaluesashighashundredsoreventhousandsoftimes,canbecalled"broadbandcommunications."

Duetothespread-spectrumsignal,itisverylowpowertransmitters,transmissionspacemostlydrownedinthenoise,itisdifficulttointerceptedbytheotherreceiver,onlyspreadingcodeswiththesame（orrandomPNcode）receiver,Gaincanbedealtwith,anddispreadingresumetheoriginalsignal.

2.Thetechnologysuperiorityofspread-spectrumcommunication.

Stronganti-interference,biterrorrateislow.Asnotedabove,thespreadspectrumcommunicationsystemduetotheexpansionofthetransmittersignalspectrum,thereceiverdispreadingreductionsignalproducedspreadinggain,therebygreatlyenhancingitsinterferencetolerance.Underthespreadinggain,orevennegativeinthesignal-to-noiseratioconditions,canalsosignalfromthenoisedrownedoutExtraction,inthecurrentbusinesscommunicationssystems,spreadspectrumcommunicationisonlyabletoworkinanegativesignal-to-noiseratioundertheconditionsofcommunication.

Anti-multi-pathinterferencecapability,increasethereliabilityofthesystem.Spread-spectrumsystemsasusedinthePNhasagoodcorrelation,correlationisveryweak.differentpathstothetransmissionsignalcaneasilybeseparatedandmayintimeandre-alignmentphase,formationofseveralsuperimposedsignalpower,therebyimprovingthesystem'sperformancetoreceiveincreasedreliabilityofthesystem.

Easytousethesamefrequency,improvingthewirelessspectrumutilization.Wirelessspectrumisveryvaluable,althoughlong-wavemicrowavehavetobeexploited,andstillcannotmeettheneedsofthecommunity.Tothisend,countriesaroundtheworldaredesignedspectrummanagement,userscanonlyusethefrequencyapplications,relyonthechanneltopreventthedivisionbetweenthechannelinterference.

Duetotheuseofspread-spectrumcommunicationrelatedreceivethishigh-tech,lowsignaloutputpower（"aW,asageneral-100mW）,andwillworkinthechannelnoiseandthermalnoiseinthebackground,easytoduplicateinthesameareausingthesamefrequency,cannowallsharethesamenarrow-bandfrequencycommunicationsresources.

Spreadspectrumcommunicationisdigitalcommunications,particularlyfordigitalvoiceanddatatransmissionwhile,spreadspectrumcommunicationwiththeirownencryption,onlyinthesamePNcodecommunicationbetweenusers,isgoodforhidingandconfidentialinnature,facilitatingcommunicationsbusiness.Easytousespread-spectrumCDMAcommunications,voicecompressionandmanyothernewtechnologies,moreapplicabletocomputernetworksanddigitizationofvoice,imageinformationtransmission.

Communicationisthemostdigitalcircuits,equipment,highlyintegrated,easyinstallation,easymaintenance,butalsoverycompactandreliable.Theaveragefailureratenotimewasverylong.

Wehavedecidedtoadoptthespread-spectrumcommunicationtechnologyconstructionof11farmterminalsubstationcommunicationssystem,Duetothespread-spectrumcommunicationbytheline-of-sighttransmissiondistancerestrictions,hasbecomeunstoppablesystemdesignpremise.

IfthePUCschedulingBuildingand11substationshavestopped,andtheproblembecomesmorecomplicated,usespreadspectrumsystemonthefeasibilitygreatlyreduced.Therefore,welookatthecityAerialtopographicalmap,initiallyidentifiedhasnotstoppedtoconsidersystemsdesign,andrequeststhecompaniesusedthisequipmentSpreadSpectrum11pointstransmissionroutingofthemeasuredandtheresultshavebeensatisfactory.

Thenspreadspectrumwirelessequipmentmarketsupplyofcash,initially,weselectedaseriesofSpreadSpectrumComlinkthirdgenerationproducts.Becausemostofthepoint-to-pointmode,Meritfunctionsofthespread-spectrumequipmentinapoint-to-multipointapplicationenvironmentsencounteredmanyproblems:

Firstistheissueoffrequencyresources.Evenaminimumof64kbit/sdatarateradio,spacealsooccupiedbandwidth5MHz,Because32ofthePNcodeisolationisonlyabout15dBm,theprojecthadtousefrequencydivisionmultipleaccess35dbtogetaroundthetheoreticalisolation.11stationswilluse11frequencies,frequencygreaterwasteofresources.ComlinkandSpreadSpectrumproductsinthesamefrequencytoachieveapoint-to-multipointcommunications.

Secondantennaerectionproblems,point-to-pointequipmentforthemainradiostation,themainstationneedtosetupanumberofterminalantennas,thevastmajorityofdomesticengineeringcompaniesusedbytheU.S.Conifer24dBiparabolicsemi-castmagnesiumgriddirectionalantenna.verticalpolarization-1mwide,itisdifficulttotopthelayoutandavoidflapandthemutualinterference,Althoughtheprojectcanbesetuptotakestratified,orthroughcooperationandontheroadtooneormoreOmnidirectionalantennalaunch,However,asconstructionofaroadandthesignalattenuation,transmissionresultisnotsatisfactory.

Inaddition,theRFcablelying,Theapplicationofnetworkmanagementsoftwaresuchfactorswehavealsodecidedtoadoptthefinal1:

00ComlinkMultipleAccessSpreadSpectrumproducts.Itssystemconfiguration,asshowninFigure2:

3.RoutingAnalysis

Combiningvisualdistanceaccessandusetheradioandantennagain,cableattenuationandenvironmentalfactors,andtestingthedesignisreasonable,determinetheattenuationaffluentchannelcapacity.Spreadspectrummicrowavelinkattenuationdependsonthereliabilitymargin.

Attenuationmargincalculationformula:

FG=GSG+GANT-LGL-LPL

FG——Attenuationmargin；

　　GSG——SystemGain（dB）；

　　GANT——AntennaGain（dBi）；

　　LGL——Connectorsandcablesattenuation（dB）；

　　LpL——Channelattenuation（dB）。

Gainspreadspectrumradiosystem:

GSG=+27-（-97）=124（dBm）；

AntennaGain:

master-use2.4GHz,12dBiOmni-DirectionalAntenna,stop-use2.4GHz,24dBiparabolicdirectionalantennas;

Connectorandcableattenuation:

cableattenuationofabout3dB,asajointdBattenuation,LGL=3+1=4（dB）;

Channelattenuationtothefarthestdistancefromthebuildingschedulingsubstation（27km）asanexample:

LPL=92.4++20lg2720lg2.4=128（dB）;

Thereforeattenuationcushion:

FG=124+12+24-2×4-128=24（dB）.

Calculatedfromtheamountofaffluentlinkcanbeseen,theprogramhaslargerreservesandthustherationaldesignoftheprogram,Accordingtothemeasuredandtheresultsshowedthechannelcanensurequalityandreliability.

4.Operationofthesystem.

SystemsinceMay2003hasbeenputintooperationmorethantwoyears,eachstationtotransmitinformation;therearetwophones,600or1200Porterremoteinformationoperations,clearvoicestation,Channelstability,withouterror,Systemnothadanyseriousinterruptionsandfailures,equipmentoperatingnormally.Thus,thespreadspectrumlinktothedesignandequipmentselectionhasbeenverygoodtomeetthevoiceandremoteautomatedinformationtransmission,Networkforthesafeandstableoperationtoprovideareliableguarantee.

5.Concludingremarks.

Spread-spectrumtechnologyintheinitialstagesofdevelopment,ithasbecomeatheoryandamajor