[毕业设计精品]脉冲宽度测量仪设计 外文及翻译

毕业设计说明书英文文献及中文翻译学生姓名学号学院信息与通信工程专业电子信息科学与技术指导教师2011年6月2011届毕业设计说明书A11A2A316A2外文文献原文FUNDAMENTALSOFTIMEANDFREQUENCYINTRODUCTIONTIMEANDFREQUENCYSTANDARDSSUPPLYTHREEBASICTYPESOFINFORMATIONTIMEOFDAY，TIMEINTERVAL，ANDFREQUENCYTIMEOFDAYINFORMATIONISPROVIDEDINHOURS，MINUTES，ANDSECONDS，BUTOFTENALSOINCLUDESTHEDATEMONTH，DAY，ANDYEARADEVICETHATDISPLAYSORRECORDSTIMEOFDAYINFORMATIONISCALLEDACLOCKIFACLOCKISUSEDTOLABELWHENANEVENTHAPPENED，THISLABELISSOMETIMESCALLEDATIMETAGORTIMESTAMPDATEANDTIMEOFDAYCANALSOBEUSEDTOENSURETHATEVENTSARESYNCHRONIZED，ORHAPPENATTHESAMETIMETIMEINTERVALISTHEDURATIONORELAPSEDTIMEBETWEENTWOEVENTSTHESTANDARDUNITOFTIMEINTERVALISTHESECONDSHOWEVER，MANYENGINEERINGAPPLICATIONSREQUIRETHEMEASUREMENTOFSHORTERTIMEINTERVALS，SUCHASMILLISECONDS1MS103S，MICROSECONDS1S106S，NANOSECONDS1NS109S，ANDPICOSECONDS1PS1012STIMEISONEOFTHESEVENBASEPHYSICALQUANTITIES，ANDTHESECONDISONEOFSEVENBASEUNITSDEFINEDINTHEINTERNATIONALSYSTEMOFUNITSSITHEDEFINITIONSOFMANYOTHERPHYSICALQUANTITIESRELYUPONTHEDEFINITIONOFTHESECONDTHESECONDWASONCEDEFINEDBASEDONTHEEARTHSROTATIONALRATEORASAFRACTIONOFTHETROPICALYEARTHATCHANGEDIN1967WHENTHEERAOFATOMICTIMEKEEPINGFORMALLYBEGANTHECURRENTDEFINITIONOFTHESISECONDISTHEDURATIONOF9，192，631，770PERIODSOFTHERADIATIONCORRESPONDINGTOTHETRANSITIONBETWEENTWOHYPERFINELEVELSOFTHEGROUNDSTATEOFTHECESIUM133ATOMFREQUENCYISTHERATEOFAREPETITIVEEVENTIFTISTHEPERIODOFAREPETITIVEEVENT，THENTHEFREQUENCYFISITSRECIPROCAL，1/TCONVERSELY，THEPERIODISTHERECIPROCALOFTHEFREQUENCY，T1/FSINCETHEPERIODISATIMEINTERVALEXPRESSEDINSECONDSS，ITISEASYTOSEETHECLOSERELATIONSHIPBETWEENTIMEINTERVALANDFREQUENCYTHE2011届毕业设计说明书A12A2A316A2STANDARDUNITFORFREQUENCYISTHEHERTZHZ，DEFINEDASEVENTSORCYCLESPERSECONDTHEFREQUENCYOFELECTRICALSIGNALSISOFTENMEASUREDINMULTIPLESOFHERTZ，INCLUDINGKILOHERTZKHZ，MEGAHERTZMHZ，ORGIGAHERTZGHZ，WHERE1KHZEQUALSONETHOUSAND103EVENTSPERSECOND，1MHZEQUALSONEMILLION106EVENTSPERSECOND，AND1GHZEQUALSONEBILLION109EVENTSPERSECONDADEVICETHATPRODUCESFREQUENCYISCALLEDANOSCILLATORTHEPROCESSOFSETTINGMULTIPLEOSCILLATORSTOTHESAMEFREQUENCYISCALLEDSYNCHRONIZATIONOFCOURSE，THETHREETYPESOFTIMEANDFREQUENCYINFORMATIONARECLOSELYRELATEDASMENTIONED，THESTANDARDUNITOFTIMEINTERVALISTHESECONDBYCOUNTINGSECONDS，WECANDETERMINETHEDATEANDTHETIMEOFDAYANDBYCOUNTINGEVENTSORCYCLESPERSECOND，WECANMEASUREFREQUENCYTIMEINTERVALANDFREQUENCYCANNOWBEMEASUREDWITHLESSUNCERTAINTYANDMORERESOLUTIONTHANANYOTHERPHYSICALQUANTITYTODAY，THEBESTTIMEANDFREQUENCYSTANDARDSCANREALIZETHESISECONDWITHUNCERTAINTIESOF11015PHYSICALREALIZATIONSOFTHEOTHERBASESIUNITSHAVEMUCHLARGERUNCERTAINTIESCOORDINATEDUNIVERSALTIMEUTCTHEWORLDSMAJORMETROLOGYLABORATORIESROUTINELYMEASURETHEIRTIMEANDFREQUENCYSTANDARDSANDSENDTHEMEASUREMENTDATATOTHEBUREAUINTERNATIONALDESPOIDSETMEASURESBIPMINSEVRES，FRANCETHEBIPMAVERAGESDATACOLLECTEDFROMMORETHAN200ATOMICTIMEANDFREQUENCYSTANDARDSLOCATEDATMORETHAN40LABORATORIES，INCLUDINGTHENATIONALINSTITUTEOFSTANDARDSANDTECHNOLOGYNISTASARESULTOFTHISAVERAGING，THEBIPMGENERATESTWOTIMESCALES，INTERNATIONALATOMICTIMETAI，ANDCOORDINATEDUNIVERSALTIMEUTCTHESETIMESCALESREALIZETHESISECONDASCLOSELYASPOSSIBLEUTCRUNSATTHESAMEFREQUENCYASTAIHOWEVER，ITDIFFERSFROMTAIBYANINTEGRALNUMBEROFSECONDSTHISDIFFERENCEINCREASESWHENLEAPSECONDSOCCURWHEN2011届毕业设计说明书A13A2A316A2NECESSARY，LEAPSECONDSAREADDEDTOUTCONEITHERJUNE30ORDECEMBER31THEPURPOSEOFADDINGLEAPSECONDSISTOKEEPATOMICTIMEUTCWITHIN09SOFANOLDERTIMESCALECALLEDUT1，WHICHISBASEDONTHEROTATIONALRATEOFTHEEARTHLEAPSECONDSHAVEBEENADDEDTOUTCATARATEOFSLIGHTLYLESSTHANONCEPERYEAR，BEGINNINGIN1972KEEPINMINDTHATTHEBIPMMAINTAINSTAIANDUTCASPAPERTIMESCALESTHEMAJORMETROLOGYLABORATORIESUSETHEPUBLISHEDDATAFROMTHEBIPMTOSTEERTHEIRCLOCKSANDOSCILLATORSANDGENERATEREALTIMEVERSIONSOFUTCMANYOFTHESELABORATORIESDISTRIBUTETHEIRVERSIONSOFUTCVIARADIOSIGNALSWHICHSECTION174AREDISCUSSEDINYOUCANTHINKOFUTCASTHEULTIMATESTANDARDFORTIMEOFDAY，TIMEINTERVAL，ANDFREQUENCYCLOCKSSYNCHRONIZEDTOUTCDISPLAYTHESAMEHOURMINUTE，ANDSECONDALLOVERTHEWORLDANDREMAINWITHINONESECONDOFUT1OSCILLATORSSIMONIZEDTOUTCGENERATESIGNALSTHATSERVEASREFERENCESTANDARDSFORTIMEINTERVALANDFREQUENCYTIMEANDFREQUENCYMEASUREMENTTIMEANDFREQUENCYMEASUREMENTSFOLLOWTHECONVENTIONSUSEDINOTHERAREASOFMETROLOGYTHEFREQUENCYSTANDARDORCLOCKBEINGMEASUREDISCALLEDTHEDEVICEUNDERTESTDUTAMEASUREMENTCOMPARESTHEDUTTOASTANDARDORREFERENCETHESTANDARDSHOULDOUTPERFORMTHEDUTBYASPECIFIEDRATIO，CALLEDTHETESTUNCERTAINTYRATIOTURIDEALLY，THETURSHOULDBE101ORHIGHERTHEHIGHERTHERATIO，THELESSAVERAGINGISREQUIREDTOGETVALIDMEASUREMENTRESULTSTHETESTSIGNALFORTIMEMEASUREMENTSISUSUALLYAPULSETHATOCCURSONCEPERSECOND1PSTHEPULSEWIDTHANDPOLARITYVARIESFROMDEVICETODEVICE，BUTTTLLEVELSARECOMMONLYUSEDTHETESTSIGNALFORFREQUENCYMEASUREMENTSISUSUALLYATAFREQUENCYOF1MHZORHIGHER，WITH5OR10MHZBEINGCOMMONFREQUENCYSIGNALS2011届毕业设计说明书A14A2A316A2AREUSUALLYSINEWAVES，BUTCANALSOBEPULSESORSQUAREWAVESIFTHEFREQUENCYSIGNALISANOSCILLATINGSINEWAVETHISSIGNALPRODUCESONECYCLE360OR2RADIANSOFPHASEINONEPERIODTHESIGNALAMPLITUDEISEXPRESSEDINVOLTS，ANDMUSTBECOMPATIBLEWITHTHEMEASURINGINSTRUMENTIFTHEAMPLITUDEISTOOSMALL，ITMIGHTNOTBEABLETODRIVETHEMEASURINGINSTRUMENTIFTHEAMPLITUDEISTOOLARGE，THESIGNALMUSTBEATTENUATEDTOPREVENTOVERDRIVINGTHEMEASURINGINSTRUMENTTHISSECTIONEXAMINESTHETWOMAINSPECIFICATIONSOFTIMEANDFREQUENCYMEASUREMENTSACCURACYANDSTABILITYITALSODISCUSSESSOMEINSTRUMENTSUSEDTOMEASURETIMEANDFREQUENCYACCURACYACCURACYISTHEDEGREEOFCONFORMITYOFAMEASUREDORCALCULATEDVALUETOITSDEFINITIONACCURACYISRELATEDTOTHEOFFSETFROMANIDEALVALUEFOREXAMPLE，TIMEOFFSETISTHEDIFFERENCEBETWEENAMEASUREDONTIMEPULSEANDANIDEALONTIMEPULSETHATCOINCIDESEXACTLYWITHUTCFREQUENCYOFFSETISTHEDIFFERENCEBETWEENAMEASUREDFREQUENCYANDANIDEALFREQUENCYWITHZEROUNCERTAINTYTHISIDEALFREQUENCYISCALLEDTHENOMINALFREQUENCYTIMEOFFSETISUSUALLYMEASUREDWITHATIMEINTERVALCOUNTERTICATICHASINPUTSFORTWOSIGNALSONESIGNALSTARTSTHECOUNTERANDTHEOTHERSIGNALSTOPSITTHETIMEINTERVALBETWEENTHESTARTANDSTOPSIGNALSISMEASUREDBYCOUNTINGCYCLESFROMTHETIMEBASEOSCILLATORTHERESOLUTIONOFALOWCOSTTICISLIMITEDTOTHEPERIODOFITSTIMEBASEFOREXAMPLE，ATICWITHA10MHZTIMEBASEOSCILLATORWOULDHAVEARESOLUTIONOF100NSMOREELABORATETICSUSEINTERPOLATIONSCHEMESTODETECTPARTSOFATIMEBASECYCLEANDHAVEMUCHHIGHERRESOLUTION1NSRESOLUTIONISCOMMONPLACE，AND20PSRESOLUTIONISAVAILABLEFREQUENCYOFFSETCANBEMEASUREDINEITHERTHEFREQUENCYDOMAINORTIMEDOMAINASIMPLEFREQUENCYDOMAINMEASUREMENTINVOLVESDIRECTLYCOUNTINGANDDISPLAYINGTHE2011届毕业设计说明书A15A2A316A2FREQUENCYOUTPUTOFTHEDUTWITHAFREQUENCYCOUNTERTHEREFERENCEFORTHISMEASUREMENTISEITHERTHECOUNTERSINTERNALTIMEBASEOSCILLATOR，ORANEXTERNALTIMEBASETHECOUNTERSRESOLUTION，ORTHENUMBEROFDIGITSITCANDISPLAY，LIMITSITSABILITYTOMEASUREFREQUENCYOFFSETFOREXAMPLE，A9DIGITFREQUENCYCOUNTERCANDETECTAFREQUENCYOFFSETNOSMALLERTHAN01HZAT10MHZ1108THEFREQUENCYOFFSETISDETERMINEDASMEASURENOMINALNOMINALFFFFWHEREFMEASURISTHEREADINGFROMTHEFREQUENCYCOUNTER，ANDFNOMINALISTHEFREQUENCYLABELEDONTHEOSCILLATORSNAMEPLATE，ORSPECIFIEDOUTPUTFREQUENCYFREQUENCYOFFSETMEASUREMENTSINTHETIMEDOMAININVOLVEAPHASECOMPARISONBETWEENTHEDUTANDTHEREFERENCEASIMPLEPHASECOMPARISONCANBEMADEWITHANOSCILLOSCOPETHEOSCILLOSCOPEWILLDISPLAYTWOSINEWAVESTHETOPSINEWAVEREPRESENTSASIGNALFROMTHEDUT，ANDTHEBOTTOMSINEWAVEREPRESENTSASIGNALFROMTHEREFERENCEIFTHETWOFREQUENCIESWEREEXACTLYTHESAME，THEIRPHASERELATIONSHIPWOULDNOTCHANGEANDBOTHWOULDAPPEARTOBESTATIONARYONTHEOSCILLOSCOPEDISPLAYSINCETHETWOFREQUENCIESARENOTEXACTLYTHESAME，THEREFERENCEAPPEARSTOBESTATIONARYANDTHEDUTSIGNALMOVESBYMEASURINGTHERATEOFMOTIONOFTHEDUTSIGNALWECANDETERMINEITSFREQUENCYOFFSETVERTICALLINESHAVEBEENDRAWNTHROUGHTHEPOINTSWHEREEACHSINEWAVEPASSESTHROUGHZEROTHEBOTTOMOFTHEFIGURESHOWSBARSWHOSEWIDTHREPRESENTSTHEPHASEDIFFERENCEBETWEENTHESIGNALSINTHISCASETHEPHASEDIFFERENCEISINCREASING，INDICATINGTHATTHEDUTISLOWERINFREQUENCYTHANTHEREFERENCEMEASURINGHIGHACCURACYSIGNALSWITHANOSCILLOSCOPEISIMPRACTICAL，SINCETHEPHASERELATIONSHIPBETWEENSIGNALSCHANGESVERYSLOWLYANDTHERESOLUTIONOFTHEOSCILLOSCOPEDISPLAYISLIMITEDMOREPRECISEPHASECOMPARISONSCANBEMADEWITHATICIFTHETWOINPUTSIGNALSHAVETHESAMEFREQUENCY，THETIMEINTERVALWILLNOT2011届毕业设计说明书A16A2A316A2CHANGEIFTHETWOSIGNALSHAVEDIFFERENTFREQUENCIES，THETIMEINTERVALWILLSCHANGE，ANDTHERATEOFCHANGEISTHEFREQUENCYOFFSETTHERESOLUTIONOFATICDETERMINESTHESMALLESTFREQUENCYCHANGETHATITCANDETECTWITHOUTAVERAGINGFOREXAMPLE，ALOWCOSTTICWITHASINGLESHOTRESOLUTIONOF100NSCANDETECTFREQUENCYCHANGESOF1107IN1STHECURRENTLIMITFORTICRESOLUTIONISABOUT20PS，WHICHMEANSTHATAFREQUENCYCHANGEOF21011CANBEDETECTEDIN1SAVERAGINGOVERLONGERINTERVALSCANIMPROVETHERESOLUTIONTO1PSINSOMEUNITS6SINCESTANDARDFREQUENCIESLIKE5OR10MHZARENOTPRACTICALTOMEASUREWITHATIC，FREQUENCYDIVIDERSORFREQUENCYMIXERSAREUSEDTOCONVERTTHETESTFREQUENCYTOALOWERFREQUENCYDIVIDERSYSTEMSARESIMPLERANDMOREVERSATILE，SINCETHEYCANBEEASILYBUILTORPROGRAMMEDTOACCOMMODATEDIFFERENTFREQUENCIESMIXERSYSTEMSAREMOREEXPENSIVE，REQUIREMOREHARDWAREINCLUDINGANADDITIONALREFERENCEOSCILLATOR，ANDCANOFTENMEASUREONLYONEINPUTFREQUENCYEG，10MHZ，BUTTHEYHAVEAHIGHERSIGNALTONOISERATIOTHANDIVIDERSYSTEMSIFDIVIDERSAREUSED，MEASUREMENTSAREMADEFROMTHETIC，BUTINSTEADOFUSINGTHESEMEASUREMENTSDIRECTLY，WEDETERMINETHERATEOFCHANGEFROMREADINGTOREADINGTHISRATEOFCHANGEISCALLEDTHEPHASEDEVIATIONWECANESTIMATEFREQUENCYOFFSETASFOLLOWSTFTWHERETISTHEAMOUNTOFPHASEDEVIATION，ANDTISTHEMEASUREMENTPERIODTOILLUSTRATE，CONSIDERAMEASUREMENTOF1SOFPHASEDEVIATIONOVERAMEASUREMENTPERIODOF24HTHEUNITUSEDFORMEASUREMENTPERIODHMUSTBECONVERTEDTOTHEUNITUSEDFORPHASEDEVIATIONSTHEEQUATIONBECOMES11T1USFOFFSET11610T86400000000US（），2011届毕业设计说明书A17A2A316A2ASSHOWN，ADEVICETHATACCUMULATES1SOFPHASEDEVIATION/DAYHASAFREQUENCYOFFSETOF1161011WITHRESPECTTOTHEREFERENCETHISSIMPLEEXAMPLEREQUIRESONLYTWOTIMEINTERVALREADINGSTOBEMADE，ANDTISSIMPLYTHEDIFFERENCEBETWEENTHETWOREADINGSOFTEN，MULTIPLEREADINGSARETAKENANDTHEFREQUENCYOFFSETISESTIMATEDBYUSINGLEASTSQUARESLINEARREGRESSIONONTHEDATASET，ANDOBTAININGTFROMTHESLOPEOFTHELEASTSQUARESLINETHISINFORMATIONISUSUALLYPRESENTEDASAPHASEPLOT，ASSHOWNINFIG176THEDEVICEUNDERTESTISHIGHINFREQUENCYBYEXACTLY1109，ASINDICATEDBYAPHASEDEVIATIONOF1NS/SDIMENSIONLESSFREQUENCYOFFSETVALUESCANBECONVERTEDTOUNITSOFFREQUENCYHZIFTHENOMINALFREQUENCYISKNOWNTOILLUSTRATETHIS，CONSIDERANOSCILLATORWITHANOMINALFREQUENCYOF5MHZANDAFREQUENCYOFFSETOF1161011TOFINDTHEFREQUENCYOFFSETINHERTZ，MULTIPLYTHENOMINALFREQUENCYBYTHEOFFSET5106116101158010500000580HZTHEN，ADDTHEOFFSETTOTHENOMINALFREQUENCYTOGETTHEACTUALFREQUENCY5，000，000HZ00000580HZ5，000，0000000580HZSTABILITYSTABILITYINDICATESHOWWELLANOSCILLATORCANPRODUCETHESAMETIMEORFREQUENCYOFFSETOVERAGIVENTIMEINTERVALITDOESNTINDICATEWHETHERTHETIMEORFREQUENCYIS“RIGHT”OR“WRONG，”BUTONLYWHETHERITSTAYSTHESAMEINCONTRAST，ACCURACYINDICATESHOWWELLANOSCILLATORHASBEENSETONTIMEORONFREQUENCYTOUNDERSTANDTHISDIFFERENCE，CONSIDERTHATASTABLEOSCILLATORTHATNEEDSADJUSTMENTMIGHTPRODUCEAFREQUENCYWITHALARGEOFFSETOR，ANUNSTABLEOSCILLATORTHATWASJUSTADJUSTEDMIGHTTEMPORARILYPRODUCEAFREQUENCYNEARITSNOMINALVALUEFIGURE177SHOWSTHERELATIONSHIPBETWEENACCURACYANDSTABILITYSTABILITYISDEFINEDASTHESTATISTICALESTIMATEOFTHEFREQUENCYORTIMEFLUCTUATIONSOFASIGNALOVERAGIVENTIMEINTERVALTHESEFLUCTUATIONSAREMEASUREDWITHRESPECTTOAMEANFREQUENCYORTIMEOFFSET2011届毕业设计说明书A18A2A316A2SHORTTERMSTABILITYUSUALLYREFERSTOFLUCTUATIONSOVERINTERVALSLESSTHAN100SLONGTERMSTABILITYCANREFERTOMEASUREMENTINTERVALSGREATERTHAN100S，BUTUSUALLYREFERSTOPERIODSLONGERTHAN1DAYSTABILITYESTIMATESCANBEMADEINEITHERTHEFREQUENCYDOMAINORTIMEDOMAIN，ANDCANBECALCULATEDFROMASETOFEITHERFREQUENCYOFFSETORTIMEINTERVALMEASUREMENTSINSOMEFIELDSOFMEASUREMENT，STABILITYISESTIMATEDBYTAKINGTHESTANDARDDEVIATIONOFTHEDATASETHOWEVER，STANDARDDEVIATIONONLYWORKSWITHSTATIONARYDATA，WHERETHERESULTSARETIMEINDEPENDENT，ANDTHENOISEISWHITE，MEANINGTHATITISEVENLYDISTRIBUTEDACROSSTHEFREQUENCYBANDOFTHEMEASUREMENTOSCILLATORDATAISUSUALLYNOSTATIONARY，SINCEITCONTAINSTIMEDEPENDENTNOISECONTRIBUTEDBYTHEFREQUENCYOFFSETWITHSTATIONARYDATA，THEMEANANDSTANDARDDEVIATIONWILLCONVERGETOPARTICULARVALUESASMOREMEASUREMENTSAREMADEWITHNOSTATIONARYDATA，THEMEANANDSTANDARDDEVIATIONNEVERCONVERGETOANYPARTICULARVALUESINSTEAD，THEREISAMOVINGMEANTHATCHANGESEACHTIMEWEADDAMEASUREMENTFORTHESEREASONS，ANONCLASSICALSTATISTICISOFTENUSEDTOESTIMATESTABILITYINTHETIMEDOMAINTHISSTATISTICISSOMETIMESCALLEDTHEALLANVARIANCE，BUTSINCEITISTHESQUAREROOTOFTHEVARIANCE，ITSPROPERNAMEISTHEALLANDEVIATIONTHEEQUATIONFORTHEALLANDEVIATIONYIS2M1YIII1YYMA01（）（）（21）WHEREYIISASETOFFREQUENCYOFFSETMEASUREMENTSCONTAININGY1，Y2，Y3，ANDSOON，MISTHENUMBEROFVALUESINTHEYISERIES，ANDTHEDATAAREEQUALLYSPACEDINSEGMENTSSECONDSLONGOR2N2XI1I2I12XXNA4A5A61（）（X）（21）WHEREXIISASETOFPHASEMEASUREMENTSINTIMEUNITSCONTAININGX1，X2，X3，2011届毕业设计说明书A19A2A316A2ANDSOON，NISTHENUMBEROFVALUESINTHEXISERIES，ANDTHEDATAAREEQUALLYSPACEDINSEGMENTSSECONDSLONGNOTETHATWHILESTANDARDDEVIATIONSUBTRACTSTHEMEANFROMEACHMEASUREMENTBEFORESQUARINGTHEIRSUMMATION，THEALLANDEVIATIONSUBTRACTSTHEPREVIOUSDATAPOINTTHISDIFFERENCINGOFSUCCESSIVEDATAPOINTSREMOVESTHETIMEDEPENDENTNOISECONTRIBUTEDBYTHEFREQUENCYOFFSETANALLANDEVIATIONGRAPHISSHOWNINFIG178ITSHOWSTHESTABILITYOFTHEDEVICEIMPROVINGASTHEAVERAGINGPERIODGETSLONGER，SINCESOMENOISETYPESCANBEREMOVEDBYAVERAGINGATSOMEPOINT，HOWEVER，MOREAVERAGINGNOLONGERIMPROVESTHERESULTSTHISPOINTISCALLEDTHENOISEFLOOR，ORTHEPOINTWHERETHEREMAININGNOISECONSISTSOFNOSTATIONARYPROCESSESSUCHASFLICKERNOISEORRANDOMWALKTHEDEVICEMEASUREDINFIG178HASANOISEFLOOROF51011AT100SPRACTICALLYSPEAKING，AFREQUENCYSTABILITYGRAPHALSOTELLSUSHOWLONGWENEEDTOAVERAGETOGETRIDOFTHENOISECONTRIBUTEDBYTHEREFERENCEANDTHEMEASUREMENTSYSTEMTHENOISEFLOORPROVIDESSOMEINDICATIONOFTHEAMOUNTOFAVERAGINGREQUIREDTOOBTAINATURHIGHENOUGHTOSHOWUSTHETRUEFREQUENCYWHEREXIISASETOFPHASEMEASUREMENTSINTIMEUNITSCONTAININGX1，X2，X3，ANDSOONISTHENUMBEROFVALUESINTHEXISERIES，ANDTHEDATAAREEQUALLYSPACEDINSEGMENTSSECONDSLONGNOTETHATWHILESTANDARDDEVIATIONSUBTRACTSTHEMEANFROMEACHMEASUREMENTBEFORESQUARINGTHEIRSUMMATION，THEALLANDEVIATIONSUBTRACTSTHEPREVIOUSDATAPOINTTHISDIFFERENCINGOFSUCCESSIVEDATAPOINTSREMOVESTHETIMEDEPENDENTNOISECONTRIBUTEDBYTHEFREQUENCYOFFSETANALLANDEVIATIONGRAPHISSHOWNINFIG178ITSHOWSTHESTABILITYOFTHEDEVICEIMPROVINGASTHEAVERAGINGPERIODGETSLONGER，SINCESOMENOISETYPESCANBEREMOVEDBYAVERAGINGATSOMEPOINT，HOWEVER，MOREAVERAGINGNOLONGERIMPROVESTHERESULTSTHISPOINTISCALLEDTHENOISEFLOORORTHEPOINTWHERETHEREMAININGNOISECONSISTSOFNOSTATIONARYPROCESSESSUCHASFLICKERNOISEORRANDOMWALKTHEDEVICEMEASUREDINFIG178HASANOISEFLOOROF51011AT100SPRACTICALLYSPEAKING，AFREQUENCYSTABILITYGRAPHALSOTELLSUSHOWLONGWENEED2011届毕业设计说明书A110A2A316A2TOAVERAGETOGETRIDOFTHENOISECONTRIBUTEDBYTHEREFERENCEANDTHEMEASUREMENTSYSTEMTHENOISEFLOORPROVIDESSOMEINDICATIONOFTHEAMOUNTOFAVERAGINGREQUIREDTOOBTAINATURHIGHENOUGHTOSHOWUSTHETRUEFREQUENCYOFFSETOFTHEDUTIFTHEDUTISANATOMICOSCILLATORSECTION174ANDTHEREFERENCEISARADIOCONTROLLEDTRANSFERSTANDARDSECTION175WEMIGHTHAVETOAVERAGEFOR24HORLONGERTOHAVECONFIDENCEINTHEMEASUREMENTRESULTFIVENOISETYPESARECOMMONLYDISCUSSEDINTHETIMEANDFREQUENCYLITERATUREWHITEPHASE，FLICKERPHASE，WHITEFREQUENCY，FLICKERFREQUENCY，ANDRANDOMWALKFREQUENCYTHESLOPEOFTHEALLANDEVIATIONLINECANHELPIDENTIFYTHEAMOUNTOFAVERAGINGNEEDEDTOREMOVETHESENOISETYPESFIG179THEFIRSTTYPEOFNOISETOBEREMOVEDBYAVERAGINGISPHASENOISE，ORTHERAPID，RANDOMFLUCTUATIONSINTHEPHASEOFTHESIGNALIDEALLY，ONLYTHEDEVICEUNDERTESTWOULDCONTRIBUTEPHASENOISETOTHEMEASUREMENT，BUTINPRACTICE，SOMEPHASENOISEFROMTHEMEASUREMENTSYSTEMANDREFERENCENEEDSTOBEREMOVEDTHROUGHAVERAGINGNOTETHATTHEALLANDEVIATIONDOESNOTDISTINGUISHBETWEENWHITEPHASENOISEANDFLICKERPHASENOISETABLE172SHOWSSEVERALOTHERSTATISTICSUSEDTOESTIMATESTABILITYANDIDENTIFYNOISETYPESFORVARIOUSAPPLICATIONSIDENTIFYINGANDELIMINATINGSOURCESOFOSCILLATORNOISECANBEACOMPLEXSUBJECT，BUTPLOTTINGTHEFIRSTORDERDIFFERENCESOFASETOFTIMEDOMAINMEASUREMENTSCANPROVIDEABASICUNDERSTANDINGOFHOWNOISEISREMOVEDBYAVERAGINGFIGURE1710WASMADEUSINGASEGMENTOFTHEDATAFROMTHESTABILITYGRAPHINFIG178ITSHOWSPHASEPLOTSDOMINATEDBYWHITEPHASENOISE1SAVERAGING，WHITEFREQUENCYNOISE64SAVERAGES，FLICKERFREQUENCYNOISE256SAVERAGES，ANDRANDOMWALKFREQUENCY1024SAVERAGESNOTETHATTHEWHITEPHASENOISEPLOTHASA2NSSCALE，ANDTHEOTHERPLOTSUSEA100PSSCALE2011届毕业设计说明书A111A2A316A2外文文献中文翻译时间和频率的基本原理介绍时间和频率标准应用于三种基本信息类型时间，时间间隔和频率时间信息有小时，分，秒通常还包括日期年，月，日用来显示和记录时间的器件叫做钟表，如果钟表标记了一件事的发生，那么这个标记叫做时间标签或时间印记日期和时间能确保事情的同步或同时发生时间间隔是两个事件持续或断续的时间，时间间隔的标准单位是秒，然而许多工程上应用要求更短的时间间隔，像毫秒，微秒，纳秒，和皮秒，时间是七个基本物理量之一，并且秒是国际单位体制制定七个基本单位之一许多区其他物理量的定义是依靠秒而定义的秒曾经定义根据地球回转率原子时代正式G5332G3999G33241967年G11458G2081SI定义秒G1038秒是G19139133原子CS133基G5589的两个G17241G12946G13466能G13435之间G17303G17813G6164G4557应的G17764G4568的9，192，631，770个G2620期G6164持续的时间G452频率是一个事件的G18337G3809G8437G6980，如果T一个G18337G3809事件的G2620期，那么频率F是G4439的G1510G6980，1/TG2465G17819来G16840频率的G1510G6980是G2620期，T1/FG2620期是时间间隔用秒表示G5468G4493G7143G11487G1998频率和时间间隔G1863G13007G5468G4506G2011频率的标准单位是G17215G1869，定义G1038G8611秒发生的事件G8437G6980或G5502G10627G8437G6980，G11017信G2507的频率通常用G993同的G17215G1869G8991量，包括G2327G17215G1869，G1818G17215G1869，G2327G1818G17215G18691KHZG11468G5415于G8611秒发生一G2327G8437事件，1MHZG11468G5415于G8611秒发生一G11346G987G8437事件1GHZG11468G5415于G8611秒发生G2325G1171G8437事件G1147生频率的G16025G13634叫做G6403G14645器，G16786G13634G993同G6403G14645器G1867有G11468同的频率叫做同步G452三种类型的时间和频率信息是G11468G1296的，时间间隔的标准单位是秒通G17819G16757G6980秒G6117G1216G11705G17959时间和日期，通G17819G16757G6980G8611秒的事件G6980或G5502G10627G6980，G6117G1216能G8991量频率于其他物理量G11468G8616时间间隔和频率的G8991量G1867有G16835G5058小，G7143于分G7524的G1260G9869G11458G2081G7380G3921的时间和频率标准是SIG16835G5058G10381015其他基本SI单位有更G3835的G16835G5058如表171G6164示G452协调全世界时间UTCG1002G11040的G1039要G5242量G4410G4466G20576G4472G8991量时间和频率标准，并发G17877的BIPM，G8873国BIPM2011届毕业设计说明书A712A8A916A8G6922G19610G14279G458140个G4466G20576G4472的200多个原子时间和频率标准包括来G14270国际标准和G6228G7427G2339G1262NIST通G17819这G1135G5191G3355G13479果G11013BIPMG1147生两个时间标准，国际原子时间TAI和G2339G16855G1852G1002G11040时间UTC，这G1135时间标准G4625G2499能地G994SI标准G6521G17829G452UTCG994TAIG6203G15904G11468同的频率，然而G4439有区G2047的TAI是G6984G6980秒，这个G993同G3800G5647G3324G3698G19283G19555G11540皮秒的G17351G2476皮秒G3698G2164G2052UTC的G8611年6月30日或12月31日G3698G2164G17317秒的G11458的G3324于是原子时间的G16835G5058G3324/09SG13781的时间标准叫UT1，G4439根据地球的回转率G452皮秒G1328G1038一个小量G3698G2164G2052UTCG8611年一G8437G11861972年G5332G3999的G452BIPM包括UTC和TAI正G16280的时间标准，G1039要的G5242量G4410G4466G20576G4472使用来G14270BIPM控制G4439G1216时钟和G6403G14645器G1147生的G6980据并G1147生真正的UTC时