IRIGB_对时信号

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1、IRIG-BTimeCodeIRIG-BTimeCodeAlthoughthesynchronizationbuscancarrymanyformsoftimesignal,theIRIG-Btimecodeisthemostwidelyusedsynchronizationsignalwithinsubstations.ThebasicformofIRIG-Bconsistsofapulse-widthmodulateddigitaldatastreamattherateof100pulsespersecond.Theleadingedgeofeachpulseispreci

2、selypositionedintimeontheincremental10mSpointwithinthesecond,whilethepulsewidthmodulationconveystimeanddateinformationrepeatingwithineach100pulseframei.e.oncepersecond.ThereareanumberofvariationsofIRIG-Btimecodesincommonuse.IRIG-Btimecodesaredefinedusinga4-characterdescriptor:"Bxyz",and"x","

3、y"and"z"havemeaningasfollows:Bxyz[format][modulationtype][frequency/resolution][codedexpression]"B"denotesIRIG-B"x"designator,modulationtypehasthreepossiblevalues:0=Unmodulated,alsocalledDClevelshift1=AmplitudeModulated(AM)sinewave2=ModifiedManchestermodulatedThe"y"designator,frequency/resol

4、utionhasvaluesasfollows:0=nocarrier/indexcountinterval(commonlyusedwithIRIG-B)1=100Hzcarrier(notusedwithIRIG-B)2=1000Hzcarrier(commonlyusedwithIRIG-B)The"z"designator,codedexpressionhasvaluesasfollows:0=BCD,CF,SBS1=BCD,CF2=BCD3=BCD,SBSBCD=BinaryCodedDecimalformat=basictime-of-yearinformation

5、(doesnotincludeyearinformation).CF=ControlFunction=additionalinformationincludingyearinformation(egIEEE1344extensionsorAFNORextensions).SBS=StraightBinarySeconds=seconds-of-dayinbinaryformat.ThevalidcombinationsinuseforIRIG-Bare:B00z,B12zandB22z.B00z(DClevel-shiftIRIG-B)B00z(DClevel-shiftIRI

6、G-B)hasbeenfavoredforusewithnewequipmentinsubstationsbecause,althoughitcannotbeusedforwiringrunsofmorethanabout100meters,itoffersgoodtimingaccuracy.AslongastheGPSclocksoutputsareisolatedandthereforebalancedthiseffectivelyeliminatesproblemsduetoinducednoisethatcancausedifficultiesusingthisfor

7、moftimecodeinsub-stations.Thiscodecanalsobeeasilytransmittedoverfiber.Demodulationisnotrequired,sothecodecanbeverysimplyreceivedandusedbyconnectedequipment.TheB00zsignalsarealreadybeingusedforsynchro-phasortiming.B12z(AmplitudeModulatedIRIG-B)B12z(