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1、107傳輸專(zhuān)業(yè)維護(hù)手冊(cè)第一章傳輸原理介紹第一節(jié)SDH信號(hào)的幀結(jié)構(gòu)和復(fù)用步驟1.1.1SDH信號(hào)——STM-N的幀結(jié)構(gòu)STM-N信號(hào)幀結(jié)構(gòu)的安排應(yīng)盡可能使支路低速信號(hào)在一幀內(nèi)均勻地、有規(guī)律的分布。為什么呢？因?yàn)檫@樣便于實(shí)現(xiàn)支路的同步復(fù)用、交叉連接（DXC）、分/插和交換，說(shuō)到底就為了方便的從高速信號(hào)中直接上/下低速支路信號(hào)。鑒于此，ITU-T規(guī)定了STM-N的幀是以字節(jié)（8bit）為單位的矩形塊狀幀結(jié)構(gòu)，如圖1-1所示。圖1-1STM-N幀結(jié)構(gòu)圖從上圖看出STM-N的信號(hào)是9行×270×N列的幀結(jié)構(gòu)。此處的N與STM-N的N相一致，取值范圍：1，4，16，64……。表示此信號(hào)由N個(gè)STM
2、-1信號(hào)通過(guò)字節(jié)間插復(fù)用而成。由此可知，STM-1信號(hào)的幀結(jié)構(gòu)是9行×270列的塊狀幀，由上圖看出，當(dāng)N個(gè)STM-1信號(hào)通過(guò)字節(jié)間插復(fù)用成STM-N信號(hào)時(shí)，僅僅是將STM-1信號(hào)的列按字節(jié)間插復(fù)用，行數(shù)恒定為9行。我們知道，信號(hào)在線路上傳輸時(shí)是一個(gè)bit一個(gè)bit6.2.6establishingconstructionsiteweldingsecondary,secondaryelectrodeconsistedofRodpiledup,weldingrodovens,incubators,thermometers,hygrometersandbackingofelectrodes,
3、receiving,paymentandrecoverysystem.Andpersonresponsibleforthesecondarydatabase.6.2.7constructionweldingmachines,grindingmachines,plasmacuttingmachinetoolexperienceisqualified.6.2.8weldingelectrodes,weldingwireselectioninlinewithnationalandindustrystandardsrequirements,weldingmaterialweldingmater
4、ialsqualitymanualshouldbeprovided,itschemicalcomposition,mechanicalpropertiesandotherindicatorsshouldconformtotherequirementsoftherelevantstandards,appearancemaynothavedefectssuchascorrosion,unqualifiedproductscannotbeused.6.2.9electrode,fluxdryingbeforeuseaccordingtotheregulations,andshouldbeke
5、ptdryduringuse,wiresshouldberemovedbeforeusingthesurfaceoil,rust,etc.Electrodesmustnotfalloff,norustspotsandobviouscracks.6.36.3.1electrodeelectrodeselectionandmanagementlisttrumpeterargonarcweldingelectrodearcweldingofsteel10#E4303J427H08Mn2SiA20#E4303J427H08Mn2SiAQ235-AE4303J422,H08Mn2SiA304E3
6、08A102H0Cr21Ni10316LE00-19A002H00Cr21Ni10321E347A137H0Cr21Ni10Ti15Cr...(2)thepurityofargoncarbonsteelandalloysteelpipeshallnotbelessthan99.9%.(3)theweldingfieldwind-proof,rain-proofmeasuresmustbetaken,whentherelativehumidityisgreaterthan90%,whenthewindspeedisgreaterthan2m/s,donotallowapplication
7、ofargonarcwelding,whenthewindspeedisgreaterthan8M/s,donotallowtheapplicationofarcwelding.Weldingshallnotbelessthan0℃ambienttemperature.(4)priortowelding,youshouldreviewthelipsize,meettherequirementsbeforethey107傳輸專(zhuān)業(yè)維護(hù)手冊(cè)107傳輸
