綜合布線基礎(chǔ)知識(shí)講義三四

第十一章關(guān)于光纖的測(cè)試光纖與銅纜的對(duì)比光纖基礎(chǔ)知識(shí)光纖的選用影響衰減的因素光纖測(cè)試設(shè)備

FiberOpticAdvantages

?光纖與銅纜的對(duì)比項(xiàng)目光纖（FIBER）銅纜（COPPER）線纜價(jià)格低較高抗電磁/射頻（EMI/RFI）干擾能力不會(huì)被干擾NEXT、FEXT等連接器抗電磁/射頻（EMI/RFI）干擾能力不存在總要被考慮接地回路不存在總要被考慮損耗低相對(duì)高帶寬高正在提高溫度穩(wěn)定性可能是個(gè)問題可能是個(gè)問題重量非常輕可能是個(gè)問題易于安裝熔接困難比較容易安裝及維修工具的價(jià)格高低網(wǎng)卡價(jià)格光/電/光轉(zhuǎn)換部件昂貴路由器便宜放大器價(jià)格光/電/光轉(zhuǎn)換部件昂貴測(cè)試工具價(jià)格昂貴的OTDR認(rèn)證測(cè)試要求損耗、傳輸延遲和長(zhǎng)度單根或成對(duì)測(cè)試測(cè)試項(xiàng)目較多，可同時(shí)雙向多線對(duì)測(cè)試光纖基礎(chǔ)知識(shí)—電磁譜Frequency(Hz)UV可見光(750-380nm)X-RaysIRAMRadioWavelength(m)101210810141010101610181UHFVHF10610-310-9常用的光波長(zhǎng)(660,850,1300,1310,&1550nm)光纖基礎(chǔ)知識(shí)—波長(zhǎng)的選擇FirstWindowSecondWindowThirdWindow波長(zhǎng)(nm)8001200160008Loss(dB/km)4多模(MD) 工作于850nm和1300nm單模(SM) 工作于1310nm和1550nm多模與單模光纖MULTIMODEFIBER–HugeVolumeShortDistance<2kmSINGLEMODEFIBER–HugeVolumeLongDistanceFrom2kmto100kmCoreCladdingCoating

MultimodeFiber

PoweredbyLEDsandVCSELsat850nmand1300nmLowcostelectronicsUsuallyHasORANGEJacketingShortDistances(<2km)Greatfor:LocalAreaNetworks,CCTV,CampusAreaNetworks,OfficesandManufacturingInexpensiveforShortDistances,ExpensiveforLongDistanceCoreDiameters:50um,62.5um&100um

SinglemodeFiber

PoweredbyLasersat1310nm,1550nmand1625nmHighPowerLongDistance–2kmto100kmGreatfor:WideAreaNetworks,Metro.AreaNetworks,CATV,Utilities&TelcosInexpensiveforLongDistanceComparedtoCopper,ExpensiveforShortDistanceCoreDiameter:9umUsuallyhasYELLOWJacketing光纜結(jié)構(gòu)表皮(材料PVC)抗拉材料緩沖填充物核

FiberOpticConnectors

光纜的接接合Mechanical機(jī)械式Quick快速Littlespecializedequipmentrequired一般不需需特殊設(shè)設(shè)備Newtechniquesandspliceconnectorshaveimprovedthelosspersplice(some<0.1dB)新技術(shù)和和連接器器改善了了接合的的損耗Goodforemergencyfieldrepairs,lowvolumes應(yīng)急，小小數(shù)量Fusion熔結(jié)Requiresspecial,expensiveequipment需要特殊殊設(shè)備Verylowloss(canbe<0.05dB)極低的損損耗Theonlymethodforlong-haullinks長(zhǎng)距離鏈鏈路的唯唯一方法法激光產(chǎn)品品的級(jí)別別ClassI－無危危險(xiǎn)ClassIIa－觀看看時(shí)間小小于1000秒則安全全ClassII－長(zhǎng)期期觀看有有危險(xiǎn)ClassIIIa－直接接觀看有有嚴(yán)重危危害ClassIIIb－直接接輻射對(duì)對(duì)眼睛和和皮膚有有嚴(yán)重傷傷害ClassIV－直接接觀看或或散射對(duì)對(duì)眼睛和和皮膚有有嚴(yán)重傷傷害LASERWARNINGTIA/EIA568BStandardCable－電纜Maximumfiberlossperkm(at850nm)3.75dBMaximumfiberlossperkm(at1300nm)1.5dBMaximumfiberlossperkm(at1310nm)1.0dBMaximumfiberlossperkm(at1550nm)1.0dBConnections(DuplexSCorST)－連接器器Maximumadapterloss:0.75dBMaximumspliceloss:0.3dBLinkLengths(backbone)－鏈路長(zhǎng)度SegmentHC-ICIC-MC62.5/125Multimode500m1500m50/125Multimode(underproposal)8/125Singlemode500m2500m光鏈路損耗的的原因光纜的材料純度材料密度的變變化光纜的彎曲程程度宏觀彎曲(安裝問題)微觀彎曲(產(chǎn)品制造問題題)光纜接合以及及連接的耦合合損耗不潔或連接質(zhì)質(zhì)量不良BarefiberThismakesyousaybadwords.密度改變DensityChange氣泡Bubble雜質(zhì)ImpurityMicrobend裂紋Macrobend造成衰減的原原因1.光纖本身的缺缺陷耦合損耗CouplingLossesAreamismatchSpacinglossAxismisalignmentAngularmisalignmentLossesatsplicesandconnectors,includingtestequipmentconnectors:光纖的測(cè)試光功率損耗插插入損耗耗

長(zhǎng)度傳傳輸時(shí)延延故障定位FIBERTEK?采用FIBERTEK?選件后，可實(shí)實(shí)現(xiàn)：損耗與與長(zhǎng)度的測(cè)試試需要雙端設(shè)