2016綜合布線基礎(chǔ)知識講義10

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

FiberOpticAdvantages

?光纖與銅纜的對比項目光纖（FIBER）銅纜（COPPER）線纜價格低較高抗電磁/射頻（EMI/RFI）干擾能力不會被干擾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高帶寬高正在提高溫度穩(wěn)定性可能是個問題可能是個問題重量非常輕可能是個問題易于安裝熔接困難比較容易安裝及維修工具的價格高低網(wǎng)卡價格光/電/光轉(zhuǎn)換部件昂貴路由器便宜放大器價格光/電/光轉(zhuǎn)換部件昂貴測試工具價格昂貴的OTDR認(rèn)證測試要求損耗、傳輸延遲和長度單根或成對測試測試項目較多，可同時雙向多線對測試光纖基礎(chǔ)知識—電磁譜Frequency(Hz)UV可見光(750-380nm)X-RaysIRAMRadioWavelength(m)101210810141010101610181UHFVHF10610-310-9常用的光波長(660,850,1300,1310,&1550nm)光纖基礎(chǔ)知識—波長的選擇FirstWindowSecondWindowThirdWindow波長(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一般不需特殊殊設(shè)備Newtechniquesandspliceconnectorshaveimprovedthelosspersplice(some<0.1dB)新技術(shù)和連接接器改善了接接合的損耗Goodforemergencyfieldrepairs,lowvolumes應(yīng)急，小數(shù)量量Fusion熔結(jié)Requiresspecial,expensiveequipment需要特殊設(shè)備備Verylowloss(canbe<0.05dB)極低的損耗Theonlymethodforlong-haullinks長距離鏈路的的唯一方法激光產(chǎn)品的級級別ClassI－無危險ClassIIa－觀看時間間小于1000秒則安全ClassII－長期觀看看有危險ClassIIIa－直接觀看看有嚴(yán)重危害害ClassIIIb－直接輻射射對眼睛和皮皮膚有嚴(yán)重傷傷害ClassIV－直接觀看看或散射對眼眼睛和皮膚有有嚴(yán)重傷害LASERWARNINGTIA/EIA568BStandardCable－電纜Maximumfiberlossperkm(at850nm)3.75dBMaximumfiberlossperkm(at1300nm)1.5dBMaximumfiberlossperkm(at1310nm)1.0dBMaximumfiberlossperkm(at1550nm) 1.0dBConnections(DuplexSCorST)－連接器Maximumadapterloss:0.75dBMaximumspliceloss:0.3dBLinkLengths(backbone)－鏈路長度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:光纖的測試光功率損耗插插入損耗耗

長度傳傳輸時延延故障定位FIBERTEK?采用FIBERTEK?選件后，可實實現(xiàn)：損耗與與長度的測試試需要雙端設(shè)備