User Manual

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FiberDistributedAntennaSystem(FiberDAS)

Fiber Optic Interface (FOI) unit

TheFOIcon vertstheRFsignalsinthedownlinktofiber ‐opticallaseroutputthatistransmittedonthefi bertothe

remoteunit.ItalsoreceivesthelaserlighttransmittedbytheRemoteUnitandconvertsitbacktoRFsignalsthatare

thenroutedtothePOIand thentotheBIU

Figure 6 Fiber Optic Interface (FOI) Unit

TheFOIisavailableineitherasingleheadfiberinterface(withWDM)configurationorwithadualheadfiber

interfacewithseparateRXandTXconnectors.

EachFO

Icanserveupto4RemoteUnitsonasinglefiber.ThedrawbackisthattheRemoteUnitsmusthavedifferent

opticalwa velengthsintheuplinktoavoidinterference.Theycanhoweversharethesameopticalwavelengthinthe

downlink.

Functional description

TheFO

Ihasanominalgainof35dBandthelasertransmittershouldseeamaximumcompositeinputpowerofca

0dBm.Thismeansthatfor0dBattenuationintheDLamaximuminputof‐35dBmcomposit epoweris

recommended(whenattenuatorsaresetto0dBm).IftheDLatte

nuatorissettoahighervaluethemaximum

recommendedinputisadjustedaccordingly.

Theoutputpo

werofthelaseriscalibratedto3000µW.Thiscanbeusedtocheckthelossoverfiberintheremote

becausetheremotereportsthereceivedopticallevels.ThelossmaybedifferentintheULcomparedtotheDL

becauseofdifferentwavelengthsonthela

ser.

TheFO

IispoweredfromtheMFUbackplaneandcommunicateswithEthernetwiththeothermodulesintheMaster

Unit.

Theun

itcontainsseveraladjustableattenuatorswhichareusedtocompensateforlossbeforetheFOI(e.g.inthe

POI)andforlossonthefiberintheuplink.TherearetwosetsofRFportsontheFOIthatcanbeusedtoconnect

signalsfromtwodifferentstripsinthePOI.

TheEt

hernetcommunicationbetweentheMasterUnitandtheRemoteUnittake splaceontwosub‐carriersinthe

FOIwheretheEthernetsignalsaresuperimposedontheRFsignals.

WARNING

Avo

idlookingintoconnectedfi bersandreceptacles.

ThelaserusedinthissystemisaClass3blaserthatproducesinvisibleinfra‐redcoherentlight.Notsafetoview

withopticalinstruments.Alwaysputtheprotectioncapsonunusedfibersandreceptacles.