User's Manual

Confidential&Proprietary43/115 SC‐DAS

2)ExpansionWavelengthDivisionMultiplexer(EWDM)
EWDM module handles the optical to RF conversion of TX signals as well as the RF to optical
conversionofRXsignals.ThismultiplexercommunicateswiththeBIUusingthebuiltinFSKmodem.
ItalsohasanATTtocompensateforopticalcableloss
betweenODUs.
Finally,ithasinternalWDMsoitneedsonlyoneopticalcabletoworkwithanROU.

Figure4.24–EWDMataglance
3)ExpansionCentralProcessorUnit(ECPU)
ECPU can query and control the state of modules installed into the OEU. This unit simultaneoulsy
communicateswiththeBIUandtheROUaswellasactingascommunicationbridgebetweenBIUand
ROU.
In addition, the unit has
a USB port for local communication which enables queryand control of
devices thorugh a PC. At the front panel, communication LED indicator indicates communication
withupperBIUandlowerROU.ItalsohasanALMLEDindicatortoshowfault.

Figure4.25–ECPUataglance
4)ExpansionRadioFrequencyModule(ERFM)
ERFMrepairsSignaltoNoisedegradedbyopticalmodules.