ERA® WCS and e-POI Subracks and Power Supply Unit Installation Guide
M0201ABK_uc
Page 60
© June 2021 CommScope, Inc.
Install and Connect the Subrack Cards
Connect the OPT Cards
OPT cards provide a 10 Gbps fiber connection between CANs, TENs, and WINs; and between CANs and TENs
and Fiber APs. Each OPT Card supports up to four SFP+ transceivers for device connections.
Connecting OPT Cards is a two-phase process:
•
"Install SFP+ Modules in the OPT Cards” on page 62
.
•
In phase 2, you connect the OPT Card to another WCS Subrack or to a Fiber AP, as required for this
installation:
–
"Cabling OPT Cards to Connect a WIN a Switching CAN” on page 64
–
"Cabling OPT Cards to Connect the TEN to a Classic CAN” on page 66
–
"Cabling OPT Cards to Connect a TEN to a Switching CAN” on page 68
–
"Cabling OPT Cards for Connecting to a Fiber AP” on page 70
Fiber Optic Link Budget in the ERA System
When designing the fiber links for the CommScope ERA system, is important to consider all the factors that
can affect link performance. These factors include TX optical power, RX sensitivity, the fiber length, the
wavelength, the number of splices, and the number of connectors. This topic briefly describes the key factors
that should be considered.
Minimum Optical Path Loss
The optical power applied to the RX input of the SFP+ module must be less than the Receiver Overload
threshold. In some cases, the Receiver Overload is less than or equal to the maximum TX Optical Power, which
allows a very short fiber jumper to be used to connect TX to RX power; however, in other cases the TX Power
exceeds the Receiver Overload threshold, so a minimum amount of optical attenuation must be applied
between the TX output and RX input to prevent overdriving the RX input. See
for a list of
SPF+ modules that are qualified for use with the ERA system.
Optical Fiber Path Loss >= TX Optical Power Max - Receiver Overload
If the path loss is below the amount of attenuation needed to prevent exceeding the Receiver Overload
threshold, then additional attenuation must be added in the link to prevent overdrive. This can be done by
adding additional fiber or by using an inline optical attenuator.
Maximum Optical Path Loss
The optical power received at the RX input must be greater than the RX Sensitivity. The RX power is equal to
the minimum TX power reduced by any optical attenuation in the TX-RX path. It is good design practice to
provide additional link margin when designing the fiber links.
Maximum Optical Path Loss <= TX Optical Power Min - RX Sensitivity – Link Margin
OPT Cards are hot swappable; you do not need to power down the CAN, TEN, or WIN to install or remove
an OPT.
