Optical Interface Board (Oib) - Cisco GS7000 Installation And Operation Manual

Chapter 2 Theory of Operation

Optical Interface Board (OIB)

Optical Interface Board Description
The Optical Interface Board (OIB) provides all interconnections between the
modules in the housing lid of the 1.2 GHz GS7000 Node. The modules in the housing
lid include the optical receiver, optical transmitter, power supply, and status
monitoring/local control modules. Each module in the lid plugs directly into the
OIB through a connector header or row of sockets. Input attenuator pads are
provided on the OIB for each optical receiver in the housing lid. Output attenuator
pads are provided on the OIB for each optical transmitter in the housing lid. All RF
and power cables running between the housing lid and base also plug into the OIB.
The OIB is field replaceable. All optical modules, power supplies, RF cables, power
cables, and OIB mounting screws must be removed in order to remove the OIB from
the housing lid.
The upstream status monitoring signal goes through LPF then splits. Splitter output
1 goes through a 17dB coupler into transmitter 1 input. Splitter output 2 goes
through a plug-in attenuator pad, a 17dB coupler and into transmitter 2 input.
The purpose of the attenuator (AT9) is to terminate the upstream status monitoring
signal going into transmitter 2 when either the node is segmented or EDR
transmitter is in use. When the node is configured in either segmented or EDR mode,
a 75 dB pad must be placed in the Tx2 SM Term.
This solution resolves the issue of transmitting and receiving duplicate copy of the
upstream signal from transponder at the CMTS.
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