User Manual

Cabinet descriptionNortel Networks Confidential 1–41
S8000/S8002/S8006 BTS Reference Manual
Back panel
The BCF back panel connects the switching part of the BTS. It provides connections
for the BCF boards (see Figure 1–19). It receives the external PCMs from the BSC
(A–bis interface) and the six private PCMs from the BTS. It also distributes the
O&M bus, its own alarms and the 48 V power supply of the ALCO board.
The BCF back panel has the following connectors:
A 37–pin female connector receives the six PCMs of the A–bis interface.
Three 25–pin female connectors distribute the O&M bus.
Three 25–pin female connectors each distribute two private PCMs.
A 3–pin connector is used for power supply.
A 4–pin connector distributes converter alarms to the ALCO unit.
Thirty 96–pin male connectors connect the P1 and P2 connectors of the
following units: PCMI, DSC, PSU, CSWM, GTW, and SYNC.
Thirteen 8–pin male connectors supply the units connected to the back–panel.
The BCF back panel also connects PCM termination resistors in order to reduce
radioelectric transmission and prevent end–of–line multiple reflection problems.
The P2 connectors are equipped with a localizing device that prevents the insertion
of a board into the wrong slot. This is done by means of cells on the back–panel that
are blocked and tabs that are cut out on the board connectors (see Figure 1–20).
The BCF back panel has only one ground. No distinction is made between logical
ground and physical ground. For units that use this distinction, the mechanical
ground is connected to the logical ground.
However, the reference 0 V of the –48 V power supply (M0 V) is not connected to
the back–panel ground.
The –48 V dc power is protected by fuses.