Specifications

Chapter 4 Diagnostics and Troubleshooting Installation and Operation Manual
4-2 Diagnostic Loopbacks FOM-E3, FOM-T3 Ver. 1.0
4.2 Diagnostic Loopbacks
Local Loopback (LLB)
FOM-E3 and FOM-T3 support activation of a local loopback, which tests the
performance of E3/T3 electrical interface of the local unit and equipment
attached to it.
The data received at the E3/T3 electrical interface is looped back to the
equipment attached to it (see
Figure 4-2 ).
E3 or T3 BERT
Coax
LO
C
Position
FOM-E3
or
FOM-T3
Figure 4-2. Local Loopback
 To activate local loopback:
• Slide the front panel TEST switch to the LOC position.
The TEST LOC indicator lights up and remains lit as long as the local
loopback is active.
Remote Loopback (RLB)
FOM-E3 and FOM-T3 support activation of a remote loopback, which tests the
performance of the local unit's E3/T3 electrical and optical interfaces and the
remote unit's optical interface.
The data received at the optical interface of the remote unit is transmitted to the
electrical interface and at the same time is looped back to the local unit (see
Figure 4-3 ).
E3 or T3 BERT
Coax Fiber Optic
REM
Position
Local
FOM-E3
or
FOM-T3
Remote
FOM-E3
or
FOM-T3
Figure 4-3. Remote Loopback
 To activate remote loopback:
• Slide the TEST switch of the local FOM-E3 or FOM-T3 to the REM position.
The TEST LOC indicator of the remote unit lights up and remains lit as
long as the remote loopback is active.