Diagnostic Loopbacks; Local Loopback (Llb); Remote Loopback (Rlb) - Black Box MT618A-ST-R2 User Manual

T3 FIBER OPTIC LINE DRIVER

5.2 Diagnostic Loopbacks

5.2.1 L L
OCAL OOPBACK
Local loopback tests the performance of the T3 electrical interface of the local line
driver and the equipment attached to it.
The data received at the T3 electrical interface is looped back to the line driver
attached to it (see Figure 5-2).
T3 Fiber
T3/E3
Optic Line
Driver
BERT
To activate local loopback, s
indicator turns On and remains lit as long as the local loopback is active.
5.2.2 R L
EMOTE OOPBACK
Remote loopback tests the performance of the local line driver's T3 electrical and
optical interfaces and the remote line driver's optical interface.
The data received at the remote line driver's optical interface is transmitted to the
electrical interface and is simultaneously looped back to the local line driver (see
Figure 5-3).
24
(LLB)
Figure 5-2. Local loopback illustrated.
lide the TEST switch to the LOC position. The LOC
(RLB)
COAX
LOC POSITION
FOM
T3 Fiber
Optic Line
T3/E3
Driver