32
LDM-144LR
5.2.2 R
EMOTE
D
IGITAL
L
OOPBACK
(REM)
The Remote digital loopback (REM) test determines the performance of both
the local and the remote LDM-144LR units, as well as their connecting lines.
The Remote Digital Loopback test consists of providing a loopback at the
remote modem, as shown in
Figure 5-2
.
1. Activate the REM loopback (see
Table 4-1
for activation instructions) to
provide a loopback at the remote LDM-144LR. The TEST indicator
should light at both the local and remote unit. (This test can also be
activated via the appropriate pin on the digital interface.)
2. Perform the BERT test as explained in
Section 5.2.1
, steps 3 and 4.
3. If step 2 indicates a fault, while the local analog loopback test described
in
Section 5.2.1
was successful for both the local and remote modems,
then the line or the line circuits of the local or the remote unit are not
functioning properly. To verify that the LDM-144LR is operating
correctly, follow the instructions below:
• Press the ANA (Analog Loopback) pushbutton on the front panel and
check that both the TEST and DCD indicators are turned on.
• If the DCD indicator is not turned on, check that the Carrier jumper J3
(CARR), is set to ON or that the RTS signal is high.
• Press the PATT pushbutton and check the following indications:
- If the ERR indicator remains turned on or blinks, then the LDM-144LR is
faulty; replace it.
- If the indications are as specified in step 3 above, restore the push-buttons
to the operation mode.
