User's Manual

134
ION-B User Manual
TFLN
Each TFLN is provided with an AGC system which compensates optical losses of <3 dB. TFLN
LED alarms switch on when the estimated optical losses are >4dB, when the AGC is not able to
compensate these losses any more.
One of LEDs,1, 2, 3 or 4, might turn on not only to indicate a high optical loss detected by the
TFLN, but also to reveal a Remote Unit failure. Understanding the reason why one of LEDs 1, 2, 3
or 4 is on (a Remote Unit failure, an optical cable fault or an external equipment malfunction)
can be done following the troubleshooting procedure reported hereinafter.
Quick Troubleshooting Procedure
(The following procedure is summarized by the fl ow-chart in fi g. 4.3.7a)
1. If the TFLN general alarm (LED “ “) is on, replace the faulty TFLN master optical TRX with
a new one and contact the manufacturer for assistance.
2. In case one of the LEDs, 1, 2, 3 or 4, is lit, the corresponding TFLN adapter might be dirty.
Try cleaning it using pure ethyl alcohol. If the LED is still lit, go to the corresponding Remote
Unit side and check the red LED on the TFAx warm side:
a. If it is off, the optical cables or the optical connections are supposed to have
some problem on UL path. Refer to fi bre optic UL troubleshooting for more
information (fi g. 21).
b. If it is on, refer to Remote Unit troubleshooting presented in the previous Remote
Unit section
Fibre Optic UL Troubleshooting
(The following procedure is summarized by the fl ow-chart in fi g. 4.3.7b)
1. Check if there is any point where the fi bre experiences a small radius of curvature.
In this case, rearrange the optical path in order to avoid sharp bends (if necessary,
replace the optical cable with a longer one). If this causes the TFLN red LED to switch off,
troubleshooting has been successful. Otherwise, follow this next step.
2. Check if the SC-APC connectors are properly installed at both fi bre ends (i.e. TFLN and
Fig. 3.6.6:
AGC thresholds vs LED alerts
0dBm
-3dBm
-4dBm
Normal
Warning
Alarm
The previous table reports a brief description of the TFLN alarms,
together with a reference to the corresponding alerted LEDs.
As the table shows, LEDs on the TFLN front panel signal all high
priority alarms while minor alarms, which detect critical situations
which should be checked and tested in order to avoid future
possible system faults, are only revealed by the LMT or the
Supervision System.