User Manual

3
7
MN024-08
As the tables show, minor alarms (low priority alarms) are revealed only by
LMT or supervision system, but not by LEDs. Minor alarms detect critical
situations which should be checked and tested in order to avoid future possible
system faults.
Each remote unit is provided with an AGC system which comes in after the
optical-to-RF conversion. This AGC can correctly compensate optical losses
when these are estimated to be <3 dB. In case optical losses are in the 3dB-
4dB range, the whole system still works, but AGC is near to its borderline
levels. The red LED switches on when the estimated optical losses are >4dB,
the AGC not being able to compensate these losses any more.
As shown in the previous table, the same red LED switches on to reveal any
major failure. Following the troubleshooting procedure reported hereinafter it
is possible to better understand what problem occurred.
1
Note:
Each remote unit is provided with an AGC system which comes in after the optical-to-RF
conversion. This AGC can correctly compensate optical losses when these are estimated to be
<3 dB. In case optical losses are in the 3dB- 4dB range, the AGC is said to be “out of range”:
the whole system still work, but AGC is near to its borderline levels. The DL power LED switches
on when the estimated optical losses are >4dB, the AGC not being able to compensate these
losses any more.
As shown in the previous table, the same red LED switches on to reveal any major failure.
Following the troubleshooting procedure reported hereinafter it is possible to better understand
what problem occurred
.
TFAx
CaseA
TFAM20
ALARM
CODE
(TSUN
descriptio
n)
ALARM
DESCRIPTION
ACTIVE
LED
SUPERVISION
PRIORITY
LEVEL
ACTION
RECOMMENDED
RELÉ
PRIORITY
LEVEL
(subrack)
Antenna DC
loop alarm
ALWAYS OK
Power
Supply alarm
UPS HW failure or
malfunction.
RF is turned OFF
RED MAJOR
Check the external
PSU. If it works
properly, return the
unit
MAJOR
Internal Bus
alarm
ALWAYS OK
DL optical
power fail
The optical power
received on the DL is
too low and can’t no
more be
compensated
RED MAJOR
Check the DL fibre
and the TFLN laser
status
MAJOR
AGC out of
range
The optical power
received is under the
allowed 3dB optical
loss but it can be
compensated
NONE WARNING
Clean optical
connectors
MINOR
DL UMTS
band alarm
HW failure on the DL
UMTS section
RED CRITICAL Return the unit MAJOR
Temperature
alarm
Over-temperature
alarm
RED
if temperature
>85°C
MINOR
Check ventilation
and environment
MINOR
Table 3.3. Description of the alarms of the TFAM20 Remote Unit, as they are
presented on LMT or Supervision Interface