Q-Lite Satellite Modem Installation and Operating Handbook
11-8
Fault Text
Notes
Relays To Ter To Sat Other
Rx warning: Backward
alarm from satellite
detected at Rx input,
indicating Tx or
downstream of Tx
equipment fault.
A backward alarm has been detected at the Rx input.
This indicates that equipment downstream of the transmit
path (i.e. from the modem Tx output) has failed and is
returning an alarm. This may be due to a downstream
receive path equipment failure, the modem Tx failing or a
satellite failure. Check the modem Tx path status. Check
the Tx IF output from the modem is connected to the
upconverter equipment and onwards. Monitor the Tx
carrier (or distant Rx if possible) with a spectrum
analyser.
D
TB
Rx warning: CAS
multiframe backward alarm
from satellite, indicating
equipment downstream of
Tx has failed to find CAS
MF sync.
A multiframe backward alarm has been detected at the
Rx input indicating that equipment downstream of the
transmit path has failed to synchronise to the CAS
multiframe and is returning an alarm. This could be
caused by any equipment from the Tx modulator
onwards but is unlikely to be other than the Tx mod, the
Rx demod, or further down the Rx path.
D
TE
Rx warning: Backward
alarm 1 (or 2 or 3 or 4)
from satellite, indicating
equipment downstream of
Tx has failed.
This indicates which of the four backward alarms are
active at the Rx input. This indicates that equipment
downstream of the transmit path (ie the distant end Rx
path or further downstream) has failed and is returning
an alarm. In Multidestinational circuits this may not
correspond to the Tx path of this modem. The fault may
be due to any receive downstream equipment, but could
be due to the relevant modem Tx output failing. Check
the relevant modem Tx path indicates OK. Check the Tx
IF output from the modem is connected to the
upconverter equipment and onwards and monitor the Tx
carrier (or distant Rx if possible) with a spectrum
analyser.
D
Rx warning: Backward
alarm at Insert MUX,
indicating equipment
downstream of Rx has
failed.
This will only be displayed if the modem if fitted with an
interface that provides four ports for separate input and
output of separate Tx/Drop and Rx/Insert PCM bearers. It
indicates a backward alarm has been detected at the Rx
bearer input. This indicates that equipment downstream
of the receive path has failed and is returning an alarm.
This may be due to any receive downstream equipment,
but could be due to the modem Rx output failing. Check
the modem Rx path indicates OK and that the Rx data
output from the modem is connected to the downstream
equipment.
D
Rx warning: The final BER
is worse than the user
threshold set for the
deferred alarm.
This indicates that the received signal has degraded
resulting in a potentially unacceptable number of errors.
D
Rx warning: Rx FIFO
underflow on ports (1 to 4).
Quad E1 card Rx problem.
Rx warning: Rx FIFO
overflow on ports (1 to 4).
Quad E1 card Rx problem.
Rx warning: Wanted Rx
input power out of range.
Indicates that the wanted signal is very low or very high.
Rx warning: Composite Rx
input power out of range.
Indicates very high level of composite power.
Rx warning: Composite to
wanted power level ratio
>37dBc.
Indicates very high level of composite-to-wanted power.
Rx warning: LinkGuard
interfererence over
threshold.
A source of interference has been detected underneath
the receive carrier that exceeds the alarm threshold set
by the user. This may be degrading the received signal
and should be investigated and reported to the satellite
operator.
Rx warning: Rx failed
LDPC/BCH decoding.
The receiver was unable to decode the demodulated
LDPC carrier successfully. This indicates either that the
satellite data has become corrupted or that there is a
configuration incompatibility between the encoder and
decoder.
