Paradise Datacom P300 Series Installation & Operating Handbook page 228

Rx Warn: Back' alm 1234 from satellite
Rx Warn: O/p clk fail=<source>, now PLL
Rx Warn: No clk ref=<source> , now int'
Rx Warn: Back' alm received at ins' mux
Rx Warn: MF Back' alm Rx'd at ins' mux
Rx Warn: X.50 Back' alm from satellite
Rx Warn: RF sig too low, now <-71dbm>
Rx Warn: RF Sig too high, now <-19dBm>
P300H P300 Series Modem Installation and Operating Handbook
catastrophic failure (and the correspondingly more significant backward Alarm above). The Modem
only detects this alarm when the Rx baseband is set to use the Insert mux in a G.732 mode and CAS
signalling has been selected (or 2048k IBS G.732 0% overhead mode with CAS is enabled). Read
the text corresponding to Rx Fault: CAS Multiframe sync los to determine why a CAS multiframe is
in use over satellite and Check the three items listed against this message on the Tx path of this
modem.
The display may show numbers or dashes (eg -2-4") corresponding to 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, monitor the Tx carrier (or distant Rx if
possible) with a spectrum analyser.
The clock selected as the Receive data output clock, (where <Source> shows the specified clock)
has failed. The modem has switched to using a backup clock generated by the Rx PLL to preserve
the receive traffic. This fault only occurs if the <source> is the same frequency as the Rx data rate,
otherwise the clock is not used directly instead it is rate converted by the Rx PLL, and it s failure
results in the fault described immediately below instead. Refer also to the description of the dialogue
under (Change, Rx, Buff/Clk, Rx Clock) to determine which signal the PLL uses as a backup clock.
The reference specified for the PLL, which generates the Rx output clock (or backup Rx clock) has
failed; the modem has switched to using the internal 1PPM reference to keep the clock available.
Check the clock <source> specified is present. If a station clock is specified as available the modem
will use this as the <source> to generate the backup Rx output clock even if Station not specified
as the primary source on the Rx Clock Mode screens. Check that the Station clock is still connected
as it is a common mistake to change the Rx Clock Mode to something other than Station , then
disconnect the station clock assuming the modem will not use it, whereas the modem will always use
it in preference to the internal 1PPM clock if it is has been told a station clock is available. (Change,
Rx, Clock/Buff, Station Clock Input).
This fault will only be displayed if the modem if fitted with an interface which provides four ports for
separate input and output of separate Tx/Drop and Rx/Insert PCM bearers. It indicates a Backward
Alarm is 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, Check
the Rx data output from the modem is connected to the downstream equipment.
This fault will only be displayed if the modem if fitted with an interface, which provides four ports for
separate input and output of separate Tx/Drop and Rx/Insert PCM bearers. It indicates a Multiframe
Backward Alarm is detected at the Rx bearer Input, this indicates that equipment downstream of the
RECEIVE path has failed to find Multiframe sync and is returning an alarm. The Modem only detects
this alarm when the Rx baseband is set to use the Insert mux in a G.732 mode and CAS signalling
has been selected. On the Rx path, if the Insert Mux bearer is set to Generate, then check the Rx
path is also utilising CAS, otherwise it will generate a bearer without a TS16 Multiframe.
This indicates the distant end equipment has an X.50 fault and is returning an X.50 backward alarm.
See the description for the message Rx Fault: X.50 de-stuff sync lost for a further description.
The Receive RF signal level is below the range specified for this equipment. Increase the level to
ensure specified performance is met.
The Receive RF signal level is above the range specified for this equipment. Decrease the level to
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