Paradise Datacom P300-VSAT Installation & Operating Handbook page 205

Text on Display
Tx Fault: Frame sync lost on Tx input
Tx Fault: TS16 MF sync lost on Tx input
Tx Fault: CRC sync lost on Tx input
Tx Fault: Dropped data is all ones (AIS)
Tx Fault: Input BER > 1E-3, [AIS forced]
Tx Fault: Clock loop fail, Tx muted
P300H
Description / Cause / Notes
The modem only detects frame sync when the Drop mux is active (or 2048k IBS G.732 0%
overhead mode is enabled). Check the bearer type is specified correctly (Change, Tx, Baseband,
Drop). This normally only occurs if either there are significant errors on the terrestrial link, or if it is
supplied with AIS and the modem is set to ignore AIS. Check that the AIS detector is not disabled
with Change, User-Opt, Operation, Actions, AIS. ALSO there is an option to make the modem re-
seek frame sync if CRC sync is lost (Change, User-Opt, Operation, Terrestrial, PCM Bearer CRC,
CRC/Frame Acq'). Check the modem is not set to expect a CRC and forcing frame re-acquisition if
CRC is lost, but there is no CRC on the PCM signal.
The modem only seeks TS16 Multiframe sync when the Tx baseband is set to use the Drop mux in
a G.732 mode and CAS signalling has been selected (or 2048k IBS G.732 0% overhead mode with
CAS is enabled). Check that a CAS multiframe is present on the PCM signal applied to the modem
(ie terrestrial TS16 contains the 16 frame multiframe sequence).
The modem only seeks Cyclic Redundancy Code (CRC) sync when the Tx baseband is set to use
the Drop mux in G.732 mode (or 2048k IBS G.732 0% overhead mode) and when set by the user
to process CRC's (Change, User-Opt, Operation, Terrestrial, PCM Bearer CRC, Process). If CRC
sync is permanently lost, check if a CRC is present on the PCM signal.
The specific timeslots dropped by the Drop Mux contain all ones (AIS). This is different to the "Tx
Fault: Data input is all ones (AIS)" message described earlier which refers to the whole PCM
bearer being AIS. In the case it is only the specific timeslots which contain AIS. This is normally
used to indicate an upstream equipment fault, it is not a modem fault. See note 4
The Bit Error Rate at the Tx input (measured on the PCM Frame Alignment Words) is worse than
-3
1x10 . This can only be due to a very poor error rate on the PCM input signal. "[AIS Forced]" is
only shown if the user option of what action to take when the BER is bad is not set to Ignore
(Change, User-Opt, Operation, Actions, BER Action). The fault is always displayed, although the
actions can be cancelled by selecting Ignore. Check the line code setting (AMI/B8ZS/HDB3)
matches the input signal on any G.703 cards in use (see note 3).
The Tx clock generation loop, which generates the timing over the satellite link has failed and the
Tx carrier is muted as a result. If the Tx Clocking (Change, Tx, Clocking) is set to "Tx Clock In",
then check the Tx Clock frequency matches the data rate (Change, Tx, Baseband, Continuous).
P300 Series Installation and Operating Handbook
Relays To Terr To Sat Other
T TB SA,SC
T (TB/TE) SC
Note 1
T
T TB SA
Opt Opt Opt
T TB SA
Opt Opt
T CM ! CM, TF
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