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Text on Display Description / Cause / Notes
Relays To Terr To Sat Other
P300H P300 Series Installation and Operating Handbook Page 223
Rx Fault: <line> off, DCE not accp't Rx data <line> depends on the interface in use and is only available if the modem is fitted with a DTE T
interface card (eg RS422 DTE=”CS”, V.35=”CTS”). This is a handshake line which is raised in
response to our RS/RTS line (if the modem interface is a DTE) which in turn indicates the output
data is valid (ie demod locked and FEC/deframing OK). It’s status can be used to determine if the
terrestrial device is accepting the modems output data. The <line> switching off may be user set to
cause this fault or be ignored (Change, Terr-Int, Control Lines). See note 5
Opt
Rx Fault: No insert bearer, generating If the Rx Baseband is set to Insert Mux, with the bearer Looped through from the Drop Mux (dialogue T
under Change, Rx, Baseband, Insert) then if the Tx input signal fails (no bearer or AIS) then this
looped bearer onto which the Rx traffic is to be inserted is not available and the Rx data would
therefore be lost as a result of a Tx fault. In such a circumstance the modem temporarily generates a
PCM bearer onto which the Rx data can be inserted to preserve the Rx traffic. See notes 6 & 9
Rx Fault: Insert bearer AIS, generating See above, see notes 6 & 9. T
Rx Fault: Ins mux bearer frame sync lost The modem only detects frame sync when the Insert Mux is active. Check the bearer type is T
specified correctly (Change, Rx, Baseband, Insert). 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. See notes 6 & 9
Rx Fault: Ins mux bearer MF sync lost The modem only seeks TS16 Multiframe sync when the Rx baseband is set to use the Insert mux in T
a G.732 mode and CAS signalling has been selected. Check that a CAS multiframe is present on
the PCM signal applied to the modem (ie terrestrial TS16 contains the 16 frame Multiframe
sequence). See note 9.
Rx Fault: Ins mux bearer CRC sync lost The modem only seeks Cyclic Redundancy Code (CRC) sync when the Rx baseband is set to use T
the Insert mux in G.732 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.
Rx Fault: Clk PLL lock fail to <source> The PLL which generates the Rx output clock (or backup Rx clock) has failed to lock to the specified T TA,TC RF
reference. Check the reference specified as <source> is the correct frequency. If a station clock is
specified as available the modem will use this 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 to generate the backup clock 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).