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Text on Display Description / Cause / Notes
Relays To Terr To Sat Other
P300H P300 Series Installation and Operating Handbook Page 227
Rx Warn: DISTANT Eb/No below threshold The DISTANT modems Receive Eb/No (ie this local modems TX CARRIER) is worse than the user D
threshold set for a deferred alarm (Change, User-Opt, Thresholds, Distant Eb/No). This may be
used as an advance warning of service degradation. This function is only available if AUPC is active,
where the local modem continuously reads the distant modems Eb/No.
Rx Warn: Turbo Decoder status This is a warning used in the engineeering debuging process it should not occur in the field. If it
does, please consult the factory.
Actions: Relays
U = Prompt Unit Fault relay. [Equivalent to SMS/IBS/IDR AE/AS1/AS1]
T = Prompt Traffic Fault relay. [Equivalent to SMS/IBS/IDR AE/AS1/AS1]
D = Deferred Alarm relay. [Equivalent to SMS/IBS/IDR none/AS2/AS2]
Actions: To Terrestrial
TA = AIS (all ones) in selected TS if the Insert mux is active, AIS over all data if not in Insert mode. If Insert mode is active and the user control “Thin Route Spoof” (Change, User opt, Operation, Terr/Sat,
Thin Route Spoof) is set to “On”, then AIS is forced over the whole PCM bearer, not just the selected timeslots to “spoof” full bearer connectivity when passed over a “Thin Route” satellite circuit (ie
not the whole bearer data rate). [Equivalent to SMS/IBS/IDR AH1&AH3/AH1/AH1]
TB = Frame Backward Alarm (in PCM Multiplex, eg G.732 TS0-NFAS bit 3). [Equivalent to SMS/IBS/IDR AH2/AH2/none]
TC = AIS (all ones) forced in the G.732 CAS `abcd` signalling nibble. Equivalent to SMS/IBS/IDR AH4/AH3/none]
TD = Force a fixed value in the G.732 CAS `abcd` signalling nibble. The fixed value is set by user control (Change, User Opt, Operation, Actions, Back’ Alarm) to be either No-Action, b=1, a=b=1, a=b=c=d=1.
[Equivalent to SMS/IBS/IDR AH5/none/none]
TE = Multiframe Backward Alarm (in PCM Multiplex, eg G.732 TS16 frame 0 of multiframe = 0000 11
11). [Equivalent to SMS/IBS/IDR AH6/none/none]
Actions: To Satellite
SA = AIS (all ones), framed and scrambled ad subject to RS coding if active. [Equivalent to SMS/IBS/IDR AK1/AD1/AD1]
SB = Frame Backward Alarm (in IBS/SMS this is direct, in IDR or when multiple backward alarms are active it corresponds to the “Rx Summary Fault Output” which is externally patched back into the
Backward Alarm inputs). [Equivalent to SMS/IBS/IDR AK2/AD2/AD2]
SC = AIS in CAS signalling carried in IBS/SMS TS16/TS48 over satellite. [Equivalent to SMS/IBS/IDR AK3/AD3/none]
SD = Multiframe Backward Alarm in IBS/SMS TS16/TS48 over satellite (TS16 frame 0 of CAS multiframe = 0000 11
11). [Equivalent to SMS/IBS/IDR none/none/none]
Actions: Other
BM= BUC Mutes (not a modem function)
CM = Carrier Mute, Tx carrier is switched off
TF = Tx Flow control, the `CTS` (Clear To Send) line is switched off
RF = Rx Flow control, the `RR` (Receiver Ready) line is switched off
Notes
1: In response to a CAS multiframe sync loss from the terrestrial port, the appropriate alarm to raise would appear to be the CAS-MF backward alarm. However as the bearer is normally looped there
is no point in raising this alarm as a CAS multiframe is required to convey it (ie the presence of the fault prevents the return alarm being sent). There are only two circumstance where the return bearer
is not dependent upon the bearer into the Insert Mux, either when the Insert Mux is generating the bearer, or when the Rx path is receiving an independent 2M stream which contain a CAS multiframe.
In these two circumstances the CAS-MF backward alarm is sent (TE), in all other circumstance the TS0 backward alarm is sent (TB).