P300H
P300 Series Installation and Operating Handbook
Page 214
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 1111). [Equivalent to SMS/IBS/IDR none/none/none]
Actions: Other
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).
2:
Normally, an incoming TS16 Multiframe backward alarm causes the modem to transmit a Satellite Frame Backward Alarm (SB) to be sent. However if the user control “Thin Route Spoof” (Change,
User opt, Operation, Terr/Sat, Thin Route Spoof) is set to “On” to “spoof” full bearer connectivity when passed over a “Thin Route” satellite circuit (ie not the whole bearer data rate), then an incoming
TS16 Multiframe backward alarm causes the modem to transmit a Satellite Multiframe Backward Alarm (SD, instead of SB) to keep the Frame and Multiframe backward alarm functions separate.
3:
Line code setting: For P1431/32 cards check the switch on the card itself. For P1440/41/42 cards which are configured from the front panel check with Change, Terr-Int, Electrical, then reselect
G.703 which is followed by the line code configuration.
4:
All ones (the Alarm Indication Signal, AIS) is a means of signalling to downstream equipment that the data being sent is not valid. It is advised to leave AIS detection enabled so the modem can
inform you when there is a fault with the traffic. If necessary (eg if the data itself contains long strings one ones) you can disable the detection of AIS and resulting actions using Change, User-Opt,
Operation, Actions, AIS.
5:
Check if this line is connected in the cable and supported by the connected device. If the line is floating (no cable/not supported) then it might `float` to the off state and intermittently raise this alarm.
6:
The modem generates a temporary backup bearer for the Insert mux when set to “Loopthrough” only if there is no bearer available. Should the operator assume the modem is set to “Generate”
not “Loopthrough”, and feed the Rx bearer output back to the Tx bearer input (including via other equipment), then it will oscillate. Temporarily generating a backup bearer when there is no bearer
incoming, then as this temporary bearer is detected at the Tx input when fed back to the modem, it will switch off this temporary bearer and return to “Loopthrough” mode whereupon as there is
now no source for the bearer (it’s a compete loop), it will fail again and switch back temporarily to generating a backup bearer. If you see the modem displaying a bearer status switching between
“Rx Fault: Ins mux bearer frame sync lost”, “Rx Fault: Insert bearer AIS, generating”, and / or “Rx Fault: No insert bearer, generating”, then check that the bearer is not set to “Loopthrough” AND
at the same time looped back to the modem Tx input, even if via other equipment.
7:
If the user control “Thin Route Spoof” (Change, User opt, Operation, Terr/Sat, Thin Route Spoof) is set to “On” to “spoof” full bearer connectivity when passed over a “Thin Route” satellite circuit
(ie not the whole bearer data rate), then a CAS backward alarm incoming on the Rx Input is passed to the terrestrial as a terrestrial Multiframe backward Alarm (SD). If “Thin Route Spoof” is not
active, the warning is still displayed but no actions are taken (ie SD is not generated).
