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Text on Display Description / Cause / Notes
Relays To Terr To Sat Other
P300H P300 Series Installation and Operating Handbook Page 222
Rx Fault: CAS Multiframe sync lost The modem cannot find the IBS CAS Multiframe sync on the receive data although it has found T TA,TC SB RF
Frame sync and TS32 Multiframe sync (otherwise the Frame/Multiframe sync messages above
would display). CAS Multiframe sync used to convey either
1) Channel Associated Signalling (CAS) in G.732 Drop/Insert modes using CAS,
2) To maintain the identity of a group of timeslots (for the `Odd values of N` such as N=7 etc).
3) To maintain Robbed Bit Signalling (RBS) in selected in T1-D4 or T1-ESC Drop/Insert modes.
Be aware that most competing modems do not support the use of a CAS Multiframe to provide any of
these three functions.
Check as follows for each use:
1) The Tx modem is set to operate in CAS mode if CAS signalling is to be conveyed within the
IBS/SMS overhead (one of the questions in the Change, Tx, Baseband, Drop menu dialogue)
2) If the Tx modem cannot use a CAS Multiframe to maintain the TS identity for the `Odd values of
N`, then to prevent this modem seeking a CAS multiframe for one of these `Odd value of N`, in the
Change, Rx, Baseband, Insert menu dialogue, when prompted “TS identity over satellite: [?]
1=Maintain (normal) 2=Don't care”, select “Don’t Care”
3) If the Tx modem cannot use a CAS Multiframe to maintain RBS over satellite, in the Change, Rx,
Baseband, Insert menu dialogue, when prompted “T1 RBS over satellite: [?] 1=Normal (or no RBS)
2=Maintain RBS”, select “Normal (or no RBS)”.
Rx Fault: Final data is all ones (AIS) The final customer data after demodulation, error correction, deframing and descrambling is all ones. T TA SB
This is normally used to indicate an upstream equipment fault (such as a lack of input clock at the Tx
end), it is not a modem fault. See note 4.
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Rx Fault: X.50 de-stuff sync lost In IBS modes at 48kbps or 56kbps the IBS specification (IESS 309) specifies that the 48/56kbps T TA SB
data is `bit stuffed` up to 64kbps according to X.50 prior to IBS framing. The bit stuffing adds an 80
bit repeating pattern which is detected at the Rx end then removed to return the data to 48/56kbps.
This message indicates the modem cannot find the 80 bit pattern in order to remove it. Check the
data is intended to be 48/56kbps X.50 stuffed to 64kbps, not raw 64kbps data. Refer also to the
Change, User, Operation, Terr/Sat, X.50 AIS dialogue description for a discussion about AIS in X.50
modes.
Rx Fault: Final BER > 1E-3 [,AIS Forced] The User (final) Bit Error Rate is worse than 1x10 . “[AIS Forced]” is only shown if the user option of T TA , SB
-3
what action to take when the BER is bad is not set to Ignore (Change, User-Opt, Operation, Actions, TC
BER Action). The fault is always displayed, although the actions can be cancelled by selecting
Ignore. The source for the BER measurement is user defined (Change, User-Opt, Operation,
Satellite, BER est’). Normally this should be set to “Auto”, however it may be user set to other BER
sources if required. It is possible to manually set the source to the inner FEC (Turbo/Vit/Seq), even
when the outer FEC (RS) is active, thereby not including the effects of the RS error correction in the
displayed user BER. Check this remains set to “Auto” unless there is good reason.
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Rx Fault: <line> off, <DTE/DCE> not ready <line> depends on the interface in use (eg RS422 DCE=”TR”, V.35=”DTR”). This is a DC control T
line which is used to indicate the terrestrial equipment is functioning properly. The <line> switching
off may be user set to cause this fault or be ignored (Change, Terr-Int, Control Lines). See note 5.
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