User Manual

AS4000 Operations and Maintenance
Section
605-0000-431
3
. Issue 1.6. Date3/2/99
Page 6 of 22 © Copyright Airspan Communications Corporation 1999
2.1.2. Loss of 2Mbit/s Signal
Message: ‘Tributary Unit:2MBS Lost’
As a result of a loss of a 2Mbit/s input the following messages
may appear.,
‘System Clock Fail’, ‘Frame Alignment Lost’, ‘AIS’.
Source: TU, 2Mbit/s connection to the CT modem shelf.
Fault Condition: AS4000 has to use its internal clock and all calls will be dropped.
Likely Cause: a. Wrong Tx/Rx connection.
b. Broken / Faulty 2Mbit/s cable.
Consequential Effect: a. All active calls will be dropped.
b. Call in progress LEDs on the CT modem card will be off
irrespective of the call state.
c. Due to the loss of network clock, there may be a single burst of
poor BER messages from the CT Modems when the system
changes over to the internal clock source.
Repair Actions:
Check connection from exchange to AS4000 shelf interface.
The 2Mbit/s OUT and IN connect to SK 15 & 16 respectively on
the modem shelf backplane
Sitespan/EM
Front Panel Alarms
DC Input
PL6
2Mbit/s IN
2Mbit/s OUT
2 Wire
Port
PL7
PL8
Baseband
Alarm
Combiner
JP6
JP7
JP1
JP2
JP5
SK16
SK15
J2
PL5
PL4
JP4
JP3
PL1
If the fault is in the exchange or transmission network then the fault should be reported as
external to the AS4000 system.