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Fig. 5
Operation and maintenance system AOM101
— Data link
OMT Operation and maintenance terminal
OMST Operation and maintenance sub-terminal
minals are handled by the exchange
itself
-equipment external to AXE 10, installed
together with and connected
to AXE 10 units. In this case alarms
from, for example, line terminals can
be handled by and presented in
AXE 10 with the aid of its interface for
receiving external alarms. Alternatively
such alarms can be collected
by the alarm concentration equipment
in the transmission maintenance
systems ZAN 101 and ZAN 201
-equipment external to AXE 10, installed
together with but not connected
to AXE 10 units
- equipment external to AXE 10, neither
installed with nor connected to
AXE 10 units. In such cases alarms
from transmission terminals and results
from quality measurements on
regenerators can be collected by
ZAN 101 or ZAN 201.
Maintenance systems for
digital transmission
equipment
AXE 10
The extensive and sophisticated operation
and maintenance functions of
AXE 10 have been described in a previous
article 3 . Only the functions that
concern the maintenance of digital
transmission systems will therefore be
described here. They include
- termination of digital links in exchange
terminals
- interfaces for collection of external
alarms
- man-machine interfaces for alarm
presentation and operator communication.
The incoming bit streams from digital
line systems are monitored by the exchange
terminals ET in accordance with
the relevant CCITT recommendations.
For maintenance alarms a choice can be
made as to alarm class, i.e. the degree of
urgency of theactions required. There is
also a choice as regards the threshold
level for the bit error rate. Faults of short
duration are considered as disturbances
and are recorded foreach digital
link. The slip rate is also monitored, and
an alarm is given when a preset value is
exceeded.
The values of the transmission parameters
can be read out by means of commands,
and are presented as the number
of disturbances per hour, number of
slips per hour and the current bit error
rate. It is also possible to test the fault
detection functions of the exchange terminal.
The AXE 10 system provides an interface
for receiving alarm information from external
equipment, for example power,
cooling and transmission equipment.
Alarms received via the interface are included
in the exchange alarm system,
and all facilities for the presentation and
routing of alarms will thus also be available
to alarms from external equipment.
Typewriters or visual display units are
used at the man-machine interface towards
AXE 10 for all operation and maintenance
activities, including fault locating
on digital transmission systems. The
following transmission maintenance
functions can be performed via this interface:
- presentation of alarms from the exchange
terminals
- presentation of collected external
alarms
- fault location by means of commands.
The man-machine interface can be remotely
connected by means of modems
e.g. to the network operation and maintenance
system AOM 101. It is also possible
to connect a portable typewriter
terminal temporarily to the remote subscriber
stage. Such a terminal would primarily
be used for functional verification
on site after repairs.
Operation and maintenance
system AOM 101
AOM 101 provides centralized operation
and maintenance of complete telecommunication
networks.