Colour Display System SEMIGRAF 240 - The history of Ericsson

Fig. 6
Excerpts from the operational manual concerning
the connection of a subscriber
The operator usually goes direct to Item 4, I.e. to the ECB,
since items 1-3 have usually been carried out beforehand
and it is only necessary to check this
Connection of a subscriber
connection
Extent
Connection of a subscriber- both as regards
hardware and software.
References
- Operational instructions for work in the MDF
(Main Distribution Frame)
- Command description for SUSNO
— Operational instructions for testing a line
— Operational instructions for reporting
Execution
Action Comments
1. Run the MDF wires See the operational instructions
for work in
the MDF
2. Insert a line adaption
board if required
3. Install the teleprinter
4. Connect in the line See the command dewith
a command scription for SUSNO
(ECB)
5. Test the line (ECB) See the operational instructions
for testing a
line
6. Report See the operational instructions
for reporting
Command description for
SUSNO
Example of a command for activating a subscriber
line
1. SUSNO: SNB=33329, DEV=LIC-3-145;
EXECUTED
SUSNO=Subscriber Number Open
SNB=33329 gives the subscriber number
DEV=LIC-3-145 gives the multiple position
The command specifies that subscriber line
number 33329 with multiple position 145 in
row section 3 is to be activated.
EXECUTED is written as an acknowledgement
that the command has been carried out.
2. SUSNO: SNB = 33329, 0EV=LIC-1-172;
NOT ACCEPTED
FAULT CODE 3
This command cannot be carried out. Fault
code 3 indicates that the subscriber line is already
activated.
The list below gives some of the checks that
are carried out by the system when the command
is executed:
- Check that the command exists
- Check that the records (SNB, DEV) exist
- Check that the punctuation marks in the
command have been used as specified
- Check that the subscriber number belongs
to a number series that is connected in the
exchange
- Check that the subscriber number is vacant
- Check that the stated multiple number belongs
to a row section that has been installed
- Check that the stated multiple number is
vacant
Maintenance
The stringent operational requirements
for the telex network and the high labour
costs for maintenance emphasize the
need for reducing the manual operation
and maintenance measures by increasing
the efficiency and by automatization.
This applies not only for the exchange
equipment but also for other
parts of the telex network, such as subscriber
equipment, trunk and local lines
etc.
In system AXB20 the maintenance functions
are to a great extent automatized
and integrated in the normal operation
of the system. The basic principle is that
the system should be self-monitoring as
far as possible, so that the need for
preventive maintenance and manual
supervision is reduced to a minimum.
The function-oriented command language,
in combination with rational
training along the lines recommended
by the manufacturer etc., enable the
personnel to learn quickly how to handle
an AXB 20 exchange correctly and
efficiently.
When a break or disturbance occurs it is
normally the system itself that detects it,
carries out automatic fault localization,
isolates the fault (blocks the faulty unit)
and informs the operator (gives an alarm
printout). When the fault disappears the
unit is deblocked and the operator is informed.
Regeneration
The system is regenerative, which
means that the exchange sends out the
characters completely undistorted even
if they are received severely (up to 46 %)
distorted. This is of great importance in
the case of the international and intercontinental
traffic with its long lines
of varying quality, but above all it means
that the requirements for the characteristics
of the subscriber lines and the
transmission qualities of the subscriber
sets can be made far less stringent than
in non-regenerative systems.
Distortion supervision
AXB 20 is equipped with automatic distortion
supervision which checks the
degree of distortion on the handled traffic.
This means that all the lines con-
109
Fig. 7
This example shows a disturbance supervision
alarm, the initiation of disturbance recording and
the resultant printout
Alarm printout
ALARM B/APT
DISTURBANCE SUPERVISION ROT = 8
END
A disturbance supervision alarm is obtained
from route 8.
Command
SVDRI:ROT = 8, OUT=SIN;
EXECUTED
The command SVDRI initiates disturbance recording
on route 8, with immediate printout of
every disturbance.
Printout from the disturbance recording
DISTURBANCE ROT=8 DEV=LIC-000-013
TIME=1116 RCODE = 4
On route 8 there was a disturbance on the line
in position 13 in row section 0 at 1116 hours. A
clear-confirmation signal had not been received
(RCODE=4).
The different disturbance codes are explained
in a printout description, from which the following
has been taken:
RCODE Cause
0 No call acknowledgement
1 No proceed-to-select signal
2 No through-connection signal
3 No answer back
4 No clear-confirmation signal
nected to the exchange are supervised
entirely automatically.
If the distortion becomes too high on a
line an alarm printout, specifying the
line, is given on a typewriter. The
typewriter need not be placed in the exchange
control room, it can for example
be installed in a separate operation and
maintenance centre. The distortion limit
that gives rise to an alarm printout can
easily be changed by means of a command.
Disturbance supervision
Disturbance supervision means that
circuits are supervised as regards various
types of disturbances, for example
missing signals in the signalling sequences.
This function gives rise to an
alarm when the ratio between the
number of disturbances and the number
of calls exceeds a certain preset value.
The alarm printout specifies the number
of the route. The alarm limit can be varied
from route to route and can easily be
changed by means of a command,
whereby the exact degree of supervision
required can be obtained.