TELE-X - a Satellite System for TV and Data Communication ...

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All interactive work with the input of
commandstakes place viathe visual display
terminal. The commands have been
designed on the basis of the CCITT Man
Machine Language (MML).
The MML command structure is frequently
used in telecommunications,
where it has proved very suitable because
of its systematic construction.
One of the main advantages of MML is
that the same language can be used in
all subsystems in large integrated systems.
Auxiliary equipment
External equipment can be connected
via connector panels (patch units) when
more extensive measurements or tests
are required over long periods, for example
for measuring the signal quality.
The equipment, which is connected in at
the terminal and line interface, includes
switched functions for monitoring the
traffic in progress and for cutting off the
connection, for example when generating
a test pattern.
Most measurement and test equipment
in the market can be connected to the
patch units.
Modular design
During the development of EDNET great
importance was attached to the modular
structure of the system. The same prin-
ciples were used as for the design of the
AXE 10 telephone system and all similar
design work within Ericsson.
The system is built up of modules consisting
of either software or hardware.
The modules have well defined interfaces.
The system is extended or equipped
with new functions by adding new
modules or exchanging existing modules
for others with new functions. This
facilitates maintenance and enables the
system to be kept up to date for a very
long time.
The modular structure makes it easier
for staff without programming knowledge
to understand the system. This furthers
the possibility of quickly reaching
a good agreement between requirements
and functions, which is particularly
important for the administration
and maintenance of the system.
ASK 101 makes it possible to duplicate
the computer and storage modules,
which means that the system is able to
function even if a fault occurs in such a
module.
Capacity
The basic version of EDNET is suitable
for the supervision of networks of greatly
varying sizes, from small ones with
few devices up to extensive networks
with up to 700 devices. Extension mod-
Fig. 3
In a packet switching network built up with
ERIPAX the modem supervision and traffic supervision
in the nodes are combined in the network
management centre, NMC, of the system. The
diagnostic channels to terminals are designed as
secondary channels, otherwise as virtual connections
in the network
NMC
NN
DTE
Ma
Network management centre with operators
Network node (packet switch)
Data terminal equipment
Modem and diagnostic unit
^ — « —
Diagnostic channel
M , _• • Diagnostic channel, on a secondary channel
Diagnostic channel, on a virtual connection In
" the packet switching network
— — — Data channel, link