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

9
Fig. 7
Mixer and preamplifier
The dimensions of high-frequency electronic
equipment are small. The low noise mixer with a
noise factor of 6 dB at 18 GHz is 100 mm long.
This mixer, like the oscillators and receivers that
have been developed by Ericsson Radio Systems,
is included in several different equipments on
board, for example, TELE-X, TV-SAT, TDF-1 and
the British UNISAT
The equipment and units in the transponder
receive and transmit chains
have mostly been space qualified in
other satellite projects (in those already
mentioned and also the French TELE­
COM project). The modifications that
have been made at this level are, for example,
frequency changes, which do
not affect the space qualification status.
The quantity of equipment is similar to
that of TV-SAT and TDF-1 For example,
the number of final amplifiers (travelling
wave tube type) is the same. The transponder
parts with the associated structure
have therefore been made so similar
as regards mechanical and thermal
properties that the overall construction
can be verified by means of calculations.
As regards the antenna reflectors the
same technology is used in all projects.
However, the electrical design of the
transponder and the whole antenna system
are new. The following development
models are therefore being manufactured
in order to be able to verify the
design before manufacture of the flight
hardware is started:
- a model of the transponders for testing
the electrical function and verification
of the performance
- a structural model of the antenna system
and tower for environmental test-
ing, mainly testing of its ability to withstand
the vibrations of the launch
- an electrical model of the antenna
system for measuring the antenna
pattern.
The final testing will take place in connection
with the integration of the whole
satellite. The purpose of the development
program is to ensure that this test
will only be a verification of the performance
before the satellite is sent to
Kourou in South America for launching.
Conclusion
The Nordic coverage of the television
service provided by TELE-X makes it a
factor to be considered in cultural policy.
Technically it is wholly in line with
the current international trend. On the
other hand the choice of system for the
data and video services is singular and is
motivated by the desire for a system with
small, cheap earth stations placed on
the subscribers' premises.
TELE-X is a first step towards a Nordic
satellite communication system which,
if the market development is favourable,
can lead to a general use of satellite terminals
for data an video in the Nordic
countries by the end of the 1980s.
References
1, Wolf, A.-W.: TELE-X-A Nordic Telecommunications
Satellite. TELE, English
edition, Vol. XXXV, No. 1, 1983.