Octavian CRISTEA, Paul DOLEA, Paul Vlăduţ DASCĂL
70 TELECOMUNICAŢII ● Anul LII, nr. 2/2009
Fig. 3.3. Ground station antenna. Fig. 3.4. Ground station command and control equipment.
In order to improve its overall performances, the
ground station has been installed in a test bed at
1200 m altitude, in a quiet electromagnetic rural area,
which is 55 km far from Cluj-Napoca, in the Apuseni
Mountains. The exact coordinates of the antenna
ground station are 46°40’34” N latitude and
23°07’45”E longitude. The ground station is located
in a small valley. It is why West and South-West
facing elevations from the ground antenna are
blocked below approximately 15º by foothills.
Until today, two types of tests have been com-
pleted with good results. The first one was to estimate
the antenna automatic pointing error, using several
known geostationary C band transponders.
The second one was to track and receive data
from the 2400 MHz AO-51 nanosatellite FM trans-
ponder [12] in order to measure the signal strength
(for this experiment the MHX-2400 modem has been
replaced with an UEK-3000 down-converter [13] and
an Icom IC-910H radio [14]).
The main results are that the antenna pointing
error is within ± 0.5
0
and that a LEO 2W FM trans-
ponder can be received from more than 2000 km
distance.
Direct earth to space communication tests using
the MHX-2400 modem could not be performed until
today, since actually there is no operational satellite
on orbit equipped with this modem. It is why several
long range terrestrial communication tests have
been planned for the next few months.
4. Conclusions
As far as it will be demonstrated in a real space
mission, this low-cost S-band ground station will pro-
vide higher speed communications with nanosatellites
than those obtained using UHF communications.
Consequently, a larger range of science objectives can
be achieved using a nanosatellite platform.
Another important feature of this ground station is
that can support any nano/micro LEO satellite mission
with minor upgrades (such as the antenna feed horn
and preamplifier or the radio unit which has to match
that one of the satellite).
This S-band ground station prototype is an
important step towards a new class of low-cost high
frequency ground stations planned at BITNET CCSS
in support of future Romanian nanosatellite missions
in low-earth orbit.
(20 paginas)
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