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AMSAT-UK ANNOUNCE NEW SATELLITE TRANSPONDER PROJECT



AMSAT-UK is delighted to be able to announce its participation in the SSETI 
ESEO satellite project.

ESEO – The European Student Earth Orbiter is a satellite planned for launch 
in late 2008 into a Geo-stationary transfer orbit similar to the initial 
orbit of AO40 and to those planned for Eagle and P3E.

In December 2005 two AMSAT-UK members were invited to attend a SSETI 
Workshop at the European Space Agencies ESTEC facility in the Netherlands.
This workshop, which lasted a week, had over eighty students in attendance 
from more than twenty universities around Europe.

The involvement of the AMSAT-UK team with the project was confirmed at the 
Workshop and the team were elected as “Honorary Members “ of the SSETI 
Association in appreciation of their work supporting the previous SSETI 
Express project.

The prime communications system for ESEO is being developed by the 
University of Wroclaw in Poland and will operate on “commercial” S-Band 
space frequencies. It will provide all the usual telecommand and telemetry 
facilities and use standard ESA CCSDS packet communication techniques.

ESEO also has a need for a redundant communications system – one that can 
operate in the event of a primary system failure but can and also function 
satisfactorily if/when the spacecraft is not in its intended earth-pointing 
mode. This is where AMSAT are planning to assist.

The current project calls for a unit that can receive telecommands from 
earth on UHF (435MHz), transfer those to the OBC via a CAN bus. 
Additionally, it must transmit telemetry and mission data to the ground on 
S-BAND (2.4GHz). We are planning to use omni-directional antenna systems so 
the data rate will necessarily be quite low although output power will be 
approx 9 watts.

When in orbit, it is likely that the student experiments will be completed 
within a few weeks/months from launch after which time it will become 
available as a linear U/S mode transponder.

The ESEO spacecraft will have a rectangular structure and a mass of 120kg. 
The solar panels will be deployable and steerable while the propulsion 
system will use Nitrogen gas.  The 50kHz wide mode U/S transponder will be 
switchable from a conventional linear design to a fully digital design based 
on DSP techniques using the G6LVB STELLA firmware. Two UHF canted monopoles 
on opposite ends of the spacecraft will be used to receive signals on U 
band. The S Band output of 9 Watts will feed two turnstiles or quadrilifar 
helixes. As well as the transponder, the unit will also provide 400 bps BPSK 
telemetry in AO40 format.

Obviously we cannot expect the transponded signals on the ground to be as 
strong as we enjoyed from AO40 but they should provide worldwide 
communication similar to the earlier AO-13 project.

The AMSAT-UK team includes G4DDK, G7OCD, G6LVB, G0MRF, & G3VZV who were 
responsible for the S-Band transmitter on SSETI Express.

This new opportunity to participate in this exciting venture is very much a 
result of the impressive support that the amateur fraternity around the 
world gave to the SSETI Express project – so thank you and congratulations!

We can also report the good news that a student team from the Technical 
University of Budapest has been added to the SSETI programme to work on the 
on-board Electrical Power System. This team, under the leadership of Dr. 
Andras (Bandi) Gschwindt, HA5WH, has masterminded similar systems on AO10, 
AO13 and AO40  all of which have proven to be extremely successful.

More news will be published as soon as it becomes available through the 
usual channels. At the time of writing the SSETI ESEO webpages are not 
up-to-date but new information is being added regularly, so please check 
www.sseti.org

73s and thanks everyone for your support!

Graham G3VZV 
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