AMSAT-UK Announce New 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-UK 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 50 kHz 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 web pages are not up-to-date but new information is being added regularly, so please check http://www.sseti.org/

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There will be a presentation on the satellite and transponder at the AMSAT-UK International Space Colloquium which will be held from Friday 28th until Sunday 30th July at the University of Surrey, Guildford, England.

AMSAT-UK produce a quarterly newsletter "Oscar News" which is full of Amateur Satellite information. For membership details contact the secretary Jim Heck G3WGM
Tel: +44 (0)1258 453959
E-mail: g3wgm@amsat.org
Website: http://www.uk.amsat.org/

http://www.southgatearc.org/news....ect.htm

73 Trevor M5AKA
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