ARLA/CLUSTER: Teste ao transponder do nanosatelite Delfi-n3Xt

[João Costa > CT1FBF]

Delfi-n3Xt transponder to be tested

Delfi Nanosatellite
Program Manager, *Jasper Bouwmeester PC4JB*, has announced tests for Feb
20-21 of the Delfi-n3Xt 435/145 MHz linear transponder for amateur radio
SSB/CW communications

Dear radio amateurs,
It has been a while since we have provided an update, so it is time to
brief you again.

*Delfi-n3Xt Status*

The satellite is doing fine and is in healthy shape. We are now almost 3
months in orbit and have fulfilled a major part of the primary mission
objectives. This means that we are close to a mission success. This does
not mean that everything works flawlessly as there are several subsystems
with issues. Given the amount of payloads and new technologies, I can only
say that this was to be expected and accounted for in the mission. Delfi
satellites are developing platforms and Delfi-n3Xt is an in-orbit test
facility. The good thing is that issues encountered are not even a final
verdict on the subsystems performance. The attitude determination and
control subsystem currently is hampered by a high magnetic noise, but might
still be tweaked and tune to see if we can get it to work properly. This
however takes some time, so we are glad that the satellite seems to be in
healthy state and we can take more time to experiment with it.

*DUDe*

We are still working on an improved version of DUDe to tackle several
issues which we and many of you have discovered and reported.
Unfortunately, many of these issues are more difficult to tackle than
anticipated and will still take a while before we can release a new solid
version of DUDe. One of the main issues is the fact that the software
freezes after receiving noise for some time, meaning that DUDe needs to be
restarted each time. Attached is a version of DUDe with a dirty fix which
resets the PLL every minute. The penalty is that a 1 or 2 frames are lost
each minute, so the performance is less than version 5.1. It is however
much more convenient for automated ground stations (like our own) and
therefore we decided to release this version.

*Transponder*

We are going to test the transponder functionality of Delfi-n3Xt this week.
I have to be honest that this functionality was implemented last minute on
the satellite and was only tested briefly in a non-representative setup. I
therefore estimate the chance that it will work at 50/50.

Our first test series will be:

Thursday 20-02-2014 at about 10:50 UT

Friday 21-02-2014 at about 9:50 UT

Friday 21-02-2014 at about 11:25 UT

After a few initial tests, and provided that it works, you are free to use
the transponder for communication. We will leave it in this mode for the
remainder of the sunlit part of the orbit, so only in Europe and Africa it
is possible to use this mode for now. If successful we will turn on the
transponder more often and for longer periods of time such that everyone
can enjoy it.



*[Inverting SSB/CW transponder• 435.530-435.570 MHz uplink LSB•
145.880-145.920 MHz downlink USB]*

*S-band Transmitter*

There seems to be a problem on the S-band transmitter causing the current
protection to kick in occasionally. Maybe this is due to charging or some
other effect, as the board is not protected by The Onboard Computer leaves
the transmitter off after several attempts as part of an internal safety
mechanism. We can still turn on the S-band transmitter through telecommand,
but this will only last for a few passes. Most cases the S-band transmitter
will thus be off and it reporting that we have turned it might not be very
effective since it might be off again by the time you read the message. If
you are still interested to try and receive the beacon signal of the
S-band, please check the regular telemetry in DUDe under ‘Status’
’Satellite Status’ ‘Subsystem Status STX’ to see if it is actually on.

J. (Jasper) Bouwmeester PC4JB, MSc.
Delfi Nanosatellite Program Manager &
Researcher Small Satellite Technology
Chair of Space Systems Engineering
Delft University of Technology

IARU coordinated Delfi-n3Xt frequencies
• 145.870 MHz Telemetry
• 145.930 MHz Telemetry
• 2405.00 MHz High speed data
• Inverting SSB/CW transponder
- 435.530-435.570 MHz uplink LSB
- 145.880-145.920 MHz downlink USB

Telemetry reception
http://www.delfispace.nl/operations/delfi-n3xt-telemetry-reception

Delfi-n3Xt
http://www.delfispace.nl/operations/radio-amateurs

Delfi-n3Xt launch
http://amsat-uk.org/satellites/dnepr-november-2013/
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