ARLA/CLUSTER: Nanosatelite Delfi-n3Xt pode estar avariado

[João Costa > CT1FBF]

Delfi-n3Xt update: Some bad news

Jasper Bouwmeester PC4JB, has announced the results of the testing
carried out on the Delfi-n3Xt CubeSat amateur radio 435/145 MHz linear
transponder.



Dear radio amateurs,

Unfortunately, we have not heard anything from Delfi-n3Xt since
Thursday 20/02 after our transponder test. During the transponder test
we could hear our side beacon at 145.870 MHz and we were still able to
switch back to normal transmission an back to transponder again (and
also received the beacon the second time). Nothing seemed to be wrong,
except for the transponder itself not properly working. The satellite
was supposed to return to nominal operations in the next orbit.

We think that a hardware failure occurred either at the second half of
the transponder orbit or during the mode switch. Since Friday we have
made many attempts to revive the satellite. Since we have an
independent radio, there was (and still is some) hope to get the
satellite back in transmission.

There are however a few points were common mode failures could occur:
the phasing circuitry which connects both transmitters and an I2C
buffer at the main bus side. We do however still have some hope that
only one radio has failed and that we might still be able to command
the satellite to use the other.

Since all trivial command schemes did not work, next week we will only
focus on a specific test to turn the transmitter on for a brief
moment. During the weekend we saw some narrow band signal at 10 kHz
below 145.870 MHz (+/- Doppler), which might potentially be related to
the local oscillator.

If we can reconstruct this a few times and clearly correlate this to
Delfi-n3Xt (we do have a lot of intermitting noises sources in the
neighbourhood) we at least know the OBC and one radio is still working
and we can commence to next steps.

We appreciate everyone’s help to listen to Delfi-n3Xt to see if there
is still some signal left. I think the best changes (besides Delft
passes in which we try to command) are when the satellite comes just
out of eclipse and is supposed to startup one of the transmitters.

Please note that it has become very crowded with CubeSats lately, so
any signals which are off in frequency (except for the -10 kHz tone),
have a very different bandwidth and/or Doppler shift are very likely
to be other satellites in the neighbourhood.

Today we had for instance Delfi-C3 almost perfectly aligned sending at
the same frequency. Delfi-n3Xt will only transmit at about 145.870
MHz.

If the situation changes, I will provide you with an update.

Best regards,

Jasper, PC4JB

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

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

Dnepr Yasny launch
http://amsat-uk.org/satellites/dnepr-november-2013/

Results of first Delfi-n3Xt transponder test
http://amsat-uk.org/2014/02/20/results-of-first-delfi-n3xt-transponder-test/

Delfi-n3Xt transponder to be tested
http://amsat-uk.org/2014/02/17/delfi-n3xt-transponder-to-be-tested/