[amsat-bb] Re: Delfi-C3 status update 30 April 2008 08:00 UTC

Robert Turlington rob_g8ate at hotmail.com
Wed Apr 30 02:51:58 PDT 2008


Hi All
I heard Delfi-c3 for about a minute ,only ,at about 0916utc this morning on 145.930+/- doppler
last evening it also switched off halfway through its obit just after 2000utc using a pointable 6el horiz quad and doppler tuned ft8476 in io92jp
Regards Robert G8ATE

> Date: Wed, 30 Apr 2008 10:16:58 +0200
> From: wjubbels at gmail.com
> To: amsat-bb at amsat.org
> CC: rascal at delfic3.nl
> Subject: [amsat-bb] Delfi-C3 status update 30 April 2008 08:00 UTC
>
> Hi all,
>
> Delfi-C3 is in orbit and healthy, despite some minor issues, please find a
> status update below:
>
> 1. Telemetry indicates that all solar panels and antennas have deployed
> properly
>
> 2. Telemetry indicates nominal values for all housekeeping values
>
> 3. We have already obtained payload data, and have been able to generate IV
> curves of the Thin Film Solar Cell experiment, note that those uring
> RASCAL can view the IV curves by clicking Options-->show IV curves in
> RASCAL.
>
> 4. The spacecraft is operating in science mode, we have had one orbit in
> emergency mode, which was most probably due to a databus issue
>
> 5. Up till now we have received 7000+ (!) frames from amateurs using RASCAL
> around the globe, amazing, thank you all so much!!
>
> 6. We have verified command uplink functionality yesterday, and were able to
> command the spacecraft today on the low elevation (4.9max) pass over our GS
> at 0737UTC
>
> 7. The spacecraft has decided to consistently use the backup radio on
> 145.930MHz for its telemetry downlink, we were able to request a full
> on-board database dump while in range of our groundstation yesterday and
> analysis of the database confirms this. We currently have a good
> understanding why this is the case. We will try to switch downlinks to the
> primary radio on 145.870MHz during the next good pass over our GS, so
> amateurs in Western Europe might want to check that frequency also and might
> experience intermittent telemetry while we are commanding. Note that we
> suspect that the TX frequency could be 1 to 2 kHz lower on this radio, so
> tuning around slowly is the best strategy.
>
> 8. The spacecraft seems to have an issue with the downlink TX switching off
> into the orbit, which is the reason while Delfi-C3 has not been heard on
> most descending passes over VK/ZL, we think we have a good understanding of
> why it is. The TX itself is fine, but it switches off automatically when it
> does not get data from the OBC for a certain amount of time. We are working
> on resolving this issue. This also happened during the pass over our GS at
> 0737 UTC but we were able to command it back on. For those in Western Europe
> we would like to ask to keep tracking Delfi-C3 even if you can not hear it
> at first, as we will try to turn the TX back on as soon as we notice that it
> has been turned off.
>
> 9. Thank you all for your observations on the spin rate, these are really
> helpful! We currently think that the spacecraft is tumbling with approx
> 10deg/second, which corresponds to a 36 second period. Since the s/c
> downlink antenna is almost truely circular, polarization sense can change
> from RHCP to LHCP completely depending on s/c orientation, we use circular
> antennas on our GS as well, and when we switch to the opposite polarizaiton
> sense the signal is wiped out completely, switching back gives solid copy
> with strong sigs.
>
> 10. NORAD object E #32787 seems to match best
>
>
> thanks for all your observations and efforts so far!
>
> 73 on behalf of the Delfi-C3 team,
>
> Wouter Jan Ubbels
> _______________________________________________
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