Skip to content

Transponder Test Today – slight change of plan

by on November 23, 2013

After some commanding “difficulties” – actually caused by a setup error here at the ground station, we can confirm that AO-73 was switched into autonomous mode during our pass on Orbit 32. Your reports are awaited with interest!

We have reviewed our plan to switch on the transponder today (Sat) and decided that rather than leave the transponder on for a whole orbit, we should put the spacecraft into ‘autonomous’ mode, whereby the transponder will automatically switch on when the spacecraft enters darkness, and switch off again when it enters sunlight.

We have revised the plan, as we feel this approach is less risky. We are very sorry to disappoint our European supporters, but we hope you appreciate that at this stage in FUNcube-1’s life we must be as cautious as possible.

The good new is that if successful on the first orbit, we will leave FUNcube-1 in autonomous mode.

We are keen to get telemetry when the transponder is on; the tlm transmitter will still be on, but at low power.

73s – The FUNcube Team

From → News

  1. Robert Bush permalink

    Is there enough time to turn on transponder, do quick check that it works in daylight (less battery drain) then go to autonomous mode?

    Rob Bush

  2. Edgar DF2MZ permalink

    Hi, it is less risky to run the transponder in darkness? What is the reason? Is the primary concern temperature increase or battery voltage? Cheers, Edgar DF2MZ

  3. That explains it. I was waiting for the transponder to activate. I think I now understand why the eclipse flag appeared when it was not in eclipse, its not an eclipse flag, its an eclipse mode flag.

    The good news is this means I can leave it on auto and go shopping.

    Mike G0MJW

  4. Jari permalink

    I track the satellite, but I note that, its trajectory wasnt what I expected, must be change within kepplerian elements? I also note that satellites telemetry was kind of garbled of its sound. I have audio sample if anyone needs it. Was it my setup or was there really something on the sat? Did anyone else note such thing?

    :Jari / OH2FQV

    • g3wgm permalink

      Hi Jari,

      Yes, we noticed a change in sound also, and have switch off the transponder until we learn more, (so FC-1 is in permnant high power tlm mode). We would be VERY interested in sound samples from you; or anyone else who has them for the last orbit. Thanks

      • Jari permalink

        Hi Mike. Where I send/ upload the audio file?


      • Jim

        For me, the telemetry would not decode for the first few minutes of the pass, even though the signal was strong. I reset the dashboard thinking it was that – it wasn’t but it eventually started working again, but only at 12:48 and not immediately. I had assumed this was my issue as others were decoding OK, for example local interference. This was 3 minutes into the pass and I would say just after it came into sunlight.

  5. g3vzv permalink

    if it is ok – please send it to me at graham @ with jim @

    many thanks

    • OK – the last pass wasn’t very high here but there was very clearly a problem with the signal, seemed to be FMing. It was weak but strong enough to have decoded previously but I got no decodes this time. The next pass is not until 7pm, so we will see.


  6. WHy transponder off when in Sunlight ? Should it not be other way round as batteries is discharging in no sunlight with transponder on ?

    Johan Visagie

  7. Jari permalink

    I suppose to have the sat abt 15:50 UTC, I see what I can do and keep up here.

    : Jari

  8. I have recorded some data from the HDSDR too, unfortunatelly the Dashboard is freezing on my PC it seems to have problems with Virtual Cable as described on the forum. I can send the bunch of wav data through some sharing service (g3vzv are you interested), but it is about 500MB for 10min time. I will record the 19UTC pass too.

  9. g3vzv permalink

    We believe that the apparent distortion in the transmitted telemetry and difficulty in decoding may have actually been occurring due to the natural phenomena of on aurora rather than a problem on board the spacecraft. We understand that another spacecraft had the same issues around the same time.

    We intend to command AO73 back into autonomous mode during the 2035 UTC pass this evening. This will mean that we should have transponder active when in eclipse and telemetry only when in sunlight.

    Everyday we learn something new!

    best 73

    FUNcube-1 team

  10. Graham,

    That’s interesting – yes it did also sound a bit like multipath and there was a flare this morning which could explain it. I would be interested in any data you have on this. Will listen again tonight – it is coming from the South so if it goes bad towards the end of the pass we will know for sure.


  11. Good signal

    powered by

  12. No trasponder active orbit #38, only telemetry in central Italy 😦

  13. Hi,
    Good first contact just now orbit 38 ascending over South Africa.
    QSO between me ZS6TW and ZS2BK (Andre) at 21:50UTC
    Good strong signals.
    Copied some telemetry also – uploaded.


  14. Andre ZS2BK permalink

    Just had my 1st excellant QSO via the Ao-73 xponder with Keith ZS6TW.
    Very strong S7-9 without pre-amp and clear SSB audio.
    Congrats to the Team.

  15. Changed antenna here today to a turnstile – signal however tonight was very weak with me and difficult to decode in dashboard. Was expecting a much bigger signal. May be the new antenna is not working – or maybe the tlm was on low power this evening? Mike G0AMO

  16. Many QSO’s, people chasing themselves on transponder, and strong/clean voices heard on Orbit No 40, 03:03 UTC 24-11-2013. Found myself rather quickly with Icom IC-910, Elk antenna, 10 watts.

  17. Alex permalink

    Managed to access the transponder while over Australia at about 22:35 UTC 23/11/2013
    Had some problems with SatPc32 and my uplink was somewhat off frequency but still heard myself (in a very squeaky voice) Problem has been fixed and will try again tonight.
    Signals were of reasonable strength on my IC910H and non elevating 10 element dual polarity yagi.

  18. SP5ULN permalink

    QSO probably one of the very first on AO-73
    SP5ULN – SP5MG
    23-11-2013 20:44:35 UTC

    Great fun!
    Thank you FUNcube team for contributing to hamradio society,
    Vy 73,
    SP5ULN Piotr

  19. AO-73’s VHF signals were received at good strength yesterday evening (23 Nov) in jo20wp during the 2034utc pass. Using a simple end-fed halfwave vertical antenna from a hilltop location I was able to copy AO-73 down to less than 1 degree of elevation. Here’s SP5ULN and SP5MG working through the transponder.

  20. Was pleased to be able to use the transponder last night at 22:15 managed to work EA1JM, 9A3ST, SP5MG, OH2FQV all with good signals.

  21. I could CW-QSO with JO2ASQ/2, JA8JXC, JA7KPI, JH1UVJ/4, JR8QFG, JM1SBU and JA3FWT via AO-73 on Orbit No 49.
    Signals from AO-73 were very strong on my IC-910D(50W) and QFH antenna.

  22. ct3fm permalink

    Congratulations, great job on FUNCUBE-1 (AO-73) Telemetry is excellent and the performance of the transponder so far is also good.
    Last night on orbit 39 ascending over Madeira Island at 22:09, worked IK0USO, EA1JM and listened 2E0SQL,SP5MG with great signals and modulation too.
    On the 2nd pass, worked CT2GOY, I think that was the 1st contact between Portuguese stations.


    Miguel – CT3FM

  23. 7J1ADJ/JR6 permalink

    Just finished installing the Dashboard and will leave the station up and if all goes well, auto fwd the TELM data back to the team. Using a TS-790A, Maspro Oscar 24 ele cross yagi’s with the Trakbox II and G-5400B (stand alone auto tracking setup). The Trakbox will tune the radio for doppler and preposition the antennas before each AOS. Recently pulled my equipment out of the closet and dusted it off after years of sitting.

  24. Congratulations to the whole team.
      excellent work, this is an example of a system to be implemented in future satellites.
    Let me ask you something that I may be making a mistake.

    Since that linked the transponder, the tlm data although weak, have values ​​in Dashboard (AP Board) quite different
    Ex Orbit 82
    Forward power: 336.57 mW
    Reverse power: 100.68 mW

    This amount of reverse power, is not a bit high?

    Again, congratulations
    from CT2GOY

    • g3vzv permalink

      Hi Luis,

      Many thanks for your kind comments about the project!

      Regarding the high apparent VSWR – we noticed data this almost immediately after launch and have been analysing it over the past few days.

      It appears that the problem occurs as the spacecraft cools down after it enters eclipse. the telemetry then returns quickly to normal when it starts to warm up again.

      We have been discussing a number of theories which relate to the design of the detector and the performance of the ADC and components around it but have not yet come to a firm conclusion. From the strength of the down-link signals we do not believe that the data is actually valid!

      We expect to be doing some further investigations with our Engineering Model and a number of prototype board here on the ground to see if we can replicate the effect over the next few weeks as suitable facilities can “borrowed”



  25. ct2goy permalink

    Hi, Graham
    Thanks for the quick response.
    I have regularly received telemetry and really I note this difference, it is likely that you have paid more attention at the time that the transponder was turned on.

    Furthermore, I have done some contacts and ran very well.
    I notice some drift in frequency, about 5 + / – Hz, when trying to sync, but I admit that is the temperature difference, the local oscillator in the transponder.

    Best regards

  26. IGOR permalink We thank for AO-73 work, we ask to include a transponder and in next weekends on April 12-12, UA9CS

  27. g3wgm permalink

    In response to UA9CS’s request. We well certainly try to have the transponder on next weekend; it will depend on how this weekends tests go, and on the availability of command stations. Pls watch this page for news, also AMSAT-BB and the Fitter Messages. 73s Jim G3WGM

  28. UA9CS permalink

    OK,Jim, fine signals today 5 th of April via AO-73 in the day time , no problem in QSO via sat , in 12 -13 April we have Gagarin Contest 2014 (via sats too) and i believe what sat will be ON , 73! UA9CS

    • UA9CS permalink

      Many QSOs today the 6 th of April 2014 in the day time , transponder work very well in AO-73 , many thanks Jim and the group , 73 UA9CS

  29. K9WXC permalink

    Pass that was over central US 15 April at 16:47-59 UTC had some anomalies. We could detect the beacon, but no telemetry “beeps” were heard, and no data could be decoded. The transponder was unexpectedly on and a strong signal was heard from one amateur station.

  30. SP5ULN permalink

    No signal from FUNcube on pass over Europe 18:05 – 18:14 UTC 2014.04.15 !!!
    I mean there were no synchronisation beeps, and rather no telemetry. I did not check beacon. AO-73 was for me 8 degrees above horizon.

  31. Jari permalink

    I track the satellite from 18:04 – 18:18 UTC 2014.04.15 – not a beep. Pass was from black sea till greenland. No signal detected audible or with spectrum analyzer.

  32. K9WXC permalink

    We confirm — FUNcube operating normally on 8 degree elevation pass over central US, 02:09 UTC. Glad to see it back!

  33. cans permalink

    how can you keep the transponders in stable temperature? (in temperature limits of transponders)

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: