AO-73 (FUNcube-1) – Image credit Wouter Weggelaar PA3WEG

After a year long period of ‘battery management’, AMSAT-UK and AMSAT-NL have restarted the transponder on AO-73.

After 10 years in orbit, the battery on the satellite has reduced capacity and until recently, has been unable to charge to the nominal 8.3V.
Following some careful battery management, where the transmitter was off during eclipse, the battery status has improved and the transponder has been reactivated.

Although the battery voltage is varying between 8.13 in sunlight and 7.8V at the end of eclipse, this is much improved on the situation earlier in the year.

Low power BPSK telemetry is transmitted on 145.935MHz
The inverting mode U/V transponder input is 435.130 to 435.150MHz
The transponder downlink is 145.970 to 145.950MHz

At the moment the satellite has a high spin rate of apx. 30 rpm and if you’ve not used AO-73 before, the downlink can be Doppler tracked successfully, but the input on 70cms is best tuned manually due to temperature drift of the receiver.

73

David G0MRF – AMSAT-UK

AO-73 (FUNcube-1) – Image credit Wouter Weggelaar PA3WEG

After some eight months in continuous sunlight, FUNcube-1 has now started to see some eclipses during each orbit.

The telemetry received has shown that the spacecraft continued to function perfectly during this period and the on board temperatures did not reach excessively high levels.

After this became clear, our next concern was the battery. Having been kept fully charged for this period, would it actually hold a charge and do its job when in eclipse?

After three weeks of increasing eclipse periods we can now see that indeed the Li battery appears to be ok and the bus voltage has not yet dropped below 8.1 volts.

So today we have changed the operating mode from high power telemetry educational mode to continuous amateur mode withe the transponder ON. The telemetry continues to be available, albeit at low power.

We will, of course, continue to carefully monitor the data but are planning to leave the spacecraft in this mode for at least the next week. Please enjoy using it!

AO-73 (FUNcube-1) – Image credit Wouter Weggelaar PA3WEG

FUNcube-1

As you will know, AO73/FUNcube-1 has been in full sunlight for over one month and has been transmitting continuously high power telemetry for most of that time. This has now been changed to full time amateur mode so the transponder is once again available. With the more stable on board temperatures being experienced, this means that the transponder frequencies are also now more stable. We expect to leave it in this mode for some weeks so that the team can determine whether or not the currents flowing from the solar panels are having any noticeable effect on the spin period.

FUNcube-2

The FUNcube-2 transponder on EO-88/UKube-1 continues to be in full time transponder mode. There are occasional breaks in service for a few seconds when the OBC reboots and the other onboard transmitter sends its CW beacon.

FUNcube-3 on Nayif-1

EO88/Nayif-1 continues to perform nominally with high power telemetry when in sunlight and amateur mode when in eclipse.

With their slightly different orbital characteristics it is useful that AO73 is now the early bird, EO88 comes over in the mid morning and UKube provides coverage in the afternoon.

We have been suffering from some network issues in relation to uploading the telemetry from the Dashboards to the Data Warehouse over the past couple of weeks. Apologies for this, but hopefully everything is now stable again. ie fingers are still crossed. Thank you for all the telemetry that you upload.

Like many other teams, we are presently waiting for the next Space-X launch from Vandenberg which is expected to be carrying a number of new amateur payloads, These will provide additional transponder and STEM capabilities for the amateur satellite service. Exciting times ahead.

73 Graham G3VZV

The FUNcube Team will be giving a presentation on JY1Sat and FUNcube Next at the AMSAT-UK Colloquium, part of the RSGB Convention, at the Kents Park Conference Centre, Timbold Drive, Milton Keynes, MK7 6BZ. Colloquium presentations will be in Lecture Room 5. Download the programme schedule from
http://rsgb.org/main/about-us/rsgb-convention/rsgb-convention-programme/

Tickets to the event are available at the door details at
http://rsgb.org/main/about-us/rsgb-convention/

There will be a live stream of the Colloquium presentations at https://batc.org.uk/live/

The time when AO-73 enters continuous sunlight, for the first time, is fast approaching. Current estimates show that this will commence on February 6th and last through until March 13th.

Obviously, the autonomous switching system that the spacecraft has been using to switch between amateur mode, with the transponder on in eclipse and educational mode with high power telemetry only in sunlight, will no longer work.

Already the periods of eclipse are reducing quite rapidly and we are therefore planning for manual mode switching to take be undertaken. This will start from the week beginning Jan 21st and will follow this initial plan.

Wednesday evening (UTC) or Thursday morning – switch to full time amateur mode – ie transponder on with low power telemetry.

Sunday evening (UTC) or Monday morning – switch to full time educational mode with high power telemetry only.

So if you are planning school demonstrations or particular DXpeditions please take this new schedule into account.

The team may have to flex this plan with experience as this situation was not allowed for in the original mission plan!

AO-73 / FUNcube-1 spin period and illumination December 2017
https://amsat-uk.org/2017/12/03/ao73-spin-period-illumination/

FUNcube Website https://amsat-uk.org/funcube/

FUNcube Yahoo Group https://amsat-uk.org/funcube/yahoo-group/

FUNcube Forum https://amsat-uk.org/funcube/funcube-forum/