SUWS WebSDR showing AO7 and 73 on April 3, 2014 at 1040 GMT

A very good set of co-incident passes of both the AO-7 and FUNcube-1 AO-73 amateur radio satellites occurred over the UK on the morning of Thursday, April 3. The two satellites were launched 39 years apart, AO-7 on November 15, 1974 and FUNcube-1 AO-73 on November 21, 2013.

Simultaneous downlinks from both satellites could be clearly seen and heard on 2m, via the Southampton University Wireless Society (SUWS) online WebSDR at http://websdr.suws.org.uk/ which is available for use world-wide.

New Helical antennas designed by Martin Ehrenfried, G8JNJ, the installation of pre-amplifiers by Noel Matthews, G8GTZ, and a new PC build by Phil Crump, M0DNY have helped to dramatically improve the overall performance, especially on the 2m and 70cm Amateur bands.

The FUNcube-1 AO-73 BPSK telemetry beacon on 145.935 MHz is now up to 20dB above the receiver noise floor, and several stations using SSB, including Martin, G8JNJ, could be clearly heard on the 2m downlink via the SDR during last weekends transponder tests.

More improvements are in the pipeline, which we hope will help to further improve the receive sensitivity and reduce the level of interfering signals that can be observed on 2m.

Anybody can operate the SUWS WebSDR to receive signals from Satellites, and we really appreciate users leaving a message in the chatbox to let us know what they have heard.

Regards,
Martin – G8JNJ
http://www.g8jnj.webs.com/

SUWS WebSDR http://websdr.suws.org.uk/

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

This weekend the FUNcube team are planning to command FUNcube-1 into full time transponder mode.

It will be commanded into transponder mode on a suitable pass over the UK  on the evening  of Friday, April 4 (likely 21:30 UT).

If all goes well, it will be left in transponder mode until the evening of Sunday, April 6 (likely 20:50 UT).

If you hear the transponder on, please feel free to use it! Enjoy!

73s Jim G3WGM

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

Results of last weekend’s tests: the transponder was maintained ON for two orbits, and we did not see any noticeable fall in battery temperature.

We are therefore proposing to repeat the test on Saturday, March 29, but leave the transponder on for a longer period. We will switch it on during the first pass over the UK (approx 10:30 UT) and switch it off during one of the evening passes over UK, the first of which is at approx 20:00 UT.

We are particularly interested to receive TLM when the satellite is coming out of eclipse (i.e. when it should be at its coldest temperature). So reception from suitably located stations would be very welcome.

If you hear the transponder on, please feel free to use it!

73s Jim G3WGM

FUNcube website http://www.funcube.org.uk/

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

FUNcube Forum http://forum.funcube.org.uk/

Final gluing of FUNcube-1 bolt by Wouter Weggelaar PA3WEG – Image credit Gerard Aalbers

On March 22, the FUNcube-1 (AO-73) CubeSat will be commanded into continuous transponder mode for one or two orbits so we can assess the effect of lower power being radiated by the sat on the battery temperature. We expect the satellite to be put into full time transponder mode (aka amateur mode) during the first morning pass on Saturday, March 22 over the UK, at approximately 0930 UT.

We are aware that the on/off timings for the transponder are not now ideal, due to seasonal changes. In the coming months the situation will get worse such that in June the transponder will only be available for very short periods in the Northern Hemisphere.

FUNcube-1 Launch Monitoring Station at the NRC Bletchley Park

We are therefore planning to alter the schedule such that the transponder is on continuously at weekends after approx 1900 UT on Fridays, to Sunday evening. This will give radio amateurs a greater opportunity to use the transponder. Unfortunately there is no way of automating this schedule, so its maintenance will rely on the availability of command stations.

Before implementing this schedule, it is necessary that we characterise the effect of maintaining transponder mode for long periods of time. We expect that the space craft will be slightly colder than when transmitting at full power, as the heat generated inside the spacecraft by the PA will be less.

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

We are concerned that this lowering of the temperature may bring the battery temp lower than is advisable. Its specification is that it should not be charged if its temperature is below -5 degrees, or some damage might be done to the battery. Currently the minimum temperature we see that the battery reaches is approximately -2 degrees.

If you notice that the transponder is open on March 22, please feel free to use it.

Please note that we have learnt from experience that commanding the sat is not an exact science, and that not all commands sent are received by the satellite, probably due to interference. We will announce on AMSAT-BB and on the FUNcube web site the progress of our tests. We would be very grateful if as many listening stations as possible receive the telemetry (TLM) using the Dashboard software and forward it to the Data Warehouse on Saturday, March 22. Thank you.

73 Jim, G3WGM

FUNcube website http://www.funcube.org.uk/

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

FUNcube Forum http://forum.funcube.org.uk/