Thursday, 29 March 2012

Well I've finally 'seen' the ISS

I have received many transmissions during day and night time passes from the International Space Station, mainly APRS and some ARISS school contacts both using the scanners and the FUNCube dongle.

However until yesterday I had never actually 'seen it' pass overhead, either due to a combination of weather or timing of the pass. The space station is huge and hence is one of the most visible man made objects in the sky when it reflects sunlight and will then appear in the sky like a moving star.

To actually see the space station the conditions must be right. The space station needs to be lit by the Sun on the side visible to the observer and the viewing point needs to be in relative darkness. A 'visible pass' can run from a few seconds to five minutes or more and the space station takes an arc through the sky.

I have created a crude diagram to try to explain what is happening, it is not to scale by any means! The observer is in shadow. The space station which is in a higher orbit comes out of the shadow and is illuminated by the sun and the light is reflected back and can be seen by the observer.

There are many many websites and applications to predict when these visible passes occur, and at the moment in the UK some extremely bright almost overhead passes are occuring in the early morning around the time I normally get up.

So yesterday and this morning I have stood outside in my dressing gown and witnessed the very bright man-made 'star' as it majestically arced overhead.

I even tried unsuccessfully to video it this morning but just got a black screen with a bright white spot... but honestly this is the International Space Station!

Given a decent pair of binoculars or a low power telescope you can see the structure and even with the naked eye it is obviously not a simple 'circle' of light.

The ISS is even larger at the moment as it has the ATV-3 resupply vehicle has just successfully docked with it and will stay attached for several months.

Thursday, 15 March 2012

Back In The Shack - Reception report VO-52

Things are hopefully get back to some form of normality here after a difficult few weeks.

During my downtime I missed the news that VO-52 HAMSAT had fallen silent on the 28th February a week after my last post. But good news the Dutch built CW/SSB transponder  was reactivated yesterday so last night and this morning I monitored a couple of passes. The transponder was certainly busy and I got some nice captured IQ files to analyse later.

Using just the loft mounted discone I monitored quite a little QSO between G7SVF and I8CVS this morning which I managed to capture using the audio recorder.

VO-52 (15-Mar-2012-0823) by nerdsville

The discone It isn't the best antenna for satellite work, especially with the FUNCube dongle as it's wideband characteristics heavy overload the front end, but it is nice capture all the same, even if it made me slight late this morning and so got caught in the school run traffic.

I did a Google search on the call signs and discovered I8CVS is Domenico Marini from Napoli Italy. Dom appears to be a well known expert in amateur satellite operation.  On that page is a picture of Dom in 2003 next to an impressive antenna array which appears to be sited on top a high rise building (oh the envy!)

While my own set up is much more modest. I have done a little tinkering, building a small UHF Yagi out of some metal coat hangers but have yet to test it in anger. I have also become a little more familiar with my FUNCube setup. I use the application and having updated to a much later beta version have had much more success. There were some issues that involved the swapping the I and Q signal on early versions but these appear to have now been corrected.

After listening to the ICQ Podcast I have been monitoring a few propagation beacons (GB3VHF and GB3BUX) (I will post more on this later) and using those beacons have got the frequency calibration more or less spot on now. I have also discovered that the Doppler Invert option needed setting so now SDR-Radio more or less correct perfectly as the satellites passes (still occasionally needs some manual interaction)

I really must make a real effort to get a licence and become less passive in this hobby, just not sure how I am going to afford an all-modes transceiver mind!