Sunday, 12 May 2013

Icelandic Meteor Reflections - Channel E4

The purchase late in 2012 of a "FunCubeDongle Pro+" opened up a new world to me - those parts of the "Low VHF" spectrum away from the amateur bands, or to be more accurate, away from the amateur 6metre (50MHz) band.

Very soon I homed in on a "new" target for meteor reception of the Skalafell TV transmitter in Iceland. This transmitter is allegedly due for closure at some point in 2013 as part of the Europe-wide "Digital Switchover" so I was naturally keen to make use of this before the big switch-off. I quickly found that it was an excellent target for meteor reflection reception, being at more or less the optimum distance away, high power (presumably) and on the air (as it turned out) 24/7.

This year's Eta Aquarid meteor shower coincided with a public holiday which meant that I wasn't working and therefore was able to pay pretty close attention to the "goings on" on all my meteor targets, and it wasn't really a surprise when I started to get some pretty impressive results on this channel (E4 - 62.25MHz).

 However, what was a surprise was the realisation that I was receiving TWO signals, the second and surprise one being a few hundred Hz below the main one.

What was really interesting to me was the similarity in some ways and difference in others between the characteristics of the received signals.

There were many occasions when coincident reflections were received, and others when there were completely separate reflections.

Similarity suggests that the two sources are relatively close together, and difference suggests that they are not _that_ close.

At the moment I am working on the assumption that they are both from Iceland, but possible in geographically separate parts of that country.

This has been further supported by a more "normal" spell of observation today when meteor activity is at a "normal" level, and, with this being early summer, some tantalising hints of more exotic propagation modes, namely "Sporadic-E". Again I have seen many examples of "co-incident" reflections (Sporadic-E ones seem to be co-incident in general), and non co-incident ones.

According to the "G0CHE" Band I TV information web page there are indeed two (suspected) Icelandic TV transmitters on channel E4, though the frequencies quoted on that site don't quite stack up with my own observations, unless the "new" signal is really Skalafell, and the one I have been referring to as Skalafell is actually Gagnheiði.

Any help in unraveling this mystery would be appreciated!

Sunday, 5 May 2013

Adlestrop (a short poem by Edward Thomas)

People who have the dubious honour of knowing me personally know that I am most certainly not an "arty" kind of person.

OK I play music semi-professionally in a "ceilidh band", and have an eclectic taste in music, well I think I have anyway,  but other forms of "high art"  (visual and the written word) are a mystery to me.   My taste seems to be very unsophisticated in comparison with that of others.

I mean, a picture should _look_ like something, shouldn't it?  I'm an engineer by profession, I believe in Ohm's Law!

However Damien Hirst makes far more money than I do, so I guess I'm the one in the wrong.

But perhaps by way of proof that I am not a complete Philistine, here is my favourite poem.

It's very short  but it evokes such imagery in my imagination that it astounds me in its brevity and seeming simplicity.  I never tire of reading it.


Yes, I remember Adlestrop --
The name, because one afternoon
Of heat the express-train drew up there
Unwontedly. It was late June.

The steam hissed. Someone cleared his throat.
No one left and no one came
On the bare platform. What I saw
Was Adlestrop -- only the name

And willows, willow-herb, and grass,
And meadowsweet, and haycocks dry,
No whit less still and lonely fair
Than the high cloudlets in the sky.

And for that minute a blackbird sang
Close by, and round him, mistier,
Farther and farther, all the birds
Of Oxfordshire and Gloucestershire.

Friday, 3 May 2013

High Altitude Ballooning

For a little while now I’ve been fascinated by the hobby of “High Altitude Ballooning“.
It’s such a short while that I can’t yet claim to be an expert in that subject, but what I have seen has really sparked my interest and imagination.

I stumbled on a page on the  "Raspberry Pi" web site, and it turned out that the "Pi" and ballooning have been bedfellows for quite a while.    Furthermore it seems that the BBC's James May (Man Lab) and Channel 5's Gadget Show  have have featured balloons, but as someone who rarely watches TV (even more rarely now Time Team has been axed!), this has only recently come to my attention.

This particular activity, and the background to it appears to pull together a number of disciplines, and it’s the amalgamation of these which has really got me excited.

Once I discovered, almost by chance that the telemetry transmitter from HABs (High Altitude Balloons) could be received at my modest radio station from a distance of 200+ miles I realised I could participate in this activity, even if I never actually went near a balloon.

Even more exciting was the realisation that many of the participants in this activity sre relatively young people.    I've long felt that it is high time that the younger element of our population took up the baton of technical innovation and put those of us of the “older generation” firmly in our place.

It’s not exclusively the dominion of the young, but there appear to be proportionally more of the younger generation taking part than say in “vanilla” Amateur Radio.


Here are a few web links to enlighten you further, if you are interested :-

UK High Altitude

SpaceNear Online Tracker (Google Maps based application) -
Note that ballooning is popular on the Continent as well as in the UK, especially in Poland.

StratoDean – a fabulous blog maintained by participants from the Forest of

Balloon flights tend to take place at weekends when the weather is favourable.  “Weather” doesn’t just mean what the weather is like at ground level, but also what the winds are doing in the stratosphere as these balloons usually achieve an altitude of over 30,000 metres (yes, 30km!), and the participants aren’t too keen on flight predictions which end in either the sea or in foreign countries!

 The above graph lifted from the online tracking application shows the flight profile of a recent flight and clearly shows what is likely to be achieved in terms of altitude and duration.

A flight in the south of England becomes audible to my station in the north of England once it gets to around 10km in altitude, and the telemetry  transmissions are generally decodable throughout this phase of the flight.

Telemetry is transmitted from the payload using small proprietary low power transmitters which happen to use part of the amateur "70cm" band, which is basically where we radio amateurs come in - many of us have high specification equipment and aerials capable of receiving these transmissions.   In my case I use my trusty Diamond dual band (2m/70cm) co-linear and my FunCubeDongle ProPlus SDR, see below.

The above picture is a composite (ie more than one image has been stitched together to make a single image) screen grab of  a “Spectrum Laboratory” screen and shows in graphical form the strength of the signal from the “Stratodean1″ flight from around 0945 UTC until about 11:30 UTC when the signal was finally lost as the payload descended under its parachute.  NOTE: The sudden “steps” in the display were caused by me adjusting my receiver to get the signal “centered” in the passband of the display, and were not caused by a problem with the payload telemetry transmitter!

Just to give you an idea of how remarkable radio transmission are above 10km, note that the transmitter power is 10mW, and the aerial on the payload is a simple ground plane affair made by using a length of stripped back coaxial cable and drinking straws!   See the StratoDean web site for more information about this and other technical details about the payload.

The screen grab below shows the flight profile for StratodeanOne and I've marked it up to highlight the part of the flight I was able to receive in Penrith (IO84 square).