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
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 Society – www.ukhas.org.uk
SpaceNear Online Tracker (Google Maps based application) - spacenear.us/tracker
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 Dean – www.stratodean.co.uk
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 spacenear.us
online tracking application shows the flight profile of a recent flight
and clearly shows what is likely to be achieved in terms of altitude
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).
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