There was a news item on Southgate Amateur Radio News recently about a balloon launch from the south of Cornwall. As it's about 200kms away from my location on the south coast of Ireland, it seemed as if it might be possible to hear the signals at 434 MHz.
I listened on 434.100 MHZ USB with my home made co-linear in the attic and sure enough, I could hear a very weak RTTY signal!
It took a while to get the FLDIGI software up and running properly as I haven't used it in many years and I was unfamiliar with the various settings. After much messing around, I got a decode like this...
*U$$1901,578,09:42:03,50.1436319,-5.4608369,29651,15,1.468*0A55
It looks like gibberish but there is data in there.
*U$$1901 seems to be the ID
578 seems to be the message number
09:42:03 is the time in UTC
50.1436319 is the latitude
-5.4608369 is the longitude
29651 is the altitude in metres
15 is the number of GPS satellites it is hearing
1.468 is the battery voltage
*0A55..?? Not sure what this is.Maybe a checksum?
As the balloon was gaining altitude, the frequency of the signal was getting lower gradually. I presume this was due to the colder temperatures? As soon as the balloon burst, the frequency went higher a lot quicker than it had gone lower on the way up. I presume this was due to the payload falling rapidly into lower warmer air before the parachute slowed it down.
As the map above shows, it was launched from Goonhilly, reached an altitude of about 37723 metres and eventually fell into the sea off the coast of Cornwall. Once the balloon was above roughly 10,000 metres, the 70cms RTTY was strong enough for me to get good decodes.
All the RTTY decodes are shown below.....
