Re: Like to track balloons? How about tracking radiosondes!

James Ewen VE6SRV

Back in my day, you had to lay on the lawn with your yagi sweeping the sky for the signal, and then use RDF techniques to chase down the payload. (Do I sound like one of those old timer ham radio guys yet?)

Before the turn of the century, I got it into my head that chasing balloons would be fun. I just happen to live 60 km due east of the local weather station WHK. Prevailing winds tend to put the flight path right overhead. We went for a tour and watched the meteorologist fill and launch a radiosonde. Then I started tracking the 400 MHz payloads using my IC-24AT and a UHF yagi antenna. I would lay on the lawn sweeping the yagi around looking for the signal. I had just moved into town and the neighbors didn't really know what to think of the nutty neighbor laying on the lawn with a tiny goofy looking ladder in his hands. The curious ones would get to stare into the blue sky and if they were lucky enough to have good eyesight, they would see the balloon flying overhead.

I soon learnt just where I would like to see the balloon burst in order to determine whether I wanted to go chase down the payload or not. Based on where the balloon was visually observed to burst, I would have a rough idea of where I needed to head to intercept the payload. Years later as the prediction software got better, we were able to determine where to head before launch, but I could still get a rough idea of where to head if I could observe the burst. Even if telemetry failed, we could get close enough to track down the RF signals.

Decoding GPS signals from the radiosondes makes it like shooting fish in a barrel! I might have to hook my SDR up to one of my old Pi3s and see what I can decode. Then I might have to go collect a bunch of radiosondes...


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