Finding a Weather Balloon

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Finding a Weather Balloon

Post by Merlinus12 » Sun Jan 26, 2020 2:08 am

Short version - I’m looking for a way to track and/or decode the APRS transmitter of an amateur weather balloon.

I’m a school teacher who will be leading a group of students launching a weather balloon for our school. We want to recover the payload - since it is worth several hundred dollars and contains all the footage of the flight.

Toward that end, we have 2 trackers. One is an APRS transmitter that should give us telemetry every 60 seconds during flight. Here’s a link to it: ... e_V1.0.pdf

My understanding is that the transmitter should work well at altitude (where it will have good LoS to multiple towers), but will likely not work once it’s landed (unless there is a lucky tower in range).

Here’s my question: is there some way our ‘recovery team’ (me and some students in a van) could use a direction finder to track the source of the APRS transmitter once we get close to the source? Would it also be possible for us to decode its signal in the field (it would be broadcasting GPS coordinates that might help us find it). What would be the best way to go about this?


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Re: Finding a Weather Balloon

Post by alanzfq » Sun Jan 26, 2020 8:12 am

Presumably a radio + computer will receive and decode the APRS?
Then have that in your van. If it is possible to receive with a directional antenna the exact position will be known. Tracking as you drive will give a good idea where it may land.
Having said that maybe a group devoted to weather balloons might be a better place to ask.
Never rely on the StratoTrack to locate your payload once it has landed. We always recommend flying a satellite tracker on your payload whenever you want to recover your payload.

Which may be good advice.


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Re: Finding a Weather Balloon

Post by Username » Sun Jan 26, 2020 7:17 pm

Where are you from?
Depend on the Country I would not publicly decode any Weather Balons. The only Amateur Radio Stuff if you have a Licence.

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Re: Finding a Weather Balloon

Post by Arlo » Mon Jan 27, 2020 1:18 am

I'm getting your intentions and it looks pretty cool.
You could build a multi element yagi antenna cut for your APRS frequency. The more the elements, the more directional it would be.
I've built several yagi's that work on 2 meters all the way up to wifi frequencies. Used a simple fiberglass pole for the boom you use to mark property boundaries, driveway edges in the winter. And the elements made of things like 10 gauge romex to brass tubing you get from the hardware and crafts store. There are a few yagi calculators freely available on the 'net to help design one.
Of course after building one to test using an sdr receiver you check if it works first. Then fire up the APRS transmitter and start checking the range and how directional it is. It would be a bear to locate the transmitter with one antenna. Better with 2, and of course with triangulation the best with 3. Perhaps tackle a few lessons on the field trip spree.
I didn't dig real deep of the data logging done with your device. Certainly if the data were stored onboard, retrieving it in the field would take a pc and all the stuff needed.
The balloon will burst at a particular height. Weather stations using radiosondes pump in a finite amount of helium, hydrogen in them for a definite ascent per minute.
I'd think that for you if you didn't want to retrieve the device a bazillion miles away, you would pump the balloon up pretty tight for a fast ascent but low altitude burst. Those balloons are extremely flexible for a purpose.
Another thing to help find it would be an 'if found please contact' tag and streamers that that would spool off from a roll hooked to little army men parachutes. Remember, there's no perceived wind when a balloon goes up. Once it starts dropping under gravity, look out!

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