I was wondering if you guys could help me choose the right hardware for my project. I read about some people at MIT who sent a weather balloon to near-space an took some pictures http://space.1337arts.com/ They used a cheap cell phone with a GPS receiver to track their balloon once it landed. Awesome right? I was always a fan of the Arduino but I want to get serious now. I think I can handle the camera set-up but the big challenge is tracking the balloon. Either the ballon uses the cellular network to transmit the location once it lands or I use a radio that transmits the location in short intervals. Preferably I would use a radio but the application for an amateur license seems quite a hassle in my country and I haven't been able to find gear in the unlicensed spectrum that can reach altitudes of 32 km. If I would be forced to use the cellular network there are two choices.
I am doing something similar and my primary concern is the price tag, my idea is to use the hwkitchen (people are really happy with it) and for the gps I am looking for a cheap ebay gps, many of them once opened up have rs232 or ttl pins, and you just have to solder.
Somebody in England was using a 12 pound gps and it had a serial line.
As you say the radio would be really nice, but only feasable if you already have a license (mandatory in my country) otherwise too expensive.
FYI, in the US it is against FCC regulations to operate a cell phone at altitude due to the problems it can cause with many different cells - a balloon at altitude may be over 400 miles from the horizon, hitting cell towers over a 5000 square mile area (e.g., the entire southeastern US in our case).
Check out APRS. Many balloons have been tracked and recovered using it (we've flown over 40).
It's not as cheap as a cell phone, but it's legal, much more reliable, and doesn't depend on being within reach of a cell phone tower to work.
APRS sounds like a good idea, I dont know the legal side of it in your country. The idea of the cell phone (or gprs) is that you can enable it based on the altitude.
APRS could be a nice solution also for me: but where do you find something simple to connect to an arduino?
I generally dislike the cell phone solution because it won't allow me to track the balloon before it comes close to the ground again. It seems that in Switzerland, where I'd like to launch the balloon, the APRS coverage is pretty good but APRS requires an amateur radio license doesn't it? Maybe I can get around getting a license by working together with the local ham radio club?
It seems that in Switzerland, where I'd like to launch the balloon, the APRS coverage is pretty good
That's very helpful, but not mandatory. You can track using just an APRS transmitter on the balloon and a receive station on your chase vehicle, assuming that you can drive from the launch site to the LZ during the flight. We do this routinely, although not so much in the fall/winter, when the balloons reach ground speeds of 150MPH+ in the jet stream.
Being a good citizen on the national APRS frequency (in the US) says you shouldn't transmit more than once a minute (Which is plenty of resolution for balloon tracking). We have moved to alternate frequencies and transmitted more often, like every 20 or 30 seconds.
APRS requires an amateur radio license doesn't it?
It does in the US, and I suspect in Switzerland, too.
Maybe I can get around getting a license by working together with the local ham radio club?
I'm not sure of the laws/radio regulations in Switzerland, but a local ham club would be a good place to start. I know in the UK their regs prevent balloon-borne amateur radio.
The hams in my area are so helpful I could probably ask for complete tracking support and someone would provide a tracker for the balloon and ground station support, but then I live in a high tech town, complete with NASA center. YMMV
Another set of restrictions are aviation regulations (FAA over here).
We can fly 12lbs on a single balloon (with a few restrictions/requirements), so you may find someone else interested who will share the cost to fly their own payload on your balloon.
