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I am thinking of making a weather balloon, but I have not found a way to transmit data between the ground station and the balloon. Do I have to buy a special part? And if I do, what is the cheapest solution? I am new to this, so please don't use too many technical terms. Thank you!

For the people that put my question on hold:

This question is just asking what part I need to transmit data from a distance. It should be able to connect to the Pi.

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    How high will your balloon go, i.e. what kind of range will we need? What kind of data & how much? Are you trying to get data from sensors on the balloon or control the balloon? Not like video streaming, right? Please clarify so people can help you. – MartinMarty May 2 '17 at 1:07
  • I'm not sure about any of the factors you talked about except for data because I want to get the major stuff out of the way first by planning. There will probably be pictures sent every few minutes, and data every few seconds from a few sensors. No control of the balloon. – Brendan Lewis May 2 '17 at 1:20
  • I will also need GPS data. – Brendan Lewis May 3 '17 at 23:41
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At those ranges Gigahertz comms (WiFi/Bluetooth) won't cut it. Check the Pi in the Sky project , which uses 433 MHz comms by default.

Depending on your range requirements you might want someone with an Amateur Radio license for ARPS on your team. Another alternative is to use LoRA , which shouldn't need a license.

Using a distributed system like UKHAS will increase your chances of actually tracking your balloon properly. Read this article by Dave Akeman for more : http://www.daveakerman.com/?p=1732

All in all i would manage my expectations. Datarates even in the megabit range are probably impossible.

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You'll only be able to transmit from so high, but maybe try using a cellular adapter?

https://www.youtube.com/watch?v=NArpvpmmpUU

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LASER!

Beam the data down!

It would be (kind of) easy to connect a laser pointer to the TX pin of your Pi, and then just feed the blinking into the RX pin of another Pi, on the ground.

Keep watching the skies!

  • I'm not sure that will work if it's cloudy. – Brendan Lewis May 5 '17 at 11:20
  • Depends on the laser! 😉 – Bex May 5 '17 at 12:03
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    Such baloons move at several km/h ... good luck making the transcievers at either end maintain line-of-sight - which is vital for laser-over-air datalinks – flakeshake May 5 '17 at 16:53
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    There might be certain legal restrictions to do so... and as flakeshake has pointed out (pun intended) the very narrow and directed characteristics of the laser beam will be much trouble. – Ghanima May 5 '17 at 17:56
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Well, your main options are Bluetooth and WiFi. There's a few things to consider before picking one:

  • Power: If the battery power you have on your weather balloon is limited, there are Bluetooth adapters and protocols that are made for very-low power applications
  • Range: outdoors and with a clear line of sight, consumer-grade Bluetooth and WiFi adapters have similar ranges (100-200 meters). You can boost the WiFi range by using a long-range antenna (like a Ubiquiti device)
  • Cost: generally speaking, WiFi adapters tend to be a bit cheaper
  • Ease of use: in my experience, Bluetooth does always work the way it should, whereas WiFi always seems to work out of the box.
  • Data bandwidth: Both Bluetooth and WiFi regularly come out with new protocols that are faster than the last. Right now, WiFi has the speed advantage.
  • Weight: well, based on all of the above, adapters come in all shapes, sizes, and weights. So, once you've narrowed down your requirements for the above, start looking for Bluetooth and WiFi adapters that fit your criteria, and consider the weight.

My gut feeling is that WiFi would be a better choice for your application. And rather than putting a big heavy antenna on your balloon, you may wish to have a big powerful antenna on your router instead, where weight and electricity should not be a problem.

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