Cheap, long range, wireless data connection?

[Messiah Khan]

Here's a question;

Is there anything out there that can provide a relatively cheap data connection (Ideally over about 20KBps) wirelessly, up to about 20kms or more in direct sight? One more rule to the game; It can't rely on networks etc that work on the ground, as I'm wanting it for something 20kms UP (as in towards space).

so far I have found radio modems, an am doing a bit of reading, but wondered if there was anything else out there.

 

[Messiah Khan]

Thanks for the suggestions. I think I can rule laser out due to how accurate it would have to be aimed, and problems with clouds etc.

To get that kind of range you'd need to exceed the legally allowed power output I'm fairly sure (or have a very sensitive reciever and very little background noise).

For reference GSM signals basically have a maximum (theoretical range of 22 miles (around 100,000 feet), which makes even that marginal. So you're getting pretty specialised. Good news is you don't want heaps of bandwidth at least - other question is do you need two way comms?

1 way comms would be fine tbh, although 2 way would be a bonus. Basically I'm thinking of launching a high altitude weather balloon, but would like to to transmit image data down as it goes up. A target of 100,000 feet would be great, so as you say GSM is marginal, but still an option.

One option that looks possible is something like;

http://www.digi.com/products/wireless/point-multipoint/xbee-pro-868.jsp