If Ham radios are out, could we use a mobile phone instead?
Or are all forms of unmanned balloon radios banned? Must check!
With a smartphone that has GPS, such as a Blackberry, we could broadcast the balloon's position straight onto Googlemaps (e.g. http://www.google.co.uk/latitude ) which surely would be a publicity coup and moreover useful for Air Traffic purposes.
The only problem is, 'phones are short range transmitters - only needing to communicate with the nearest cell base station a few miles away. We will reach altitudes as high as 20 miles.
Maybe a quick way around this would be to have a parabolic dish on the balloon gondola, pointing straight down. It doesn't need to be steered.
I have already checked with Paul and we can design and 3D print parabolas OK. We could spray it with aluminised paint or line it with mylar. We could even print it as a mesh to save weight, allowing for the wavelength of the 'phone signals.
This gives our 'phone a tighter focussed beam facing straight down from altitude. This would presumably cover one or more base stations at a higher signal strength (instead of the signal going off in all directions as it would usually)
Would this be enough??
Again, something to test!
The 'phone could be mounted directly at the prime focus of the dish. Perhaps it could even be hung there by ropes. That way it will be more likely to withstand the landing, especially if we cocoon it somehow.