His first pico-balloon (PS-2, ironically) only stayed up for fifteen hours and made it under 800km away. Practice makes perfect? We’ve written up WSPR on a Raspberry Pi (code and hardware ...

Now you can do it all with WSPR and [TechMinds] suggests a moderately-priced dedicated WSPR transmitter to do the job. You can see a video about the results of this technique below. While WSPR is ...