RAMFly can sing ....

Well actually, more like tweet (like a bird, not like a teenager...) 

I spent way too long again last night, but eventually I got a basic radio telemetry setup working. I can now transmit information a massive 1.5m across my desk. That's without antenna and other required things which should boost the range to many Km.

Ramfly transmitting dummy data across my bench - click to expand

Here you can see my receiver collecting strings from the RFM22B. The second line has a receive fault (but the spelling mistake is all mine ... :) This was at 50 bps, 100+ proves very unreliable. However, remember there are no antenna though. The blue/yellow band at the bottom of the image is called the 'waterfall' and allows you to visualise non visual energy. Yellow/Red indicates energy and the darker parts silence. You can see here a 1200Hz sound and 1675 Hz sound. These are the sounds produced by the SDR radio in response to frequency shifts and corresponding Upper Side Band (USB) frequency compared with the reference frequency. The better the transmission the brighter/narrower the yellow/red bands will be. Although you can't see very well, there are two vertical red lines (directly beneath the red scale markers). These have to be very precisely aligned with the yellow/red waterfall marks to indicate the two frequencies produced by the payload. The horizontal blue band is the gap between two transmissions.

Wanna hear ramfly sing? 

The good chaps on freenode #highaltitude were very helpful. I was labouring under a misapprehension about how to set up dl-fldigi for a couple of hours - very frustrating