Optical communications

G4HJW's over the horizon 

(9km disatan) optical signal

Before my 2013 stroke, I really enjoyed my experiments out in the field with homebrew optical kit. Everything was home made: the electronics, the optics and even some of the test gear. This really is an area that is ideal for simple homebrewing. Sadly, I am too wobbly to do field work these days.  Truthfully, all the gear can be made in the "back of the garage" (mine was!) and it is easier than microwaves as all you need is a scope, multimeter and a weak LED source.

My "specialisation" was over the horizon weak optical signals. I managed to reach 8.1km non line-of-sight using a 481THz red LED with QRSS3. Nothing at all could be seen in the sky, yet there was perfect decoding on the PC. Had I been fit, I am sure much further would have been possible. As there were no clouds, I think this was clear air scattering.

What was needed was a much better tripod which was more stable and could be repeatably set in the right direction. My cheap tripod was wobbly and far from suitable. Accurate alignment is important. Once aligned there was the signal.

G4HJW's signal was way above the noise at 9km non line-of-sight (see photo above).

See https://sites.google.com/site/g3xbmqrp3/optical