Good optical comms site

On my own main website is some information (now very dated!) about my own experiments with optical communications at 481THz (red light). I was mainly interested in over the horizon, weak signal modes.

I was quite amazed to clearly detect my optical beacon over the horizon when nothing was visible in the sky. There were no clouds so I assume this was clear air scattering off dust particles.  This was using QRSS3 and a PC to "see" the signal. My own experiments stopped shortly after my 2013 stroke. I did try one experiment out portable since, but I was too clumsy. I have not tried anything portable since 2014.

All the gear needed is quite simple to make and all the test gear needed easy to fabricate. I made a very weak signal source using a very very dim LED to test the receivers. This was mounted near the ceiling of a darkened room. With a good RX this should be received OK. If you cannot detect modulation on a very dim LED your RX is not good enough.

I still have all my optical kit. If anyone local wants to borrow it to carry on the experiments, I'd be very happy. They must be local as I will want the gear back.

Another good resource is http://www.modulatedlight.org/optical_comms/optical_index.html