15 Nov 2011
Now I am about to start something new: 481THz band communications! This is 623nm red light for the uninitiated. This evening I've made a start by ordering some suitable components to allow benchwork to start next week. My initial tests will be low powered beaconing with a portable receiver walking down the road. Assuming this is promising, I'll then refine the kit and organise optics to give some "antenna gain" to allow much greater range.
There are a lot of resources on the internet about light beam communication, especially using high power LEDs and there was an excellent series of inspiring articles about this in the March-May RadCom this year.