Today I completed my first keyed optical beacon transmitter (with 100mm optics) which I'll be
using for tests at greater range than hitherto. The 481THz
(red light) beacon sends my callsign in either 10wpm CW, QRSS30 or
QRSS60 as well as a continuous carrier or a 30sec on/off sequence. The TX uses a sub-carrier of 1.082kHz or 8.659kHz, the frequency being derived from an HF crystal divided down in a 4060. The message comes from a K1EL K-ID2 programmed PIC. Initial tests this afternoon at dusk allowed me to copy the 1.082kHz 10wpm CW sub-carrier signal by reflection off a wall across the street at decent strength.
My next challenges are to find some local paths of a few kilometres to check the beacon and the receiver. I'd also like to try some non line-of-sight paths, possibly including cloud-bounce.