New 481THz QRSS3 beacon ready for action

Completed 481THz beacon electronics

This afternoon I finished off the electronics build of the new dual frequency optical beacon TX for 481THz (red light) over-the-horizon (NLOS) tests. In the end I opted for QRSS3 on a choice of 2 sub-carrier frequencies selected by toggle switch together with the option of a continuous sub-carrier transmission on either frequency to help beam alignment. I have not incorporated an FSK facility at present. All that remains is to align my sighting scope with the optics so that I can use this to help with aiming. Currently the beam appears off-centre in the spotting scope cross-hairs.

As I now have the option of a lower sub-carrier frequency, I need to revisit the improved RX to see if I can better optimise sensitivity at the lower frequency. Theoretically the detector should be several dB more sensitive at a lower sub-carrier frequency which should help with NLOS tests where signals are weak.

The beacon is powered by a 19.5V 4.5A ex-Dell laptop SMPSU, although I only need around 300-400mA with the current LED, which is exceedingly bright.  In the picture above you can see the BACK of the LED and that is pretty bright. At least with the PSU the whole beacon is self-contained.