Over The Horizon Radars (OTHR) are used by the military of several countries to detect planes and ships in distant locations.
While tuning across the 10 metre beacon band today, I came across an OTHR signal with a buzzing noise on 28.222 MHz. I used the FT8 waterfall display on WSJT-X to see what the signal looked like...
The Green horizontal lines are just the 15 second time stamps from the programme. What's of interest here are vertical lines which are spaced about 50 Hz apart. As you can see, it switches off at 08:44 UTC.
This is a video I found on YouTube which has a recording of the same type of signal but at a lower frequency....
