OVER THE HORIZON RADAR (OTHR).
Over-the-horizon radar, or OTH (sometimes called beyond the horizon, or BTH), is a type of radar system with the ability to detect targets at very long ranges, typically hundreds to thousands of kilometres, beyond the radar horizon, which is the distance limit for ordinary radar.
Over-the-horizon (OTH) radars continue to plague various amateur radio bands.
Over-the-horizon (OTH) radars continue to plague various amateur radio bands.
Jindalee Operational Radar Network (JORN)
OTHR on 40m, September 2018
OTHR during 2018 Harry Angel Sprint.
OTHR on 80m
Over the Horizon Radar on 80m, as seen from a KiwiSDR receiver in New Zealand.
References.
1. Wikipedia, 2020, <https://en.wikipedia.org/wiki/Over-the-horizon_radar>
2. ARRL, 2020, <http://www.arrl.org/news/over-the-horizon-radars-causing-widespread-interference-on-40-meters>