Over-the-horizon radar
Powerful military radars that bounce signals off the ionosphere to see thousands of miles away. They often spill into shortwave bands, including ham bands.
ModeOver-the-horizon radar
FamilyRadar
Audio exampleComing
What does it sound like?
Plate 44Radar
A rapid, harsh tapping or 'woodpecker' sound, or a fast sweeping buzz.
Field marksHarsh tapping or buzzingSweeps many times a secondWide: often 10 kHz or more
Who uses it?
Defense organizations in several countries.
Where and when can I hear it?
Anywhere from about 5 to 28 MHz; they move frequency often and can be very wide.
Easily confused with
- Time signal station: time stations tick once a second on fixed frequencies