The woodpecker came back, and it is on your band
2026-03-12 · EA5IYR
If you have tuned around 14 MHz and heard a rapid, mechanical knocking march across the band, you have met an over-the-horizon radar.
Listeners of a certain age will recognise the sound. The Soviet Duga system, active from 1976 to 1989, was nicknamed the Russian woodpecker for exactly this noise. Its modern successor, the 29B6 "Container", sounds much the same. Why it has to be so loud
Ordinary radar is line of sight. It cannot see past the curve of the Earth, which is a hard limit on early warning.
Over-the-horizon radar gets around this the way shortwave broadcasting does — by refracting off the ionosphere.
That buys enormous range: Container reaches around 3,000 kilometres. The transmitter sits near Gorodets in Nizhny Novgorod Oblast; the receiving array is about 300 km away near Kovylkino, in Mordovia. They are separated because a receiver that sensitive cannot sit next to a transmitter that powerful.
The catch is that the ionosphere only refracts HF. To use it you must transmit in the 3–30 MHz band — the same spectrum as international broadcasters, aeronautical and maritime traffic, and every amateur allocation there is. What it actually does to the band
The signal has been logged roughly between 9.2 and 19.7 MHz. It runs about 40 pulses per second with a bandwidth near 14 kHz, using frequency modulation on pulse. It can put multiple beams on multiple frequencies at once, which is why it can appear in several places at the same time.
Fourteen kilohertz is wide. A shortwave broadcast channel is around ten; an SSB voice channel under three. When the radar lands on you, it does not degrade the channel — it takes it.
As of 2026 there are two operational systems, with at least one more planned. Nobody is doing anything wrong, exactly
This is what makes HF interference politically strange. There is no international body that can simply order a strategic early-warning radar off a frequency. Coordination happens, complaints get filed, and the radar keeps running, because the country operating it has decided that seeing 3,000 kilometres matters more than a clear band.
Shortwave has always been a commons with no enforcement. Most of the time that works, because most users are trying to be heard rather than to deny. A radar is not trying to deny anything either — the interference is simply the cost of the physics. Hearing it yourself
Tune slowly across 14 or 15 MHz on a WebSDR in Eastern Europe and listen for a knocking that sweeps and stops rather than fades. Once you have heard it you will never mistake it for anything else.
If you log it, note the frequency and the time in UTC. Which frequencies these systems use, and when, is not published by anyone — it is known because listeners write it down.
---
Sources: Wikipedia, Radartutorial, GlobalSecurity, Signal Identification Wiki.