The Air Horn: a long blast on 4930 kHz from Smolensk, now silent

What you hear

When it was on the air, the station held 4930 kHz with a long, flat blast like a horn, repeated at a steady pace around the clock. The nickname needs no explanation. Compared with the Pip's tick or the Squeaky Wheel's scrape, the blast is slow and heavy, and in that part of the band it is not easily mistaken for anything else.

In December 2023 the sound changed: the frequency began carrying the same honking marker as the Goose, the station near Smolensk that lives on 4310 and 3243 kHz. Whether that meant two channels sharing one marker generator, a reorganisation of the net, or something else again, nobody outside the system knows. At the time of writing the frequency is quiet, and the catalogue lists the station as inactive.

Who transmits and why

The transmitter is placed near Smolensk, in western Russia, and the station belongs to the same family of channel markers as the Buzzer, the Pip, the Squeaky Wheel, the Goose and the Alarm. The purpose of such a marker is well understood in general terms, even if nobody has confirmed it for this station in particular: it keeps a frequency occupied for a net that may need it at any moment, tells the stations of that net that the channel is alive, and makes interference obvious. The net is assumed to be military. Beyond that, little is known about the Air Horn, and this article does not pretend otherwise. Its history is short, it did not become known for its voice traffic, and most of what is documented about it is the sound and the dates.

Markers like this one appear and vanish as the networks behind them are rebuilt. Listeners keep a chronicle of them, noting when a sound starts, changes or stops, and that chronicle is the only history these stations have. The Air Horn's chapter in it may be finished, or it may be between chapters.

Listening to it, when it is there, is simply receiving a signal sent openly in the clear.

When and where to listen

The frequency to check is 4930 kHz, and unlike most of its relatives the station did not use a separate night frequency: it stayed put around the clock. 4930 kHz is in the 60 metre range, which covers a few hundred kilometres by day and reaches much further after dark. The receivers that heard it best were in the Baltic states, Poland, Finland and Sweden; from western Europe it was a night-time signal. There is a broadcasting band around 4900 kHz, so weak distant broadcasters can sit nearby in the evening; the marker, when present, is unmistakable.

USB, as the program sets it, is right for an AM-compatible marker; AM also works. Expect silence, and treat anything you hear as news.

In ShackDeck

Station catalogue → Mystery stations → The Air Horn. The program picks a public receiver that covers 4930 kHz, tunes it and sets USB. No receiver, antenna or account of your own is needed. An empty waterfall on the frequency is the expected result for now; check back occasionally, because this family of stations has a habit of returning.