Letter beacon

They have been classified into a number of groups according to transmission code and frequency, and it is supposed that the source for most of them is Russia and began during the Soviet Union.

Their presence became known to the wider amateur radio community in 1978, when beacon "W" started transmitting on 3584 kHz, in the 80 meters band.

[1] In 1982, there were also reports, supposedly based on HF direction finding by the US military, that beacon "K" transmitting on 9043 kHz was located at 48°30′N 134°58′E / 48.500°N 134.967°E / 48.500; 134.967, near the city of Khabarovsk in the USSR.

The following call signs and frequencies of cluster beacons were reported between September 2007 and November 2008 in the Numbers&Oddities newsletter,[8] Utility DX Forum[9] and ENIGMA-2000:[10] Occasionally, some cluster beacons (especially "F" and "M") have been reported transmitting on frequencies different from their regular channel for short periods.

However, the majority of solitary beacons, most notably "P" on various MF and HF frequencies, transmit their single-letter identifier in Morse code.

It was reported in "Numbers and Oddities", issue 142, that beacon C on 8000 kHz also transmitted messages under the regular call sign RIW, which is allocated to a Russian naval communication station in Khiva, Uzbekistan.

They transmitted their Morse code single letter identification by shifting the frequency of the carrier by approximately 1000 Hz.

[5] Robert Connolly also links "P" channel marker with communications facilities at the Russian naval base of Kaliningrad.

[7] "P" transmissions carrying Russian navy "XXX" (flash priority) Morse code messages with call signs RPM and RDL further support this view.