Letter beacon
Encyclopedia
Letter beacons are radio transmissions of uncertain origin and unknown purpose, consisting of only a single repeating Morse code
letter. 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.
They are also often referred to as:
band. There is indirect evidence that this particular transmitter was located in Cuba.
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, near the city of Khabarovsk
in the USSR. A few years later, it was suggested that the “K” beacons were actually located at Petropavlovsk
on the Kamchatka Peninsula and the “U” beacons were located at the Barents Sea
coast, between Murmansk
and Amderma
.
According to D.W. Schimmel, in 1986 the Federal Communications Commission
(FCC) released the following HF direction finding
results for single letter beacons, all of which indicate locations in the USSR:
The link with the USSR and, more recently, Russia is further supported by the existence of single letter beacons transmitting letters existing only in the Cyrillic Morse code alphabet
.
The ENIGMA group also accepted these locations for cluster beacons "C", "D", "P" and "S", adding Vladivostok for beacon "F".
A recent source (2006) regarding locations was published on the Web by Ary Boender. This publication also contains an extensive list of letter beacon frequencies, both current and historical. The following locations are given for cluster beacons:
For solitary beacons and markers, Boender suggests these locations:
Transmissions of the "P" beacon in December 2007, even on medium frequency
(420 and 583 kHz), suggest the Russian naval base at Kaliningrad as a possible source. Kaliningrad officially uses the ITU registered call sign
RMP.
The following call signs and frequencies of cluster beacons have been reported recently (September 2007 to November 2008) in Numbers&Oddities newsletter, Utility DX Forum and ENIGMA-2000:
Occasionally, some cluster beacons (especially "F" and "M") have been reported transmitting on frequencies different from their regular channel for short periods.
A few solitary beacons, like "R" on 4325.9 and 5465.9 kHz, operate exactly like the cluster beacons, sending only their single letter identifier.
However, the majority of solitary beacons, most notably "P" on various MF and HF frequencies, transmit their single-letter identifier in Morse code. Sometimes the routine transmission is interrupted and brief messages are sent in fast Morse code or in an FSK digital mode. Therefore, a more appropriate term for these beacon-like single-letter transmissions is "channel markers" , as their purpose is to occupy and identify a particular HF transmission channel when no traffic is transmitted. There is no evidence that the cluster beacon "P" and the solitary beacon "P" are directly related.
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.
There are also a few oddities transmitting signals with poor modulation and irregular timing, like "V" on 5342 and 6430.7 kHz.
The following call signs and frequencies of solitary beacons and markers have been reported recently (September 2007 to September 2009) in Numbers&Oddities newsletter, Utility DX Forum and ENIGMA-2000:
.
ENIGMA-2000, the internet based ENIGMA successor group, revised the original ENIGMA designators. The current designations for letter beacons are the following (since 2007):
purposes. Some stations of this family, in particular the “U” beacon, have been implicated in deliberate jamming
.
According to ENIGMA, cluster beacons are used by the Russian navy (especially its submarine branch) to find the most suitable radio frequency for contact based on current radio propagation conditions.
Robert Connolly also links "P" channel marker with communications facilities at the Russian naval base of Kaliningrad . "P" transmissions carrying Russian navy "XXX" (flash priority) Morse code messages with call signs RPM and RDL further support this view.
and medium frequency
bands; most of them are listed in appropriate aviation handbooks and their transmission mode is A2A (full carrier with audio modulation).
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
letter. 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.
They are also often referred to as:
- SLB, or "Single Letter Beacons"
- SLHFB, or "Single Letter High Frequency Beacons"
- SLHFM, or "Single Letter High Frequency Markers"
- Cluster beacons
- MX — an ENIGMA and ENIGMA-2000 designation.
Transmission locations
These radio transmissions were discovered in the late 1960s. Their presence became known to the wider amateur radio community in 1978, when beacon “W” started transmitting on 3584 kHz, in the 80 meters80 meters
The 80 meter or 3.5 MHz band is a core amateur radio frequency band, allocated frequencies from 3.5 to 4.0 MHz in IARU Region 2, and generally 3.5 to 3.8 or 3.9 MHz in Regions 1 and 3 respectively. The portion of the band used for phone communications is sometimes referred to as 75 meters...
band. There is indirect evidence that this particular transmitter was located in Cuba.
In 1982 there were also reports, supposedly based on HF direction finding
Huff-Duff
High-frequency direction finding, usually known by its abbreviation HF/DF is the common name for a type of radio direction finding employed especially during the two World Wars....
by the US military, that beacon “K” transmitting on 9043 kHz was located at 48°30′N 134°58′E, near the city of Khabarovsk
Khabarovsk
Khabarovsk is the largest city and the administrative center of Khabarovsk Krai, Russia. It is located some from the Chinese border. It is the second largest city in the Russian Far East, after Vladivostok. The city became the administrative center of the Far Eastern Federal District of Russia...
in the USSR. A few years later, it was suggested that the “K” beacons were actually located at Petropavlovsk
Petropavlovsk-Kamchatsky
Petropavlovsk-Kamchatsky is the main city and the administrative, industrial, scientific, and cultural center of Kamchatka Krai, Russia. Population: .-History:It was founded by Danish navigator Vitus Bering, in the service of the Russian Navy...
on the Kamchatka Peninsula and the “U” beacons were located at the Barents Sea
Barents Sea
The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents...
coast, between Murmansk
Murmansk
Murmansk is a city and the administrative center of Murmansk Oblast, Russia. It serves as a seaport and is located in the extreme northwest part of Russia, on the Kola Bay, from the Barents Sea on the northern shore of the Kola Peninsula, not far from Russia's borders with Norway and Finland...
and Amderma
Amderma
Amderma is an urban-type settlement in Nenets Autonomous Okrug, Russia, located 490 km from Naryan-Mar on the coast of Kara Sea. It was established in 1933. Population: 650 ; 5,100 ; 2,900 . Fluorite deposits are located in the vicinity of Amderma, but the mines have been abandoned since...
.
According to D.W. Schimmel, in 1986 the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) released the following HF direction finding
Huff-Duff
High-frequency direction finding, usually known by its abbreviation HF/DF is the common name for a type of radio direction finding employed especially during the two World Wars....
results for single letter beacons, all of which indicate locations in the USSR:
| ID letter | Location |
|---|---|
| C | Moscow Moscow Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent... , RUS |
| D | Odessa Odessa Odessa or Odesa is the administrative center of the Odessa Oblast located in southern Ukraine. The city is a major seaport located on the northwest shore of the Black Sea and the fourth largest city in Ukraine with a population of 1,029,000 .The predecessor of Odessa, a small Tatar settlement,... , UKR |
| O | Moscow Moscow Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent... , RUS |
| P | Kaliningrad Kaliningrad Kaliningrad is a seaport and the administrative center of Kaliningrad Oblast, the Russian exclave between Poland and Lithuania on the Baltic Sea... , RUS |
| S | Arkhangelsk Arkhangelsk Arkhangelsk , formerly known as Archangel in English, is a city and the administrative center of Arkhangelsk Oblast, Russia. It lies on both banks of the Northern Dvina River near its exit into the White Sea in the north of European Russia. The city spreads for over along the banks of the river... , RUS |
| U | Between Murmansk Murmansk Murmansk is a city and the administrative center of Murmansk Oblast, Russia. It serves as a seaport and is located in the extreme northwest part of Russia, on the Kola Bay, from the Barents Sea on the northern shore of the Kola Peninsula, not far from Russia's borders with Norway and Finland... & Amderma Amderma Amderma is an urban-type settlement in Nenets Autonomous Okrug, Russia, located 490 km from Naryan-Mar on the coast of Kara Sea. It was established in 1933. Population: 650 ; 5,100 ; 2,900 . Fluorite deposits are located in the vicinity of Amderma, but the mines have been abandoned since... , RUS |
| Z | Mukachevo, UKR |
The link with the USSR and, more recently, Russia is further supported by the existence of single letter beacons transmitting letters existing only in the Cyrillic Morse code alphabet
Other alphabets in Morse code
This is a summary of the use of Morse code to represent alphabets other than Latin.-Greek:The Greek Morse code alphabet is very similar to the Latin alphabet. It uses one extra letter for Greek letter "Χ" and does not use the codes for Latin letters "J", "U" and "V".The tonos is not transmitted in...
.
The ENIGMA group also accepted these locations for cluster beacons "C", "D", "P" and "S", adding Vladivostok for beacon "F".
A recent source (2006) regarding locations was published on the Web by Ary Boender. This publication also contains an extensive list of letter beacon frequencies, both current and historical. The following locations are given for cluster beacons:
| ID letter | Location |
|---|---|
| A | Astrakhan Astrakhan Astrakhan is a major city in southern European Russia and the administrative center of Astrakhan Oblast. The city lies on the left bank of the Volga River, close to where it discharges into the Caspian Sea at an altitude of below the sea level. Population:... , RUS (tentative) |
| C | Moscow Moscow Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent... , RUS |
| D | Sevastopol Sevastopol Sevastopol is a city on rights of administrative division of Ukraine, located on the Black Sea coast of the Crimea peninsula. It has a population of 342,451 . Sevastopol is the second largest port in Ukraine, after the Port of Odessa.... , UKR |
| F | Vladivostok Vladivostok The city is located in the southern extremity of Muravyov-Amursky Peninsula, which is about 30 km long and approximately 12 km wide.The highest point is Mount Kholodilnik, the height of which is 257 m... , RUS |
| K | Petropavlovsk-Kamchatsky Petropavlovsk-Kamchatsky Petropavlovsk-Kamchatsky is the main city and the administrative, industrial, scientific, and cultural center of Kamchatka Krai, Russia. Population: .-History:It was founded by Danish navigator Vitus Bering, in the service of the Russian Navy... , RUS |
| M | Magadan Magadan Magadan is a port town on the Sea of Okhotsk and gateway to the Kolyma region. It is the administrative center of Magadan Oblast , in the Russian Far East. Founded in 1929 on the site of an earlier settlement from the 1920s, it was granted the status of town in 1939... , RUS |
| P | Kaliningrad Kaliningrad Kaliningrad is a seaport and the administrative center of Kaliningrad Oblast, the Russian exclave between Poland and Lithuania on the Baltic Sea... , RUS |
| S | Severomorsk Severomorsk Severomorsk is a closed town in Murmansk Oblast, Russia, located about north of Murmansk along the Kola Bay. Population: This is the main administrative base of the Russian Northern Fleet. Severomorsk has the largest drydock on the Kola Peninsula.... , RUS |
For solitary beacons and markers, Boender suggests these locations:
| ID letter | Location |
|---|---|
| L | Tirana Tirana Tirana is the capital and the largest city of Albania. Modern Tirana was founded as an Ottoman town in 1614 by Sulejman Bargjini, a local ruler from Mullet, although the area has been continuously inhabited since antiquity. Tirana became Albania's capital city in 1920 and has a population of over... , ALB (inactive) |
| R | Izhevsk Izhevsk Izhevsk is the capital city of the Udmurt Republic, Russia, situated on the Izh River in the Western Urals. Population: From 1984 to 1987 Izhevsk carried the name Ustinov |Minister of Defense of the USSR]], Marshal of the Soviet Union, Dmitry Ustinov). The city is an important industrial center,... (Ustinov), RUS |
| P | Kaliningrad Kaliningrad Kaliningrad is a seaport and the administrative center of Kaliningrad Oblast, the Russian exclave between Poland and Lithuania on the Baltic Sea... , RUS |
| V | Khiva Khiva Khiva is a city of approximately 50,000 people located in Xorazm Province, Uzbekistan. It is the former capital of Khwarezmia and the Khanate of Khiva... , UZB |
Transmissions of the "P" beacon in December 2007, even on medium frequency
Medium frequency
Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...
(420 and 583 kHz), suggest the Russian naval base at Kaliningrad as a possible source. Kaliningrad officially uses the ITU registered call sign
Call sign
In broadcasting and radio communications, a call sign is a unique designation for a transmitting station. In North America they are used as names for broadcasting stations...
RMP.
Types
The single letter beacons can be classified into two groups, "cluster beacons" and "channel markers". A beacon "P" exists in both groups. A third group, called FSK beacons, is now extinct. The following sections list the beacons currently (December 2007) active, according to published listeners’ reports.Cluster beacons
A group of radio beacons with single-letter identifiers ("C", "D", "M", "S", "P", "A", "M" and "K") have been regularly reported near 3594, 4558, 5154, 7039, 8495, 10872, 13528, 16332 and 20048 kHz. The term "cluster beacons" is frequently used for them, as they transmit in parallel on frequencies only 0.1 kHz apart. These beacons transmit only their single-letter identifier in standard CW (A1A) using Morse code.The following call signs and frequencies of cluster beacons have been reported recently (September 2007 to November 2008) in Numbers&Oddities newsletter, Utility DX Forum and ENIGMA-2000:
| ID letter | Frequencies (kHz) |
|---|---|
| D | 3593.7, 4557.7, 5153.7, 7038.7, 8494.7, 10871.7, 13527.7, 16331.7, 20047.7 |
| P | 3593.8, 4557.8, 5153.8, 7038.8, 8494.8, 10871.8, 13527.8, 16331.8, 20047.8 |
| S | 3593.9, 4557.9, 5153.9, 7038.9, 8494.9, 10871.9, 13527.9, 16331.9, 20047.9 |
| C | 3594.0, 4558.0, 5154.0, 7039.0, 8495.0, 10872.0, 13528.0, 16332.0, 20048.0 |
| A | 3595.1, 4558.1, 5154.1, 7039.1, 8495.1, 10872.1, 13528.1, 16332.1 |
| F | 7039.2, 8495.2, 10872.2, 16332.2 |
| K | 5154.3, 7039.3, 8495.3, 10872.3, 13528.3 |
| M | 5154.4, 7039.4, 8495.4, 10872.4, 13528.4, 16332.4 |
Occasionally, some cluster beacons (especially "F" and "M") have been reported transmitting on frequencies different from their regular channel for short periods.
Solitary beacons and channel markers
A second family of letter beacons includes all those operating outside the clusters. For this reason, they are often called "solitary beacons" or "solitaires". They also transmit their single-letter identifier in standard CW (A1A) using Morse code.A few solitary beacons, like "R" on 4325.9 and 5465.9 kHz, operate exactly like the cluster beacons, sending only their single letter identifier.
However, the majority of solitary beacons, most notably "P" on various MF and HF frequencies, transmit their single-letter identifier in Morse code. Sometimes the routine transmission is interrupted and brief messages are sent in fast Morse code or in an FSK digital mode. Therefore, a more appropriate term for these beacon-like single-letter transmissions is "channel markers" , as their purpose is to occupy and identify a particular HF transmission channel when no traffic is transmitted. There is no evidence that the cluster beacon "P" and the solitary beacon "P" are directly related.
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.
There are also a few oddities transmitting signals with poor modulation and irregular timing, like "V" on 5342 and 6430.7 kHz.
The following call signs and frequencies of solitary beacons and markers have been reported recently (September 2007 to September 2009) in Numbers&Oddities newsletter, Utility DX Forum and ENIGMA-2000:
| ID letter | Frequencies (kHz) |
|---|---|
| R | 4325.9, 5465.9 |
| V | 3658.0, 5141, 5342, 6430.7, 6809, 7027.5, 8103.5, 10202 |
| P | 420, 583, 3167, 3291, 3327, 3699.5, 3837, 4031, 4043, 4079 |
| C | 8000 |
FSK beacons
This group includes the "K" and "U" beacons, which are no longer active. They transmitted their Morse code single letter identification by shifting the frequency of the carrier by approximately 1000 Hz. This mode of "FSK-CW" is designated F1A. The use of FSK indicated that the transmitter was suitable for FSK data transmissions, like radioteletypeRadioteletype
Radioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers running software to emulate teleprinters, connected by radio rather than a wired link.The term radioteletype is used to...
.
ENIGMA designation
ENIGMA devised a naming scheme for all stations in their sphere of interest. In the original scheme, the following identifications were issued to letter beacons:| ENIGMA ID | Description |
|---|---|
| MX | Cluster beacons |
| MXV | Irregular “V” beacons, not in clusters |
| MXS | Solitaires: letter beacons out of cluster bands |
| MXF | FSK beacons (K, U), no longer active in 1995 |
ENIGMA-2000, the internet based ENIGMA successor group, revised the original ENIGMA designators. The current designations for letter beacons are the following (since 2007):
| ENIGMA ID | Description |
|---|---|
| MX | Solitary HF single letter beacons |
| MXI | Single letter beacons in clusters |
| MXII | FSK beacons (K, U), no longer active |
| MXV | Irregular “V” transmissions |
| MXP | Letter beacons also sending messages |
| MXIII | (deleted, merged with MX) |
| MXIV | (deleted, merged with MX) |
Applications
The purpose of the letter beacons is not yet known with certainty. Many theories have appeared in specialized publications, but none is based on documentary evidence. They have been postulated to be radio propagation beacons, channel markers, or beacons used in tracking satellites or for civil defenseCivil defense
Civil defense, civil defence or civil protection is an effort to protect the citizens of a state from military attack. It uses the principles of emergency operations: prevention, mitigation, preparation, response, or emergency evacuation, and recovery...
purposes. Some stations of this family, in particular the “U” beacon, have been implicated in deliberate jamming
Radio jamming
Radio jamming is the transmission of radio signals that disrupt communications by decreasing the signal to noise ratio. Unintentional jamming occurs when an operator transmits on a busy frequency without first checking whether it is in use, or without being able to hear stations using the frequency...
.
According to ENIGMA, cluster beacons are used by the Russian navy (especially its submarine branch) to find the most suitable radio frequency for contact based on current radio propagation conditions.
Robert Connolly also links "P" channel marker with communications facilities at the Russian naval base of Kaliningrad . "P" transmissions carrying Russian navy "XXX" (flash priority) Morse code messages with call signs RPM and RDL further support this view.
Similar systems
A few aero navigation non-directional beacons also transmit single letter identification codes. They can be easily distinguished from letter beacons because they transmit in the allocated low frequencyLow frequency
Low frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...
and medium frequency
Medium frequency
Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...
bands; most of them are listed in appropriate aviation handbooks and their transmission mode is A2A (full carrier with audio modulation).
See also
- Types of radio emissionsTypes of radio emissionsThe International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier...
- Numbers stationNumbers stationA numbers station is a shortwave radio station of uncertain origin. In the 1950s, Time magazine reported that the numbers stations first appeared shortly after World War II and were using a format that had been used to send weather data during that war.Numbers stations generally broadcast...
- RACONRaconA racon is a radar transponder commonly used to mark maritime navigational hazards. The word is a portmanteau of RAdar and beaCON.When a racon receives a radar pulse, it responds with a signal on the same frequency which puts an image on the radar display...
- Secret broadcastSecret broadcastA secret broadcast is, simply put, a broadcast that is not for the consumption of the general public. The invention of the wireless was initially greeted as a boon by armies and navies. Units could now be coordinated by nearly instant communications. It soon became clear that radio was a double...
- Electric beaconElectric beaconElectric beacons are a kind of beacon used with direction finding equipment to find ones relative bearing to a known location .The term electric beacon includes radio, infrared and sonar beacons.- Radio beacons :...
Further reading
- Spooks mailing list.
- Numbers and Oddities: Ary Boender compiles this monthly bulletin with reception reports of various mysterious transmissions and makes it available for download at his personal web site.