Aradiolistening station (also: listening post, radio intercept station or wireless intercept station, W/T station forwireless telegraphy) is a facility used for militaryreconnaissance, especiallytelecommunications reconnaissance (also known assignals intelligence SIGINT) by "intercepting" radiotransmitter communications. In contrast to the originaleavesdropping on anacousticspeech conversation, radio eavesdropping stations are used to eavesdrop on theinformation transmittedwirelessly usingradio technology. For this purpose, highly sensitiveradio receivers and suitablereceiving antennas are used (see images).
AfterHeinrich Hertz (1857–1894) succeeded in 1886 as the first to generate electromagnetic waves in theultra-short wave range, andGuglielmo Marconi (1874–1937) around 1900 was able to increase the range of his radio transmissions to hundreds of kilometers, thusradiotelegraphy technology was used in theFirst World War (1914–1918), for example: within theGerman Imperial Army, theImperial Russian Army (with fatal consequences in theBattle of Tannenberg due to intercepted Russian radiogram traffic by Germany and Austria),[1] and inaeronautical radio communication. Conversely, France was already using theEiffel Tower, which was closed to the public during the first year of the War, as a radio listening station to interceptwireless telegraphy (see image). There, in addition to other French listening stations, encrypted wireless telegraphy messages from the Germanwestern front were intercepted, the message content of which would later be deciphered, notably by FrenchmanGeorges Painvin. This includes the so-calledRadiogram of Victory (Radiogramme de la Victoire); theADFGVX-telegram cipher used by the German Imperial Army.
In theinterwar period between the end ofWorld War I and the beginning ofWorld War II,radio technology had developed considerably and was now used extensively by all warring parties. Detection and evaluation of radio transmissions had become all the more important and were operated by all sides. The encrypted German communications (Enigma,Lorenz, etc.), which were intercepted by British radio listening stations around the world, were of vital importance to the war effort.
Dozens of so-called Government Communications Wireless Stations (GCWS), orY-stations for short which had initially been established duringWorld War I,[2] and theAdmiralty Civilian Shore Wireless Service (ACSWS), were used by the British for this purpose, inGreat Britain and elsewhere.German Intercept Station Operations during World War II were comparable, albeit less effective, in the form of theGeneral der Nachrichtenaufklärung (General Intelligence Service) of theGerman Army and theB-Dienst (observation service) of theKriegsmarine (German Navy).
With the approach of theCold War, modern radio listening stations established themselves on both sides of theIron Curtain, especially in the dividedAllied-occupied Germany. Up until 1989, for example, there were two powerful monitoring systems on the summit of theBrocken, which lies directly on the formerinner German border. One belonged to the Soviet military secret serviceGRU and was thus also the westernmost outpost of theSoviet Union, the other was subordinate to the main Department III (radio reconnaissance, radio defense) of the Ministry for State Security (Stasi) of theGerman Democratic Republic (GDR). The stations had the code names "Yenisei" and "Urian", the latter colloquially known as the "Stasi mosque" (Stasi-Mosche). After 1989, a much larger listening complex was planned on the Brocken summit, which was no longer implemented due to the fall of theBerlin Wall and thepeaceful revolution in the German Democratic Republic.
During the Cold War period, theUnited States Army Security Agency built an airspace surveillance and listening station on the man-made hill calledTeufelsberg, located in the formerWest Berlin region ofWest Germany, to listen to Soviet, East German and otherWarsaw Pact nations' military radio communications traffic.[3][4] The listening station named Field Station Berlin (also known as USM 620 Kilo) was mainly operated by the USNational Security Agency (NSA) and served as part of the worldwide surveillance networkECHELON.[4] The installation was also shared with theBritish Army 26th Signal Battalion and13th Signal Regiment since it was located in theBritish occupation zone. During theGerman reunification process in 1989 and 1990, the facility's electronic equipment was removed and the amassedclassified information archives destroyed as it had become redundant with the end of the Cold War. In 1991 the US and British withdrew from Teufelsberg, and theSenate of Berlin sold the 4.7-hectare (12-acre) area of the listening station for 5.2 millionDeutsch Mark to a private investor consortium.[3][4]
A so-called "listening station" in the corner building onMittelstrasse/Neustädtische Kirchstrasse inBerlin centre (Mitte-district), was believed to have been used between 1977 and 1989 by the East German Ministry for State Security (Stasi) to listen to theAmerican embassy on the opposite side of the street.[5]
Thesuperpowers and their allies in particular still operate a wide-ranging network of eavesdropping listening stations around the world. One of the most famous isECHELON, which is operated by theintelligence agencies of theUnited States,United Kingdom,Canada,Australia, andNew Zealand. Another is the SwissOnyx interception system, andFrenchelon used byFrance.
Stationary radio listening stations inGermany are, for example, theFederal Intelligence Service (BND) outposts located inBad Aibling andGablingen; both are former US listening stations built during the Cold War inAllied-occupied Germany and are now operated by the German Federal Intelligence Service (BND). InEngland,RAF Menwith Hill should be mentioned,[6] includingBBC Monitoring atCrowsley Park andGovernment Communications Headquarters (GCHQ) inCheltenham.
There are also mobile radio listening stations, such as specially adapted radio intercept road vehicles and mobile field tent stations,[7][8][9]reconnaissance ships or specialreconnaissance aircraft for telecommunication reconnaissance.[7]
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