Central Intelligence Agency
The Central Intelligence Agency (CIA), is an independent civilian foreign intelligence service of the United States federal government. The agency is
tasked with gathering, processing and analyzing national security
information around the world, mainly through human intelligence (HUMINT) .
The CIA was established on 31 December 1948 as the
Office of Scientific Intelligence (OSI), by merging the
Scientific Branch of the Office of Reports and Estimates,
and the Nuclear Energy Group of the Office of Special Operations (OSO).
It is also the successor to the Central Intelligence Group (CIG) and,
to some extent, the World War II Office of Strategic Services (OSS).
Although most of the information is gathered overseas, the CIA also collects
some of its data domestically.
The CIA is the only US agency which is authorized by US law to carry out
overseas covert activities on behalf of the President of the United States.
Unlike the Federal Bureau of Investigation (FBI),
the CIA is not a law enforcement agency and has therefore
no legal jurisdiction.
CIA equipment on this website
As a foreign intelligence agency, the CIA has always made heavy use of
so-called covert listening devices,
commonly known as bugs.
In the early days of the electronic espionage tradecraft, such listening devices
were small microphones
that were connected to a listening post
through fixed wires, which is why such a bug is also known as a wire
(even though today many are wireless).
In the periode following WWII, when effectively the
Cold War had begun,
wireless radio bugs were introduced, that were built with a mixture of
miniature valves (tubes) and early transistors. Good example of such bugs
are the SRT-1, SRT-3 and the SRT-5.
The general CIA expression for these devices was Surveillance Radio
Transmitter or SRT.
In most cases these wireless radio bugs were developed by the CIA, or by a third
party on behalf of the CIA. They were neither small nor very sophisticated,
and could easily be detected by someone who was scanning the frequency bands.
In 1952 a mysterious type of listening device was discovered in the study of
the US Ambassador in Moscow. The device had apparently been planted there by
the Soviets in 1945, and was based on a hitherto unknown technology,
which is why the Americans nicknamed it
In a reaction to
this, the CIA initiated a secret research project under the name
which was eventually carried out by the
Dutch Radar Laboratory (NRP)
in Noordwijk (Netherlands).
This research resulted in the development of a series of bugs that did not
need a local power source (such as batteries), but were driven by a very
strong radio signal, the so-called activation beam, from a nearby listening
post (LP). Such bugs were known as Passive Elements or PE,
but they were also identified with the project name Easy Chair
or EC. An example is the EC Mark I.
By the mid-1960s, the technology behind the PE devices was outdated,
as both parties (East and West) had meanwhile developed suitable countermeasures
against them. Furthermore, they had both been complaining about their offices
and embassies being 'bombarded' by the other party, with strong microwave
signals that could potentially cause 'health issues' to their personnel.
From that moment on, a new generation of bugs were developed for
the CIA, mainly by external contractors, such as the
NRP who had previously
made the Easy Chair equipment.
These new SRT bugs were identified by 3-digit numbers,
and introduced audio-masking techniques that made detection of these
devices extremely difficult.
Examples of such audio-masking techniques are
subcarrier modulation, hum-injection and
noise controlled pulse position modulation.
The image on the right shows an
SRT-107 with its antenna,
which uses the latter audio-masking technique.
Devices like the SRT-107
were not particularly small by today's standards, but were really
state-of-the-art when they were first introduced.
They could be fitted in a pre-drilled 1 1/8" hole
and were commonly embedded in a building or inside furniture.
It was the CIA's intention to regularly introduce new audio-masking
and modulation techniques, to defeat the Soviet countermeasures.
Development of special surveillance equipment was sometimes carried out
by the CIA's Technical Services Division (TSD), but more commonly by
third parties under CIA contract. In the latter case, the project names
and designators were always assigned by the CIA. Project numbers consisted
of a three letter prefix, followed by 1, 2 or 3 digits. For surveillance
radio equipment, the project designator was generally of the form SRS-150,
in which SRS means Surveillance Radio System.
In such radio systems, receivers are commonly identified with the letters SRR
(Surveillance Radio Receiver), e.g. SRR-150, and transmitters are known
as SRT (Surveillance Radio Transmitter), e.g. SRT-150. Below is a
non-exhaustive overview of known receivers and transmitters (bugs) that follow
these rules. Devices developed under the
Easy Chair (EC) contract
between 1954 and 1960, are an exception to this rule. These devices
commonly have the letters 'EC' in their name.
The following receivers were developed by or for the Technical Services
Division (TSD) of the CIA:
- 50-200 MHz
- 50-400 MHz
- 30-1000 MHz
SRR-100Covert surveillance monitor
1956Easy Chair Passive Element (PE) via radio
1957Easy Chair Passive Element (PE) via telephone line
1958Easy Chair Passive Element (PE) with extended performance
1959Easy Chair ?
1960Multi-channel Easy Chair
1960Wired bugging of on-hook telephone sets
?First generation radio bugs (peanut tubes and transistors)
?Rarely used version
1959All transistor 5 mW bug at the size of a pack of cigarettes
1967300 MHz with audio masking
1969300 MHz with audio masking
1967230-250 MHz with audio masking and switch receiver
?Car Overhearing (CO) bug
1975300 MHz wit SC/Noise audio masking
19741500 MHz bug with sophisticated RP audio masking
Standard continuously-operated FM or AM radio bugs are easily found with a
surveillance receiver that is suitable for the frequency range in
which the bug operates. In addition they can be found accidently by someone
who is searching the frequency spectrum, or as a result of RF interference
with ordinary domestic equipment, such as radio and television sets.
For this reason, the more professional bugs have some kind of audio
masking. Most masking techniques involve the use of subcarrier
modulation (SC), which is easily defeated by a suitable bug tracer.
Others involve the introduction of sophisticated novel modulation
techniques, such as pulse position modulation.
SCAudio modulated onto a subcarrier
SC/HumAudio modulated onto subcarrier, hum injected in the audio band
SC/NoiseAudio modulated onto subcarrier, noise injected in the audio band
PPMPulse position modulation
PPM/RPPulse position modulation with Random Pulse (RP) rejection
PPM/TPPulse position modulation with Tripple Pulse (TP)
PPM/DPPulse position modulation with Dirty Pulse (DP) masking
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