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Covert listening devices

This part of the website is dedicated to small devices that are used to covertly record or intercept a conversation. Such devices are commonly known as bugs and are usually hidden inside the room where a conversation takes place, but may also be hidden inside a wall or work through it.

According to Wikipedia, a bug is a covert listening device [1]. Although many bugs have a built-in transmitter (radio bug), this is by no means mandatory. They can also be wire-based (wire bugs) or connected to existing devices (wire tap bugs). Some bugs are in fact recording devices that are collected after the conversation has taken place. Some modern bugs have a built-in video camera and a TV-transmitter, allowing the conversation to be viewed in a nearby room as well. Some devices are available from commercial shops and websites, such as The Spy Shop and eBay, whilst others are made especially for government agencies and are not available to the general public.

Bugs on this website
The Thing, also known as The Great Seal Bug, planted by the USSR in the office of the American Ambassador. British resonant cavity microphone, similar to The Thing Secret CIA research project to develop Passive Bugs, carried out by the NRP in The Netherlands Transistorized Russian bug used by the KGB around 1964 Easy Chair resonant cavity microphone 290 MHz bug with TP audio masking 350 MHz bug with RP audio masking Rectangular version of SRT-56
1500 MHz bug with RP audio masking Low-power version of the SRT-91 Miniature 350 MHz transmitter (bug) with Dirty Pulse (DP) audio masking Subcarrier modulated bug from another contractor Minature 290 MHz transmitter (bug) with SC audio masking Minature 70 MHz switch-receiver Subminiature transmitter developed as part of the Super Pulse project Soviet bug inside IBM Selectric typewriter - Operation GUNMAN
Using a regular telephone set as a bug - even when the handset is 'on-hook' Simple commercial and self-build FM radio bugs Spy-Shop PS-006 Ballpoint Bug with free-running FM transmitter Spy-Shop PS-002 Sugar Cube Bug with free-running FM transmitter Telephone microphone radio bug Subminiture transmitter that can be hidden in the knot of a necktie A.T.E.T. S-35 subminiature covert listening transmitter (radio bug) Audiotel SCX subcarrier radio bug
Professional crystal-based Mactron FM radio bug Mactron Mark II bug with built-in microphone pre-amplifier Mactron Beacon for tracking and tracing Telephone line bug based on a Mactron FM transmitter Dummy bug, formed by a silicium ciode, in the shape of a hockey puck Audiotel MCX Power Line Bug
Professional RF bug hidden inside the enclosure of a power adapter Audiotel wall probe microphone with extremely sensitive amplifier
Czechoslovakian radio bug Sophisticated masked subcarrier bug found at an OPEC conference in the late 1970s Bulgarian telephone line-carrier bug East German wired audio bug 'Bremen 20' used by the Stasi DDR telephone line carrier bug Stasi wired audio bug (NF) Long-range DDR miniature 375 MHz radio bug with microphone Short-range DDR miniature 950 MHz radio bug with built-in microphone
Medium-range DDR miniature 950 MHz radio bug with pre-amplifer Long-range DDR miniature 950 MHz radio bug with power amplifier Mobile 972 MHz bug with subcarrier audio-masking (DDR & Bulgaria) RF bug 31217-132 (Botond) concealed in piece of wood RF bug 31217-1 in vertical stick (950 MHz) High-performance mercury batteries developed for the CIA's bugs

 Index of bugs
 Bug finding equipment

Complete surveillance systems
CIA surveillance system SRS-35 CIA surveillance system SRS-52 CIA surveillance system SRS-56 CIA surveillance system SRS-91 CIA surveillance system SRS-153 Path loss survey system Path loss survey system (wideband) Path loss survey system (narrowband)
Related subjects
Central Intelligence Agency (USA)
SRR-52 listening post receiver SRR-56 listening post receiver Improved modular surveillance receiver (vertical model) Improved modular surveillance receiver (horizontal model) Modular surveillance receiver for RP and DP masked bugs SRR-145 down-converter SRR-153 surveillance receiver
Rohde & Schwarz EB-100 portable surveillance receiver Czechoslovakian VHF or UHF bug receiver Special receiver for BODIL B1 carrier bug Wire tapping (eavesdropping on landlines)
Audio masking
Professional radio bugs often feature a technique known as audio masking, or just masking, to hide the intelligence from casual eavesdroppers as well as professional sweep teams. Masking commonly involves techniques like subcarrier modulation and Pulse Position Modulation (PPM).

 More about audio masking

Example of subcarrier modulation )SC). Click for further information.

Help us expand this section
This section of the website is by no means finished or complete. We are still looking for additional bugs to expand our collection and show them on the website. We are particularly interested in bugs that were used by the Stasi, the secret police of the former DDR (East Germany). If you have any bugs or related devices that are not shown here, please contact us.

Four different versions. From front to rear: the original Mactron, the Beacon, the Mark II and a prototype of the Mark III

  1. Wikipedia, Covert listening device
    Retrieved April 2013.
Further information
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Crypto Museum. Created: Monday 29 April 2013. Last changed: Friday, 19 October 2018 - 20:28 CET.
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