Physical Search Efforts
The third part of a sweep is a detailed visual search of the area. This will reveal eavesdropping devices that RF sweeps and telephone testing will not find. Typical devices that can only be found by a visual inspection are:
Audio recording devices including digital recorders.
Loudspeakers used for paging and fire alarm annunciation which can be used as microphones.
Dormant RF transmitters
Remotely controlled RF transmitters
Covert video cameras
Contact and spike microphones
Audio leakage paths to other areas- through floors, ceilings, and walls
Vulnerability of the area to external audio intercept devices like IR and laser listening systems.
To make the search thorough and exacting we use a variety of equipment. Some are highlighted below:
Video Inspection Tool
We use this to see into inaccessible places where listening devices can be hidden. Places like HVAC ducts, radiators and air terminal units, and lots of other areas.
Our cameras are equipped with IR LEDs to illuminate dark areas. Because they are sensitive in IR wavelenghts, our cameras will detect infrared transmitters operating in the area.
We also use borescopes and flexible optical and video fiberscopes.
Nonlinear Junction Detector
NJDs are used to detect electronic devices. They use a radio frequency technique to indicate the presence of transistors, diodes, and other semiconductor components. We use the most powerful and sensitive NJDs available in the US.
Our equipment inventory includes a high gain audio amplifier. We test low voltage wiring, speakers and PA systems for room audio. With its contact microphone, we can test wall surfaces, plumbing, and HVAC installations for the ability to pass room audio out of the area.
We use infrared thermal imaging to aid in the detection of hidden devices.
The thermal imager reveals the tiny amounts of heat radiated by many
types of eavesdropping devices.
Click on the picture for more information.
What are we looking for?
These are two miniature microphones used in audio surveillance devices. In normal life, they're used in hearing aids. Imagine trying to find one of these in your office. You have to rely on trained, skilled personnel with the right equipment to be sure the area is clean. Simple detection gadgets won't find it and untrained sweepers won't recognize the installation methods or symptoms. Click on the picture for other miniature microphone photos.