How is a Bug Sweep Conducted?

While bug sweeping may look simple on TV, it is actually very difficult to perform. A trained sweeper must use a practiced and learned methodology that can defeat any perpetrator's technology and also any steps they may have taken steps to avoid detection.

The most common and affordable eavesdropping devices emit some type of radio frequency which transmits data. Because of that, a TSCM expert will always start by attempting to detect any radio signal. The eavesdropping device is transmitting a radio signal containing the information being collected, whether it's video, audio or any another type of data. The operator must sweep through all possible frequencies in order to catch the correct radio signal. It's almost like tuning your car radio to catch the news but a bit more complex.

However, that sweep will only catch the most basic of eavesdropping devices because perpetrators will try to avoid detection using techniques other forms, like burst transmission or spread spectrum transmissions.

Burst Transmissions - A type of device that collects information over a period of time and then sends it out all at once in a short burst so the sweeper won't be able to detect the signal unless they're listening at exactly the right time.

Spread Spectrum Transmissions - This device spreads a signal over a larger spectrum of radio frequency than a normal radio transmission, so that the signal is too quiet to be picked up unless the sweeping equipment is specially attuned to catch the correct spread spectrum transmission.


"The best way to put your mind at ease is to know for sure" Detective Raymond C. Ranno

Types Of TSCM Countermeasures Equipment Used

  • Multimeter - A basic scientific tool that can detect electrical currents.
  • Time-domain reflectometer (TDR) - Used to test the integrity of phone lines.
  • Frequency scanner with a range of antennas and filters - Used to scan for radio frequencies
  • Spectrum analyzer and vector signal analyzer - Used for more advanced analysis of threatening and non threatening radio signals.
  • Nonlinear junction detector - Used to detect other hidden eavesdropping devices
  • Portable x-ray machine - Used to look for bugs inside of walls and objects.
  • Computer security devices - Used to detect computer-related threats.
  • Flashlight and traditional tools - These are used when all the high tech gadgets fail and you need to go in manually.

Evidence Chain of Custody

Ranno Investigative Services' company policy is that if any eavesdropping devices are located in your home, car or office, we collect the evidence and attempt to begin a chain of custody record of that item. We photograph the item in its current position as well as videotape the scene and location of the item. We then use gloves to remove the item while recording the event and place the item into a sealed bag and seal the bag with a dated and signed label, preserving the integrity of the item in order for it to be turned over to a local or state police department. You are then provided a full investigative report and copies of the DVD or photographs and any chain of custody logs.

As you can clearly see, bug sweeping is a complicated process that requires not only a large number of electronics, but also the knowledge of how perpetrators operate. We have to anticipate where they would place their bugs and how they would use them in order to catch them.