Electronic Listening Bugs

You must have come across the term electronic bugs in many popular espionage novels. But what exactly are electronic listening bugs and how are they used? Get answers to the questions in detail.
Techspirited Staff
Last Updated: Aug 8, 2018
Having been fed on a steady diet of spy novels, espionage and counterintelligence novels for a long time, people have a fascination for electronic listening devices, popularly known as bugs. Electronic bugs are used as a form of electronic surveillance and laymen know about them, because of their depiction in spy movies.
In reality they are often used by law enforcement officials to monitor the activities of terrorist groups and organized crime groups. But electronic surveillance devices are not just used by law enforcement officials.
Listening bugs are extensively used for covert operations of intelligence and counterintelligence agencies of various nations to acquire vital information. It is also used for industrial espionage and by private investigators in the course of an investigation.
An electronic listening bug is in essence an assembly of a microphone and a radio transmitter. The microphone receives the sound waves and then converts it into an electrical signal which is then transmitted to the radio transmitter in the bug. The audio signals thus, transmitted can be either heard directly or can be recorded.
How an Electronic Listening Bug Works
There are different types and models of electronic listening devices but all of them have one feature in common, which is their small size. This makes it very suitable to be concealed in any place be it in a pen or a telephone.
Electronic bugs can be essentially classified into three different categories; active listening bug, passive listening bug and wired bug. All of these bugs use radio frequency for transmission. Any other type of bugs that uses highly sophisticated and advanced technology for surveillance have also been invented and are used by secret intelligence services.
As mentioned earlier electronic listening bugs consists of a small microphone and a radio transmitter. The microphone picks up the audio signal from the room (i.e when a person in the vicinity of the bug speaks or any other sound in the room), and then converts these sound waves into electrical signals.
The electrical signals are then amplified and modulated and transmitted by the radio transmitter. One of the basic and simplest of all electronic listening bug is the active bug. In an active listening bug the transmitter of the bug assembly remains active at all times.
In layman's terms, the electronic bug will keep on transmitting any audio signal whether it is voice or otherwise. There is no scope to turn off the device remotely once it starts transmitting the sound waves through the transmitter.
The second type of electronic listening bug is the passive electronic bug. In this type of bug, the bug can be triggered to turn on whenever required and it is one of the most popular electronic bugs or devices used. It can either be activated through sound or it can be activated by an outside signal source.
These type of bugs are rather difficult to detect and they are more frequently used as they are more efficient than active listening bugs. Because these bugs can be turned on to transmit audio signals when required, they are more feasible and efficient.
The person who is doing the surveillance can turn on the device when the subject is in the room speaking of relevant information that is being sought. This helps to save battery life of the bug and also dispels the need to listen in on irrelevant information.
The third type of electronic spy listening device known as a wired electronic bug. It consists of a microphone that is concealed in one location with the transmitter concealed in another location. All electronic listening bugs needs a power source  to work.
Low end models are usually powered by batteries that are inbuilt into the bugging system. However, sophisticated electronic bugs employ a more novel way of obtaining power for its transmission, like leaching power from AC lines of a residence or office building or DC power from a vehicle.
Electronic surveillance is widespread and electronic listening devices are employed to obtain classified information. It is not just law enforcement agencies and secret services that use electronic bugs, but many small and large criminal organizations and industrial organizations use them extensively.
They are also available to purchase online, although there are many federal and state laws that prohibit its use in many countries. Electronic bugs can be detected by listening device detectors and they are many private investigating firms that offer counter surveillance bug sweeps services to detect them.