Mouchard électronique

A covert listening device, more commonly known as a bug or a wire, is usually a combination of a miniature radio transmitter with a microphone. The use of bugs, called bugging, or wiretapping is a common technique in surveillance, espionage and police investigations. Self-contained electronic covert listening devices came into common use with intelligence agencies in the 1950s, when technology allowed for a suitable transmitter to be built into a relatively small package. By 1956, the US Central Intelligence Agency was designing and building "Surveillance Transmitters" that employed transistors, which greatly reduced the size and power consumption. With no moving parts and greater power efficiency, these solid-state devices could be operated by small batteries, which revolutionized the process of covert listening. A bug does not have to be a device specifically designed for the purpose of eavesdropping. For instance, with the right equipment, it is possible to remotely activate the microphone of cellular phones, even when a call is not being made, to listen to conversations in the vicinity of the phone. Among the earliest covert listening devices used in the United States of America was the dictograph, an invention of Kelley M. Turner patented in 1906 (US Patent US843186A). It consisted of a microphone in one location and a remote listening post with a speaker that could also be recorded using a phonograph. While also marketed as a device that allowed broadcasting of sounds, or dictating text from one room to a typist in another, it was used in several criminal investigations. A "wire" is a device that is hidden or concealed under a person's clothes for the purpose of covertly listening to conversations in proximity to the person wearing the "wire". Wires are typically used in police sting operations in order to gather information about suspects. The act of "wearing a wire" refers to a person knowingly recording the conversation or transmitting the contents of a conversation to a police listening post.