Fifty-one years ago, Herman James, a North Carolina mountain man, was drafted by the Army. On his first day in basic training, the Army issued him a comb. That afternoon the Army barber sheared off all his hair.
On his second day, the Army issued Herman a toothbrush. That afternoon the Army dentist yanked seven of his teeth.
On the third day, the Army issued him a jock strap.
The Army has been looking for Herman for 51 years.
There are three types of devices used for remote electronic room surveillance: transmitters, microphones, and PLD’s, or passive listening devices.
Transmitters, or more properly, a transmitting device, contains a microphone, a transmitter, and a power source. A high tech, state of the art clandestine transmitter could be as small as one-quarter inch on each side, with a built-in antenna. Depending on the environment, weather, and frequency, it could transmit reliably one-half to three-quarters of a mile. Obviously, the surveillance team would not be hindered by wires if they used this type of device.
Microphones, as you probably know, come in just about any configuartion you can imagine. Basically, a microphone is either wireless or wired. Next time you watch television, notice what I mean. Notice how a person might walk around with a wireless mike in her hand, with the little external antenna poking out of the bottom. Or, she may be wearing a lapel mike, with a cord running to a power pack and transmitter, about the size of a package of cigarettes, concealed behind her back. Be aware, however, that the microphone itself is probably no larger than your pinky nail. The rest of the space is taken up by the circuitry and the battery. Most of the battery-driven devices have an on/off switch to conserve the battery.
Another configuration of a miniature battery-driven (or “wireless”) device might be the “body wire” used by undercover agents. The power source on these devices has no switch. You can imagine why.
Wired microphone are a real challenge to emplace. However, they are extremely reliable, provide high fidelity for recording (at a remote monitoring site), and can last indefinitely. They are normally powered by a host source. That means that the buggee (party being bugged) provides the electricity so that the bugger (person doing the bugging) can do the job. (Isn’t that poetic? I am listening surreptitiously to your most intimate conversations, while you provide the power source for my listening devices!)
The PLD’s do not transmit at all unless they are interrogated or actuated by an outside signal. (This concept is applied as well in the Voice Actuated microcassette players that are used as telephone recording devices.) This passive feature makes a room bug almost impossible to detect except by physical examination. Good for bugging embassies. And company presidents. And contract negotiators. And limousines….
Speaking of high tech, don’t all these devices need antennas, and aren’t antennas several yards long?
Yes they do and no they are not. An antenna is cut and trimmed according to the frequency to which it must respond. The length can be mathematically miniaturized. The micro-mini devices carry built-in antennas that have been mathematically trimmed. And by the way, all those electric cords and interior wiring you have in your office and home are great antennas. Any line that carries alternating current (ac) will carry a radio frequencyt (rf) signal as well. For example, ye olde cheapo intercom systems: plug ‘em into the wall outlet, press the button, and talk. How do you think your conversations are transmitted? Rf on ac!
One more thing. Any wire that is carrying an rf signal emanates that signal within the space surrounding the wire itself. This concept is related to the physics phenomenon of inductance. In plain terms, it means that an eavesdropper does not have to physically attach bug wires (properly called an interceptor device) to a transmitting set of wires (like telephone lines in a phone closet in a large office building). In fact, to do so might change the electrical characteristics — the impedance — of the phone line. Instead, he would just need to find the right set of wires and magnetically secure an inductive listening device to the wires with electrician’s tape.
This same method used be frequently used by industrial espionage agents that could gain surreptitious access to target office suites. They would remove the backs of selected telephone sets, emplace the little SED, and close up the back of the set. The quiescent bug, not electronically involved with the telephone line, would not change the impedance of the line, and could remain undetected indefinitely.
Meanwhile, back at your place….
While this series will continue, I understand that you may have questions that I do not address in the blog. Or perhaps you simply do not want the world to know your business. If you would like to correspond with me directly, at PITORRI AND ASSOCIATES, LLC, by all means do so by email at email@example.com.
Next time: What about computers? Are they vulnerable to eavesdropping?