How Spy Gear Works

­Surveillance can be a powerful tool in the hands of criminals, too. If a burglar wants to steal from a particular house, for instance, he or she doesn't simply walk in through the front door whenever it's convenient and start taking valuables. Chances are the burglar monitors activity around the home, checking to see when its owners come and go and how often the house is left empty. If the burglar is very precise about gathering information, he or she might use surveillance equipment to spy on the house.

But for almost every type of spy gear, there is what's called countersurveillance, or CS. When someone gathers information on an unsuspecting person using spy gear like audio and video surveillance, the one doing the spying is on the offensive and is actively seeking out intelligence. But if the person under surveillance somehow becomes aware of suspicious activity and wants to stop or confuse the one keeping an eye on him, he has the option to go on the defensive and use countersurveillance devices.

Various countersurveillance gadgets perform a variety of different tasks, but most are built to scramble, confuse or detect any type of hostile technology that might be in use as a spy tool. CS devices focus on combating video and audio surveillance that's installed covertly, and these specialized devices have the ability to find the location of a transmitter and identify the kind of signal it emits.

So how do you know when to use countersurveillance equipment? Paying close attention to four simple details -- time, environment, distance and demeanor -- can uncover someone if that person is sloppy in his surveillance techniques. How much time a person spends in an area could potentially give him away. The location, or environment, and the distance at which someone stays are also important. If you consistently spot someone parked down the street at odd hours of the night, for instance, you might have reason to think the stranger is conducting surveillance. How a person acts, or his demeanor, can also give someone away. A frequently nervous individual could inadvertently show concern over getting caught. Once you have good reason to believe a person or an area is under surveillance, it's probably time to use the necessary CS equipment.