Sensors are one of the most overlooked components of any security system. Without them you might not know that a burglar had just broken into your business, the temperature in the computer room was rising to dangerous levels or that a burst water pipe was flooding your data center. Sensors detect things and then initiate an alarm, turn devices on or off or contact a central station for help from first responders. Here’s a look at some of the most common sensor types:
- Magnetic contacts, based on a simple open/close electric circuit, are used most often on doors and windows. A switch is mounted to the door or window and held closed by a magnet. When the door/window is opened so is the switch, which in turn sends an electric signal to an alarm panel.
- Glass break detectors listen for sound or the shockwaves glass makes as it’s broken.
- Shock sensors detect movement caused by force or pressure changes if an intruder attempts to enter a building by force or by cutting a windowpane for example.
- Panic buttons are widely used on campuses and in bank and retail operations enabling employees to immediately contact first responders for emergency assistance. These devices may also take the form of a key fob or wearable pendant.
- Environmental sensors detect temperature changes or indicate the presence of water.
- Motion detectors are one of the more commonly used and important types of sensors. They detect a person moving inside a building or along a perimeter. They typically use either radar/ultrasonic or passive infrared technologies to do their jobs. If something disturbs the device’s reflection pattern a signal is sent to the alarm panel.
Most of today’s sensors are available in both wired and wireless versions. Typically, wired sensors are less expensive. But there may be increased installation costs to run wire from the sensor to the alarm panel. Wireless sensors are more flexible in how they can be positioned, making them ideal for remote sites or historical buildings where preserving the structure is critical.
Many sensors are now being embedded with intelligence that helps them distinguish between threatening and non-threatening situations. For example, a fly on the lens of a non-intelligent motion detector can look the same as a six-foot man standing seven feet away. Advanced sensors can tell the difference.
Newer motion detectors have five dimensions (5D) of signal processing that involves the analysis of an object’s shape, size, speed, duration in an area and environmental factors. The 5D processing provides optimal discrimination between a low-speed intruder and environmental signals such as reflected sunlight. The sensor’s sophisticated algorithms, using pattern analysis, can even determine an intruder’s motion direction.
Sensors will continue to evolve to help stay ahead of intruders. We’ll see accuracy increase with advances such as 5D technology. Sensors will be available in ever-smaller sizes. Sensor costs will continue to fall. Wireless sensors will become more prevalent. And look for sensors to become available for a wider range of uses.