| The home security motion detector is the where the | | | | Dual Tech |
| entire home security system is activated. These are | | | | One of the challenges in motion detectors comes |
| the "input" points for the entire system. They initiate | | | | from household pets. How do these sensors |
| the signals that result in the alert or the alarm being | | | | discriminate between the movement of a person and |
| triggered. These sensors come in a variety of types | | | | that of a dog or cat? Dual tech sensors combine the |
| and are based on various technologies. Quite frankly, | | | | infrared with microwave technology (below) and are |
| choosing the appropriate sensors is a critical step in | | | | better able to be set to ignore animal movements. |
| planning your home security system. | | | | Microwave |
| Magnetic | | | | These sensors emit microwave energy to detect |
| These are the most common sensors in home | | | | movement. Some properties of microwave energy |
| security and are used as door and window alarms. | | | | do not make it suitable for most home applications |
| The device is installed so that a circuit is created | | | | (such as penetrating through walls to pick up motion |
| when the door or window is shut. When opened, the | | | | in other rooms). Most commonly it is found as an |
| circuit is broken and the security system is triggered. | | | | automatic door sensor as you have seen in many |
| Infrared | | | | businesses. |
| Motion detectors are the second most common | | | | Ultrasonic |
| sensors in home security systems and infrared | | | | These sensors are either active (emitting high |
| sensors are the most frequently used. Sometimes | | | | frequency sound) or passive (detecting sounds). |
| called PIR (passive infrared) sensors, they are able to | | | | These sensors are among the most sensitive and |
| detect radiated body heat. The cheapness and | | | | therefore among the most expensive. They are not |
| reliability of this sensor has made it standard in most | | | | used in typical residential applications. |
| security systems. | | | | The purpose of all home security motion detectors is |
| Shock (or Glass Break) | | | | to first, detect motion, then to send a signal to the |
| More commonly known as glass break sensors, these | | | | systems control panel which will in turn trigger the |
| actually detect the shock wave created from | | | | appropriate alert (a siren, a chime, a light, a phone |
| breaking a window. These devices are also known as | | | | call, etc.) The most common combination of sensors |
| "acoustic" or "sound" detectors. Often they are used | | | | in a standard security system are magnetic and |
| as a redundant monitor for the magnetic sensors | | | | infrared detectors. |
| mentioned above. | | | | |