What Makes a Motion "Dual Tech"?

A motion is "Dual Tech" if it uses both passive infrared (PIR) technology and microwave technology to detect the presence of motion. Both the device's PIR sensor and its microwave sensor must be triggered in order for an alarm event to occur. This is good for reducing false alarms.

When thinking about a dual tech motion detector, both PIR technology and microwave technology should be considered. This is because a dual tech motion includes two separate sensors. One sensor is used for detecting changes in infrared energy, and the other uses microwave signals. Unless both of these sensors are triggered, an alarm event will not occur. Dual technology sensors are used in areas where an environmental factor, such as sunlight that could quickly raise the IR energy level in an area, might sometimes cause a PIR-exclusive sensor to produce a false alarm. This type of environmental change will not activate the microwave portion of the sensor.

A PIR sensor works by looking out for changes in infrared energy. When the sensor first activates, it will take note of the current infrared energy in its detection area. If a significant new mass comes into the view of the sensor, it will result in a sharp change in detected infrared energy. This will cause the PIR sensor to activate. The sensitivity of the PIR sensor can be adjusted by increasing or decreasing its pulse count. A higher pulse count will make the PIR sensor less sensitive, while a lower pulse could will cause the PIR sensor to respond more easily.

A microwave sensor continuously sends out microwave signals to detect motion. These microwave signals are sent out and away from the motion detector. When these signals reach an object, they will bounce back at the motion sensor. The device takes note of both the pattern and the rate at which these signals return to the sensor. If they continue to reach the sensor at the same rate and pattern, then that means no motion is present. But if this pattern or rate changes, then it must mean that a new person or object has come into the room. If this happens, the microwave sensor will activate.

To prevent false alarms, both the PIR sensor and the microwave sensor on a dual-tech motion must activate within a certain period of time in order for an alarm to take place. If only one technology activates, then the sensor will not activate, and the system's programmed response will not occur.