What is a PIR sensor?
At the heart of any motion sensing camera is a PIR (Pryoelectric Infra-Red) motion detection sensor. A PIR sensor measures the reflected Infrared radiation from objects in its range. As an object moves into the range of the sensor and if it is reflecting a different amount of radiation the sensor will output the changing values of the radiation levels. The detection of the change in this reflected radiation is, very adequately, assumed to be motion of an object – hence why the PIR is commonly used for motion detection. The PIR sensors come in many formats and they usually detect motion in one or two vectors of travel. Commonly, most of the PIR sensor, used in the field, will be more effective in detecting movement in the horizontal vector of movement. They will also be more effective when detecting an object that is moving perpendicular to the sensor and less effective when detecting movement when the object is moving towards or away from the sensor. Some sensors will detect both horiz
