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Motion vs. Presence Sensing

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The Difference Between Motion & Presence Sensing
Motion Sensor	Motion Sensors are used to activate the door when it detects a moving object, such as a pedestrian or a shopping cart. Motion sensors can typically distinguish between objects moving towards the door or away from the door. Motion sensors cannot detect still objects such as a person stopped in the opening or closing path of the door.
Presence Sensor	Presence Sensors detect both moving and non-moving objects in the path of the door and signal the door accordingly. NABCO Entrances utilizes infrared technology in its presence sensors.
Hybrid Sensor	Motion/Presence Hybrid Sensors or Sensor Systems provide the activation capabilities of motion sensors with the pedestrian protection of presence sensors. NABCO Entrances has sensors and systems that combine both technologies in a single unit or as a system of sensing units to give you the best product for your application and budget.
How Microwave Technology Works Microwave Sensors utilize the Doppler Effect principle. The sensor emits a very high frequency microwave signal. The high frequency enables the sensor to better detect slower moving objects. When the wave encounters a moving object, it bounces back and its frequency is changed proportionately to the speed of the object. This change in frequency triggers the sensor.
How Infrared Technology Works In general, infrared sensors work by emitting an invisible pulsed light signal. The receiver then looks for the reflected signal back and reacts to changes in the reflection of the signal that indicates a presence in its detection area. There are two types of infrared technology: Diffused and Distance Measuring Infrared. Diffused Infrared Sensors work by flooding pulsed infrared light over a specific area below the sensor down to floor level. It then uses the reflected infrared as its base of reference. Foreign objects entering the detection area alter the infrared base reference level and trigger activation. NABCO Sensors using this technology are Acusensor 1B, Acuvision and the infrared part of Acumotion A. Distance Measuring Infrared Sensors work by focusing active pulsed infrared into a spot (or series of spots) using optical lenses. The NABCO Acugard 3 is a Distance Measuring Sensor. Using infrared emitting LED's, it directs a series of infrared beams to points in space within the vicinity of the door. When an object enters one of the beam areas, the beam is bounced off the target and reflected back to a position sensitive infrared receiver. This is an excellent sensor for mounting on swing doors since it is not dependent on the floor as the infrared base of reference. PDF Downloads: About Sensors (262 k) Sensor Selection Chart (46 k) Sensor Detection Patterns (1,480 k)