You probably know those invisible servants who helpfully open department store doors, switch on outside lighting when you( or your cat) walk by or open the lap when you approach the basin. Everywhere motion detectors are installed which trigger those procedures. Most of the time the PIR( Passive InfraRed) principle is used. What about utilizing this technology for BASIC-Tiger?A PIR motion sensor
Motion detectors are available for little money, but they are mostly integrated into complete systems, such as outside lighting. Single detectors are usually designed as components of home electricity systems. For a developer it is less attractive to “ cannibalize” a complete lighting just for an integrated motion detector. Besides interated sensors both on the supply side(220V) and from the output system(replays or triacs) can only be adapted to the BASIC-Tiger system with much effort, because it works with 5V supply voltage and levels between 0 and 5 V. the aim of this article is to find out about the technology of PIR sensors, introduce a suitable sensor construction kit for developers and discuss application options for the AG-security system.
Passive InfraRed- that is all we need to know, A PIR sensor passively infrared radiation in its surrounding area, since this technology is also used in fire detectors, sensors are also called pyrosensors. They are called passive because they only analyse signals which are transmitted from the object itself. In contrast to radar or ultrasound sensors an activetransmitter is not needed, Infrared is the wavelength beyond visible red light. Here wavelength around a few um are analysed- the specific heat radiation which is emitted by eg, the human body. It is obvious that a PIR motion detector only reacts to objects that are distinctly warmer that the surroundings, for example humans, animals or warm vehicles. It is important to know that the sensors does not sense absolute heat radiation but only temporal and local changes in radiation. That is required to avoid steady and immobile heat radiators to set off the switching operation.www.aglysecurity.com
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