Smaller shops or barbershops, often have a beam of light crossing the room near the door, which ends up in a photo-sensor on the other side of the room. When a customer breaks that beam, the bell rings.
Bigger markets have automated doors, the black bulb above the door sends a burst of microwave radio energy, and waits for the reflected energy to bounce back. When a person walks into that field, the amount of energy is changed,...resulting in the door to open. Therefor you can't just run in a market, the doors wont open fast enough . So no kidz, it doesn't have a little leprecon in it, which presses a button to open the doors!!
Same thing with ultrasonic sound waves used by bats for example, they bounce back off a target and create an image. These are what we call active sensors. They send out energy, and detect changes in them .
Motion Sensor
The motion sensing system is a passive sensor. It detects infrared energy. Human beings have a skin temperature of approximately 36° Celsius or 93° Fahrenheit, this produces an infrared energy with a wavelength between 9 and 10 micrometers. When infrared energy is detected, that infrared light bumps electrons of the sensors substrate, these are amplified and result in a signal. People who have these little sensors, may notice that the sensing light doesn't go off when you're standing still. That's because the sensor is programmed to sense rapidly changes, you don't want every change of infrared light setting off the alarm .
If you're searching for a hack in this system, ...than this is your lucky day, because you can. The sensors are sensitive in a range of 8 - 12 micrometers. So all you need to do is calculate what body temperature you got to have to produce waves of 7 micrometers or less. I'm not responsible if you got hypothermia afterwards . Or maybe you could build a glass bulb around you, glass doesn't let the infrared waves through, think of a greenhouse, the light goes in , but then it's trapped inside... so beware of people passing by in the possession of glass bulbs...
Footnote: During Operation: Desert Storm. The US military used infrared vision equipped tanks to spot and fight hostile tanks at night. Result: hostile tanks getting slaughtered like a sitting duck, technology = win
About the Author
I'm Jan Vansteenlandt, i'm 19 years old, i still attend school.
My articles will be around the technology topic, and all it's subcategories. Normally IT-related.
I hope you enjoy them
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. So no kidz, it doesn't have a little leprecon in it, which presses a button to open the doors!!
