How does the motion detection work?

[LindaLou]

Can someone be more specific with how the motion detection picks up motion.  I read about the infrared and the heat, but how far from the camera does the sensor reach?

[jguerdat]

Officially, up to 20 feet.  I've had it reach much further but it depends on what is in the field of view and how big/fast the moving object is (e.g. it will pick up a car but not a person).

[TomMac]

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LindaLou wrote:

Can someone be more specific with how the motion detection picks up motion.  I read about the infrared and the heat, but how far from the camera does the sensor reach?

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As mentioned, Arlo recommends about 20 feet range on the IR sensor.

Specificly how the sensor works... is think of a checkerboard ( square boxes ) as the IR hits the sensor, the IR usu must hit more than one or two boxes as the object giving off the IR moves ( if not moving across the board or just hitting one box doesn't start motion detect )...there's also a timing factor built in as to how fast thru multiple boxes the IR must go before trigger.

Also, the sensor does not pick up heat but IR and the Reflection of IR.... usu the biggest form of IR is the sun moving accross the sky and/or the reflection of sun from a car/car windshield or even sometimes other objects like leaves blowing.

So the best way to get detection working properly is to have it angled down a bit ( cuts out the sun and reflections alot ) and try to get the subject to cut accross the field of view.... after this it's a matter of fine tuning by adjusting the sensitivity ( "more-less videos" ) to eliminate false detects.

[R_Lowe]

Well geez Tom, if you don't really know, then, uh, why just guess at the answers...?  haha. 

Seriously, great answer and thanks for educating all of us (or ignorant lunks like me).  Interesting!

[TomMac]

Well I did use some poetic license with the describtion, but its the easiest way to decribe how it works...

A lot of the work is done by the lens too, usu a Fresnel lens ( sort of segmented lens ) that concentrates IR light to the sensor (in sections) as the chip really doesn't have as many boxes like a checkerboard. ( usu alot less, sometimes only 2 )