Wireless connectivity?

Hey guys,

Is it possible to get two Arduino boards to recognize each other's presence when they are in close proximity to one another? If so, would it be possible for them to recognize how far apart they are from each other?



Depending on your requirements for "close proximity" there are a few ways: infrared, ultrasonic, radio. Infrared & ultrasonic would work up to maybe a few yards, but would also be limited to line-of-sight, and with emitters/detectors facing toward each other. Low-power radio could work up to 100 ft or possibly a bit more, would work through (most) walls, and would be omni-directional.

As far as distance.... well, that's a lot harder. Light and radio signals travel 300000 meters (984252 ft) per millisecond. Very hard to time. Ultrasonic would be easier to time at 0.343 m / mS (1.12 ft/mS). But since the receiving Arduino wouldn't know went the pulse was sent, it would have to immediately send a pulse back and the first Arduino would have to calculate from the total round-trip time. This is assuming line-of-sight and not bouncing off of any walls or other objects.

I suppose there are some other more exotic techniques that could work with a good bit of R&D... maybe low-frequency EMF for proximity detection, and measuring signal strength for a very rough distance estimate.

IIRC there is a project in "Making Things Talk" that uses the XBee radios to measure signal strength to determine an approximate distance.

(* jcl *)

www: http://www.wiblocks.com twitter: http://twitter.com/wiblocks blog: http://luciani.org

Excellent, thanks for the feedback!

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(* jcl *)

www: http://www.wiblocks.com twitter: http://twitter.com/wiblocks blog: http://luciani.org