Hi Darcy,<div><br></div><div>I've had occasion to think about similar things over the last couple of years. I wasn't sure what exactly you meant by '20 foot distance'. </div><div>Do you mean track them in 3 dimensions inside a 20 ft radius? If so, then you probably want to go with machine vision (kinect (1st gen) is probably easier to get up and running but there are some libraries for doing this with a webcam (not as performant)). </div>
<div><br></div><div>If you mean measure a linear distance from the source to the person, or a boolean indication of the presence of a person, up to 20ft away, then I would say something similar to the hardware you're currently using. I would note that in my experience these are not created equally. I like the MB1210 (<a href="http://www.abra-electronics.com/products/MB1210-Ultrasonic-Range-Finder-%252d-XL%252dMaxSonar%252dEZ1.html" target="_blank">http://www.abra-electronics.com/products/MB1210-Ultrasonic-Range-Finder-%252d-XL%252dMaxSonar%252dEZ1.html</a>). It was the most reliable out to just less than 20 ft, and is specifically calibrated for people detection. </div>
<div><br></div><div>Good luck!</div><div>-a</div>
<div><br>On Wednesday, February 5, 2014, Darcy Whyte <<a>darcy@inventorartist.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">I was just thinking. In the endgame I want to be tracking a person moving over a 20 foot distance. <div><br></div><div>I'm starting to think I might need to try something else. Ideas?</div></div><div class="gmail_extra">
<br clear="all"><div><div dir="ltr"><br><div><div><br></div><div><div>--</div><div>Darcy Whyte</div><div><br></div><div>Art+ <a href="http://inventorartist.com/" target="_blank">inventorArtist.com</a> | Aviation <a href="http://rubber-power.com/" target="_blank">rubber-power.com</a></div>
<div>Contact: <a>darcy@inventorArtist.com</a> | 613-563-3634 by appointment (no text)</div></div></div><div><br></div></div>
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<br><br><div class="gmail_quote">On Wed, Feb 5, 2014 at 2:02 PM, Darcy Whyte <span dir="ltr"><<a>darcy@inventorartist.com</a>></span> wrote:<br>
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<div dir="ltr">Hi, I have one of these (I think) <a href="http://ramshackblog.blogspot.ca/2012/02/ultrasonic-range-finder-using-sdm-io.html" target="_blank">http://ramshackblog.blogspot.ca/2012/02/ultrasonic-range-finder-using-sdm-io.html</a><div>
<br></div><div>It has four pins.</div><div><br></div><div>I've got it working using the code at that page. It measures really well up to about 30cm then after that it just prints out 999 cm?</div><div><br></div><div>
I noticed with a piece of paper I can get further (around 70cm). </div>
<div><br></div><div>It's supposed to be good for 150cm. </div><div><br></div><div>Any ideas what's going on here?</div><div><br></div><div>I have two of them and I tried the other one (in case it was a bu component). But same result...</div>
<div><div dir="ltr"><br><div><div><br></div><div><div>--</div><div>Darcy Whyte</div><div><br></div><div>Art+ <a href="http://inventorartist.com/" target="_blank">inventorArtist.com</a> | Aviation <a href="http://rubber-power.com/" target="_blank">rubber-power.com</a></div>
<div>Contact: <a>darcy@inventorArtist.com</a> | <a href="tel:613-563-3634" value="+16135633634" target="_blank">613-563-3634</a> by appointment (no text)</div>
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