Im not sure that is how they work, I read about them in the mobile robotics book. the more heat an object emits the larger the output pulse so you could set the sensitivity by ignoring all pulses below a certain level. You can also tell which direction an object is travelling in by analysing the output. I cant remember much about them, just a few bits from that book so I may be wrong. ----- Original Message ----- From: "James Paul" To: Sent: Tuesday, February 27, 2001 6:33 PM Subject: Re: [EE]: Infrared Detector vs Pet > Justin, > > Typically I believe the way these things discriminate between man > and beast is that they aim the devices so that the bottom of the > cone of coverage is about 2-3 feet off the floor. That way, most > house pets won't set off the alarm because it is not within the > transmitted beam. However, humans, being substantially taller > than most house pets, is within the beam, and does set off the > alarm. > > Regards, > > Jim > > > > > > > > > On Tue, 27 February 2001, Justin Fielding wrote: > > > > > Lookup pyrometers, they may be a good way to do this as you could adjust the > > sensitivity. They actually work by detecting movement of body heat ( I > > think). With an IR beam it is all or nothing, > > > > > > ----- Original Message ----- > > From: "Simon Ethier" > > To: > > Sent: Tuesday, February 27, 2001 5:21 PM > > Subject: Re: [EE]: Infrared Detector vs Pet > > > > > > > I don't really know ... All I'd like to do is build a cheap but effective > > > "IR" detector that do not triggers with pets like cats ... > > > > > > Thanks > > > > > > ----- Original Message ----- > > > From: "Justin Fielding" > > > To: > > > Sent: Tuesday, February 27, 2001 11:59 AM > > > Subject: Re: [EE]: Infrared Detector vs Pet > > > > > > > > > > I assume that you are talking about IRbeams (which must be broken to > > > trigger > > > > alarm) rather than a PIR detector (using a pyrometer). > > > > > > > > > > > > ----- Original Message ----- > > > > From: "Simon Ethier" > > > > To: > > > > Sent: Tuesday, February 27, 2001 4:07 PM > > > > Subject: [EE]: Infrared Detector vs Pet > > > > > > > > > > > > Hi, I'm wondering.. I heard in a publicity of an alarm company that they > > > > have an infrared detecter which can make the difference between pet and > > > > human (how, I don't know ... ok it don't really "make" the difference, > > but > > > > the IR won't react to a cat for exemple, but will react to a human) I > > > found > > > > this very cool, especially if you have pet at your house... > > > > > > > > I'd like to build something like that ... Do any of you guys know what > > is > > > > the trick ? Is it less sensitive ? Does it require a minimum of > > movement > > > > ... > > > > > > > > Thanks > > > > --- > > > > Simon Ethier > > > > sethier@justine.umontreal.ca > > > > ICQ 66019153 > > > > > > > > -- > > > > http://www.piclist.com hint: The list server can filter out subtopics > > > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > -- > > > > http://www.piclist.com hint: The list server can filter out subtopics > > > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > > > > > > > -- > > > http://www.piclist.com hint: The list server can filter out subtopics > > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > > > > > > > > > -- > > http://www.piclist.com hint: The list server can filter out subtopics > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > jim@jpes.com > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics