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Like to know more about the PIR sensor — Parallax Forums

Like to know more about the PIR sensor

whiteoxewhiteoxe Posts: 794
edited 2014-05-05 06:20 in Robotics
This is what it says on the Parallax Sensor pages about this dome looking sensor...

""The PIR Sensor detects motion by measuring changes in the infrared (heat) levels emitted by surrounding objects. When motion is detected the PIR sensor outputs a high signal on its output pin.""

So it looks like it can detect movment in a 365 degree range ? But when it detects movement will it be able to signal which direction the movment was ? and as its 'Heat Seeking' , it would not pick up any obstacles if thet didnt emmit heat like a person or animal ?

Comments

  • PublisonPublison Posts: 12,366
    edited 2014-05-03 16:11
    whiteoxe wrote: »
    This is what it says on the Parallax Sensor pages about this dome looking sensor...

    ""The PIR Sensor detects motion by measuring changes in the infrared (heat) levels emitted by surrounding objects. When motion is detected the PIR sensor outputs a high signal on its output pin.""

    So it looks like it can detect movment in a 365 degree range ? But when it detects movement will it be able to signal which direction the movment was ? and as its 'Heat Seeking' , it would not pick up any obstacles if thet didnt emmit heat like a person or animal ?

    Not sure where you got the 365 degree range from?

    The new wide angle PIR will detect in a 180 degree range. It will detect changes in infrared range, like a person or animal, but will also detect aan object that has an infrared signature, such as a hot piece of steel.

    See PIR Sensor
  • whiteoxewhiteoxe Posts: 794
    edited 2014-05-03 16:30
    iT WAS JUST A GUESS from the look of the PIR, i had read the link , must have missed that part (180 degree)

    but even though it detects movment in a 180 range, will it be able to signal where that movment came from ? I am guessing it definitely would.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-05-03 16:33
    The PIR only tells you if there is movement, not where the movement is.

    If you used multiple sensors you can locate the movement. (You didn't hear it from me, but there are inexpensive PIR sensors on ebay.)

    Or if you use a more expensive sensor you can produce a very low resolution thermal image. (Phil does some really cool stuff!)
  • whiteoxewhiteoxe Posts: 794
    edited 2014-05-03 17:36
    tHANKS dUANE, PS. I'm cutting up some foam board this morning, looking a bit like your pictures :)
  • Jim the HermitJim the Hermit Posts: 79
    edited 2014-05-05 06:20
    I was experimenting with one the other day- they're extremely sensitive -I couldn't walk slow enough to avoid detection, although I suppose if I practiced enough I could.
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