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Detecting PIR Sensors in Trail Cameras
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Detecting PIR Sensors in Trail Cameras

by Uke on Wed Aug 25, 2010 10:00 am

I live in a rural area with many trails and roads through the forest. With the drop in prices of trail cameras a lot of hunters are placing trail cameras along these roads and trails. The trail cameras use PIR sensors to take a photo of anything passing by the camera. At night, the cameras use either a normal flash which is visible or a IR flash.

I spend a lot of time on these trails and roads so I would like to know if there is a sensor that could detect the cameras so I can avoid them. I looked at the the PIR tutorial and it looks like they are a passive system so it might be hard to do. Another option would be to transmit a IR signal and try to trigger the camera before you pass it. Most cameras take 1-3 pictures and then delay for a set amount of time before taking another picture. Any help is appreciated.
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Re: Detecting PIR Sensors in Trail Cameras

by richms on Wed Aug 25, 2010 11:00 am

PIR's detect a much longer wavelength than IR LEDs put out, so dont bother trying that to trigger them.

Being that they are passive, they are not emmiting anything easy to detect. The ones I have seen only ever intentionally transmit something when they have detected motion as the wireless link between the PIR and the camera trigger. If that was 433MHz or whatever the other common frequency is for that, you could transmit constantly, to jam it, but that will not help with the ones that are hardwired.

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Re: Detecting PIR Sensors in Trail Cameras

by zener on Wed Aug 25, 2010 1:20 pm

You could detect the flash but that is about it. I suppose you could then find it and erase it.

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Re: Detecting PIR Sensors in Trail Cameras

by adafruit_support_bill on Wed Aug 25, 2010 1:51 pm

Get a dog (or better yet, build a robot!) and have him run up the trail ahead of you.

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Re: Detecting PIR Sensors in Trail Cameras

by Uke on Wed Aug 25, 2010 5:40 pm

Thanks for the ideals. We do hike with our dogs but they are not good off leash. I thought about detecting the flash but the flash only goes off at night. I have an inexpensive trail camera myself and have been playing with it to see if there is a way to detect it. I tried a radar detector but did not get any response. The radar detector picks up motion detectors at stores but they must be using an active system.

We live in northern Washington state near the Canadian border and there are others besides hunters that are using motion detectors on the trails/roads. We have had several banned growing operations busted and some of them use motion detectors to alarm them of intruders. Law enforcement also uses them to look for illegal banned and illegal entry into the United States. Also wildlife studies use the cameras for taking pictures of wildlife such as bears, wolves and wolverines.

I guess its time to put my aluminum foil hat and body suit on.
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Re: Detecting PIR Sensors in Trail Cameras

by pstemari on Wed Aug 25, 2010 9:56 pm

I believe the PIR is looking for any change in the view at its wavelengths, so an IR LED flashlight at the appropriate frequency ought to be able to set it off. Detecting it would require a sensitive RF detector looking for noise from its processor clock.
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Re: Detecting PIR Sensors in Trail Cameras

by zener on Thu Aug 26, 2010 12:56 am

I think you would need an incandescent flashlight with an IR filter. That might do the trick.

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Re: Detecting PIR Sensors in Trail Cameras

by Entropy on Thu Aug 26, 2010 10:12 am

Uke wrote:Thanks for the ideals. We do hike with our dogs but they are not good off leash. I thought about detecting the flash but the flash only goes off at night. I have an inexpensive trail camera myself and have been playing with it to see if there is a way to detect it. I tried a radar detector but did not get any response. The radar detector picks up motion detectors at stores but they must be using an active system.

We live in northern Washington state near the Canadian border and there are others besides hunters that are using motion detectors on the trails/roads. We have had several banned growing operations busted and some of them use motion detectors to alarm them of intruders. Law enforcement also uses them to look for illegal banned and illegal entry into the United States. Also wildlife studies use the cameras for taking pictures of wildlife such as bears, wolves and wolverines.

I guess its time to put my aluminum foil hat and body suit on.

Yes, most supermarket/store motion detectors use a 10 GHz or 24 GHz Doppler radar technique, not PIR. They operate in a very similar manner to older (and maybe current?) police speed radars.
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