IR Cameras effect on Alarm PIRs

[bhop]

Hello,

Apologies if this has been asked before, I did search the forum but could not find any similar topics.

I have some internal wireless cameras with inbuilt IR LEDs which activate at night. These are positioned in the same areas as my alarm system PIR sensors, facing towards the sensors.

Will the IR light from the cameras effect the sensitivity of the alarm PIR sensors by flooding the area with IR light and perhaps blinding the sensors? ...or perhaps even cause false triggering of the sensors?

Many thanks,

bhop.

 

[Porque223]

There is at least one way this can be tested.

 

[EightyTwo]

I think it's unlikely that the cameras will affect the PIRs. There is a possibility that they might trigger the PIRs when the IR switches on but I guess that your cameras are on the ceiling and should, therefore, be out of view of the PIRs. Also, the PIRs will be looking for a longer wavelength of IR than the LEDs are producing. Remember that PIRs are looking for moving heat sources and the cameras should be stationary. I'm sure that the LEDs will have a negligable heating effect on the room so they shouldn't affect the 'contrast ratio' and hence the sensitivity of the PIRs' views.

As Porque223 says, there's an easy way to find out!!

 

[Porque223]

Remember that PIRs are looking for moving heat sources and the cameras should be stationary.

Good point.

 

[bhop]

Thank you for the replies.

Whilst I agree that the PIRs are looking for moving IR sources, my concern is that by flooding the room with IR light that the sensitivity of the PIRs would be reduced.

However, it appears that the PIRS are looking for IR in the 5 - 14μm wavelength range, whereas the IR LEDs on the camera are in the 850nm range. So, I am hoping that the PIRs are oblivious to the IR light from the cameras.

Any thoughts on this theory from techy guru's?

I will fully test it, but thought I would check first before mounting the cameras and potentially causing "cry wolf" false alarms.

Cheers,

bhop.

 

[RigidRaider]

Surely the IR from the cameras will be considerably weaker than, say, that from a radiator or burning stove. Yet our alarm doesn't trigger if the heating comes on or we go out and leave the stove lit.