Hi everyone! I am using arduino to make an electronic arduino based device that monitors how far you are away from people. For that, it uses a PIR sensor. I am trying to limit the range of the PIR sensor to 6 feet, is there a way I can do that?
Not with any real practicality.
You could tell it to ignore anything above a certain threshold being about the best you can get.
Another alternate method would be to diffuse the Fresnel lens cover more but that would be something of trial and error.
Although I am fairly new to the Arduino game, I think you can adjust its threshold, however, you can only do that provided there is a potentiometer or two on the PIR sensor. The sensitivity potentiometer should be adjusted to reduce the range. I am welcome to any corrections.
The sensitivity potentiometer should be adjusted to reduce the range.
What do you call range?
The sensor measures infrared (IR) light radiating from objects in its field of view and in common modules they are wired to detect a difference in temperature (thermal radiation) in the environment caused by human body or an animal for example.
To do this they use a pair of sensors wired as opposite inputs to a differential amplifier so that PIR measurements cancel each other thus the average temperature of the field of view is removed from the electrical signal.
The field of view is the result of the radiation going through fresnel lenses and hitting one of the two sensors. Thus the device is only seeing what comes from various beams.
When a subject with different IR pattern goes by from one beam to another, the detector will only intermittently see the moving subject. This results in a rapidly changing sensor signal which triggers the device. A slowly changing signal will be ignored by the electronics.
It is my understanding that the sensitivity potentiometer controls that part: how fast the underlying signal change has to be to trigger the motion detection, It won’t affect distance, the sensor has no clue if the IR beam received is a small object close by or a large object at a distance.