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### How does the 1111 Motion sensor work?

Posted: Thu Jun 28, 2018 10:16 am
Hi there,

I'm using interface kit 1019 and the motion sensor 1111. I just tested the sensor. It is likely that when there's nothing move in the field, the analog output would be 2.5v. When something was moving in the field, the output voltage would change. The problem is that I can't find the rule about how it changed. Sometimes it went down and sometimes up. I thought it might be related to the distance between the moving object and the sensor and it might also be related to the moving direction of the object (from the center to the side in the field or otherwise).

Also, besides the rules of the value changing, is there any ways to quantify the motion? Like to detect the moving direction with the sensor.

Thank you greatly for the kind help!

Here's the link to the sensor:
https://www.phidgets.com/?tier=3&catid=10&pcid=8&prodid=81

### Re: How does the 1111 Motion sensor work?

Posted: Thu Jun 28, 2018 10:42 am
The rule for the output as a result of motion is a lot more simplified than you are seemingly hoping for. PIR sensors are generally designed to detect motion in 1 dimension; ie it either sees movement or not, and provides very little information about the movement, other than the "amount of movement" it saw. The best way to describe it is that the change in output voltage is proportional to both the size of the object divided by the distance from it, and also the speed of the moving object. (a faster moving object will produce a higher swing in output voltage)

If you want to detect direction of movement you need arrays of PIR sensors. A 2x2 grid of sensors would allow for a minimal amount of detection in both X and Y directions

### Re: How does the 1111 Motion sensor work?

Posted: Thu Jun 28, 2018 12:09 pm
Thank you, fraser! That makes sence.