I was actually doing some research about motion/gesture sensors. well there are different types of motion sensors like : Passive Infrared (PIR), Area reflection type, Ultrasonic, and etc.
Well, I know that even proximity sensors are widely used as motion sensors. Since it doesn't emit the rays can i consider proximity sensors as PIR sensors?
1. Does it belong to PIR group?
on the other hand, there are some proximity detectors which they combine proximity sensor and the LED.
2. Are these proximity detectors simply behave like Rx/Tx pair sensors?