Infrared Sensors FAQQHoｗ far is detection distance of Pyroelectric infrared sensor?

Since the detection distance changes by various conditions, it cannot be specified.
The detection distance changes by the following conditions.
(1) Sensitivity of the sensor itself
(2) Type of Fresnel lens (mirror)
(3) Circuit condition
(Amplification factor, frequency characteristic of the amplifier circuit, threshold of the comparator, etc.)
(4) Environment temperature
(5) Condition of the object (people)
(Moving speed, height of people, clothing, moving direction, etc.)