Instar IN-MOTION 300, Быстрое руководство по установке, Страница: 10 / 14

The greatest drawback of the PIR sensor is that it will detect anything that is mov-
ing - air, shadows, grass, etc - and has a temperature differing from ambient. Many
schemes have been tried to minimize this problem, but in harsh outdoor settings,
some “falsing” is unavoidable. Below are some tips to help you minimize false
events.
Point the sensor away from the rising or setting sun. In general, North or South
works well, but your local site conditions could dictate otherwise.
Keep the sensor aimed at an area that will not have intense, direct sunlight warm-
ing all or part of the detection area. Shadows of trees or clouds moving across a
sun-warmed area can cause a momentary temperature drop which could cause
a false event to be recorded. Warmed air rising from the ground can cause prob-
lems too.
Wind can also cause movement of the object you have your sensor mounted to.
Make sure to secure your sensor to an object that will not sway in strong winds.
Any movement of the equipment may be interpreted as motion by the sensor.
Wind can cause false events. The moving air might be warmer or cooler than the
background. Place the sensor in an area sheltered from strong winds.
If the area is known to have many small birds / mammals, you will surely get
many empty pictures, as these active, fast animals will often leave the frame be-
fore a picture can be taken (also see P ulse C ount C ompensation, next page).
Even in a shaded area, keep the sensor pointed away from dense shrubs or trees
that can retain the days warmth. A warm evergreen or other dense shrub will
hold the days heat. If the air temperature drops at night - and the still warm shrub
moves in the wind, this movement could be detected.
Tall, sun-warmed grasses or other vegetation blowing in a breeze can be detected.
Point the sensor away from dense, sun-warmed vegetation which can trap heat.
Do not place the sensor in a location where direct, bright sunlight will fall on
the sensor window.
How do I minimize false alerts?