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Environment monitoring
Functional Principle
The smoke alarm has 3 ultrasonic sensors. The functional principle is similar to a car parking
aid. The sensors emit ultrasonic waves. These ultrasonic waves are reflected by objects
around the detector. The reflections are received and evaluated by the detector. The distance
between the object and the detector is calculated by evaluating the time between emitting the
ultrasonic waves and receiving the reflections. If this distance is less than 50 cm, early smoke
detection is no longer ensured. In this case, the environment monitoring is activated.
In addition to the environment, the smoke inlet opening is also monitored. This is achieved
with the aid of a light guide. This light guide forms the smoke inlet opening. For monitoring, inf-
rared light is sent through the light guide and the signal strength at the end of the light guide is
measured. If the smoke inlet opening is blocked and no early smoke detection is ensured, this
causes a measurable signal reduction at the end of the light guide. In this case, environmental
monitoring is also activated.
Signaling of environmental monitoring
This signals the response of the environment monitoring:
k
optical: red LED flashes twice every 30 seconds
k
acoustic:
k
Environment monitoring Ultrasound: no acoustic signaling
k
Environment monitoring Smoke inlet opening: Signal tone with reduced volume 3x every
5 minutes
