e1276e
13
Siemens Building T
echnologies
Cerberus Division
09.2000
”Smoothing filter”
Time
Signal [%]
0
10
20
30
40
50
60
70
80
90
100
110
0% compensation value
(NFW)
30% response threshold 3
(standard)
3 sec.
12 sec.
48 sec.
0 sec.
Measured
value
A
A
A
C
C
C
50% response threshold 3
65% response threshold 3
(high)
(low)
Smoothings
B
NFW x 1.5
120
130
140
150
Three “smoothing filters” A, B and C are used. They are characterized by the time it takes
to reach response threshold 3 of the corresponding sensitivity setting.
If the smoothed signal reaches response threshold 1 or 2, in the interactive system the
corresponding mode is activated by means of the corresponding danger level. These le-
vels are not evaluated in the collective system.
If the smoothed signal reaches response threshold 3, the alarms in the alarm counter are
added up. Upon reaching the given value, danger level 3, i.e. an alarm is activated.
According to the diagnosis made, other alarm parameters are automatically selected:
Diagnosis “Fire or slowly-developing fire”
⇒
alarm activation after
≤
6s
(smoothing A + 20 alarm counts)
Diagnosis “Noise or repeated interruption”
⇒
alarm activation after
≤
16s
(smoothing C + 20 alarm counts)
Diagnosis “Test filter”
⇒
alarm activation after
≤
10s
(smoothing A + 40 alarm counts)
Smoothing filter B filters out reflections.
Reflecting or shining surfaces, which are too near at the path of the beam, can impair the
detector.
Smoothing B > actual compensation value x 1.5 = reflection
