Soft dB Opus Suite Data Logger Module - Manual (Page 57)

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Appendix 2: 1/3 Octave Filters – IEC 61260 Class 1/ANSI S1.11
1/3 Octave Filters
The 1/3 octave filters are computed at low-level in real time (at 48 kHz) on the digital signal
processor (DSP) of the Concerto system. The filters comply with all requirements of IEC 61260 for
Class 1.
Frequency Range
20 Hz to 20 kHz.
Filter Shape
The following curve presents the filter shape test done for the 1000 Hz 1/3 octave band. The red and
green curves represent the limits associated with the IEC standard (Class 1).
1/3 octave Filter Shape Test at 1000 Hz
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
100 1000 10000
Frequence (Hz)
A
tte
n
u
a
ti
o
n
d
B
Measurement High limit Low limit