76
1. Theory
<Table 1. Parameters of the transfer functions of frequency weightings >
Band-limiting
Acceleration-velocity
transition
Upward step
Weighting
1
f
Hz
2
f
Hz
3
f
Hz
4
f
Hz
4
Q
5
f
Hz
5
Q
6
f
Hz
6
Q
k
W
0.4 100 12.5 12.5
0.63
2.37
0.91
3.35
0.91
d
W
0.4 100 2.0 2.0
0.63
∞
-
∞
-
f
W
0.08 0.63
∞
0.25 0.86
0.0625
0.80 0.1 0.80
WBCombined 0.7943 100
-
5.684 -
∞
-
∞
-
c
W
0.4 100 8.0 8.0
0.63
∞
-
∞
-
e
W
0.4 100 1.0 1.0
0.63
∞
-
∞
-
j
W
0.4 100
∞
∞
- 3.75
0.91
5.32
0.91
h
W
6.310 1258.9
15.915
15.915
0.64
∞
-
∞
-
b
W
0.4 100 16 16
0.55
2.5 0.9
4.0
0.95
The frequencies
1
f
to
6
f
and the resonant quality factors
4
Q
to
6
Q
are parameters of the
transfer functions determining the overall frequency weighting, referred to acceleration as input
quantity. The transfer function is expressed as a product of several factors.
a) Band-limiting(Two-pole filter with Butterworth characteristics,
1
2
1/ 2
Q
Q
=
=
)
High-pass :
( )
2
2
2
2
1
1
1
1
2
1
2
2
1
h
s
H
s
s
s
s
s
ω
ω
ω
ω
=
=
+
+
+
+
Low-pass :
( )
2
2
2
2
2
2
2
2
2
2
1
2
1
2
1
l
H s
s
s
s
s
ω
ω
ω
ω
ω
=
=
+
+
+
+
b) a-v transition(proportionality to acceleration at lower frequencies, proportionality to velocity at
higher frequencies)
Содержание SLA-PA201
Страница 64: ...64 Appendix 1 The Theory for calculating RMS by ISO2631 and ISO8041 ...
Страница 67: ...67 Appendix 2 Frequency Response of Filter in the Vibration Level Meter ...
Страница 75: ...75 Appendix 3 Theory of WBCombined Filter and Frequency Response ISO6954 Filter ...
Страница 79: ...79 Fig 2 Lowpass Filter with 100Hz Cutoff Fig 3 a v transition Frequency Response ...
Страница 88: ...88 Fig 12 Error between theoretical value and measured value ...
