Larson Davis HVM200 Reference Manual

HVM200 Reference Manual Downloading Data 3-14
% determine parameters for band limiting high pass and low pass
[b1,a1] = butter (2,f1/nyq, 'high' ); % High pass
[b2,a2] = butter (2,f2/nyq); % Low pass
% determine parameters for a-v transition
B3 = [1/w3 1];
A3 = [1/w4/w4 1/Q4/w4 1];
[b3,a3] = bilinear (B3, A3, fs);
% determine parameters for upward step
B4 = [1/w5/w5 1/Q5/w5 1]*w5*w5/w6/w6;
A4 = [1/w6/w6 1/Q6/w6 1];
[b4,a4] = bilinear (B4, A4, fs);
% Apply filter to input signal vector x (output to signal vector y)
y = filter (b2, a2, x); % Apply low-pass band limiting
y = filter (b1, a1, y); % Apply high-pass band limiting
y = filter (b3, a3, y); % Apply a-v transition
y = filter (b4, a4, y); % Apply upward step
end
Table 3.1 Parameters and transfer functions of the frequency weightings (source: ISO 8041)
Weighting
Band-limiting a-v-transition Upward step Gain
f
1
Q1
f
2
Q
2
f
3
f
4
Q
4
f
5
Q
5
f
6
Q
6
K
Hz Hz Hz Hz Hz Hz
W
b
0,4 1/ 100 1/ 16 16 0,55 2,5 0,9 4 0,95 1,024
W
c
0,4 1/ 100 1/ 8 8 0,63 ∞ 1 ∞ 1 1
W
d
0,4 1/ 100 1/ 2 2 0,63 ∞ 1 ∞ 1 1
W
e
0,4 1/ 100 1/ 1 1 0,63 ∞ 1 ∞ 1 1
W
f
0,08 1/ 0,63 1/ ∞ 0,25 0,86 0,0625 0,80 0,10 0,80 1
W
h
10
8/
10
1/ 10
31/
10
1/ 100/(2π) 100/(2π) 0,64 ∞ 1 ∞ 1 1
W
j
0,4 1/ 100 1/ ∞ ∞ 1 3,75 0,91 5,32 0,91 1
W
k
0,4 1/ 100 1/ 12,5 12,5 0,63 2,37 0,91 3,35 0,91 1
NOTE 1 For weighting Wb, Table A.1 of ISO 2631-4:2001 rounds the value of parameter Q
1
to 2 decimal
places. The parameter specified here is the exact value.
NOTE 2 For weighting Wh, Table A.1 of ISO 5349-1:2001 rounds the values of parameters f
1
, f
2
, f
3
and f
4
to
5 significant figures and parameter Q
1
to 2 decimal places. The parameters specified here are the exact
values.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

Larson Davis HVM200 Specifications

General

Brand	Larson Davis
Model	HVM200
Category	Measuring Instruments
Language	English