Larson Davis HVM200, Справочное руководство

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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
Q
1
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 W b, 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 W h, 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