Digital Signal Processing Reference
In-Depth Information
4
2
0
-2
-4
1,50
0,75
0,00
-0,75
0,150
Test si gnal
W avelet with lar ge scaling ( low fr equency )
Momentary CWT
A
-0,125
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
ms
4
2
0
-2
-4
3,5
2,5
1,5
0,5
-0,5
-1,5
0,125
0,075
0,025
-0,025
-0,075
-0,125
Momentary CWT
B
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
ms
4
2
0
-2
-4
5
3
1
-1
-3
0,100
0,050
0,000
-0,050
-0,100
M omentary CW T
C
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
ms
4
2
0
-2
-4
7,5
W avelet with small scaling ( high fr equency )
-5,0
0,100
0,050
0,000
-0,050
-0,100
Momentary CWT
D
50
50
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
550
550
600
600
650
650
700
700
750
750
800
800
850
850
900
900
950
950
Scaling
CW T ( Continuous W avelet Tr ansfor m
ms
ms
A
B
C
D
Illustration 65:
Representation of details and CWT with a logarithmic scaling
Above five different points of time in the wavelet transformation with five differently scaled windows with
each momentary CWT are reproduced. These five representations are marked below in the sonogram by
letters. This should make the interpretation even clearer.
As a result of the usual representation with logarithmic scaling the higher frequency areas are stretched.
As a result, the V-shaped funnels from Illustration 64 have become round arches.
