
58 Practical Biomedical Signal Analysis Using MATLAB
R
A
d
2
0
x(n)=x(n)
?>=<89:;
h ↓
p
p
p
xxp
p
p
?>=<89:;
g ↓
N
N
N
''
N
N
N
A
d
2
−1
x(n)
?>=<89:;
h ↓
s
s
s
yy
s
s
s
?>=<89:;
g ↓
N
N
N
&&
N
N
N
D
d
2
−1
x(n)
A
d
2
−2
x(n)
?>=<89:;
h ↓
u
u
u
zzu
u
u
?>=<89:;
g ↓
N
N
N
&&
N
N
N
D
d
2
−2
x(n)
... ...
FIGURE 2.17: Cascade of filters producing the discrete wavelet transform coef-
ficients. In this algorithm the signal is passed through the cascade, where at each
step the approximation of signal from the previous step is low-pass and high-pass
filtered, by convolving with h and g, respectively. Each of the filtered sequences is
downsampled by factor 2 (on the scheme it is marked as ↓). Next the approximation
is passed to the follo ...