Digital Signal Processing Reference
In-Depth Information
MATLAB Problems
3.52 Compute the 16-point and 32-point DFTs of the 4-point sequence x(n)
=
{ 10 . 50 0 . 5 } . Plot their magnitudes and compare them.
3.53 Compute the 24-point DFT of the sequence in Problem 3.52, plot the
magnitude of this DFT. Now compute 24-point IDFT of this DFT and
compare it with x(n) given above.
3.54 Plot the magnitude of the following transfer functions:
1 . 2 z 1
0 . 5
+
X 1 (z)
=
1 + 0 . 2 z 1
+ 0 . 4 z 2
z 3
z 4
+ 0 . 06 z 5
+
z 3
0 . 8 z 5
z 1
+
6
X 2 (z)
=
1
+
z 1
+
0 . 8 z 2
0 . 4 z 3
0 . 3 z 4
+
z 5
+
0 . 05 z 6
z 2 )
( 1
0 . 3 z)( 1
+
0 . 2 z
+
X 3 (z)
=
(z 2
+ 1 . 0 )(z 2
+ 0 . 2 z
0 . 1 z
+ 0 . 05 )(z
0 . 3 )
z
z
+ 0 . 5
0 . 8
z
X 4 (z)
=
0 . 4
0 . 1 ) 2 +
z
+
(z
+
3.55 Plot the magnitude and phase responses of the following functions:
0 . 2 e
0 . 9 e j 2 ω
+
H 1 (e )
=
1 0 . 6 e
+ 0 . 6 e j 2 ω
0 . 5 e j 3 ω
e j 4 ω
+
1 + 0 . 4 e
H 2 (e )
=
1
+
0 . 5 e
0 . 4 e j 2 ω
+
e j 3 ω
+
0 . 3 e j 4 ω
+
0 . 1 e j 5 ω
H 3 (e )
H 1 (e )H 2 (e )
=
3.56 Evaluate the magnitude response of the transfer function H(z) at ω
=
0 . 365 π and at ω
= 0 . 635 π :
z 1
0 . 25 +
H(z)
=
1
0 . 8 z 1
+
0 . 4 z 2
0 . 05 z 3
3.57 From the real sequence x(n)
={ 1 12 . 50 12 } , show
that the DFT of [ x e (n) ] = Re X(k) where the even part x e (n)
= [ x(n)
+
n)) N ] / 2.
3.58 From the real sequence in Problem 3.57, obtain its odd part and show that
its DFT
x((
=
j Im X(k) .
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