Digital Signal Processing Reference
In-Depth Information
and ancillary condition y [ 1] = 2.
(a) Determine the response y [ k ] by iterating the difference equation for
0 k 5.
(b) Determine the zero-state response y zi [ k ] for 0 k 5.
(c) Calculate the zero-input response y zs [ k ] for 0 k 5.
(d) Verify that y [ k ] = y zi [ k ]+ y zs [ k ].
10.2 Repeat Problem 10.1 for the applied input x [ k ] = 0.5 k u [ k ] and the input-
output relationship
y [ k + 2] y [ k + 1] + 0 . 5 y [ k ] = x [ k ] ,
with ancillary conditions y [ 1] = 0 and y [ 2] = 1.
10.3 Repeat Problem 10.1 for the applied input x [ k ] = ( 1) k u [ k ] and the
input-output relationship
y [ k + 2] 0 . 75 y [ k + 1] + 0 . 125 y [ k ] = x [ k ] ,
with ancillary conditions y [ 1] = 1 and y [ 2] =− 1 .
10.4 Show that the convolution of two sequences a k u [ k ] and b k u [ k ]isgiven
by
( k + 1) a k u [ k ]
a = b
( a k u [ k ]) ( b k u [ k ]) =
1
a b ( a k + 1 b k + 1 ) u [ k ]
a = b .
10.5 Calculate the convolution ( x 1 [ k ] x 2 [ k ]) for the following pairs of
sequences:
(a) x 1 [ k ] = u [ k + 2] u [ k 3] ,
x 2 [ k ] = u [ k + 4] u [ k 5];
(b) x 1 [ k ] = 0 . 5 k u [ k ] ,
x 2 [ k ] = 0 . 8 k u [ k 5];
(c) x 1 [ k ] = 7 k u [ k + 2] ,
x 2 [ k ] = 0 . 4 k u [ k 4];
(d) x 1 [ k ] = 0 . 6 k u [ k ] ,
x 2 [ k ] = sin( π k / 2) u [ k ];
(e) x 1 [ k ] = 0 . 5 k ,
x 2 [ k ] = 0 . 8 k .
10.6 For the following pairs of sequences:
k
0 k 3
2
1 k 2
(a) x [ k ] =
and
h [ k ] =
0
otherwise
0
otherwise;
2 k 0 k 3
0 otherwise,
calculate the DT convolution y [ k ] = x [ k ] h [ k ] using (i) the graphical
approach and (ii) the sliding tape method.
k k 2
0
(b) x [ k ] =
and
h [ k ] =
otherwise
10.7 Using the sliding tape method and the following equation:
y [ k ] =
h [ m ] x [ k m ] ,
m =−∞
calculate the convolution of the sequences in Example 10.8 and show that
the convolution output is identical to that obtained in Example 10.8.
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