2.4 MATLAB Laboratory Experiment on Signals
Purpose: This experiment introduces the graphical representation of common signals
used in linear systems. Time shifting, time scaling, signal addition, and signal multiplica-
tion will also be demonstrated. It is important to emphasize that signals are mathematical
functions—thus, the signal operations given in the following are known from calculus.
Part 1. Use MATLAB to plot the following continuous-time signals in the time
interval
.
1.
(unit step signal),
.
2.
(unit rectangular pulse),
!"
#
$
#%&
.
3.
'
(unit ramp signal),
'
#&
'
(%&
4.
)+*,
(unit triangular pulse),
)+*
)+*
(%-
.
Part 2. Plot approximations of the impulse delta signal and the sinc signal.
5. Plot an approximation for
.
(impulse delta signal). Hint:
.
can be
approximated by a rectangular pulse of width
/
and amplitude
"0
/
when
/21
. Take
/43
65 6775 877759
.
6. Use
:;<=
3 :>;9<?A@
>0
@
with t=-5:0.1:5;t=-15:0.1:15;
t=-30:0.1:30. The
:B;C<!=
signal can be obtained as
:>;9<=
3 :>;9<DE@
5F0
@
.
(Note that the operation
5F0
stands for pointwise division.) MATLAB also has the
built-in function sinc. To get information about any MATLAB function, type help
function name; in this case type help sinc.
Part 3. In this part, we demonstrate time scaling and time shifting operations. Plot
the signals given in the following. Take t=0:0.1:6.28.
7.
GIH
3J:>;9<?
G"K,
3L:>;9<?
8$
G"M
3N:B;9<?
"
. Plot all three signals in the
same figure. Use plot(t,y1,’o’,t,y2,’—’,t,y3).
8.
:>;9<OAP7
-">
:>;9<?
8"
. Explain the figures obtained in (7) and (8).
9.
Q,RDSUTA:>;9<DAV
for
VW3
65F7"X
. Use
5 Y
as pointwise multiplication. Comment on
the effect of time scaling.
Part 4. Some signal operations. Plot the following signals.
10.
D
Z%
'
.
11.
K
Z%
)
M
.
12.
=U[:D
$%
:B;C<?
8"B
. Expand the time axis such that it includes one signal period.
Part 5. Calculate and plot the following discrete-time signals.
13.
F\]-^>
'
F\?%&8$
.
14.
'
F_\+`U(Y
\]a8
15.
_65 ,Bb
\]&8Y
F_\%c"
.
Submit a report composed of fifteen figures for fifteen problems and, where required,
comment on the results obtained.
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