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1100 ⏐⏐⏐ PULSE WAVEFORMS AND THE R-C RESPONSE
EXAMPLE 24.5 Determine the pulse repetition rate and duty cycle
for the trigger waveform of Fig. 24.14.
Solution:
div.
T � (2.6 div.)(10 ms/div.) � 26 ms
1 1
prf � � ���38,462 kHz
T 26 ms
tp � (0.2 div.)(10 ms/div.) � 2 ms
2 ms
Duty cycle � � �100% ���100% � 7.69%
T
26 ms
24.4 AVERAGE VALUE
t p
v
V
0.5 V
t
0 Horizontal sensitivity = 10 �s/div. �
FIG. 24.14
Example 24.5.
The average value of a pulse waveform can be determined using one of
two methods. The first is the procedure outlined in Section 13.6, which
can be applied to any alternating waveform. The second can be applied
only to pulse waveforms since it utilizes terms specifically related to
pulse waveforms; that is,
V av � (duty cycle)(peak value) � (1 � duty cycle)(V b)
(24.5)
In Eq. (24.5), the peak value is the maximum deviation from the reference
or zero-volt level, and the duty cycle is in decimal form. Equation
(24.5) does not include the effect of any tilt pulse waveforms with
sloping sides.
EXAMPLE 24.6 Determine the average value for the periodic pulse
waveform of Fig. 24.15.
Solution: By the method of Section 13.6,
G �
T � (12 � 2) ms � 10 ms
G � �
44 � 10
� �4.4 mV
�9
32 � 10
���6
10 � 10 �9 � 12 � 10 �9
���
10 � 10 �6
area under curve
��
T
(8 mV)(4 ms) � (2 mV)(6 ms)
����
10 ms