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USER’S GUIDE
19 2015
PULSED DC WAVEFORMS
Figure 1 shows a graphic representation
of two pulsed DC waveforms. The top
waveform is a Standard Pulsed Waveform
with a Cycle Frequency of 5 Hertz and a
25% duty cycle. The bottom waveform
depicts a Burst of 3 pulses with a burst
frequency of 20Hz, a duty cycle of 50%
and a cycle frequency of 5 Hertz.
Other characteristics of a Pulsed DC
Waveform are the Period and the Pulse
Width.
The Period of a waveform is simply
the inverse of the Frequency. For the
Standard Pulse in Figure 1 the period is
1-second divided by 5-Hertz which is 200
milliseconds. The Cycle period of the Burst
Waveform of Figure 1 is the same as the
cycle period of the standard waveform:
200 milliseconds. The Burst Period is
1-second divided by the burst frequency of
20-Hertz which make the Burst Period 50
milliseconds.
The Pulse Width of these waveforms are
the duty cycle times the Period. For a
standard waveform the duty is multiplied
by the Cycle Period but for a Burst
Waveform the duty is multiplied by the
Burst Period. For the Standard wave the
Pulse Width would be 0.25 times 200
milliseconds which is 50 milliseconds.
The Pulse Width for the Burst Waveform
would be the duty cycle time the Burst
Period, 0.50 times 50 milliseconds or 25
milliseconds.
When selecting the parameters for a
waveform it is best to determine, in
advance, the setting that will produce
the desired output. When changing
the settings of an existing waveform,
consider the side effect that a change,
such as frequency, will have on another
characteristic, such as pulse width. Note
also that when configuring for a burst
of pulses that the cycle period must be
greater than the product of the burst
period time the number of pulses. (While
in theory the relation may be greater or
equal, but the resultant waveform would
then be identical to a standard waveform.
The Burst waveform in Figure 1 could
conceivably have 4 pulses in each burst
but that would make it a standard wave at
20hz and in reality the timing granularity
may not allow it.)
Figure 1