User manual
5-16 Return to Section Topics 3390-900-01 Rev. C / January 2009
Section 5: Waveform Output Operations Model 3390 Arbitrary Waveform Generator User’s Manual
• Square waveform with 50% duty cycle
• URamp (up or positive ramp with 100% symmetry)
• DRamp (down or negative ramp with 0% symmetry)
• Triangle waveform (ramp with 50% symmetry)
• Noise waveform
• Arbitrary waveform (limited to 4 K points with automatic decimation)
Select the external modulating source to modulate the carrier waveform with an external signal
present at the Modulation In connector on the rear panel.
Width deviation
The width deviation represents the peak variation in the pulse width of the modulation output
based on that of the original carrier waveform. The range of the width deviation is from 0 s to
1000 s, and the default is 10 μs.
The deviation cannot be greater than the pulse width of the carrier waveform, and has the
following constraints:
WidthDeviation
≤
PulseWidth - Wmin
WidthDeviation
≤
Period - (PulseWidth + Wmin)
Where: Wmin is the minimum pulse width as described in the Pulse waveform section.
Choosing the external source means the modulation is controlled by the specified width deviation
and the ±5 V signal levels of the external waveform. When the external waveform is at +5 V, the
output will reach the maximum pulse width. When the external waveform is at -5 V, the output will
reach the minimum pulse width.
To set up PWM:
1. Press the Pulse soft key. Follow the instructions for setting up a pulse waveform as given in
this publication. Refer to Section 4, Setup Basics for assistance.
2. Press the Mod key to access the modulation menu.
3. Press the soft key under Src to select between internal source (Int) and external source
(Ext) for the modulating waveform (Figure 5-15). If internal source is selected:
a) Press the soft key under Shape to select the modulating waveform. If arbitrary
waveform (Arb) is chosen, the instrument will use the currently selected arbitrary
waveform. Press the Mod key to see which arbitrary modulating waveform is
currently selected.
b) Press the soft key under PWM / Freq. Use the navigation wheel with the cursor
keys to change the value, and then press another soft key to finish the entry and
exit. Or use the numeric keypad to enter a desired value and then press the soft key
under the desired units to finish the entry, or the soft key under Cancel to cancel the
changes.
Figure 5-15:
Press the soft keys corresponding with PWM
4. Press the soft key under Width / Dev (Figure 5-15). Use the navigation wheel with the
cursor keys to change the value, and then press another soft key to finish the entry and exit.
Or use the numeric keypad to enter a desired value and then press the soft key under the
desired units to finish the entry, or the soft key under Cancel to cancel the changes.