User manual

3390-900-01 Rev. C / January 2009 Return to Section Topics 5-11
Model 3390 Arbitrary Waveform Generator User’s Manual Section 5: Waveform Output Operations
enabled, the previously selected modulation is automatically disabled. In addition, when frequency
modulation is enabled, sweep mode and burst mode are disabled.
Carrier waveform
The default carrier waveform is sine. You can also choose square, ramp, and arbitrary waveforms.
The default carrier frequency is 1 kHz for all waveforms. Each carrier waveform has its own
acceptable range of frequencies. Refer to Table 4-1: Waveform function frequency ranges for
details.
Modulating waveform
The Model 3390 accepts either an internal or external modulating source.
The default source is internal with a default frequency of 100 Hz (the acceptable range is 2 mHz to
20 kHz). The default internal modulating waveform is a sine waveform, but you can also select
from the following:
• 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.
Frequency deviation
The frequency deviation represents the peak variation in the frequency of the modulation output,
based on that of the carrier waveform. The default value is 100 Hz. If a value is set greater than
allowed, the instrument will automatically adjust it to the instrument maximum. Each type of carrier
waveform has a different acceptable range:
• Sine: 1 μHz to 25.05 MHz (at carrier frequency = 25.05 MHz)
• Square: 1 μHz to 12.55 MHz (at carrier frequency = 12.55 MHz)
• Ramp: 1 μHz to 150 kHz (at carrier frequency = 150 kHz)
• Arbitrary: 1 μHz to 5.05 MHz (at carrier frequency = 5.05 MHz)
The maximum allowable value is also affected by the following:
• The frequency deviation cannot be greater than the carrier frequency.
• The sum of frequency deviation and the carrier frequency cannot be greater than the
maximum frequency of the selected carrier waveform plus 100 kHz; (50.1 MHz for sine;
25.1 MHz for square; 300 kHz for ramp; and 10.1 MHz for arbitrary waveforms).
Choosing the external source means the modulation is controlled by the specified frequency
deviation and the ±5 V signal levels of the external waveform. When the external waveform is at
+5 V, the output will reach positive maximum frequency deviation. When the external waveform is
at -5 V, the output will reach negative maximum frequency deviation.
To set up frequency modulation:
1. Select the carrier waveform (Sine, Square, Ramp, or Arb). Follow the instructions for
setting up that specific waveform as given in this publication. Refer to Section 4, Setup
Basics for assistance.
2. Press the Mod key to access the modulation menu.