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Chapter 4 Remote Interface Reference
Frequency Modulation (FM) Commands
4
• If the deviation causes the carrier waveform to exceed a frequency
boundary for the current duty cycle (square waveform only),
the function generator will automatically adjust the duty cycle to the
maximum value allowed with the present carrier frequency. From the
remote interface, a “Settings conflict” error will be generated and the
duty cycle will be adjusted as described.
•
If you select the
External
modulating source (
FM:SOUR EXT
command
),
the deviation is controlled by the ±5V signal level present on the rear-
panel Modulation In connector. For example, if you have set the
frequency deviation to 100 kHz, then a +5V signal level corresponds
to a 100 kHz increase in frequency. Lower external signal levels
produce less deviation and negative signal levels reduce the
frequency below the carrier frequency.
FM:STATe {OFF|ON}
FM:STATe?
Disable or enable FM. To avoid multiple waveform changes, you can
enable FM after you have set up the other modulation parameters.
The default is OFF. The :STAT? query returns “0” (OFF) or “1” (ON).
• The function generator will allow only one modulation mode to be
enabled at a time. For example, you cannot enable FM and AM at the
same time. When you enable FM, the previous modulation mode is
turned off.
• The function generator will not allow FM to be enabled at the same
time that sweep or burst is enabled. When you enable FM, the sweep
or burst mode is turned off.
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