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SECTION 3
Note that the duty cycle setting also changes the duty cy-
de of the SYNC OLIT signal.
To extend the duty cycle range, use the burst oscillation
mode and one square waveform
cycle. Refer to para-
graph 3.5.9 for details on setting the oscillation
mode.
Synchronous
Output
Figure 3-9 illustrates
the phase relationship
between the
waveform
and synchronous
output (SYNC OUT) at he-
quencies below 1kHz. Note that at high frequencies, in-
ternal circuit delays result in a substantial phase differen-
tial between the waveform
output and synchronous
out-
put signals.
3.5.9
Oscillation
Mode
Oscillation
Mode Selection
Pressing the MODE key displays the current oscillation
mode along with its corresponding
number and enables
oscillation
mode selection. Available
oscillation
modes
include continuous,
burst, and gate modes.
To select the oscillation
mode with the numeric
keys,
simply press the numeric key that corresponds to the de-
sired oscillation
mode. For example press 1 to select the
burst mode. Pressing the numeric key will change the set-
ting immediately;
it is not necessary to press a units key
when setting the osc&tion
mode.
When the Model 3930A displays the current oscillation
mode, and mode selection
is enabled, you can also
change the mode by turning the MODIFY knob. Turning
the knob clockwise increases the oscillation
mode num-
ber, while turning the knob counter-clockwise
decreases
the oscillation
mode number (one digit per detent set-
ting). When the highest
or lowest
mode number
is
reached, the number will wrap around to the lowest or
highest value (mode values range between 0 and 2). Note
that the cursor position is fixed, and the step size is fixed
atil.
Continuous
Mode
When the continuous
mode is selected, the instrument
generates the selected waveform
continuously.
Trigger-
ing is not required, and the selected burst cycle and inter-
nal rate parameters
have no effect on the output
wavefcmn.
3-24
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