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Chapter 5, FRONT PANEL OPERATION
When the VCO is enabled, the internal oscillator's output frequency can be
modulated by a signal applied to the ADC1 auxiliary input. The controls operate as
follows:-
CENTER FREQUENCY
This control may be set to any value between 0.001 Hz and 250.00 kHz. Adjustment
is faster using the Keypad or Active Cursor controls - see section 4.1.04.
FREQUENCY SPAN
This control defines the maximum frequency span that will be applied to the
oscillator signal. For example, when set to ±100.00 Hz, the change will be
±100.00 Hz about the quiescent level.
Note: The center frequency
the span frequency must not exceed the frequency
limits of the oscillator (0 to 250 kHz). Hence the center frequency plus the span
frequency cannot exceed 250.0 kHz and the center frequency must be greater than
or equal to the span frequency. For example, at 125 kHz center frequency the
maximum span frequency is
125 kHz; at 10k Hz center frequency the maximum
span frequency is
10 kHz; at 240 kHz center frequency the maximum span
frequency is also
10 kHz. When set from the front panel the center frequency
has priority over the span frequency.
CENTER VOLTAGE
This control sets the input voltage corresponding to the quiescent oscillator
frequency.
VOLTAGE SPAN
This control sets the range of input voltages that will be translated into the set
frequency span.
FILTER CONTROL
The VCO control signal can be filtered by a simple digital low-pass FIR filter before
being applied to the oscillator, which can be useful for eliminating noise or glitches
on the signal. This control adjusts the filter; when set to 0 the filter is turned off; as
the number is increased, increased filtering is applied.
VCO ENABLED
This control turns the VCO control on and off
Pressing the Previous Menu key returns control to the Oscillator Menu.
5.3.14 Auto Functions Menu
When Main Menu 1 is displayed, pressing a key adjacent to the Auto Functions item
accesses the Auto Functions menu, which is shown in figure 5-18
5-25
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