Chapter 5, WEB CONTROL PANEL OPERATION 
5-30 
5.3.14 Oscillator: Modulation Control 
 
Figure 5-32, Oscillator Panel, Modulation Controls 
The internal oscillator output in the model 7230 can be amplitude or frequency 
modulated using an external control voltage using the controls on this panel, shown 
on figure 5-32. 
Frequency (VCO) group 
  Enable FM 
When checked, this control turns the frequency modulation on; when cleared, it 
turns it off. 
  Center frequency 
This control may be set to any value between 0.001 Hz and 120.000 or 
250.000 kHz.  
  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 centre frequency. 
  Note: The center frequency 
 the span frequency must not exceed the 
frequency limits of the oscillator (0 to 120 or 250 kHz). Hence the center 
frequency plus the span frequency cannot exceed 120 or 250.0 kHz and the 
center frequency must be greater than or equal to the span frequency. For 
example, for an instrument fitted with the 7230/99 option 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.. 
  Center voltage 
This control sets the input voltage corresponding to the centre frequency.