Chapter 6, COMPUTER OPERATION 
6-24 
FMFILTER [n]  Oscillator frequency modulation filter control command 
The value of n sets the oscillator frequency modulation voltage low-pass filter 
control in the range 0 to 10. The value of 0 gives the widest bandwidth for this filter, 
with the value of 10 the lowest. 
FMSPANF[.] [n]   Oscillator frequency modulation span frequency command 
In fixed point mode n sets the oscillator frequency-modulation span frequency in 
mHz. The range of n is 0 to 125,000,000 representing 0 to ± 125 kHz; in floating 
point mode n sets the span frequency in Hz. The range of n is 0 to 1.25E5. 
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 setting the center frequency and span frequency 
under computer control it is recommended to first set the span frequency to zero 
followed by the center frequency to the required value and finally the span 
frequency to the required value. This will avoid potential problems with the new 
center frequency being rejected because it is not a legal value when compared with 
the old span frequency. 
FMVSPAN[.] [n]   Oscillator frequency modulation voltage span command 
The value of n sets the oscillator frequency modulation span voltage; in fixed point 
mode n is an integer in the range 0 to +10000, corresponding to a range from 
0.000 V to 10.000 V, and in floating point mode it is in volts. 
Note: The span voltage plus the center voltage cannot exceed 
10.000 V 
6.7.07 Analog Outputs 
CH n
1
 [n
2
]  DAC analog output control 
Defines what outputs appear on the DAC1, DAC2, DAC3 and DAC4 connectors on 
the rear panel.  
n
2
  Signal (DAC1) 
0  X % (2.5 V FS) 
1  Noise % (2.5 V FS) 
2  Ratio: (10 × X%/ADC 1) 
3  Log Ratio: log
10
 (10  X%/ADC1) 
4  Equation 1 
5  Equation 2 
6  User DAC1 
7  Main signal channel ADC output  (digital signal monitor 1) 
8  Magnitude2 % (2.5 V FS) (dual mode only) 
n
2
  Signal (DAC2) 
0  Y % (2.5 V FS) 
1  Noise % (2.5 V FS) 
2  Ratio: (10 × X%/ADC 1) 
3  Log Ratio: log
10
 (10  X%/ADC1) 
4  Equation 1