Ametek 7270 Instruction Manual page 100

Chapter 5, FRONT PANEL OPERATION
5-52
N%fs
+300
+100
0
NOTE: When NOISE is selected as an output, the noise measurement mode
(Configuration Menu) must be ON. If it is not, a warning message is displayed
which offers the option of turning it on or deselecting NOISE as an analog
output.
RATIO (2.5V fs)
When set to RATIO the corresponding DAC connector on the rear panel of the
instrument outputs a voltage related to the result of the RATIO calculation,
which is defined as follows:-


10 X output
 
RATIO

ADC1 Input
where X output is the X channel output as a percentage of the full-scale
sensitivity and ADC 1 is the voltage (expressed in volts) applied to the ADC 1
input connector on the rear panel of the instrument. Hence, for example, if the
instrument were measuring a 100 mV signal when set to the 500 mV sensitivity
setting, the X channel output were maximized and a 1 V signal were applied to
the ADC1 input, then the value of RATIO would be:-

0.1

10

0.5
 
RATIO
1.000



RATIO 2
The relationship between the voltage at the DAC connector and the RATIO
value is defined as follows:-
RATIO
+7.5
+2.5
0
-2.5
-7.5
LOG RATIO
When set to LOG RATIO the corresponding DAC connector on the rear panel of
the instrument outputs a voltage related to the LOG RATIO calculation, which is
defined as follows:-



LOG RATIO log
10

where X output is the X channel output as a percentage of the full-scale
sensitivity and 1 is the voltage (expressed in volts) applied to the ADC 1 input
connector on the rear panel of the instrument. Hence, for example, if the
instrument were measuring a 100 mV signal when set to the 500 mV sensitivity
DAC Voltage
7.5 V
2.5 V
0.0 V








DAC Voltage
7.5 V
2.5 V
0.0 V
-2.5 V
-7.5 V
 
10 X output


ADC1 input