SDS2000 X HD Ser vice Manual
27
The Self Calibration procedure is described in the section
. If the environmental
temperature changes by more than 5
℃
, the Self Calibration operation must be performed to achieve
the specified performance.
5.1
To Verify DC Gain Accuracy
To calculate the DC gain error of a vertical scale, at least nine input and reading values are required
to generate a two-dimensional array.
Use the least square method below to fit the DC Gain error:
Gain error = LINEST( V
error1
:V
error9
, V
setting1
:V
setting9
)
Where:
“ LINEST ” is a function in Microsoft EXCEL© that uses the “ least squares ” method to calculate
a line that best fits your dataset. It creates a two-dimensional array by using the least square
method and then returns an array describing the line. The first value of the returned array
represents the slope of the fitting line.
“ V
setting
” represents the DC voltage output of the 9500B.
“ V
measure
” represents the measurement value on the oscilloscope.
“ V
error
” represents the difference between the voltage setting and the measurement value.
Table 3 Instance of Gain Error Calculation
Vsetting(mV)
Vmeasure(mV)
Verror(mV)
Gain error
Point 1
-3
-3.08
-0.08
0.36%
Point 2
-2.25
-2.34
-0.09
Point 3
-1.5
-1.59
-0.09
Point 4
-0.9
-0.97
-0.07
Point 5
0
-0.00
0
Point 6
0.89
0.821
-0.069
Point 7
1.5
1.43
-0.07
Point 8
2.25
2.186
-0.064
Point 9
3
2.93
-0.07
