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SDS2000X HD Service Manual
5.3
To Verify DC Measurement Accuracy
Some products do not list the DC measurement accuracy in the datasheet, but it can be calculated
by combining the DC gain Accuracy and Offset Accuracy. Verifying this specification is not necessary
if the DC gain accuracy and Offset accuracy had been verified.
Table 8 DC Measurement Accuracy
DC Measurement Accuracy
±(DC gain accuracy x | Vs Offset sOffset accuracy)
Use the method below to calculate the High/Low limiting for the DC measurement results:
Upper limit = V
setting
+ (DC gain accuracy x | V
setting
+ Offset
setting
| + Offset accuracy)
Lower limit = V
setting
- (DC gain accuracy x | V
setting
+ Offset
setting
| + Offset accuracy)
Where:
“ Vsetting ” represents DC voltage output by the 9500B.
“ Offsetsetting ” represents the offset value setting on an oscilloscope.
Table 9 Instance of DC Measurement Limiting Calculation
1V/div
Vsetting
(V)
Offsetsetting
(V)
Vmean
(V)
Lower limit
(V)
Upper limit
(V)
Setting 1
3
0
2.944
3.056
Setting 2
-3
0
-3.056
-2.944
Upper limit = 3V + (|3V + 0|*0.5% + 0V*0.5% + 1V/div*8div*0.5% + 1mV) = 3.056 V
Lower limit = 3V - (|3V + 0|*0.5% + 0V*0.5% + 1V/div*8div*0.5% + 1mV) = 2.944 V
The instance above give the DC measurement limiting with two different input and offset settings.
Here the limiting calculation with no Zero offset is not listed, because the calculation process is
complicated. It is not recommended to verify the device with no zero offset setting
( offset ≠ 0 ).
Steps:
The equipment and device configuration sequence is the same as the Offset Accuracy verification
setting.
