Accuracy Specifications - Agilent Technologies 34420A User Manual

Chapter 8
To Calculate Total Measurement Error
Difference Error This example demonstrates how to compute the total measurement error
when using the Difference Function. Assume a difference measurement
Example
is made with the following conditions:
To compute the total measurement error using the 90-day accuracy
specifications for the error:
Channel 1 (% of reading + % of range) + Channel 2 (% of reading + % of range).
Channel 1 Reading Error = 0.0025%
Channel 1 Range Error = 0.0004%
Channel 2 Reading Error = 0.0020%
Channel 2 Range Error = 0.0004%
Total Error = 25 V + 4 V + 24 V +
Difference = 1 V
For difference measurements, if both channel 1 and channel 2 are using
the same range, the % of reading error can be applied directly to to the
voltage difference. In the example, if both channels are using
the 1 V range, the total reading error can be computed as:
Reading Error = 0.0025%
Channel 1 Range Error = 0.0004%
Channel 2 Range Error = 0.0004%
Total Error = 5 V + 4 V + 4 V = 13 V
Difference = 1 V
Using NULL on each input channel will reduce the % of range error in
the measurement to the noise level of the meter.
Channel 1, 1 V input on the 1 Volt range
Channel 2, 1.2 V input on the 10 Volt range
=
1.2 V
1.2 V =
1 V = 25 V
1 V = 4 V
1.2 V = 24
V
10 V = 40 V
V = 93 V
40
0.2 V ± 93 V
( 1.2 V 1 V ) = 5 V
1 V = 4 V
1 V = 4 V
0.2 V ± 13 V
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