Agilent Technologies 34420A, Руководство пользователя

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Difference Error
Example This example demonstrates how to compute the total measurement error
when using the Difference Function. Assume a difference measurement
is made with the following conditions:
•
Channel 1 , 1 V input on the 1 Volt range
•
Channel 2 , 1.2 V input on the 10 Volt range
To compute the total measurement error using the 90-day accuracy
specifications for the error:
Channel 1 (% of r % of range) + Channel 2 (% of r % of range).
Channel 1 Reading Error
=
0.0025%
∗
1 V
=
25
µ
V
Channel 1 Range Error
=
0.0004%
∗
1 V
=
4
µ
V
Channel 2 Reading Error
=
0.0020%
∗
1.2 V
=
24
µ
V
Channel 2 Range Error
=
0.0004%
∗
10 V
=
40
µ
V
Total Error
=
25
µ
V
+
4
µ
V
+
24
µ
V
+
40
µ
V
=
93
µ
V
Difference
=
1 V
−
1.2 V
= −
0.2 V
±
93
µ
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%
∗ (
1.2 V
−
1 V
) =
5
µ
V
Channel 1 Range Error
=
0.0004%
∗
1 V
=
4
µ
V
Channel 2 Range Error
=
0.0004%
∗
1 V
=
4
µ
V
Total Error
=
5
µ
V
+
4
µ
V
+
4
µ
V
=
13
µ
V
Difference
=
1 V
−
1.2 V
= −
0.2 V
±
13
µ
V
Using NULL on each input channel will reduce the % of range error in
the measurement to the noise level of the meter.
8
Chapter 8
To Calculate Total Measurement Error
283