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Uncertainty Equation
General form of uncertainty equation is:
2
u
Hence,
2
u
1mW
(
)
–
CCF u CF
⋅
(
)
Assuming that there is no correlation exists between the 8 input variables.
Voltage Measurements Uncertainty
Since the manufacturer's data is used to determine the standard uncertainty, the
analysis used is the Type A method.
The 3458A DMM Uncertainty is calculated with reference to the Appendix A of the
3458A Operating Manual.
A normal distribution is assumed, as the 3458A Manual has not specified the type
of distribution used on the measurement.
Both V
at the output of the 432A using a 3458A DMM. The approximate values of V
and V
10 V scale.
For the 3458A DMM, the specified accuracy for the 10 volt scale is: 8ppm of
Reading + 0.5 ppm of Range
Keysight E4416A/E4417A Power Meters Service Guide
Measurement Uncertainty Analysis - Power Reference Level Test
N
2
2
∑
y ( )
=
c
iu
x i
( )
i
=
1
2
CV 0 u V 0
⋅
+
CV 0 u V 0
(
)
2
2
+
CM s u M s
⋅
(
)
and V
values are calculated by subtracting V
0
1
for no power (V
ref
0
N
N
⎛
⎜
∑
∑
+
2
c i c j u x i x j
⎜
⎝
i
=
1
j
=
i
+
1
2
⋅
+
CV comp u V comp
(
)
2
+
C Rep u Rep
⋅
(
)
) and for 1 mW power (V
⎞
⎟
,
(
)
⎟
⎠
2
⋅
+
(
)
+
C Drift u Drift
⋅
(
)
from V
as measured
ref
comp
) are 5 V with the DMM on the
1
C
2
CR u R ( )
⋅
+
...
2
comp
151
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