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A normal distribution is assumed, as the 3458A Manual has not specified the type of
distribution used on the measurement.
Both V
the output of the 432A using a 3458A DMM. The approximate values of V
V
ref
scale.
For the 3458A DMM, the specified accuracy for the 10 volt scale is:
8ppm of Reading + 0.5ppm of Range
with;
0.15ppm of Reading + 0.01ppm of Range per °C (temp coefficient Tcal ±5 °C)
± 8.75 ppm of Reading + 0.55ppm of Range
Therefore,
(
U V
comp
For V0 and V1, two measurements are taken, so the uncertainty is equated to the RSS
of using two DMMs;
U(Vcomp)
U(V
U(V
Mismatch
The Mismatch uncertainty was previously determined as being:
Note
Agilent E4416A/E4417A Service Guide
Measurement Uncertainty Analysis – Power Reference Level Test
and V
values are calculated by subtracting V
0
1
for no power (V
) and for 1mW power (V
0
8.75
)
(
)
±
=
U V
=
---------------------- -
ref
1000000
Voltage measurement
)
0
)
1
(
MsUncertainty magnitude
This is the worst-case uncertainty for mismatch and occurs when the
incident and reflected waves are 180 degrees out of phase.
Measurement Introduction
from V
ref
) are 5V with the DMM on the 10V
1
×
×
5
0.55
10
±
+
----------------------- -
=
49.25uV
1000000
Uncertainty
49.25 µV
69.65 µV
69.65 µV
)
2P s P d
=
as measured at
comp
and
comp
C-5
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