Measurement Uncertainty Analysis – Power Reference Level Test
Measurement Introduction
Agilent E4416A/E4417A Service Guide
B-5
A normal distribution is assumed, as the 3458A Manual has not specified the type of
distribution used on the measurement.
Both V
0
and V
1
values are calculated by subtracting V
ref
from V
comp
as measured at
the output of the 432A using a 3458A DMM. The approximate values of V
comp
and
V
ref
for no power (V
0
) and for 1mW power (V
1
) are 5V with the DMM on the 10V
scale.
For the 3458A DMM, the specified accuracy for the 10 volt scale is:
8ppm of R 0.5ppm of Range
with;
0.15ppm of R 0.01ppm of Range per
°
C (temp coefficient Tcal ±5
°
C)
± 8.75 ppm of R 0.55ppm of Range
Therefore,
For V0 and V1, two measurements are taken, so the uncertainty is equated to the RSS
of using two DMMs;
Mismatch
The Mismatch uncertainty was previously determined as being:
Note
This is the worst-case uncertainty for mismatch and occurs when the
incident and reflected waves are 180 degrees out of phase.
Voltage measurement
Uncertainty
U(Vcomp)
49.25
µ
V
U(V
0
)
69.65
µ
V
U(V
1
)
69.65
µ
V
U V
comp
(
)
U V
ref
(
)
8.75
5
×
1000000
-----------------------
0.55
10
×
1000000
------------------------
+
±
49.25uV
±
=
=
=
MsUncertainty magnitude
(
)
2P
s
P
d
=
4402serv.book Page 5 Tuesday, October 14, 2003 3:18 PM
Summary of Contents for E4418B
Page 19: ...1 Specifications 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
Page 37: ...2 Performance Tests 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
Page 69: ...3 Adjustments 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
Page 81: ...4 Theory of Operation 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
Page 95: ...5 Replaceable Parts 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
Page 119: ...6 Troubleshooting 4402serv book Page 1 Tuesday October 14 2003 3 18 PM ...
