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Measurement Uncertainty Analysis – Power Reference Level Test
Measurement Introduction
B-12 Agilent E4416A/E4417A Service Guide
Combined Standard Uncertainty (uc(y))
1 Using Agilent’s standard 95.5% confidence the coverage factor is k = 2.00
Expanded Uncertainty
The expanded uncertainty is: U= 3.030 µW, as a percent of 1.000 mW: U = 0.303%
Table B-2: Combined Standard Uncertainty
Symbol
Source of
Uncertainty
Value
Probability
Distribution
Divisor Ci
Ui
/µW
U(V
0
) Two Voltage
measurements on a
3458A DMM
69.65 µV Normal 2 2.129x10
-04
V/Ω 0.007
U(V
1
) Two Voltage
measurements on a
3458A DMM
69.45 µV Normal 2 1.224x10
-02
V/Ω 0.426
U(V
comp
) Voltage measurement
on 3458A DMM
49.25 µV Normal 2 -1.245x10
-02
V/Ω 0.307
U(R) 4 wire Resistance
measurement on
3458A DMM
0.0046 Ω Normal 2 -4.727x10
-06
W/Ω 0.012
U(CF) Calibration factor for
Thermistor
0.002 Normal 2 -9.696x10
-04
W 1.070
U(M
s
) Mismatch between the
DUT and the
Thermistor
0.0012 U shaped √2 -9.454x10
-04
W 0.885
U(Drift) Drift of 8478B
Thermistor
0.0006 Normal 2 1.00x10
-03
W 0.6
U(Rep) Repeatability of the
complete measurement
0.057 µW Normal 1 1 0.057
Uc Combined Uncertainty Normal 1.515
U
1
Expanded Uncertainty k=2 Normal 3.030