Agilent Technologies E4418B, Руководство по обслуживанию

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Measurement Uncertainty Analysis – Power Reference Level Test
Measurement Introduction
B-12 Agilent E4416A/E4417A Service Guide
Combined Standard Uncertainty (
u
c(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
µ
W
, 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
/
µ
W
U(V
0
) Two Voltage
measurements on a
3458A DMM 69.65
µ
V Normal 2 2.129x10
-04
V/
Ω
0.007
U(V
1
) Two Voltage
measurements on a
3458A DMM 69.45
µ
V Normal 2 1.224x10
-02
V/
Ω
0.426
U(V
comp
) Voltage measurement
on 3458A DMM 49.25
µ
V 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
µ
W Normal 1 1 0.057
Uc Combined Uncertainty Normal 1.515
U
1
Expanded Uncertainty k=2 Normal 3.030
4402serv.book Page 12 Tuesday, October 14, 2003 3:18 PM