Service manual

Measurement
Uncertainty
Calculations
Measurement uncertainties for the Datron 4708 source are calculated
using the 90-day accuracy specifications in the Datron 4708 User’s
Handbook:
Measurement Uncertainty = Datron Accuracy + Calibration
Uncertainty, where Datron Accuracy (ppm) = Accuracy Relative to
Calibration Standards = ± (ppm OUTPUT + ppm FS)
and FS = 2 x range for all ranges except 1000V
FS = 1100 for the 1000V range
The assumed test conditions are:
• Temperature of 23
o
C± 1
o
C
• 90 days since last calibration
• 4-wire sense function for ohms measurements
Calculate DCV
Measurement
Uncertainty
From Section 6 - Specifications of the Datron 4708 User’s Handbook,
DC Voltage (Option 10) Accuracy (90 days since calibration and 23
o
C
± 1
o
C) follows, where Datron Accuracy = ± (ppm OUTPUT + ppm
FS).
Datron
OUTPUT
(DCV)
Datron
Range
(Volts)
Datron
Accuracy
(ppm)
Calibration
Uncertainty
(ppm)
0.1
0.9
7.0
58.0
300.0
1.0000000V
1.0000000V
10.000000V
100.00000V
1000.0000V
2 + 0.4
2 + 0.4
1 + 0.15
2 + 0.25
3 + 0.25
2
2
1.5
2
2
Example: Calculate DC Voltage Measurement Uncertainty
Since Measurement Uncertainty = Datron Accuracy + Calibration
Uncertainty, for a 7.0 DCV OUTPUT and the Datron 4708 range set to
10.000000 V, Measurement Uncertainty (µV)= ± [(1.0 x 7.0) + (2 x 0.15
x 10)] + 1.5 = ± 11.5 µV = ± 0.0000115 V.
Or, with a 300 DCV OUTPUT and the 1000.0000V range,
Measurement Uncertainty (µV) = ± [(3.0 x 300) + (0.25 x 1100)] + 2.0
= ± 1177 µV = ± 0.001177 V.
A-4 Calculating Multimeter Accuracy