User Manual

7
Table 2 - External Fact ors
Error Source Conditions
The root sum square (RSS) uncertainty is the industry
standard met
hod for combining independent uncer-
tainties. To determine the TPS's RSS uncertainty:
1. Square each uncertainty factor.
2.
Add these values together.
a. Take the square root of this sum.
Other
a
< 40 °C or > 100 MHz ± 0.50%
Resolution ± ½ smallest displayed digit
(e.g. for a mW scale, three decimal
places are displayed. ½ the smallest is
0.5 µW)
Zero Set
†
± 0.125 µW
Noise
b
above 1. 05 mW ± 0.7 µW
105 µW to 1.05 mW ± 0.4 µW
below 105 µW ± 0.2 µW
a. Above 40 °C, when making measurements at frequencies
between 40 and 100 MHz, add 1.1%.
b. After a 5 minute warm-up, measured over a 5 minute
interval and 2 standard deviations
Attenuator
Uncertainty
Frequency dependent
Cable Uncertainty Frequency and length dependent
(± 5% at 1 GHz for a ‘reasonable’
1.5 m cable)