U2042XA Datasheet, PDF (21/25 Pages) Keysight Technologies – U2040 X-Series Wide Dynamic Range Power Sensors

21 | Keysight | U2040 X-Series Wide Dynamic Range Power Sensors – Data Sheet
Appendix A
Uncertainty calculations for a power measurement (settled, average power)
(Specification values from this document are in bold italic, values calculated on this page are underlined.)
Process:
1. Power level: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
W
2. Frequency:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Calculate sensor uncertainty:
Calculate noise contribution
– If in Free Run mode, Noise = Measurement noise x free run multiplier
– If in Trigger mode, Noise = Noise-per-sample x noise per sample multiplier
Convert noise contribution to a relative term ¹ = Noise/Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
Convert zero drift to relative term = Drift/Power =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
RSS of above terms = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
4. Zero uncertainty
(Mode and frequency dependent) = Zero set/Power =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
5. Sensor calibration uncertainty
(Sensor, frequency, power and temperature dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
6. System contribution, coverage factor of 2 ≥ sys_rss =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
(RSS three terms from steps 3, 4 and 5)
7. Standard uncertainty of mismatch
Max SWR (frequency dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convert to reflection coefficient, | r_Sensor | = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . . . . . . . . . .
Max DUT SWR (frequency dependent) =. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convert to reflection coefficient, | r_DUT | = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Combined measurement uncertainty @ k = 1
( ) ( ) ^UC ⁼
—^M—^a—^x—(—^r—^D—^U—^T)—^•——^M—^a—^x—(—^r—^S—^en—^s—^or)
2
+
—^s—^y—^s—^rs—^s
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
√2
2
%
Expanded uncertainty, k = 2, = U_C • 2 = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
%
1.  The noise to power ratio for average only mode is capped at 0.01% for MU calculation purposes.