N1923A Datasheet, PDF (17/19 Pages) Keysight Technologies – Wideband Power Sensors

17 | Keysight | 8990B Peak Power Analyzer and N1923A/N1924A Wideband Power Sensors - Data Sheet
Worked Example
Uncertainty calculations for a power measurement (settled, average power)
[Specification values from this document are in bold, values calculated on this page are underlined.]
Process
1. Power level ..............................................................................................................................................
2. Frequency ................................................................................................................................................
3. Calculate meter uncertainty:
Calculate noise contribution
Noise = Noise-per-sample x noise per sample multiplier = 3 μW x 1
Convert noise contribution to a relative term1 = Noise/Power = 3 μW/1 mW ................................
Instrumentation linearity .....................................................................................................................
Drift .........................................................................................................................................................
RSS of above three terms ≥ Meter uncertainty = ............................................................................
4. Zero uncertainty
(Mode and frequency-dependent) = Zero set/Power = 200 nW/1 mW .........................................
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, | ρ_Sensor | = (SWR–1)/(SWR+1) = ..................................................
Max DUT SWR (frequency-dependent) = .........................................................................................
Convert to reflection coefficient, | ρ_DUT | = (SWR–1)/(SWR+1) = .....................................................
8. Combined measurement uncertainty @ k=1
( ) ( ) ^{UC =}
Max(ρ_DUT ) _⦁ Max(ρ_Sensor )
2
+
√2
sys_rss ²
2
...................................................................
Expanded uncertainty, k = 2, = UC _⦁ 2 = ...............................................................................................
1.  The noise-to-power ratio is capped for powers > 100 μW, in these cases use: Noise/100 μW.
1 mW
1 GHz
0.3%
0.8%
0.85%
0.02%
4.0%
4.09%
1.2%
0.091%
1.26%
0.115%
2.045%
4.09%