09 | Keysight N1911A/N1912A P-Series Power Meters and N1921A/N1922A Wideband 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: ..............................................................

2. Frequency: ...............................................................

3. Calculate meter 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

Instrumentation linearity .................................................

Drift ..................................................................

RSS of above three terms => Meter uncertainty = ..........................

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 three terms from steps 3, 4 and 5)

7. Standard uncertainty of mismatch

Max SWR (Frequency dependent) = ..........................................

convert to reflection coefficient, | ρ

Max DUT SWR (Frequency dependent) = ......................................

convert to reflection coefficient, | ρ

8. Combined measurement uncertainty @ k=1

............................

Expanded uncertainty, k = 2, = U

1. The noise to power ratio is capped for powers > 100 uW, in these cases use: Noise/100 µW.

%

%

%

%

%

%

%

%

%

%

W

Max(

2

+

2

2

2