Agilent Technologies N1911A Manual de usuario descargar pdf (Pagina 10)

Worked Example

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: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1mW

2. Frequency: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 GHz

3. Calculate meter uncertainty: In free run, auto zero mode average = 16

Calculate noise contribution

• If in Free Run mode, Noise

= Measurement noise x free run multiplier = 50 nW x 0.6 = 30 nW

• If in Trigger mode, Noise

= Noise-per-sample x noise per sample multiplier

Convert noise contribution to a relative term

= Noise/Power = 30 nW/100 uW . . . . . . . . 0.03%

Instrumentation linearity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8%

Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –

RSS of above three terms => Meter uncertainty

= . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8%

4. Zero Uncertainty

(Mode and frequency dependent) = Zero set/Power

= . . . . . . . . . . . . . . . . . . . . . . . . . 0.03%

5. Sensor calibration uncertainty

300 nW/1 mW

(Sensor, frequency, power and temperature dependent) = . . . . . . . . . . . . . . . . . . . . . . . 4.0%

6. System contribution

, coverage factor of 2 => sys

rss

= . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.08%

(RSS three terms from steps 3, 4 and 5)

7. Standard uncertainty of mismatch

Max SWR (Frequency dependent) = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.25

convert to reflection coefficient, |

Sensor

| = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . 0.111

Max DUT SWR (Frequency dependent) = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.26

convert to reflection coefficient, |

DUT

| = (SWR–1)/(SWR+1) = . . . . . . . . . . . . . . . . . . . . 0.115

8. Combined measurement uncertainty @ k=1

. . . . . . . . . . . . . . . . . . . . . 2.23%

Expanded uncertainty, k = 2, = U

• 2 = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±4.46%

15. The noise to power ratio is capped for powers > 100 uW, in these

cases use: Noise/100 µW instead.

Max(r

DUT

) • Max(r

Sensor

) sys

rss

1 2 ... 5 6 7 8 9 10 11 12

Comentarios a estos manuales

Sin comentarios

Agilent Technologies N1911A Manual de usuario Pagina 10

Comentarios a estos manuales

Relacionado con productos y manuales para Multímetros Agilent Technologies N1911A