Boonton 4240 RF Power Meter Uživatelský manuál stáhnout pdf (Strana 113)

Boonton 4240 Series RF Power Meter

6.2 M

The 424

Standard year

calibratio

chapter assumes that the power meter is being maintained correctly and is within its valid calibration period.

Measure

and the

mathema error is obtained by combining the linear

(percent) ources in cu take into account the statistical

shape of e expe

Note tha ed given in either percent or dB. The following

formulas ay be

Section 6.2.1 outlines all the parameters that contribute to the power measurement uncertainty followed by a discussion on

the method and calculations used to express the uncertainty.

Section

Section 6. sors with complete

Uncertai y Budg

6.2.1 Uncertainty

The total measurem s:

easurement Accuracy

0 Series includes a precision, internal, 50 MHz RF reference calibrator that is traceable to the National Institute for

s and Technology (NIST). When the instrument is maintained according to the factory recommended one

n cycle, the calibrator enables you to make highly precise measurements of CW signals. The error analyses in this

ment uncertainties are attributable to the instrument, calibrator, sensor, and impedance mismatch between the sensor

device under test (DUT). Individual independent contributions from each of these sources are combined

tically to quantify the upper error bound and probable error. The probable

s on a root-sum-of-squares (RSS) basis. RSS uncerta ty cal lations also

th cted error distribution.

t uncertainty figures for individual components may be provid

m used to convert between the two units:

= (10

(UdB/10)

- 1) × 100 and U

= 10 × Log

(1 + (U

/ 100))

6.2.2 continues discussing each of the uncertainty terms in more detail while presenting some of their values.

2.3 provides Power Measurement Uncertainty calculation example for a CW Power sen

nt ets.

Contributions.

ent uncertainty is calculated by combining the following term

Uncertainty Source Distribution Shape K

1. Instrument Uncertainty Normal 0.500

2. Calibrator Level Uncertainty Rectangular 0.577

. Calibrator Mismatch Uncertainty U-shaped 0.707

.577

4. Source Mismatch Uncertainty U-shaped 0.707

5. Sensor Shaping Error Rectangular 0.577

6. Sensor Temperature Coefficient Rectangular 0.577

7. Sensor Noise Normal 0.500

8. Sensor Zero Drift Rectangular 0

9. Sensor Calibration Factor Uncertainty Normal 0.500

he formula for worst-case measurement uncertainty is:

WorstCase

= U

+ U

+ ... U

here U

through U

represent each of the worst-case uncertainty terms.

Application Notes

6-5

1 2 ... 108 109 110 111 112 113 114 115 116 117 118 ... 127 128

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