IEC TR 61000-1-6:2012

IEC/TR 61000-1-6 ®
Edition 1.0 2012-07
TECHNICAL
REPORT
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –
Part 1-6: General – Guide to the assessment of measurement uncertainty

IEC/TR 61000-1-6:2012(E)
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IEC/TR 61000-1-6 ®
Edition 1.0 2012-07
TECHNICAL
REPORT
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –

Part 1-6: General – Guide to the assessment of measurement uncertainty

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 33.100 ISBN 978-2-83220-204-3

– 2 – TR 61000-1-6 © IEC:2012(E)
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, symbols and abbreviations . 8
3.1 Terms and definitions . 8
3.2 Symbols . 14
3.3 Abbreviations . 15
4 General . 16
4.1 Overview . 16
4.2 Classification of uncertainty contributions . 16
4.3 Limitations of the GUM . 17
4.4 Principles . 18
5 Measurement uncertainty budget development . 20
5.1 Basic steps . 20
5.2 Probability density functions . 24
5.2.1 Rectangular . 24
5.2.2 Triangular . 26
5.2.3 Gaussian . 28
5.2.4 U-Shape . 32
5.3 Concept of Type A and Type B evaluation of uncertainty . 35
5.3.1 General considerations . 35
5.3.2 Type A evaluation of standard uncertainty . 36
5.3.3 Type B evaluation of standard uncertainty . 40
5.4 Sampling statistics . 42
5.4.1 General considerations . 42
5.4.2 Sample mean and sample standard deviation . 42
5.4.3 Sample coefficient of variation . 43
5.4.4 Limits of sample-statistical confidence intervals . 43
5.4.5 Sampling distribution and sampling statistics of mean value . 44
5.4.6 Sampling distribution and sampling statistics of standard deviation . 47
5.5 Conversion from linear quantities to decibel and vice versa . 49
5.5.1 General considerations . 49
5.5.2 Normally distributed fluctuations . 49
5.5.3 Uniformly distributed fluctuations . 52
6 Applicability of measurement uncertainty . 52
7 Documentation of measurement uncertainty calculation . 56
Annex A (informative) Example of MU assessment for emission measurements . 57
Annex B (informative) Example of MU assessment for an immunity test level setting . 64
Bibliography . 67

Figure 1 – Classification of uncertainty components associated with the experimental
evaluation of uncertainty in EMC testing and measurement . 16

TR 61000-1-6 © IEC:2012(E) – 3 –
Figure 2 – Classification of uncertainty components associated with site uncertainty
(e.g. reverberation chambers) . 17
Figure 3 – Example of g(x’) . 19
Figure 4 – Impact of g(x) on interpretation of x’ . 19
Figure 5 – Estimate returned by the measurement system . 20
Figure 6 – Rectangular PDF . 25
Figure 7 – Triangular PDF . 27
Figure 8 – Normal PDF for standardized X . 29
Figure 9 – U-shaped PDF . 33
Figure 10 – Example of a circuit . 33
Figure 11 – Limits of 95 %, 99 % and 99,5 % confidence intervals for W as a function
of N for measurements using a rectilinear antenna or single-axis probe . 46
Figure 12 – Limits of 95 %, 99 % and 99,5 % confidence intervals for A as a function
of N for measurements using a rectilinear antenna or single-axis probe . 47
Figure 13 – 95 % confidence intervals for S as a function of N for measurements
X
using a single-axis detector . 48
Figure 14 – PDF of B for a Rayleigh distributed A at selected values of σ . 51
Figure 15 – Measurement uncertainty budget for a quantity to be realized in the test
laboratory . 53
Figure 16 – Relationship between measurement uncertainty budgets for a quantity to
be realized in the test laboratory and tolerances given for this quantity in the applicable
basic standard . 54
Figure 17 – Situations, where and how an instrument is suitable for tests and/or
measurements as specified in the applicable basic standard with tolerances . 55
Figure A.1 – Deviation of the peak detector level indication from the signal level at
receiver input for two cases, a sine-wave signal and an impulsive signal (PRF 100 Hz) . 60

Table 1 – Basic steps for calculating MU . 20
Table 2 – Expressions used to obtain standard uncertainty . 23
Table 3 – Examples of circuit parameters . 35
Table 4 – Values of the expansion coefficient η(ν) which transforms the standard
deviation to the Type A standard uncertainty . 39
Table A.1 – Radiated disturbance measurements from 1 GHz to 18 GHz in a FAR at a
distance of 3 m . 58
Table B.1 – Uncertainty budget of the radiated immunity test level (80 MHz –
1 000 MHz) . 65

– 4 – TR 61000-1-6 © IEC:2012(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 1-6: General –
Guide to the assessment of measurement uncertainty

FOREWORD
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