Computation of waveform parameter uncertainties

IEC 62754:2017 This document specifies methods for the computation of the temporal and amplitude parameters and their associated uncertainty for step-like and impulse-like waveforms. This document is applicable to any and all industries that generate, transmit, detect, receive, measure, and/or analyse these types of pulses.

Calcul des incertitudes des paramètres des formes d'onde

L'IEC 62754:2017 Le présent document spécifie les méthodes de calcul des paramètres temporels et d'amplitude des formes d'onde échelonnées et de type impulsion, ainsi que leurs incertitudes associées. Le présent document concerne tous les secteurs industriels qui génèrent, transmettent, détectent, reçoivent, mesurent et/ou analysent ces types d'impulsions.

General Information

Status
Published
Publication Date
23-May-2017
Current Stage
PPUB - Publication issued
Start Date
24-May-2017
Completion Date
24-May-2017
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IEC 62754
Edition 1.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Computation of waveform parameter uncertainties
Calcul des incertitudes des paramètres des formes d'onde
IEC 62754:2017-05(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62754
Edition 1.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Computation of waveform parameter uncertainties
Calcul des incertitudes des paramètres des formes d'onde
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20 ISBN 978-2-8322-4345-9

Warning! Make sure that you obtained this publication from an authorized distributor.

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Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62754:2017  IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 Waveform measurement ................................................................................................ 16

4.1 General ................................................................................................................. 16

4.2 Waveform parameters ........................................................................................... 17

4.3 Waveform measurement process .......................................................................... 17

4.3.1 General ......................................................................................................... 17

4.3.2 General description of the measurement system ............................................ 18

5 Waveform and waveform parameter corrections ............................................................ 19

5.1 General ................................................................................................................. 19

5.2 Waveform parameter corrections .......................................................................... 19

5.3 Waveform corrections and waveform reconstruction.............................................. 20

5.3.1 General ......................................................................................................... 20

5.3.2 Sample-by-sample correction ........................................................................ 20

5.3.3 Entire waveform correction ............................................................................ 20

6 Uncertainties ................................................................................................................. 22

6.1 General ................................................................................................................. 22

6.2 Propagation of uncertainties ................................................................................. 22

6.2.1 General ......................................................................................................... 22

6.2.2 Uncorrelated input quantities ......................................................................... 23

6.2.3 Correlated input quantities ............................................................................. 23

6.3 Pooled data and its standard deviation.................................................................. 23

6.4 Expanded uncertainty and coverage factor............................................................ 25

6.4.1 General ......................................................................................................... 25

6.4.2 Effective degrees of freedom ......................................................................... 27

6.5 Entire waveform uncertainties ............................................................................... 28

7 Waveform parameter uncertainties ................................................................................ 29

7.1 General ................................................................................................................. 29

7.2 Amplitude parameters ........................................................................................... 30

7.2.1 State levels.................................................................................................... 30

7.2.2 State boundaries ........................................................................................... 35

7.2.3 Waveform amplitude (state levels) ................................................................. 36

7.2.4 Impulse amplitude (state levels) .................................................................... 37

7.2.5 Percent reference levels (state levels, waveform amplitude) .......................... 37

7.2.6 Transition settling error (state levels, waveform amplitude) ............................ 38

7.2.7 Overshoot aberration (state levels, waveform amplitude) ............................... 38

7.2.8 Undershoot aberration (state levels, waveform amplitude) ............................. 39

7.3 Temporal parameters ............................................................................................ 39

7.3.1 Initial instant .................................................................................................. 39

7.3.2 Waveform epoch ............................................................................................ 40

7.3.3 Reference level instants (percent reference levels, waveform epoch,

initial instant) ................................................................................................. 41

7.3.4 Impulse centre instant (impulse amplitude, reference level instants) .............. 42

7.3.5 Transition duration (reference level instants) ................................................. 42

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IEC 62754:2017  IEC 2017 – 3 –

7.3.6 Transition settling duration (reference level instants) ..................................... 43

7.3.7 Pulse duration (reference level instants) ........................................................ 43

7.3.8 Pulse separation (reference level instants) .................................................... 43

7.3.9 Waveform delay (advance) (reference level instants) ..................................... 44

8 Monte Carlo method for waveform parameter uncertainty estimates .............................. 44

8.1 General guidance and considerations ................................................................... 44

8.2 Example: state level .............................................................................................. 44

Annex A (informative) Demonstration example for the calculation of the uncertainty of

state levels using the histogram mode according to 7.2.1.2................................................... 46

A.1 Waveform measurement ....................................................................................... 46

A.2 Splitting the bimodal histogram and determining the state levels ........................... 46

A.3 Uncertainty of state levels ..................................................................................... 47

Annex B (informative) Computation of Σ andΣ for estimating the uncertainty of
L Y

state levels using the shorth method according to 7.2.1.3 ..................................................... 49

Bibliography .......................................................................................................................... 52

Figure 1 – Reference levels, reference level instants, waveform amplitude, and

transition duration for a single positive-going transition ........................................................... 7

Figure 2 – Overshoot, undershoot, state levels, and state boundaries for a single

positive-going transition ........................................................................................................ 11

Figure 3 – Creation of measured, corrected, and reconstructed waveforms and the

final estimate of the input signal ............................................................................................ 17

Figure 4 – Example of waveform bounds focusing on the trajectories that impact pulse

parameter measurements ..................................................................................................... 28

Figure 5 – Relationship between selected waveform parameters .......................................... 30

Figure A.1 – Waveform obtained from the measurement of a step-like signal from

which the state levels and uncertainties are calculated ......................................................... 46

Figure A.2 – Histograms of state s1 (a) and state s2 (b) of the step-like waveform

plotted in Figure A.1 ............................................................................................................. 47

(α)
Figure B.1 – Diagram showing location of waveform elements, y , in Y and Y , and
(β) 1 2

the construction of Y from Y and Y ..................................................................................... 49

1 2

Table 1 – Value of the coverage factor k that encompasses the fraction p of the t -

distribution for different degrees of freedom (from ISO/IEC Guide 98-3) ............................... 26

Table 2 – Different methods for determining state levels, as given in IEC 60469, and

their uncertainty type and method of computation ................................................................. 31

Table 3 – Different methods for determining state boundaries and their uncertainty type

and method of computation ................................................................................................... 36

Table 4 – Variables contributing to the uncertainty in overshoot ............................................ 39

Table 5 – Variables contributing to the uncertainty in the reference level instant ................... 42

Table A.1 – Uncertainty contributions and total uncertainty for level(s ) determined from

histogram modes .................................................................................................................. 48

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– 4 – IEC 62754:2017  IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPUTATION OF WAVEFORM PARAMETER UNCERTAINTIES
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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International Standard IEC 62754 has been prepared by IEC technical committee 85:

Measuring equipment for electrical and electromagnetic quantities.
The text of this International Standard is based on the following documents:
FDIS Report on voting
85/585/FDIS 85/X588/RVD

Full information on the voting for the approval of this International Standard can be found in

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This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The terms used throughout this document which have been defined in Clause 3 are in italic

type.
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IEC 62754:2017  IEC 2017 – 5 –

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– 6 – IEC 62754:2017  IEC 2017
COMPUTATION OF WAVEFORM PARAMETER UNCERTAINTIES
1 Scope

This document specifies methods for the computation of the temporal and amplitude

parameters and their associated uncertainty for step-like and impulse-like waveforms. This

document is applicable to any and all industries that generate, transmit, detect, receive,

measure, and/or analyse these types of pulses.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60469:2013, Transitions, pulses and related waveforms – Terms, definitions and

algorithms
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
aberration region
3.1.1
post-transition aberration region

interval between a user-specified instant and a fixed instant, where the fixed instant is the first

sampling instant succeeding the 50 % reference level instant for which the corresponding

waveform value is within the state boundaries of the state succeeding the 50 % reference

level instant

[SOURCE: IEC 60469:2013, 3.2.1.1, modified – the note 1 to entry has been deleted.]

3.1.2
pre-transition aberration region

interval between a user-specified instant and a fixed instant, where the fixed instant is the first

sampling instant preceding the 50 % reference level instant for which the corresponding

waveform value is within the state boundaries of the state preceding the 50 % reference level

instant

[SOURCE: IEC 60469:2013, 3.2.1.2, modified – the note 1 to entry has been deleted.]

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IEC 62754:2017  IEC 2017 – 7 –
3.2
amplitude
3.2.1
impulse amplitude

difference between the specified level corresponding to the maximum peak (minimum peak) of

the positive (negative) impulse-like waveform and the level of the state preceding the first

transition of that impulse-like waveform
[SOURCE: IEC 60469:2013, 3.2.3.1]
3.2.2
waveform amplitude
difference between the levels of two different states of a waveform
SEE Figure 1.
50 % reference level instant
10 % reference level instant 90 % reference level instant
90 % reference level
50 % reference level
10 % reference level
Transition occurrence instant
Transition duration
Base state
Waveform epoch
IEC
Figure 1 – Reference levels, reference level instants, waveform amplitude, and
transition duration for a single positive-going transition

[SOURCE: IEC 60469:2013, 3.2.3.2, modified – the Note 1 to entry has been deleted and the

reference to Figure 1 has been added.]
3.3
correction

operation that combines the results of the conversion operation with the transfer function

information to yield a waveform that is a more accurate representation of the signal

Note 1 to entry Correction may be effected by a manual process by an operator, a computational process, or a

compensating device or apparatus. Correction shall be performed to an accuracy that is consistent with the overall

accuracy desired in the waveform measurement process.
[SOURCE: IEC 60469:2013, 3.2.4]
Waveform amplitude
Offsett
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– 8 – IEC 62754:2017  IEC 2017
3.4
coverage factor

numerical factor used as a multiplier of the combined standard uncertainty in order to obtain

an expanded uncertainty
Note 1 to entry: A coverage factor, k, is typically in the range 2 to 3.

Note 2 to entry: Coverage factor is also defined as a “number larger than or equal to one by which a combined

standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty,” (See ISO/IEC

Guide 99:2007, 2.38).

[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.6, modified – the Note 2 to entry has been added.]

3.5
degrees of freedom

in general, the number of terms in a sum minus the number of constraints on the terms of the

sum
[SOURCE: ISO/IEC Guide 98-3:2008, C.2.31]
3.6
impulse response

output signal from an instrument, device, or system that is the result of an input signal, where

this input signal can be described by a unit impulse function, δ(t):
δ(t= 0) = 1
(1)
δ(t≠ 0) = 0
3.7
instant

particular time value within a waveform epoch that, unless otherwise specified, is referenced

relative to the initial instant of that waveform epoch
[SOURCE: IEC 60469:2013, 3.2.13]
3.7.1
initial instant
first sample instant in the waveform
[SOURCE: IEC 60469:2013, 3.2.13.3]
3.7.2
impulse center instant

instant at which a user-specified approximation to the maximum peak (minimum peak) of the

positive (negative) impulse-like waveform occurs
[SOURCE: IEC 60496:2013, 3.2.13.2]
3.7.3
reference level instant
instant at which the waveform intersects a specified reference level
SEE Figure 1.

[SOURCE: IEC 60469:2013, 3.2.13.5, modified – the reference to Figure 1 has been added.]

---------------------- Page: 10 ----------------------
IEC 62754:2017  IEC 2017 – 9 –
3.8
interval

set of all values of time between a first instant and a second instant, where the second instant

is later in time than the first

Note 1 to entry: These first and second instants are called the endpoints of the interval. The endpoints, unless

otherwise specified, are assumed to be part of the interval.
[SOURCE: IEC 60469:2013, 3.2.15]
3.9
level
constant value having the same units as y
SEE Figure 1.
Note 1 to entry: y is the signal.

[SOURCE: IEC 60469:2013, 3.2.17, modified – the reference to Figure 1 has been added as

well as the note 1 to entry.]
3.9.1
percent reference level
reference level specified by:
y = y + (y − y )
x% 0% 100% 0%
(2)
100%
where
0 % < x < 100 %
y = level of low state
y = level of high state
100%
y , y , and y are all in the same unit of measurement
0% 100% x%
SEE Figure 1.

Note 1 to entry: Commonly used reference levels are: 0 %, 10 % , 50 %, 90 %, and 100 %.

[SOURCE: IEC 60469:2013, 3.2.17.3, modified – the reference to Figure 1 has been added.]

3.10
measurand
quantity intended to be measured
[SOURCE: ISO/IEC Guide 99:2007, 2.3, modified – the notes have been deleted.]
3.11
measurement model
model of measurement
model
mathematical relation among all quantities known to be involved in a measurement
[SOURCE: ISO/IEC Guide 99:2007, 2.48, modified – the notes have been deleted.]
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– 10 – IEC 62754:2017  IEC 2017
3.12
measurement uncertainty
uncertainty of measurement
uncertainty

non-negative parameter characterizing the dispersion of the quantity values being attributed

to a measurand, based on the information used

Note 1 to entry Measurement uncertainty is also defined as a “parameter, associated with the result of a

measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand,”

(See ISO/IEC Guide 98-3:2008, 2.2.3).

[SOURCE: ISO/IEC Guide 99:2007, 2.26, modified – the notes have been deleted and the

note 1 to entry has been added.]
3.12.1
standard measurement uncertainty
standard uncertainty of measurement
standard uncertainty
measurement uncertainty expressed as a standard deviation

Note 1 to entry: Standard measurement uncertainty is also defined as an “uncertainty of the results of

measurement expressed as a standard deviation,” ( See ISO/IEC Guide 98-3:2008, 2.3.1).

[SOURCE: ISO/IEC Guide 99:2007, 2.30, modified – the note 1 to entry has been added.]

3.12.2
combined standard measurement uncertainty
combined standard uncertainty
standard measurement uncertainty that is obtained using the individual standard

measurement uncertainties associated with the input quantities in a measurement model

Note 1 to entry: Combined standard uncertainty is also defined as a “standard uncertainty of the result of a

measurement when that result is obtained from the values of a number of other quantities, equal to the positive

square root of a sum of terms, the terms being the variances or covariances of these other quantities weighted

according to how the measurement result varies with changes in these quantities,” (See ISO/IEC Guide 98-3:2008,

2.3.4).

[ISO/IEC Guide 99:2007, 2.31, modified – the note has been deleted and the note 1 to entry

has been added.]
3.12.3
expande
...

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