IEC 61000-4-15:2010

Electromagnetic compatibility (EMC) - Part 4-15: Testing and measurement techniques - Flickermeter - Functional and design specifications

IEC 61000-4-15:2010 is available as IEC 61000-4-15:2010 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 61000-4-15:2010 gives a functional and design specification for flicker measuring apparatus intended to indicate the correct flicker perception level for all practical voltage fluctuation waveforms. Information is presented to enable such an instrument to be constructed. A method is given for the evaluation of flicker severity on the basis of the output of flickermeters complying with this standard. The flickermeter specifications in this part of IEC 61000 relate only to measurements of 120 V and 230 V, 50 Hz and 60 Hz inputs. Characteristics of some incandescent lamps for other voltages are sufficiently similar to the values in Table 1 and Table 2, that the use of a correction factor can be applied for those other voltages. Some of these correction factors are provided in the Annex B. Detailed specifications for voltages and frequencies other than those given above, remain under consideration. The object of this part of IEC 61000 is to provide basic information for the design and the instrumentation of an analogue or digital flicker measuring apparatus. It does not give tolerance limit values of flicker severity. This second edition cancels and replaces the first edition published in 1997 and its Amendment 1 (2003) and constitutes a technical revision. This new edition, in particular, adds or clarifies the definition of several directly measured parameters, so that diverging interpretations are avoided. It has the status of a basic EMC publication in accordance with IEC Guide 107.
  The contents of the corrigendum of March 2012 have been included in this copy.

Compatibilité électromagnétique (CEM) - Partie 4-15: Techniques d'essai et de mesure - Flickermètre - Spécifications fonctionnelles et de conception

IEC 61000-4-15:2010 est disponible sous forme de IEC 61000-4-15:2010 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
IEC 61000-4-15:2010 traite des spécifications fonctionnelles et de conception d'un appareil mesurant le flicker, destiné à indiquer le niveau correct de perception du flicker du flux lumineux (le flicker) pour toutes les formes d'ondes de fluctuation de la tension rencontrées dans la pratique. On y présente des informations permettant de construire un tel instrument. Une méthode d'évaluation de la sévérité du flicker est fournie à partir des résultats obtenus avec des flickermètres en conformité avec cette norme. Les spécifications du flickermètre dans cette partie concernent uniquement les mesures desentrées de120 V et 230 V, 50Hz et 60Hz. Les caractéristiquesde certaineslampesà incandescence pour d'autres tensions sont suffisamment similaires aux valeurs des Tableaux 1 et 2 pour que l'utilisation d'un facteur de correction puisse être appliquée à ces autres tensions. Certains de ces facteurs de correction sont fournis à l'Annexe B. Des spécifications détaillées pour des tensions et des fréquences autres que celles données ci-dessus sont à l'étude. L'objet de la présente partie de la CEI 61000 est de fournir les informations nécessaires à la conception et à la réalisation d'un flickermètre analogique ou numérique. Elle ne spécifie pas les valeurs limites tolérables du flicker. Cette deuxième édition annule et remplace la première édition publiée en 1997 et son amendement 1 (2003), et constitue une révision technique. Cette nouvelle édition, en particulier, ajoute ou clarifie la définition de plusieurs paramètres mesurés directement, de telle façon que l'on évite des interprétations divergentes. Elle a le statut de publication fondamentale en CEM en accord avec le Guide 107 de la CEI. Le contenu du corrigendum de mars 2012 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 23-Aug-2010
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.100.20 - Immunity
• Technical Committee: SC 77A - EMC - Low frequency phenomena
• Drafting Committee: WG 2 - TC 77/SC 77A/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 31-Aug-2010
• Completion Date: 24-Aug-2010

Relations

• Corrected By: IEC 61000-4-15:2010/COR1:2012 - Corrigendum 1 - Electromagnetic compatibility (EMC) - Part 4-15: Testing and measurement techniques - Flickermeter - Functional and design specifications
• Effective Date: 05-Sep-2023
• Revises: IEC 61000-4-15:1997 - Electromagnetic compatibility (EMC) - Part 4: Testing and measurement techniques - Section 15: Flickermeter - Functional and design specifications
• Effective Date: 05-Sep-2023
• Revises: IEC 61000-4-15:2010/ISH1:2017 - Interpretation Sheet 1 - Electromagnetic compatibility (EMC) - Part 4-15: Testing and measurement techniques - Flickermeter - Functional and design specifications
• Effective Date: 05-Sep-2023
• Revises: IEC 61000-4-15:1997/AMD1:2003 - Amendment 1 - Electromagnetic compatibility (EMC) - Part 4: Testing and measurement techniques - Section 15: Flickermeter - Functional and design specifications
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61000-4-15 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-15: Testing and measurement techniques – Flickermeter – Functional
and design specifications
Compatibilité électromagnétique (CEM) –
Partie 4-15: Techniques d’essai et de mesure – Flickermètre – Spécifications
fonctionnelles et de conception

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]
IEC 61000-4-15 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-15: Testing and measurement techniques – Flickermeter – Functional
and design specifications
Compatibilité électromagnétique (CEM) –
Partie 4-15: Techniques d’essai et de mesure – Flickermètre – Spécifications
fonctionnelles et de conception

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 33.100.20 ISBN 978-2-88912-076-5
 IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 61000-4-15
Edition 2.0  2010-08
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-15: Testing and measurement techniques –
Flickermeter – Functional and design specifications

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 77A: EMC – Low frequency
phenomena, of IEC technical committee 77: Electromagnetic compatibility.
The text of this interpretation sheet is based on the following documents:
FDIS Report on voting
77A/966/FDIS 77A/973/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
Interpretation of requirements for rectangular voltage modulation with duty ratio
according to IEC 61000-4-15: Electromagnetic compatibility (EMC) – Testing and
measurement techniques – Flickermeter – Functional and design specifications.
IEC 61000-4-15 Ed 2 gives requirements in 6.8 for what is called “Rectangular voltage
changes with 20 % duty cycle”. Table 11 provides the test specification for rectangular voltage
changes with duty ratio. The requirements per Table 11 and the associated tests patterns
caused some questions in the past year, and therefore IEC/SC77A/WG-2 wishes to clarify the
title and interpretation per 6.8 which should be read as follows:
6.8 Rectangular voltage modulation for 20 % of the time
The amplitude of the test voltage U is rectangularly modulated with a 50 % duty cycle at 28
Hz. Every minute the amplitude modulation is switched on for 12 s and off for 48 s. Table 11
specifies the modulation depth in terms of voltage fluctuation (∆U/U), which is further
specified in Annex B. The transition time at the edges of the rectangular modulation shall be
less than 0,5 ms.
The ten-minute P indication of the meter under test shall be 1,00 with a tolerance of ± 5 %.
st
Figure 1 shows a ∆U/U = 35 % for illustration purposes, as a 1 % to 2 % modulation would not
be visible. Only 400 ms of the time axis is depicted, showing 200 ms on each side of the
modulation on/off switching at 12 s.
NOTE The above text in 6.8 will be considered as a replacement for the original text when
IEC 61000-4-15 is updated either through an amendment or replaced by a new edition.
__________
ICS 33.100.20
– 2 – 61000-4-15 © IEC:2010
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope and object .7
2 Normative references.7
3 Parameters and symbols.8
3.1 Directly measured parameters and characteristics .8
3.1.1 General .8
3.1.2 Half period rms value of the voltage .8
3.1.3 Half period rms value characteristics.8
3.1.4 Relative half period rms value characteristics.8
3.1.5 Steady state voltage and voltage change characteristics .8
3.1.6 Steady state voltage change .9
3.1.7 Maximum voltage change during a voltage change characteristic .9
3.1.8 Maximum steady state voltage change during an observation period .9
3.1.9 Maximum absolute voltage change during an observation period .10
3.1.10 Voltage deviation .10
3.1.11 Centre voltage .10
3.2 Symbols .10
4 Description of the instrument .11
4.1 General .11
4.2 Block 1 – Input voltage adaptor.11
4.3 Block 2 – Squaring multiplier.11
4.4 Block 3 – Weighting filters .12
4.5 Block 4 – Squaring and smoothing .12
4.6 Block 5 – On-line statistical analysis .12
4.7 Outputs .13
4.7.1 General .13
4.7.2 P output.13
lin
4.7.3 P output .13
inst
4.7.4 P output .13
st
4.7.5 P output .13
lt
4.7.6 d-meter outputs .13
5 Specification.13
5.1 Response and accuracy.13
5.2 Input voltage ranges .18
5.3 Voltage adaptor .18
5.4 Weighting filters.18
5.5 Weighting filter response in block 3.18
5.6 Squaring multiplier and sliding mean filter .19
5.7 General statistical analysis procedure .19
5.7.1 General .19
5.7.2 Short-term flicker evaluation .19
5.7.3 Long-term flicker evaluation .20
6 Flickermeter tests .20
6.1 General .20
6.2 Sinusoidal/rectangular voltage changes .21

61000-4-15 © IEC:2010 – 3 –
6.3 Rectangular voltage changes and performance testing.21
6.4 Combined frequency and voltage changes – Class F1 flickermeters .22
6.5 Distorted voltage with multiple zero crossings – Class F1 flickermeters .23
6.6 Bandwidth test using harmonic and inter-harmonic side band modulation .23
6.7 Phase jumps – Class F1 flickermeters .24
6.8 Rectangular voltage changes with 20 % duty cycle .24
6.9 d parameter test, d , d , and d(t) > 3,3% .25
c max
7 Environmental and other requirements .27
7.1 General .27
7.2 Insulation, climatic, electromagnetic compatibility, and other tests.27
Annex A (normative) Techniques to improve accuracy of flicker evaluation .
...

IEC 61000-4-15 ®
Edition 2.0 2010-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

Electromagnetic compatibility (EMC) –
Part 4-15: Testing and measurement techniques – Flickermeter – Functional
and design specifications
Compatibilité électromagnétique (CEM) –
Partie 4-15: Techniques d’essai et de mesure – Flickermètre – Spécifications
fonctionnelles et de conception

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
 IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
 Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
 Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
 Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
 Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
 Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
 Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]
IEC 61000-4-15 ®
Edition 2.0 2010-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

Electromagnetic compatibility (EMC) –
Part 4-15: Testing and measurement techniques – Flickermeter – Functional
and design specifications
Compatibilité électromagnétique (CEM) –
Partie 4-15: Techniques d’essai et de mesure – Flickermètre – Spécifications
fonctionnelles et de conception

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.20 ISBN 978-2-
IEC 61000-4-15 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-15: Testing and measurement techniques – Flickermeter – Functional
and design specifications
Compatibilité électromagnétique (CEM) –
Partie 4-15: Techniques d’essai et de mesure – Flickermètre – Spécifications
fonctionnelles et de conception

 IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 61000-4-15
Edition 2.0  2010-08
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-15: Testing and measurement techniques –
Flickermeter – Functional and design specifications

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 77A: EMC – Low frequency
phenomena, of IEC technical committee 77: Electromagnetic compatibility.
The text of this interpretation sheet is based on the following documents:
FDIS Report on voting
77A/966/FDIS 77A/973/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
Interpretation of requirements for rectangular voltage modulation with duty ratio
according to IEC 61000-4-15: Electromagnetic compatibility (EMC) – Testing and
measurement techniques – Flickermeter – Functional and design specifications.
IEC 61000-4-15 Ed 2 gives requirements in 6.8 for what is called “Rectangular voltage
changes with 20 % duty cycle”. Table 11 provides the test specification for rectangular voltage
changes with duty ratio. The requirements per Table 11 and the associated tests patterns
caused some questions in the past year, and therefore IEC/SC77A/WG-2 wishes to clarify the
title and interpretation per 6.8 which should be read as follows:
6.8 Rectangular voltage modulation for 20 % of the time
The amplitude of the test voltage U is rectangularly modulated with a 50 % duty cycle at 28
Hz. Every minute the amplitude modulation is switched on for 12 s and off for 48 s. Table 11
specifies the modulation depth in terms of voltage fluctuation (∆U/U), which is further
specified in Annex B. The transition time at the edges of the rectangular modulation shall be
less than 0,5 ms.
The ten-minute P indication of the meter under test shall be 1,00 with a tolerance of ± 5 %.
st
Figure 1 shows a ∆U/U = 35 % for illustration purposes, as a 1 % to 2 % modulation would not
be visible. Only 400 ms of the time axis is depicted, showing 200 ms on each side of the
modulation on/off switching at 12 s.
NOTE The above text in 6.8 will be considered as a replacement for the original text when
IEC 61000-4-15 is updated either through an amendment or replaced by a new edition.
__________
ICS 33.100.20
– 2 – 61000-4-15 © IEC:2010
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope and object .7
2 Normative references.7
3 Parameters and symbols.8
3.1 Directly measured parameters and characteristics .8
3.1.1 General .8
3.1.2 Half period rms value of the voltage .8
3.1.3 Half period rms value characteristics.8
3.1.4 Relative half period rms value characteristics.8
3.1.5 Steady state voltage and voltage change characteristics .8
3.1.6 Steady state voltage change .9
3.1.7 Maximum voltage change during a voltage change characteristic .9
3.1.8 Maximum steady state voltage change during an observation period .9
3.1.9 Maximum absolute voltage change during an observation period .10
3.1.10 Voltage deviation .10
3.1.11 Centre voltage .10
3.2 Symbols .10
4 Description of the instrument .11
4.1 General .11
4.2 Block 1 – Input voltage adaptor.11
4.3 Block 2 – Squaring multiplier.11
4.4 Block 3 – Weighting filters .12
4.5 Block 4 – Squaring and smoothing .12
4.6 Block 5 – On-line statistical analysis .12
4.7 Outputs .13
4.7.1 General .13
4.7.2 P output.13
lin
4.7.3 P output .13
inst
4.7.4 P output .13
st
4.7.5 P output .13
lt
4.7.6 d-meter outputs .13
5 Specification.13
5.1 Response and accuracy.13
5.2 Input voltage ranges .18
5.3 Voltage adaptor .18
5.4 Weighting filters.18
5.5 Weighting filter response in block 3.18
5.6 Squaring multiplier and sliding mean filter .19
5.7 General statistical analysis procedure .19
5.7.1 General .19
5.7.2 Short-term flicker evaluation .19
5.7.3 Long-term flicker evaluation .20
6 Flickermeter tests .20
6.1 General .20
6.2 Sinusoidal/rectangular voltage changes .21

61000-4-15 © IEC:2010 – 3 –
6.3 Rectangular voltage changes and performance testing.21
6.4 Combined frequency and voltage changes – Class F1 flickermeters .22
6.5 Distorted voltage with multiple zero crossings – Class F1 flickermeters .23
6.6 Bandwidth test using harmonic and inter-harmonic side band modulation .23
6.7 Phase jumps – Class F1 flickermeters .24
6.8 Rectangular
...