IEC TR 63158:2018

Equipment for general lighting purposes - Objective test method for stroboscopic effects of lighting equipment

IEC TR 63158:2018(E) describes an objective stroboscopic effect visibility (SVM) meter, which can be applied for performance testing of lighting equipment under different operational conditions.
The stroboscopic effects considered in this document are limited to the objective assessment by a human observer of visible stroboscopic effects of temporal light modulation of lighting equipment in general indoor applications, with typical indoor light levels (> 100 lx) and with moderate movements of an observer or nearby handled object ( The contents of the corrigendum of July 2018 have been included in this copy.

General Information

• Status: Published
• Publication Date: 18-Mar-2018
• ICS: 29.140.01 - Lamps in general
• Technical Committee: TC 34 - Lighting
• Current Stage: PPUB - Publication issued
• Start Date: 19-Mar-2018
• Completion Date: 10-Apr-2018

Relations

• Corrected By: IEC TR 63158:2018/COR1:2018 - Corrigendum 1 - Equipment for general lighting purposes - Objective test method for stroboscopic effects of lighting equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TR 63158 ®
Edition 1.0 2018-03
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – Objective test method for
stroboscopic effects of lighting equipment

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.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
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.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TR 63158 ®
Edition 1.0 2018-03
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – Objective test method for

stroboscopic effects of lighting equipment

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.140.01 ISBN 978-2-8322-5488-2

– 2 – IEC TR 63158:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, abbreviated terms and symbols . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 9
3.3 Symbols . 10
4 General . 10
5 Laboratory and equipment requirements . 11
5.1 Schematic of the measurement setup . 11
5.2 Laboratory and environmental conditions . 12
5.3 Electrical power source . 12
5.4 Optical test environment . 12
5.5 Light sensor and amplifier . 13
5.6 Signals to be measured . 13
5.7 Duration of the measurement . 13
5.8 Signal processing . 13
5.8.1 Anti-aliasing filter . 13
5.8.2 Sampling frequency . 14
5.8.3 Signal resolution . 14
5.9 SVM calculation . 14
5.10 Verification noise-level of the setup . 14
6 Stroboscopic effect visibility meter . 15
6.1 General . 15
6.2 Verification. 15
6.3 Evaluation of results . 15
7 Test setup and operating conditions . 16
7.1 General . 16
7.2 Ageing . 16
7.3 Mounting . 16
7.4 Stabilization before measurement . 16
7.5 Operation . 16
8 General test procedure . 16
9 Application-specific equipment, procedures and conditions . 17
9.1 General . 17
9.2 Phase cut dimmer compatibility test of lighting equipment . 17
9.3 Controlgear testing . 17
9.4 In-situ testing . 18
10 Test report . 18
11 Measurement uncertainties . 18
11.1 General . 18
11.2 Verification tests . 18
11.2.1 General . 18
11.2.2 Stroboscopic effect visibility meter . 18
11.2.3 Electrical power source parameters . 18

11.2.4 Electromagnetic compatibility and test environment . 19
11.2.5 Light sensor and amplifier . 19
11.2.6 Overall noise-level of the setup. 19
11.2.7 Repeatability . 19
11.3 Quality assurance . 19
Annex A (normative) Specification of the stroboscopic effect visibility meter . 20
A.1 Background. 20
A.2 Detailed specifications of the stroboscopic effect meter . 21
A.2.1 Schematic of the SVM meter. 21
A.2.2 Block a: illuminance adapter . 21
A.2.3 Block b: calculation of spectrum . 22
A.2.4 Block c: weighting with the stroboscopic effect sensitivity curve . 22
A.2.5 Block d: summation of the weighted spectrum . 22
A.3 Numerical implementation of SVM . 23
A.4 Example. 24
A.5 Verification waveform of the stroboscopic effect meter . 24 ®
A.6 Example of SVM implementation in MATLAB . 27
Annex B (informative) Uncertainty considerations . 28
B.1 General . 28
B.2 General symbols . 28
B.3 Measurand . 28
B.4 Influence quantities . 28
Annex C (informative) Examples of test results . 31
C.1 SVM measurement results of conventional lighting equipment . 31
C.2 SVM test under dimming conditions . 32
Bibliography . 34

Figure 1 – Schematic of the stroboscopic effect measurement method . 10
Figure 2 – Different possible applications for an SVM test . 11
Figure 3 – Schematic of the TLA measurement method . 12
Figure 4 – Dimmer compatibility testing . 17
Figure 5 – Controlgear testing . 17
Figure A.1 – Structure of the stroboscopic effect visibility meter . 21
Figure A.2 – SVM sensitivity threshold T . 23
Figure A.3 – Example of an illuminance signal with a ripple . 26
Figure B.1 – Fishbone diagram representing the categories of influence quantities
contributing to the uncertainty of the SVM measurement . 29
Figure C.1 – Normalized light ripple of conventional lighting equipment . 32
Figure C.2 – Graphical SVM results of four samples of lighting equipment under
dimming conditions . 33

Table A.1 – Specification of the parameters of the verification waveforms . 27
Table B.1 – Influence quantities and their recommended tolerances . 30
Table C.1 – Numerical results of SVM calculations of conventional lighting equipment . 31
Table C.2 – Numerical results of SVM calculations of four samples of lighting
equipment under dimming conditions . 33

– 4 – IEC TR 63158:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
OBJECTIVE TEST METHOD FOR STROBOSCOPIC
EFFECTS OF LIGHTING EQUIPMENT
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 63158, which is a Technical Report, has been prepared by IEC technical committee
34: Lamps and related equipment.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
34/436/DTR 34/496/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
 reconfirmed,
 withdrawn,
 replaced by a revised edition, or
 amended.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of July 2018 have been included in this copy.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC TR 63158:2018 © IEC 2018
INTRODUCTION
The fast rate at which solid state light (SSL) sources can change their intensity is one of the
main drivers behind the revolution in the lighting world and applications of lighting. Linked to
the fast rate of the intensity change is a direct transfer of the modulation of the driving
current, both intended and unintended, to a modulation of the luminous flux. This light
modulation can give rise to changes in the perception of the environment. While in some very
specific entertainment, scientific or industrial applications a change of perception due to light
modulation is desired, for most everyday applications and activities the change is detrimental
and undesired. The general term used for these changes in the perception of the environment
is “temporal light artefacts” (TLAs) and these can have a large influence on the judgment of
the light quality. Moreover, the visible modulation of light can lead to a decrease in
performance, increased fatigue as well as acute health problems like epileptic seizures and
migraine episodes [1][3] .
Different terms exist to describe the different types of TLAs that may be perceived by humans.
The term ‘flicker’ refers to light variation that may be directly perceived by an observer.
‘Stroboscopic effect’ is an effect which may become visible for an observer when a moving or
rotating object is illuminated (CIE TN 006:2016).
Possible causes for light modulation of lighting equipment that may give rise to flicker or
stroboscopic effect are:
– AC supply combined with light source technology and its controlgear topology;
– dimming technology of externally applied dimmers or internal light level regulators;
– mains voltage fluctuations caused by electrical apparatus connected to the mains
(conducted electromagnetic disturbances) or intentionally applied for mains-signalling
purposes.
Lighting products that show unacceptable stroboscopic effect are considered as poor quality
lighting.
Until recently, modulation depth (MD) – also called percent flicker – and flicker index (FI) were
often used to quantify flicker or stroboscopic effect. It has been shown that both these metrics
are not able to objectively score the level of flicker or stroboscopic effect as actually
perceived by humans [1]. Therefore, instead of MD and FI, for ‘flicker’ the IEC-standardized
LM
) is used, which is derived from the widely applied and
‘short-term flicker severity’ ( P
st
accepted IEC-standardized P -metric to assess the impact of voltage fluctuations on flicker
st
[5]. For the objective assessment of stroboscopic effect, the stroboscopic effect visibility
measure (SVM) is available [6].
In 2013, a clear need was identified for an objective test method for testing lighting equipment
against flicker caused by voltage fluctuations induced by switching loads such as household
appliances. Technical committee 34 developed and verified an objective test method for
LM
flicker using the flicker metric P . This objective flicker test method is described in
st
IEC TR 61547-1 [5].
In recent years the interest in objective testing of stroboscopic effect has also increased
considerably. In the near future, CIE will start developing a basic standard on TLA metrology
including objective test methods for flicker and stroboscopic effect.
This document provides practical considerations and application examples on how to
objectively quantify the stroboscopic effect performance of lighting equipment in terms of
SVM.
______________
Numbers in square brackets refer to the Bibliography.

EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
OBJECTIVE TEST METHOD FOR STROBOSCOPIC
EFFECTS OF LIGHTING EQUIPMENT
1 Scope
This document describes an objective stroboscopic effect visibility (SVM) meter, which can be
applied for performance testing of lighting equipment under different operational conditions.
The stroboscopic effects considered in this document are limited to the objective assessment
by a human observer of visible stroboscopic effects of temporal light modulation of lighting
equipment in general indoor applications, with typical indoor light levels (> 100 lx) and with
moderate movements of an observer or nearby handled object (< 4 m/s). Details on restriction
of the applicability of the stroboscopic effect visibility measure is given in Clause A.1.
For assessing unwanted stroboscopic effects in other applications, such as the misperception
of rapidly rotating or moving machinery in an industrial environment for example, other
metrics and methods can be required.
The object of this document is to establish a common and objective reference for evaluating
the performance of lighting equipment in terms of stroboscopic effect. Temporal changes in
the colour of the light (chromatic effects) are not considered in this test. This document
describes the methodology for SVM and does not define any limits.
The objective method and procedure described in this document are based on
CIE TN 006:2016 on temporal light artefacts (TLAs).
The method described in this document can be applied to objectively assess the stroboscopic
effect of lighting equipment that is powered from any type of source, AC mains, DC mains,
battery fed or fed through an external dimmer.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, abbreviated terms and symbols
3.1 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
3.1.1
auxiliary equipment
AuxEq
peripheral equipment that is part of the system under test

– 8 – IEC TR 63158:2018 © IEC 2018
3.1.2
equipment-under-test
EUT
equipment subjected to stroboscopic visibility tests
3.1.3
temporal light artefact
TLA
change in visual perception, induced by a light stimulus the luminance or spectral distribution
of which fluctuates with time, for a human observer in a specified environment
Note 1 to entry: The change of visual perception is a result of comparing the visual perception of the environment
lit by the modulated light to the visual perception of the same person in the same environment, when the
environment is lit by non-modulated light.
[SOURCE: CIE TN 006:2016, 2.4.1]
3.1.4
flicker
perception of visual unsteadiness induced by a light stimulus the luminance or spectral
distribution of which fluctuates with time, for a static observer in a static environment
Note 1 to entry: The fluctuations of the light stimulus with time include periodic and non-periodic fluctuations and
may be induced by the light source itself, the power source or other influencing factors.
Note 2 to entry: Flicker is a type of temporal light artefact.
[SOURCE: CIE TN 006:2016, 2.4.2, modified – Note 3 has been deleted.]
3.1.5
stroboscopic effect
change in motion perception induced by a light stimulus the luminance or spectral distribution
of which fluctuates with time, for a static observer in a non-static environment
EXAMPLE 1 For a square periodic luminance fluctuation, moving objects are perceived to move discretely rather
than continuously.
EXAMPLE 2 If the frequency of a periodic luminance fluctuation coincides with the frequency of a rotating object,
the rotating object is perceived as static.
Note 1 to entry: The stroboscopic effect is a type of temporal light artefact.
[SOURCE: CIE TN 006:2016, 2.4.3]
3.1.6
static observer
observer who does not move her/his eye(s)
Note 1 to entry: Only large eye movements (saccades) fall under this definition. An observer who only does
involuntary micro-saccades is considered static.
[SOURCE: CIE TN 006:2016, 2.4.5]
3.1.7
static environment
environment that does not contain perceivable motion under non-modulated lighting
conditions
[SOURCE: CIE TN 006:2016, 2.4.6]

3.1.8
average observer
observer representing the mean characteristics of a specified population of sighted individuals
Note 1 to entry: The population in question depends on the application a lighting system is designed for. It can
also include specific groups of observers as for example migraine sufferers. A general average observer is based
on data aggregated across gender and age but specific observers can be defined for subgroups.
[SOURCE: CIE TN 006:2016, 2.3.1]
3.1.9
visible artefact
perceptual effect of a light modulation detected by an average observer with a probability
higher than 50 %
[SOURCE: CIE TN 006:2016, 2.3.2]
3.1.10
visibility threshold
level of light modulation, at which an average observer, when presented with and questioned
about the visibility of an artefact, can detect the artefact with a probability of 50 %
[SOURCE: CIE TN 006:2016, 2.3.3]
3.1.11
stroboscopic effect visibility
measuremeasure of stroboscopic effect evaluated over a specified time interval of a relatively
short duration
Note 1 to entry: The duration is typically 1 s, in accordance with CIE TN 006.
3.1.12
modulation depth
property of waveform calculated by taking the ratio of the difference between the maximum
and minimum intensity to the sum of the maximum and minimum intensity
Note 1 to entry: Often, MD is calculated over one fundamental period of waveform modulation, however it can be
calculated also over a much longer time over a multiple number of periods.
Note 2 to entry: MD is also often expressed as a percentage, by multiplying the ratio by 100 %.
3.2 Abbreviated terms
AC alternating current
ADC analog to digital converter
CIE Commission Internationale de l'Éclairage
DC direct current
DFT discreet Fourier transform
EUT equipment under test
FFT fast Fourier transform
Hz hertz
IEEE Institute of Electrical and Electronics Engineers
kHz kilohertz
LED light emitting diode
MD modulation depth
TLA temporal light artefact
– 10 – IEC TR 63158:2018 © IEC 2018
PoE power over Ethernet
RMS root mean square
TN technical note
SNR signal to noise ratio
SSL solid state lighting
SVM stroboscopic effect visibility measure
THD total harmonic distortion
TLD tapped linear driver
3.3 Symbols
C gain of the light amplifier
A
C(f) spectrum of normalized signal
E(t) illuminance
m modulation depth of the modulation of the verification waveform
ver
f modulation frequency
m
LM
P short-term flicker severity
st
E
SVM SVM-value of the standardized illuminance waveform E(t)
EUT
SVM SVM-value of the illuminance of an EUT measured with the SVM-meter
SVM noise stroboscopic effect visibility measure noise level
T measuring period
test
u(t) mains voltage signal
u (t) output voltage of the light sensor amplifier
E
4 General
The generic schematic diagram of the stroboscopic effect measurement setup is depicted in
Figure 1.
The light output of the system under test is measured. Subsequently SVM is calculated from
the measured light waveform. Details on the test setup and equipment are given in Clause 5.
The specification of the objective stroboscopic effect meter to calculate SVM is given in
Clause 6.
Light waveform
Objective stroboscopic
effect meter
Light output
including
modulations
Electrical
power SVM
Light measurement
system
System
under test
IEC
Figure 1 – Schematic of the stroboscopic effect measurement method

The type of equipment under test (EUT) may depend on the purpose of the test. For instance
the following different application tests may be considered (see Figure 2):
– testing the intrinsic performance of lighting equipment such as luminaires, controlgear or
integrated lamps;
– testing the performance of lighting equipment under dimming conditions.
Note that in each of these different test applications, there is a difference between the EUT
and the auxiliary equipment, which is peripheral equipment that is part of the system under
test (to enable testing), but not part of the test. Application-specific setup and equipment
requirements are given in Clause 9.
5 Laboratory and equipment requirements
5.1 Schematic of the measurement setup
The general schematic diagram of the SVM measurement setup is depicted in Figure 3.
General requirements for the equipment and laboratory are given in the subsequent
subclauses. Application-specific (auxiliary) equipment is specified in Clause 9.
EUT
Light output
e.g. luminaire,
Electrical power
including
integrated lamp
(mains, PoE, DC,…)
modulations
IEC
a) Light source as EUT
Auxiliary
equipment
EUT
Light output
light
e.g.
Electrical power
including
source
controlgear
(mains, PoE, DC,…)
modulations
IEC
b) Control gear as EUT
Auxiliary
equipment
EUT
Light output
Lighting
Electrical power External
including
equipment
(mains, PoE, DC,…) dimmer
modulations
IEC
c) Setup with external dimmer
Figure 2 – Different possible applications for an SVM test

– 12 – IEC TR 63158:2018 © IEC 2018
Determination of
Calculation
light level or
of
other parameters
SVM
Optically
shielded
Electrical
enclosure
power
Light
Light
sensor
EUT/
Data
waveform
Main Amplifier
auxilliary acquisition
source and filter
equipment and storage
Light source
(EUT/auxiliary equipment)
Stable/vibration-free base
IEC
Figure 3 – Schematic of the TLA measurement method
5.2 Laboratory and environmental conditions
It is recommended to execute the measurements in a room or setup where environmental
effects such as electromagnetic disturbances, ambient light and vibrations have negligible
impact (see also 5.4).
It is recommended to apply ambient temperatures that lie within the specified operating
temperature of the EUT and measurement equipment.
5.3 Electrical power source
The electrical power source connected to the EUT and to auxiliary equipment, if applicable,
shall be a stable source at the specified nominal frequency, voltage (or current) level, and
capable of providing the required power level.
The nominal value of the rated supply voltage of the EUT, or rated supply current of the EUT
shall be measured at the supply terminals of the EUT.
It is recommended that the nominal value of the test voltages, or supply current, and
frequency (if applicable), are within the tolerance interval of ± 0,5 % (RMS-level in the case of
alternating current).
For SVM measurements, the level of voltage fluctuations and harmonics on the mains power
source shall be sufficiently low.
Low-frequency voltage fluctuations (below 50 Hz) are less important for SVM measurements.
The harmonic distortion of the mains source in the frequency range up to 2 kHz should be
limited. A maximum total harmonic distortion of the voltage (THDv) of 4 % is recommended.
5.4 Optical test environment
The illuminance of the light source of the EUT is to be measured for processing by the SVM
meter. There is no need for measuring the absolute value. Only the relative illuminance is to
be determined.
The light source of the EUT and the light sensor are to be located in an optically shielded
environment to avoid disturbances from light sources other than the EUT.

The test environment should also be mechanically robust to avoid vibrations of the EUT and
light sensor as that may give rise to unwanted variations in the illuminance.
Most lighting equipment have a non-uniform distribution of light and therefore it is
recommended to measure indirectly via a reflecting surface. An integrating sphere, such as an
Ulbricht sphere, may be applied. This may be convenient because then the orientation and
alignment of the EUT with respect to the light sensor is less critical.
5.5 Light sensor and amplifier
A photodiode with a filter and an appropriate amplifier is to be applied for measuring the
illuminance (or more specifically: the relative illuminance) of the EUT.
The photodiode, optical filter and amplifier combination should satisfy the following
characteristics.
a) The optical filter should match the photodiode to the eye sensitivity curve of CIE 1931
which is the CIE 1931 standard observer function specified in ISO 11664-1:2007.
b) The cut-off frequency of the amplifier should enable measurement of all SVM-relevant
frequencies (up to 2 kHz). A 3 dB cut-off frequency of 3 kHz is recommended (see 5.8.1).
c) The output voltage of the amplifier should vary linearly with the illuminance and no offset-
voltage should be present.
5.6 Signals to be measured
The output voltage ut() of the light sensor amplifier is measured as a function of time over a
E
period T . The output voltage ut() varies linearly with the illuminance E()t :
test E
u ()t C⋅ E()t is measured between 0 < tT< (1)
EA test
where C is the constant including the gain of the amplifier and which links the output voltage
A
of the light sensor amplifier to the illuminance.
In certain applications, additional parameters might be measured during the test. For
example, in the case of dimming or light regulation the light level of the light source may be of
interest. See Clause 9 for application specific requirements.
The signal can be measured with an oscilloscope. It is recommended to apply an appropriate
low-pass filter in the oscilloscope to limit the noise.
The measured signal is to be recorded for further processing (see 5.8).
5.7 Duration of the measurement
The duration of the test (duration of the data acquisition after the stabilization period) shall be
a minimum of 1 s.
5.8 Signal processing
5.8.1 Anti-aliasing filter
The light output of some types of lamps may contain spectral components at frequencies well
above 2 kHz (kHz-range) that are not producing visible stroboscopic effect. Depending on the
sampling frequency (see 5.8.2) these higher frequency components may be undersampled
and this may lead to aliasing which gives artefacts in the light sensor signal. It is
recommended to avoid such aliasing effects by applying a low-pass filter between the
amplifier output of the light sensor and the measurement system. A cut-off frequency of at
least 3 kHz is recommended. However, the cut-off frequency should also be limited to avoid
the need for high sampling frequencies.
=
– 14 – IEC TR 63158:2018 © IEC 2018
st
EXAMPLE A 1 order low-pass filter with a 3 dB cut-off frequency of 3 kHz will have an attenuationof 10 dB at
9 kHz and -1,6 dB at 2 kHz. For adequate acquisition of the signal up to 9 kHz, a sampling frequency of at least
18 kS/s applies. A higher order Butterworth filter increases the accuracy.
5.8.2 Sampling frequency
For processing of the signals, in accordance with the Nyquist criterion, the sampling
frequency shall be at least twice the bandwidth of the signal, which is approximately twice the
highest frequency within the signal to be measured.
For incandescent lighting technology, the illuminance signal has a spectrum of interest that is
at least twice the spectrum of the mains signal for incandescent lamps. For non-incandescent
types of lighting equipment much higher frequencies in the kHz region may be present,
depending on the controlgear technology applied. The frequency range above 2 kHz is not of
interest for stroboscopic effect and therefore these should be filtered before sampling (see
5.8.1). ®
For the MATLAB implementation of the SVM meter given in [16] a sampling rate of at least
20 kS/s is recommended.
5.8.3 Signal resolution
In 5.10 it is recommended to have a noise level of SVM < 0,05. Various influence quantities
may contribute to this noise level. The quantization noise from the analog-to-digital convertor
(ADC) is one contributing factor. It is recommended that the quantization noise contribution
from the ADC is 0,2 times the overall noise level, which gives SVM < 0,01. The consequence
for the minimum number of bits N for the ADC is as follows.
For a light waveform with 100 Hz sinusoidal modulation, a level of SVM = 1 is generated with
approximately 25 % modulation depth (see Figure A.2). In order to enable measurement of an
SVM level of 0,01, the spectral component which contributes to SVM = 0,01 is -52 dB down
the average light level; see Formula (A.4). An accurate measurement of such a spectral
component can be achieved if the signal to noise ratio (SNR) due to quantization is at least
10 dB lower, i.e an SNR level of -62 dB.
-bit ADC, expressed in dB, is
The signal-to-noise ratio of the spectrum calculated for an N
SNR(N) 6,02N+1,76 (2)
In practice this means that at least a 12-bit ADC is required.
5.9 SVM calculation
The SVM calculation and verification method is detailed in Clause 6.
5.10 Verification noise-level of the setup
In theory, if the illuminance from the EUT's light source were constant, then SVM = 0. In a
practical setup however, if an EUT with constant light level is measured, the SVM result may
be not equal to zero, due to modulations arising from the light sensor and its amplifier and
due to numerical artefacts. This may give a non-zero result and is called the stroboscopic
effect visibility measure noise level of the setup: SVM .
noise
______________
MATLAB is the trademark of a product supplied by The MathWorks, Inc. This information is given for the
convenience of users of this document and does not constitute an endorsement by IEC of the product named.
=
The noise level SVM can be verified as follows.
noise
Install a suitable DC-fed reference light source, either an incandescent or halogen lamp. Feed
the lamp with a constant voltage. Verify that the voltage of this reference light source has a
tolerance interval of less than ± 0,5 % during the recording of the reference waveform.
Measure the illuminance and determine the actual SVM-level using the stroboscopic effect
visibility measure meter and verify whether the actual level satisfies the following:
SVM < 0,05 (3)
noise
6 Stroboscopic effect visibility meter
6.1 General
For an objective assessment of the stroboscopic effect, the SVM-meter specified in Annex A
is used.
6.2 Verification
Verification of the stroboscopic effect visibility meter may be performed using the procedure
and reference waveforms given in Clause A.5.
It is recommended that the outcome of the verification test satisfies the following for the
reference waveforms given in Clause A.5:
E E
SVM − SVM / SVM x 100 % < 5 % (4)
E
where SVM is the reference SVM value of the verification illuminance waveform E(t) applied;
see Formulae (A.7) and (A.8), and SVM is the SVM-value measured at the output of the SVM
meter for the frequencies, amplitudes and reference waveforms listed in Table A.1.
6.3 Evaluation of results
For actual light waveforms, the SVM level that is measured by the SVM meter may range
between 0 and near 9: SVM = 0 is obtained for a waveform without any modulation, while
SVM ≈ 9 is obtained for a 100 % rectangular pulse-modulated waveform with an infinitely small
duty cycle.
SVM is an objective measure derived from laboratory and perception studies with persons.
SVM results can be interpreted as follows (CIE TN 006:2016). If the value of the visibility
measure equals one, the modulated light waveform produces stroboscopic effect that is just
visible, i.e. at visibility threshold. This means that an average observer will be able to detect
the artefact with a probability of 50 %. If the value of the visibility measure is above unity, the
effect has a probability of detection of more than 50 %. If the value of the visibility measure is
smaller than unity, the probability of detection is less than 50 %. These visibility thresholds
show average detection of an average human observer in a population under laboratory
conditions, i.e. the observer is aware that he/she is trying to observe stroboscopic effect.
Visibility, however, is not the same as acceptability in actual applications. The acceptability
level of an artefact might be well above the visibility threshold. Acceptability depends on the
duration of exposure, the type of activities (criticality) and typical speed of movement involved
in these activities. Examples of measured SVM levels of conventional lighting equipment are
given in Clause C.1.
– 16 – IEC TR 63158:2018 © IEC 2018
7 Test setup and operating conditions
7.1 General
The EUT should be tested with
...