EN 61920:2004

Infrared free air applications

describes the classification of IR devices into groups and classes in order to identify and clarify problems caused by mutual interference. Mutual interference is caused by the increasing parallel application of different infrared (IR) systems.

Nichtleitungsgebundene Infrarot-Anwendungen

Applications infrarouge en mode non guidé

describes the classification of IR devices into groups and classes in order to identify and clarify problems caused by mutual interference. Mutual interference is caused by the increasing parallel application of different infrared (IR) systems.

Infrardeče brezžične aplikacije (IEC 61920:2004)

General Information

• Status: Published
• Publication Date: 29-Mar-2004
• Withdrawal Date: 28-Feb-2007
• ICS: 31.260 - Optoelectronics. Laser equipment
• ICS: 33.100 - Electromagnetic compatibility (EMC)
• Technical Committee: CLC/TC 100X - Audio, video and multimedia systems and equipment and related sub-systems
• Drafting Committee: IEC/TC 100 - IEC_TC_100
• Parallel Committee: IEC/TC 100 - IEC_TC_100
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 30-Mar-2004
• Completion Date: 30-Mar-2004
• Ref Project: SIST EN 61920:2004 - Infrared free air applications

Relations

• Replaces: EN 61920:1998 - Infrared transmission systems - Free air applications
• Effective Date: 29-Jan-2023

Overview

EN 61920:2004 (Infrared free air applications), adopted by CLC/CENELEC from IEC 61920:2004, defines a classification framework for infrared (IR) systems that operate in free air. The standard addresses mutual interference arising when multiple IR systems operate in parallel and provides criteria to identify, classify and reduce interference risks for IR radiators and receivers. The standard covers intentionally or unintentionally used IR systems in the wavelength range 700 nm to 1600 nm (free-air indoor and outdoor applications). Fibre‑optic systems are excluded.

Key Topics

• Objective: Prevent or minimize mutual interference and enable coexistence of different IR products.
• Scope limits: Applies to free‑air IR systems (700–1600 nm); excludes fibre optics and does not prescribe safety limits for optical radiation.
• Classification criteria for radiators: wavelength ranges, frequency ranges, radiant intensity, radiation angle, and duration of radiation.
• Classification criteria for receivers: wavelength/selectivity, frequency response, sensitivity and directivity.
• Measurement & tolerances: defines measurement conditions and tolerances for class data.
• Product grouping & user areas: guidance for grouping IR products and mapping typical application environments.
• Interference mitigation: methods for minimizing mutual interferences, graphical representation of IR systems, and marking requirements.
• Relationship to OSI model: relevant primarily to the physical layer for information‑carrying IR systems.

Applications and Users

Who uses EN 61920:2004:

• Manufacturers of IR transmitters and receivers (remote controls, IR links, sensors).
• System integrators and facility planners designing spaces with multiple IR systems (conference rooms, theatres, industrial sites).
• Test labs and compliance engineers assessing interference risk and device classification.
• Product managers planning coexistence strategies for consumer and professional IR equipment.

Practical value:

• Helps identify potential cross‑talk and reception problems before deployment.
• Supports product labelling and documentation so integrators can select compatible devices.
• Guides facility layout, emitter placement and receiver orientation to reduce interference.
• Useful when designing or validating IR solutions that operate at the physical layer of communication systems.

Related standards

Relevant normative and informative references cited in EN 61920:2004 include:

• IEC 60747-5-1 (optoelectronic devices)
• IEC 60050-713 / 60050-845 (vocabulary entries for radiocommunications/lighting)
• ISO/IEC 7498-1 (OSI basic reference model - physical layer relevance)
• IEC 60825-1 and IEC 61603 series (noted in the EN bibliographic annex)

EN 61920 is especially useful when used alongside device‑level optoelectronic standards and application‑specific standards to ensure robust, interoperable IR deployments.

Standards Content (Sample)

SLOVENSKI SIST EN 61920:2004
STANDARD
september 2004
Infrardeče brezžične aplikacije (IEC 61920:2004)
Infrared free air applications (IEC 61920:2004)
ICS 31.260 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61920
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2004
ICS 31.260; 33.100 Supersedes EN 61920:1998

English version
Infrared free air applications
(IEC 61920:2004)
Applications infrarouge  Nichtleitungsgebundene
en mode non guidé Infrarot-Anwendungen
(CEI 61920:2004) (IEC 61920:2004)

This European Standard was approved by CENELEC on 2004-03-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61920:2004 E
Foreword
The text of document 100/717/FDIS, future edition 2 of IEC 61920, prepared by IEC TC 100, Audio,
video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and
was approved by CENELEC as EN 61920 on 2004-03-01.
This European Standard supersedes EN 61920:1998.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2004-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-03-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61920:2004 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60825-1 NOTE Harmonized as EN 60825-1:1994 (not modified).
IEC 61603-1 NOTE Harmonized as EN 61603-1:1997 (not modified).
IEC 61603-2 NOTE Harmonized as EN 61603-2:1997 (not modified).
IEC 61603-3 NOTE Harmonized as EN 61603-3:1998 (not modified).
IEC 61603-6 NOTE Harmonized as EN 61603-6:2002 (not modified).
__________
- 3 - EN 61920:2004
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application 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.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-713 1998 International Electrotechnical - -
Vocabulary
Part 713: Radiocommunications:
transmitters, receivers, networks and
operation
IEC 60050-845 1987 Chapter 845: Lighting - -

database
IEC 60417 Graphical symbols for use on - -
equipment
IEC 60747-5-1 1997 Discrete semiconductor devices and EN 60747-5-1 2001
integrated circuits
Part 5-1: Optoelectronic devices –
General
ISO/IEC 7498-1 1994 Information technology - Open systems EN ISO/IEC 7498-1 1995
interconnection - Basic reference model
Part 1: The basic model
INTERNATIONAL IEC
STANDARD 61920
Second edition
2004-01
Infrared free air applications
© IEC 2004 ⎯ Copyright - all rights reserved
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 the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale U
International Electrotechnical Commission
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For price, see current catalogue

– 2 – 61920 © IEC:2004(E)
CONTENTS
FOREWORD.3
1 Scope and object .5
2 Normative references.5
3 Terms and definitions .6
4 Symbols.9
4.1 General.9
4.2 Radiators.9
4.3 Receivers.9
5 Classification.10
5.1 General.10
5.2 Physical characteristics of radiators .10
5.2.1 General.10
5.2.2 Ranges of wavelength (criterion 1) .10
5.2.3 Ranges of frequency (criterion 2) .12
5.2.4 Radiant intensity (criterion 3) .12
5.2.5 Angle of radiation (criterion 4) .12
5.2.6 Duration of radiation (criterion 5).12
5.2.7 Identification example for a radiator .13
5.3 Physical characteristics of receivers.13
5.3.1 General.13
5.3.2 Ranges of wavelength and selectivity (criterion 6) .13
5.3.3 Frequency response (criterion 7).14
5.3.4 Sensitivity (criterion 8) .14
5.3.5 Directivity (criterion 9) .14
5.3.6 Example of a receiver .14
5.4 Tolerances.15
5.4.1 Measurement conditions.15
5.4.2 Tolerances of data .15
5.5 Product groups.17
5.6 User areas.18
5.7 Graphical representation of IR systems.18
6 Method for minimizing mutual interferences .20
7 Marking.21
8 Relationship between IR basic standard and application standards.21
Annex A (informative) Example for possible priorization.22
Annex B (informative) Examples of λ/f-diagrams.23
Annex C (informative) Survey of standardization activities in the field of Infrared.27
Bibliography .28

61920 © IEC:2004(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INFRARED FREE AIR APPLICATIONS
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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.
International Standard IEC 61920, has been prepared by technical area 3, Infrared systems
and applications, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
100/717/FDIS 100/749/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 61920 © IEC:2004(E)
The committee has decided that the contents of this publication will remain unchanged until
2006. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

61920 © IEC:2004(E) – 5 –
INFRARED FREE AIR APPLICATIONS
1 Scope and object
This International Standard describes the classification of IR devices into groups and classes
in order to identify and clarify problems caused by mutual interference. Mutual interference is
caused by the increasing parallel application of different infrared (IR) systems.
Due to its physical characteristics, the possibility of local limitation is a special feature of IR
radiation.
In this standard, the wavelength range from 700 nm to 1 600 nm is considered. All systems
based on free air application which intentionally or unintentionally use IR radiation in this range,
are included. Products which unintentionally emit IR radiation, such as illumination equipment
are not deemed to be IR application systems. They are, however, integrated into this standard
in order to enable facility planners to take into consideration and to foresee provisions against
disturbance of IR application systems by such unintentionally emitted radiation.
The object of this standard is to prevent or at least to minimize mutual interference and to allow
the coexistence of different IR products. It is intended to identify each IR product by its
characteristics, according to the classification criteria.
It is not the object of this standard to describe the consequences of interference between IR
systems or safety aspects of optical radiation.
All applications of fibre-optic technology are excluded.
In this context “free air” means freely radiated IR in indoor or outdoor applications.
If the IR systems are used for information transmission, this standard is only relevant in
connection with the physical layer of the open systems interconnection (OSI) reference model
(ISO 7498-1).
NOTE The reader should be aware that a risk of interference between different infrared systems as assessed by
this standard is based on general parameters and therefore cannot take all the parameters involved into account. In
many cases the practical results may differ from those expected, for example the positioning of sender and receiver
and the choice of advanced coding and decoding schemes. All these factors beyond the physical layer may have an
effect on the final result.
2 Normative references
The following referenced documents are indispensable for the application 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 60050-713:1998, International Electrotechnical Vocabulary (IEV) – Part 713: Radio-
communications: transmitters, receivers, networks and operation
IEC 60050-845:1987, International Electrotechnical Vocabulary (IEV) – Chapter 845: Lighting

– 6 – 61920 © IEC:2004(E)
IEC 60417-DB:2002 , Graphical symbols for use on equipment
IEC 60747-5-1:1997, Discrete semiconductor devices and integrated circuits – Part 5-1:
Optoelectronic devices – General
ISO/IEC 7498-1:1994, Information technology – Open systems interconnection – Basic
reference model: The basic model
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply:
3.1
bandwidth (of a receiver, amplifier or network)
extent of a continuous range of electrical frequencies or optical wavelengths over which the
response does not differ from its nominal value by more than a specified amount
[IEV 713-06-19, modified]
3.2
directivity
defined by two angles β and β for describing the dependence of the receiver’s sensitivity
A B
from the direction of incidence. The direction in which the receiver output V [mV] is maximum
might be called optical receiver axis.
s /2
max.
s /2
max.
β
B
β
A
s /2
max.
s
max.
IEC  2895/03
s /2
max.
Figure 1 – Directivity and related characteristics
In a sensitivity diagram, the two angles β and β within which the sensitivity is greater than or
A B
equal to half of the maximum sensitivity (see Figure 1) characterize the directivity
[IEC 60747-5-1, 6.3.5.2, modified]
3.3
fluorescent lamp
discharge lamp of the low pressure mercury type in which most of the light is emitted by one or
several layers of phosphors excited by the ultraviolet radiation from the discharge
[IEV 845-07-26]
3.4
harmonic
integer multiple of a basic frequency
___________
‘DB’ refers to the IEC on-line database.

61920 © IEC:2004(E) – 7 –
3.5
interference
disturbance experienced in the reception of a wanted signal, caused by an unwanted signal or
noise
3.6
infrared radiation
optical radiation for which the wavelengths are longer than those for visible radiation
[IEV 845-01-04]
NOTE For infrared radiation, the range between 780 nm and 1 mm is commonly subdivided into:
IR-A 780 nm to 1 400 nm;
IR-B 1,4 µm to 3 µm;
IR-C 3 µm to 1 mm.
3.7
infrared system
system which uses IR radiation in free air application consisting of IR radiator and IR receiver
3.8
irradiance
E
irradiance (at a point of a surface) is the quotient of the radiant flux dΦ incident on an element
e
of the surface containing the point, by the area dA of that element
E =dΦ /dA
e
NOTE Irradiance is expressed in [mW/m²].
[IEV 845-01-37]
3.9
modulation frequency
electrical signal frequency which modulates the IR radiation
3.10
peak intensity
I
p
maximum intensity I [mW/sr] of the optical radiation inside the optical radiation pattern
p
NOTE It should be taken into account that a different radiation pattern may occur in different wavelength ranges in
the same application.
3.11
radiant intensity
I
e
quotient of the radiant flux dΦ leaving the source and propagated in the element of solid angle
e
dΩ containing the given direction, by the element of solid angle
I =dΦ /dΩ
e e
NOTE Radiant intensity is expressed in [mW/sr].
[IEV 845-01-30]
3.12
radiation characteristic
defined by two angles α and α for describing the beam characteristic of IR emission.
A B
References are the points of half optical radiant intensity. α is the angle of maximum
A
divergence, α is the angle perpendicular to the plane expanded by α , where α ≥ α (similar
B A A B
to 3.2)
– 8 – 61920 © IEC:2004(E)
3.13
relative spectral electrical output
V
rf
of a receiver is its output V [mV/Hz] as a function of the frequency f divided through its
f
maximum value V [mV/Hz]
max
V = V /V × 100
rf f max
NOTE Relative spectral electrical output is expressed in [%].
3.14
relative spectral sensitivity
s
rλλλλ
ratio of the sensitivity s of the detector at wavelength λ to a given reference value s
λ max
s = s /s × 100
rλ λ max
NOTE Relative spectral sensitivity is expressed in [%].
[IEV 845-05-57, modified]
3.15
(maximum) spectral sensitivity
s(max)
quotient of the (maximum) current of the photo diode I [µA/nm] and the irradiance E
(max)
[mW/m²] as a function of the wavelength λ
s = I /E
max max
NOTE Spectral sensitivity is expressed in [(µA × m²)/(mW × nm)].
[IEV 845-05-56, modified]
3.16
steradian
SI unit of solid angle. Solid angle that, having its vertex at the centre of a sphere, cuts off an
area of the surface of the sphere equal to that of a square with sides of length equal to the
radius of the sphere
[IEV 845-01-20]
3.17
wavelength
distance in the direction of propagation of a periodic wave between two successive points at
which the phase is the same
[IEV 845-01-14]
3.18
radiator
IR emitting source, consisting of one or more emitter components, with a specific radiation
characteristic
3.19
(selective) receiver
one or more IR detectors, which are mostly embedded in signal processing components and
representing a specific IR receiving directivity
NOTE Selective receivers have a limited spectral bandwidth within the whole IR spectrum.

61920 © IEC:2004(E) – 9 –
4 Symbols
4.1 General
As this document is concerned with interference, commonly between two different IR systems
(for example between the radiators of a system 1 and the receivers of a system 2), symbols of
similar or equal meaning such as bandwidths B, wavelengths λ or frequencies f shall be
i i i
identified in the following by the index 1 for radiators (Ÿ system 1) and index 2 for receivers (Ÿ
system 2).
4.2 Radiators
B electrical bandwidth [kHz]
1f
B optical bandwidth [nm]
1λ
f modulation frequency [kHz]
f frequency at the modulated peak intensity I [kHz]
p pf
f lower band limiting frequency [kHz]
1l
f upper band limiting frequency [kHz]
1u
I time averaged total optical radiant intensity [mW/sr]
o
I total optical peak intensity [mW/sr]
p
I spectral optical peak intensity [mW/(sr × nm)]
pλ
I spectral optical radiant intensity [mW/(sr × nm)]
eλ
I
spectral modulated radiant intensity [mW/(sr × Hz)]
ef
I
spectral modulated peak intensity [mW/(sr × Hz)]
pf
sr steradian
α angle of maximum divergence
A
α angle perpendicular to α
B A
wavelength [nm]
λ
wavelength at the optical peak intensity I [nm]
λ
pλ
p
lower band limiting wavelength [nm]
λ
1l
upper band limiting wavelength [nm]
λ
1u
4.3 Receivers
B electrical bandwidth [kHz]
2f
B optical bandwidth [nm]
2λ
received frequency [kHz]
f
f frequency at maximum response [kHz]
max
f lower band limiting frequency [kHz]
2l
f upper band limiting frequency [kHz]
2u
E irradiance [mW/m²]
I maximum photo current [µA/nm]
max
s relative spectral sensitivity [%]
rλ
s maximum spectral sensitivity [µA m²/mW × nm]
max
V relative spectral electrical output [%]
rf
– 10 – 61920 © IEC:2004(E)
V maximum spectral electrical output [mV/Hz]
max
angle of maximum reception
β
A
β angle perpendicular to β
B A
wavelength [nm]
λ
λ wavelength at maximum sensitivity [nm]
max
λ lower band limiting wavelength [nm]
2l
upper band limiting wavelength [nm]
λ
2u
5 Classification
5.1 General
The classification considers four main aspects for description of IR systems consisting of
radiators and receivers:
– physical characteristics of radiators (see 5.2);
– physical characteristics of receivers (see 5.3);
– product groups (see 5.5);
– user areas (see 5.6).
5.2 Physical characteristics of radiators
5.2.1 General
There are five criteria, 1 to 5, on which the classification for physical characteristics of
radiators is based. They are operating characteristics, selected from the rated values given by
the manufacturer (see Table 1).
5.2.2 Ranges of wavelength (criterion 1)
The lower (λ ) and the upper (λ ) optical wavelengths determine the optical range of an IR
1l 1u
radiator. Both the lower and the upper optical wavelengths of an IR radiator are defined by the
reduction of the peak intensity I by 3 dB, taking into account the effects of temperature and
pλ
component deviations (see Figure 2).

61920 © IEC:2004(E) – 11 –
I
pλ
B = λ − λ
1λ 1u 1l
Wavelength λ  nm
λ λ λ
1l p 1u
IEC  2896/03
Figure 2 – Spectral emission and definition of optical bandwidth
Spectral optical radiant
intensity I [mW/(sr × nm)]
eλ
3 dB
– 12 – 61920 © IEC:2004(E)
5.2.3 Ranges of frequency (criterion 2)
The lower (f ) and upper (f ) modulation frequencies determine the bandwidth B of the
1l 1u 1f
modulated IR radiant intensity. These frequencies are defined as those two utmost frequencies
including any harmonics and measured with a meter having a bandwidth of at least 10 times
the operating frequency, at which the intensity is 10 dB below the modulated peak intensity I
pf
(see Figure 3).
Harmonics greater than 1/10 of the highest intensity I should be taken into account, notably
pf
with respect to the influences of temperature and component tolerances. For criterion 2 it is
only important to know the upper and lower band limiting frequencies; the possible influence of
modulation is not taken into account in this definition.
I
pf
B = f −f
1f 1u 1l
f f f
1l p 1u
Frequency f  kHz
IEC  2897/03
Figure 3 – Spectral emission and definition of electrical bandwidth
5.2.4 Radiant intensity (criterion 3)
The intensity of IR radiators is characterized by the time averaged total optical radiant intensity
I [mW/sr] and the total optical peak intensity I [mW/s
...