SIST EN 303 348 V1.2.1:2021
(Main)Audio frequency induction loop drivers up to 45 amperes in the frequency range 10 Hz to 9 kHz - Harmonised Standard for access to radio spectrum
Audio frequency induction loop drivers up to 45 amperes in the frequency range 10 Hz to 9 kHz - Harmonised Standard for access to radio spectrum
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop drivers operating from 10 Hz to 9 kHz used in Audio Frequency Induction Loop System (AFILS) with an upper
limit of 45 Arms.
NOTE 1: The object of an AFILS is to transmit an audio signal to people with hearing difficulties. The receiver in
this case is normally a hearing aid or cochlear implant with a built in telecoil, both of which are covered
by ETSI EN 300 422-4 [i.11].
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• with (an) output connection(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers induction loop drivers with output connectors. Integral antenna systems are covered by
ETSI EN 300 422-4 [i.11].
NOTE 2: The relationship between the present document and essential requirements of article 3.2 of Directive
2014/53/EU [i.1] is given in annex A.
Gonilniki za avdiofrekvenčne indukcijske zanke do 45 amperov v frekvenčnem območju od 10 Hz do 9 kHz - Harmonizirani standard za dostop do radijskega spektra
General Information
Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 303 348 V1.2.1:2021
01-september-2021
Gonilniki za avdiofrekvenčne indukcijske zanke do 45 amperov v frekvenčnem
območju od 10 Hz do 9 kHz - Harmonizirani standard za dostop do radijskega
spektra
Audio frequency induction loop drivers up to 45 amperes in the frequency range 10 Hz to
9 kHz - Harmonised Standard for access to radio spectrum
Ta slovenski standard je istoveten z: ETSI EN 303 348 V1.2.1 (2021-06)
ICS:
11.180.15 Pripomočki za gluhe osebe in Aids for deaf and hearing
osebe z okvaro sluha impaired people
33.160.50 Pribor Accessories
SIST EN 303 348 V1.2.1:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 303 348 V1.2.1:2021
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SIST EN 303 348 V1.2.1:2021
ETSI EN 303 348 V1.2.1 (2021-06)
HARMONISED EUROPEAN STANDARD
Audio frequency induction loop drivers up to 45 amperes
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard for access to radio spectrum
---------------------- Page: 3 ----------------------
SIST EN 303 348 V1.2.1:2021
2 ETSI EN 303 348 V1.2.1 (2021-06)
Reference
REN/ERM-TG17-161
Keywords
cochlear implant, harmonised standard,
hearing aid, inductive
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871
Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Notice of disclaimer & limitation of liability
The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of
experience to understand and interpret its content in accordance with generally accepted engineering or
other professional standard and applicable regulations.
No recommendation as to products and services or vendors is made or should be implied.
In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.
Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not
limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property
rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages
for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use
of or inability to use the software.
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.
© ETSI 2021.
All rights reserved.
ETSI
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SIST EN 303 348 V1.2.1:2021
3 ETSI EN 303 348 V1.2.1 (2021-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 9
3.3 Abbreviations . 10
4 Technical requirements specifications . 10
4.1 Environmental conditions . 10
4.1.1 Environmental profile . 10
4.2 General requirements . 10
4.2.1 Presentation of induction loop driver equipment for testing purposes . 10
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Driver shut-off facility . 11
4.2.5 No input signal, no output signal . 11
4.2.6 Information from the manufacturer. 11
4.2.7 Test jig . 11
5 Testing for compliance with technical requirements . 11
5.1 Environmental conditions for testing . 11
5.1.1 General requirements . 11
5.1.2 Normal temperature and humidity . 12
5.1.3 Test power source . 12
5.1.3.1 General requirements . 12
5.1.3.2 External test power source . 12
5.1.3.2.0 General . 12
5.1.3.2.1 Mains voltage . 12
5.1.3.2.2 Other power sources . 12
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.0 General . 13
5.2.1.1 Signal input for testing . 13
5.2.2 Loop connections . 13
5.2.2.1 General . 13
5.2.2.2 Artificial Loop . 13
5.3 Induction loop driver . 14
5.3.1 General . 14
5.3.2 In band and out of band emission limits . 14
5.3.2.1 Definition . 14
5.3.2.2 Methods of measurement . 14
5.3.2.3 Values . 14
5.3.3 Spurious domain emission limits . 14
5.3.3.1 Definition . 14
5.3.3.2 Methods of measurement . 15
5.3.3.3 Values . 15
5.4 Interpretation of the measurement results . 15
ETSI
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SIST EN 303 348 V1.2.1:2021
4 ETSI EN 303 348 V1.2.1 (2021-06)
Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 16
Annex B (informative): Technical overview . 17
B.1 Induction loop drivers . 17
B.1.1 General . 17
B.1.2 Frequency response . 17
B.1.3 Field strength . 17
B.1.4 General performance criteria . 17
B.2 Translation of H-Field values to loop current values . 17
Annex C (informative): The relationship between loop current and H-Field strength . 19
Annex D (informative): How to construct a test fixture incorporating an artificial loop . 21
Annex E (normative): Induction loop driver emission levels and spectrum mask
measurements . 23
Annex F (informative): Maximum Measurement Uncertainty . 24
Annex G (informative): Bibliography . 25
Annex H (informative): Change history . 26
History . 27
ETSI
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SIST EN 303 348 V1.2.1:2021
5 ETSI EN 303 348 V1.2.1 (2021-06)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its
Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the
®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This Harmonised European Standard (EN) has been produced by ETSI Technical Committee Electromagnetic
compatibility and Radio spectrum Matters (ERM).
The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [i.8] to
provide one voluntary means of conforming to the essential requirements of Directive 2014/53/EU on the harmonisation
of the laws of the Member States relating to the making available on the market of radio equipment and repealing
Directive 1999/5/EC [i.1].
Once the present document is cited in the Official Journal of the European Union under that Directive, compliance with
the normative clauses of the present document given in table A.1 confers, within the limits of the scope of the present
document, a presumption of conformity with the corresponding essential requirements of that Directive and associated
EFTA regulations.
National transposition dates
Date of adoption of this EN: 26 May 2021
Date of latest announcement of this EN (doa): 31 August 2021
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 28 February 2022
Date of withdrawal of any conflicting National Standard (dow): 28 February 2023
ETSI
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SIST EN 303 348 V1.2.1:2021
6 ETSI EN 303 348 V1.2.1 (2021-06)
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
Audio Frequency Induction Loop System (AFILS) has been on the market since the middle of the twentieth century,
with the first recognizable patents appearing circa 1938. AFILS are primarily used to facilitate improved
communication to people with impaired hearing and are an important tool in the reduction of discrimination against
disabled people. They are also used in a number of industries including Broadcast and studio.
The present document covers the "drivers" for the loop antenna and represents the performance of equipment which is
currently on the market, which has not previously been subjected to compliance to a "radio" directive.
AFILS are installed in places of worship, places of entertainment, places of education, ticket booths and service
counters, etc. as well as in domestic situations, providing huge benefits to users with impaired hearing.
AFILS provide an audio frequency magnetic field that couples with a receiving coil (telecoil) fitted in hearing aids,
cochlear implants, loop listeners and testing devices. This magnetic field is generated in a wire loop that is fed by an
audio frequency driver which is capable of driving current through the "induction loop" which, in turn, is fed from
external signals such as those generated by microphones, audio-visual equipment and musical instruments.
AFILS operate below 9 kHz and have a very limited range (some few metres) and there is no known evidence of
interference with radio equipment.
2
AFILS are provided in a range of sizes and can cover areas up to approximately 3 000 m . They are also used in
vehicles and lifts and interaction with structural metal means that a complete AFILS can only be tested when fitted in
their final location. This means that the "Loop" is as an external antenna which is not covered by the Radio Equipment
Directive [i.1] and the present document only covers "Drivers".
The market for AFILS is relatively small compared with technologies such as RFID, and is physically separated from
most radio systems, so the opportunity for mutual interference problems is reduced compared to other users of the
spectrum in this frequency range.
As AFILS drivers use base band audio signals without additional carrier tones, and so when no input signal is present,
there will be no output signal and so no magnetic field will be generated, ensuring spectrum efficiency.
The present document has been developed in response to Directive 2014/53/EU [i.1] and is the first radio standard that
has been produced for AFILS equipment and has been prepared to allow the assessment of audio frequency induction
loop drivers and receivers for compliance with Directive 2014/53/EU [i.1].
ETSI
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SIST EN 303 348 V1.2.1:2021
7 ETSI EN 303 348 V1.2.1 (2021-06)
1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop drivers operating from 10 Hz to 9 kHz used in Audio Frequency Induction Loop System (AFILS) with an upper
limit of 45 A .
rms
NOTE 1: The object of an AFILS is to transmit an audio signal to people with hearing difficulties. The receiver in
this case is normally a hearing aid or cochlear implant with a built in telecoil, both of which are covered
by ETSI EN 300 422-4 [i.11].
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• with (an) output connection(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers induction loop drivers with output connectors. Integral antenna systems are covered by
ETSI EN 300 422-4 [i.11].
NOTE 2: The relationship between the present document and essential requirements of article 3.2 of Directive
2014/53/EU [i.1] is given in annex A.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced document are necessary for the application of the present document.
[1] Void.
[2] CEPT/ERC/Recommendation 74-01E (Siófok 98, Nice 99, Sesimbra 02, Hradec Kralove 05,
Cardiff 11): "Unwanted Emissions in the Spurious Domain".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Directive 2014/53/EU of the European Parliament and of the Council of 16 April 2014 on the
harmonisation of the laws of the Member States relating to the making available on the market of
radio equipment and repealing Directive 1999/5/EC.
[i.2] Void.
ETSI
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SIST EN 303 348 V1.2.1:2021
8 ETSI EN 303 348 V1.2.1 (2021-06)
[i.3] Void.
[i.4] IEC 60118-4:2014: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing
aid purposes - Magnetic field strength".
[i.5] Void.
[i.6] Void.
[i.7] Void.
[i.8] Commission Implementing Decision C(2015) 5376 final of 4.8.2015 on a standardisation request
to the European Committee for Electrotechnical Standardisation and to the European
Telecommunications Standards Institute as regards radio equipment in support of Directive
2014/53/EU of the European Parliament and of the Council.
[i.9] Void.
[i.10] Void.
[i.11] ETSI EN 300 422-4: "Wireless Microphones; Audio PMSE up to 3 GHz; Part 4: Assistive
Listening Devices including personal sound amplifiers and inductive systems up to 3 GHz;
Harmonised Standard covering the essential requirements of article 3.2 of Directive 2014/53/EU".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in Directive 2014/53/EU [i.1] and the following apply:
artificial loop: load equal to the nominal resistance and impedance of the loop specified by the manufacturer
audio frequency induction loop driver: audio amplifier designed to drive audio-frequency current in an inductive
loop, thus generating an audio-frequency magnetic field
Audio Frequency Induction Loop System (AFILS): system including induction loop driver(s), microphones and/or
other signal sources, in which a magnetic field is created by the flow of audio-frequency current in a conductor arranged
in the form of a loop or coil
clipping: form of waveform distortion that occurs when an induction loop driver is overdriven and attempts to deliver
an output voltage or current beyond its maximum capability
conducted measurements: measurements that are made using a direct connection to the equipment under test
hearing aid: personal amplification system, worn entirely on the listener, which is designed to enable a person with
impaired hearing to hear more easily
hearing instrument: hearing aid or cochlear implant
hearing loop system: non-technical name for AFILS used by the hard-of-hearing community
in band emissions: emissions on a frequency or frequencies which are inside the necessary bandwidth (10 Hz to 9 kHz)
induction loop: current carrying loop or coil of an AFILS used to create the magnetic field
NOTE: This is equivalent to the term "antenna" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
induction loop driver: audio driver designed to drive an induction loop
NOTE: This is equivalent to the term "transmitter" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
ETSI
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SIST EN 303 348 V1.2.1:2021
9 ETSI EN 303 348 V1.2.1 (2021-06)
induction loop listener: portable listening device that is designed to give an audible output in response to signals
produced by an AFILS
induction loop monitor receiver: equipment designed to verify the performance of an AFILS by audio and visual
means:
a) providing visible indication that it is powered and indicating when the strength of the magnetic field produced
by the loop falls within a specified range; and
b) providing an audio-frequency output by which the sound quality of the AFILS transmissions can be assessed
induction loop system: See AFILS.
internal loop: loop designed as a fixed part of the equipment, without the use of an external connector and as such
which cannot be disconnected from the equipment by the user
loop: See induction loop.
loop listener: See induction loop listener.
metal compensation: method of compensating for amplitude and frequency dependant magnetic field losses due to the
interaction of the magnetic field generated by the loop with nearby metal
mobile audio frequency induction loop driver: equipment normally installed in a vehicle (bus, coach, train, etc.)
out of band emissions: emissions on a frequency or frequencies immediately outside the necessary bandwidth (10 Hz
to 9 kHz), but excluding spurious emissions
phased loop array: system of overlapping loops in which the currents are out of phase with each other used to provide
an even field strength and to limit overspill of the magnetic field
portable audio frequency induction loop driver: driver intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: load, stated by the manufacturer, to which the driver output is connected for measurement purposes
-1
reference magnetic field strength level: 0 dB reference for magnetic field strength levels, which is 400 mAm
spurious emissions: emissions on a frequency or frequencies which are outside the necessary bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and
frequency conversion products, but exclude out-of-band emissions.
telecoil: magnetic pickup coil intended to receive signals from an audio frequency induction loop system
NOTE: A telecoil can be part of a hearing aid, cochlear implant, or of any other device for receiving signals from
an audio frequency induction loop system in accordance with IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
A ampere
C correction factor
E electrical field strength
f frequency
f centre fr
...
ETSI EN 303 348 V1.2.1 (2021-06)
HARMONISED EUROPEAN STANDARD
Audio frequency induction loop drivers up to 45 amperes
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard for access to radio spectrum
---------------------- Page: 1 ----------------------
2 ETSI EN 303 348 V1.2.1 (2021-06)
Reference
REN/ERM-TG17-161
Keywords
cochlear implant, harmonised standard,
hearing aid, inductive
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871
Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Notice of disclaimer & limitation of liability
The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of
experience to understand and interpret its content in accordance with generally accepted engineering or
other professional standard and applicable regulations.
No recommendation as to products and services or vendors is made or should be implied.
In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.
Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not
limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property
rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages
for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use
of or inability to use the software.
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.
© ETSI 2021.
All rights reserved.
ETSI
---------------------- Page: 2 ----------------------
3 ETSI EN 303 348 V1.2.1 (2021-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 6
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 9
3.3 Abbreviations . 10
4 Technical requirements specifications . 10
4.1 Environmental conditions . 10
4.1.1 Environmental profile . 10
4.2 General requirements . 10
4.2.1 Presentation of induction loop driver equipment for testing purposes . 10
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Driver shut-off facility . 11
4.2.5 No input signal, no output signal . 11
4.2.6 Information from the manufacturer. 11
4.2.7 Test jig . 11
5 Testing for compliance with technical requirements . 11
5.1 Environmental conditions for testing . 11
5.1.1 General requirements . 11
5.1.2 Normal temperature and humidity . 12
5.1.3 Test power source . 12
5.1.3.1 General requirements . 12
5.1.3.2 External test power source . 12
5.1.3.2.0 General . 12
5.1.3.2.1 Mains voltage . 12
5.1.3.2.2 Other power sources . 12
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.0 General . 13
5.2.1.1 Signal input for testing . 13
5.2.2 Loop connections . 13
5.2.2.1 General . 13
5.2.2.2 Artificial Loop . 13
5.3 Induction loop driver . 14
5.3.1 General . 14
5.3.2 In band and out of band emission limits . 14
5.3.2.1 Definition . 14
5.3.2.2 Methods of measurement . 14
5.3.2.3 Values . 14
5.3.3 Spurious domain emission limits . 14
5.3.3.1 Definition . 14
5.3.3.2 Methods of measurement . 15
5.3.3.3 Values . 15
5.4 Interpretation of the measurement results . 15
ETSI
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4 ETSI EN 303 348 V1.2.1 (2021-06)
Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 16
Annex B (informative): Technical overview . 17
B.1 Induction loop drivers . 17
B.1.1 General . 17
B.1.2 Frequency response . 17
B.1.3 Field strength . 17
B.1.4 General performance criteria . 17
B.2 Translation of H-Field values to loop current values . 17
Annex C (informative): The relationship between loop current and H-Field strength . 19
Annex D (informative): How to construct a test fixture incorporating an artificial loop . 21
Annex E (normative): Induction loop driver emission levels and spectrum mask
measurements . 23
Annex F (informative): Maximum Measurement Uncertainty . 24
Annex G (informative): Bibliography . 25
Annex H (informative): Change history . 26
History . 27
ETSI
---------------------- Page: 4 ----------------------
5 ETSI EN 303 348 V1.2.1 (2021-06)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its
Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the
®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This Harmonised European Standard (EN) has been produced by ETSI Technical Committee Electromagnetic
compatibility and Radio spectrum Matters (ERM).
The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [i.8] to
provide one voluntary means of conforming to the essential requirements of Directive 2014/53/EU on the harmonisation
of the laws of the Member States relating to the making available on the market of radio equipment and repealing
Directive 1999/5/EC [i.1].
Once the present document is cited in the Official Journal of the European Union under that Directive, compliance with
the normative clauses of the present document given in table A.1 confers, within the limits of the scope of the present
document, a presumption of conformity with the corresponding essential requirements of that Directive and associated
EFTA regulations.
National transposition dates
Date of adoption of this EN: 26 May 2021
Date of latest announcement of this EN (doa): 31 August 2021
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 28 February 2022
Date of withdrawal of any conflicting National Standard (dow): 28 February 2023
ETSI
---------------------- Page: 5 ----------------------
6 ETSI EN 303 348 V1.2.1 (2021-06)
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
Audio Frequency Induction Loop System (AFILS) has been on the market since the middle of the twentieth century,
with the first recognizable patents appearing circa 1938. AFILS are primarily used to facilitate improved
communication to people with impaired hearing and are an important tool in the reduction of discrimination against
disabled people. They are also used in a number of industries including Broadcast and studio.
The present document covers the "drivers" for the loop antenna and represents the performance of equipment which is
currently on the market, which has not previously been subjected to compliance to a "radio" directive.
AFILS are installed in places of worship, places of entertainment, places of education, ticket booths and service
counters, etc. as well as in domestic situations, providing huge benefits to users with impaired hearing.
AFILS provide an audio frequency magnetic field that couples with a receiving coil (telecoil) fitted in hearing aids,
cochlear implants, loop listeners and testing devices. This magnetic field is generated in a wire loop that is fed by an
audio frequency driver which is capable of driving current through the "induction loop" which, in turn, is fed from
external signals such as those generated by microphones, audio-visual equipment and musical instruments.
AFILS operate below 9 kHz and have a very limited range (some few metres) and there is no known evidence of
interference with radio equipment.
2
AFILS are provided in a range of sizes and can cover areas up to approximately 3 000 m . They are also used in
vehicles and lifts and interaction with structural metal means that a complete AFILS can only be tested when fitted in
their final location. This means that the "Loop" is as an external antenna which is not covered by the Radio Equipment
Directive [i.1] and the present document only covers "Drivers".
The market for AFILS is relatively small compared with technologies such as RFID, and is physically separated from
most radio systems, so the opportunity for mutual interference problems is reduced compared to other users of the
spectrum in this frequency range.
As AFILS drivers use base band audio signals without additional carrier tones, and so when no input signal is present,
there will be no output signal and so no magnetic field will be generated, ensuring spectrum efficiency.
The present document has been developed in response to Directive 2014/53/EU [i.1] and is the first radio standard that
has been produced for AFILS equipment and has been prepared to allow the assessment of audio frequency induction
loop drivers and receivers for compliance with Directive 2014/53/EU [i.1].
ETSI
---------------------- Page: 6 ----------------------
7 ETSI EN 303 348 V1.2.1 (2021-06)
1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop drivers operating from 10 Hz to 9 kHz used in Audio Frequency Induction Loop System (AFILS) with an upper
limit of 45 A .
rms
NOTE 1: The object of an AFILS is to transmit an audio signal to people with hearing difficulties. The receiver in
this case is normally a hearing aid or cochlear implant with a built in telecoil, both of which are covered
by ETSI EN 300 422-4 [i.11].
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• with (an) output connection(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers induction loop drivers with output connectors. Integral antenna systems are covered by
ETSI EN 300 422-4 [i.11].
NOTE 2: The relationship between the present document and essential requirements of article 3.2 of Directive
2014/53/EU [i.1] is given in annex A.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced document are necessary for the application of the present document.
[1] Void.
[2] CEPT/ERC/Recommendation 74-01E (Siófok 98, Nice 99, Sesimbra 02, Hradec Kralove 05,
Cardiff 11): "Unwanted Emissions in the Spurious Domain".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Directive 2014/53/EU of the European Parliament and of the Council of 16 April 2014 on the
harmonisation of the laws of the Member States relating to the making available on the market of
radio equipment and repealing Directive 1999/5/EC.
[i.2] Void.
ETSI
---------------------- Page: 7 ----------------------
8 ETSI EN 303 348 V1.2.1 (2021-06)
[i.3] Void.
[i.4] IEC 60118-4:2014: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing
aid purposes - Magnetic field strength".
[i.5] Void.
[i.6] Void.
[i.7] Void.
[i.8] Commission Implementing Decision C(2015) 5376 final of 4.8.2015 on a standardisation request
to the European Committee for Electrotechnical Standardisation and to the European
Telecommunications Standards Institute as regards radio equipment in support of Directive
2014/53/EU of the European Parliament and of the Council.
[i.9] Void.
[i.10] Void.
[i.11] ETSI EN 300 422-4: "Wireless Microphones; Audio PMSE up to 3 GHz; Part 4: Assistive
Listening Devices including personal sound amplifiers and inductive systems up to 3 GHz;
Harmonised Standard covering the essential requirements of article 3.2 of Directive 2014/53/EU".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in Directive 2014/53/EU [i.1] and the following apply:
artificial loop: load equal to the nominal resistance and impedance of the loop specified by the manufacturer
audio frequency induction loop driver: audio amplifier designed to drive audio-frequency current in an inductive
loop, thus generating an audio-frequency magnetic field
Audio Frequency Induction Loop System (AFILS): system including induction loop driver(s), microphones and/or
other signal sources, in which a magnetic field is created by the flow of audio-frequency current in a conductor arranged
in the form of a loop or coil
clipping: form of waveform distortion that occurs when an induction loop driver is overdriven and attempts to deliver
an output voltage or current beyond its maximum capability
conducted measurements: measurements that are made using a direct connection to the equipment under test
hearing aid: personal amplification system, worn entirely on the listener, which is designed to enable a person with
impaired hearing to hear more easily
hearing instrument: hearing aid or cochlear implant
hearing loop system: non-technical name for AFILS used by the hard-of-hearing community
in band emissions: emissions on a frequency or frequencies which are inside the necessary bandwidth (10 Hz to 9 kHz)
induction loop: current carrying loop or coil of an AFILS used to create the magnetic field
NOTE: This is equivalent to the term "antenna" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
induction loop driver: audio driver designed to drive an induction loop
NOTE: This is equivalent to the term "transmitter" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
ETSI
---------------------- Page: 8 ----------------------
9 ETSI EN 303 348 V1.2.1 (2021-06)
induction loop listener: portable listening device that is designed to give an audible output in response to signals
produced by an AFILS
induction loop monitor receiver: equipment designed to verify the performance of an AFILS by audio and visual
means:
a) providing visible indication that it is powered and indicating when the strength of the magnetic field produced
by the loop falls within a specified range; and
b) providing an audio-frequency output by which the sound quality of the AFILS transmissions can be assessed
induction loop system: See AFILS.
internal loop: loop designed as a fixed part of the equipment, without the use of an external connector and as such
which cannot be disconnected from the equipment by the user
loop: See induction loop.
loop listener: See induction loop listener.
metal compensation: method of compensating for amplitude and frequency dependant magnetic field losses due to the
interaction of the magnetic field generated by the loop with nearby metal
mobile audio frequency induction loop driver: equipment normally installed in a vehicle (bus, coach, train, etc.)
out of band emissions: emissions on a frequency or frequencies immediately outside the necessary bandwidth (10 Hz
to 9 kHz), but excluding spurious emissions
phased loop array: system of overlapping loops in which the currents are out of phase with each other used to provide
an even field strength and to limit overspill of the magnetic field
portable audio frequency induction loop driver: driver intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: load, stated by the manufacturer, to which the driver output is connected for measurement purposes
-1
reference magnetic field strength level: 0 dB reference for magnetic field strength levels, which is 400 mAm
spurious emissions: emissions on a frequency or frequencies which are outside the necessary bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and
frequency conversion products, but exclude out-of-band emissions.
telecoil: magnetic pickup coil intended to receive signals from an audio frequency induction loop system
NOTE: A telecoil can be part of a hearing aid, cochlear implant, or of any other device for receiving signals from
an audio frequency induction loop system in accordance with IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
A ampere
C correction factor
E electrical field strength
f frequency
f centre frequency in Hz
C
H magnetic field strength
Hf H-field-strength limit
H H-field strength at the centre of the frequency of interest
C
H H-field-strength limit for radiated spurious emissions
S
I audio frequency in band output current
C
ETSI
---------------------- Page: 9 ----------------------
10 ETSI EN 303 348 V1.2.1 (2021-06)
I spurious output current
S
λ wavelength
N number of turns for a loop
P power
t time
Ω ohm
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFILS Audio Frequency Induction Loop System
NOTE: Also known as a Hearing Loop.
AMN Artificial Mains Network
CDN Coupling/Decoupling Network
CEPT Conférence Européenne des Postes et Télécommunications
EC European Community
EFTA European Free Trade Association
ERC European Radiocommunications Committee
EU European Union
EUT Equipment Under Test
ISN Impedance Stabilization Network
LISN Line Impedance Stabilization Network
RF Radio Frequency
RFID Radio Frequency Identification Device
rms root mean square
SRD Short Range Device
4 Technical requirements specifications
4.1 Environmental c
...
Draft ETSI EN 303 348 V1.2.0 (2021-02)
HARMONISED EUROPEAN STANDARD
Audio frequency induction loop drivers up to 45 A
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard for access to radio spectrum
---------------------- Page: 1 ----------------------
2 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Reference
REN/ERM-TG17-161
Keywords
cochlear implant, harmonised standard,
hearing aid, inductive
ETSI
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Important notice
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The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
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Users of the present document should be aware that the document may be subject to revision or change of status.
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and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.
© ETSI 2021.
All rights reserved.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.
3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and
of the oneM2M Partners.
®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
---------------------- Page: 2 ----------------------
3 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 9
3.3 Abbreviations . 10
4 Technical requirements specifications . 10
4.1 Environmental conditions . 10
4.1.1 Environmental profile . 10
4.2 General requirements . 10
4.2.1 Presentation of induction loop driver equipment for testing purposes . 10
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Driver shut-off facility . 11
4.2.5 No input signal, no output signal . 11
4.2.6 Information from the manufacturer. 11
4.2.7 Test jig . 11
5 Testing for compliance with technical requirements . 11
5.1 Environmental conditions for testing . 11
5.1.1 General requirements . 11
5.1.2 Normal temperature and humidity . 12
5.1.3 Test power source . 12
5.1.3.1 General requirements . 12
5.1.3.2 External test power source . 12
5.1.3.2.0 General . 12
5.1.3.2.1 Mains voltage . 12
5.1.3.2.2 Other power sources . 12
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.0 General . 13
5.2.1.1 Signal input for testing . 13
5.2.2 Loop connections . 13
5.2.2.1 General . 13
5.2.2.2 Artificial Loop . 13
5.3 Induction loop driver . 14
5.3.1 General . 14
5.3.2 In band and out of band emission limits . 14
5.3.2.1 Definition . 14
5.3.2.2 Methods of measurement . 14
5.3.2.3 Values . 14
5.3.3 Spurious domain emission limits . 14
5.3.3.1 Definition . 14
5.3.3.2 Methods of measurement . 15
5.3.3.3 Values . 15
5.4 Interpretation of the measurement results . 15
ETSI
---------------------- Page: 3 ----------------------
4 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 16
Annex B (informative): Technical overview . 17
B.1 Induction loop drivers . 17
B.1.1 General . 17
B.1.2 Frequency response . 17
B.1.3 Field strength . 17
B.1.4 General performance criteria . 17
B.2 Translation of H-Field values to loop current values . 17
Annex C (informative): The relationship between loop current and H-Field strength . 19
Annex D (informative): How to construct a test fixture incorporating an artificial loop . 21
Annex E (normative): Induction loop driver emission levels and spectrum mask
measurements . 23
Annex F (informative): Maximum Measurement Uncertainty . 24
Annex G (informative): Bibliography . 25
Annex H (informative): Change history . 26
History . 27
ETSI
---------------------- Page: 4 ----------------------
5 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This draft Harmonised European Standard (EN) has been produced by ETSI Technical Committee Electromagnetic
compatibility and Radio spectrum Matters (ERM), and is now submitted for the combined Public Enquiry and Vote
phase of the ETSI standards EN Approval Procedure.
The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [i.8] to
provide one voluntary means of conforming to the essential requirements of Directive 2014/53/EU on the harmonisation
of the laws of the Member States relating to the making available on the market of radio equipment and repealing
Directive 1999/5/EC [i.1].
Once the present document is cited in the Official Journal of the European Union under that Directive, compliance with
the normative clauses of the present document given in table A.1 confers, within the limits of the scope of the present
document, a presumption of conformity with the corresponding essential requirements of that Directive, and associated
EFTA regulations.
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 18 months after doa
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
---------------------- Page: 5 ----------------------
6 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Introduction
Audio Frequency Induction Loop System (AFILS) has been on the market since the middle of the twentieth century,
with the first recognizable patents appearing circa 1938. AFILS are primarily used to facilitate improved
communication to people with impaired hearing and are an important tool in the reduction of discrimination against
disabled people. They are also used in a number of industries including Broadcast and studio.
The present document covers the "drivers" for the loop antenna and represents the performance of equipment which is
currently on the market, which has not previously been subjected to compliance to a "radio" directive.
AFILS are installed in places of worship, places of entertainment, places of education, ticket booths and service
counters, etc. as well as in domestic situations, providing huge benefits to users with impaired hearing.
AFILS provide an audio frequency magnetic field that couples with a receiving coil (telecoil) fitted in hearing aids,
cochlear implants, loop listeners and testing devices. This magnetic field is generated in a wire loop that is fed by an
audio frequency driver which is capable of driving current through the "induction loop" which, in turn, is fed from
external signals such as those generated by microphones, audio-visual equipment and musical instruments.
AFILS operate below 9 kHz and have a very limited range (some few metres) and there is no known evidence of
interference with radio equipment.
2
AFILS are provided in a range of sizes and can cover areas up to approximately 3 000 m . They are also used in
vehicles and lifts and interaction with structural metal means that a complete AFILS can only be tested when fitted in
their final location. This means that the "Loop" is as an external antenna which is not covered by the Radio Equipment
Directive [i.1] and the present document only covers "Drivers".
The market for AFILS is relatively small compared with technologies such as RFID, and is physically separated from
most radio systems, so the opportunity for mutual interference problems is reduced compared to other users of the
spectrum in this frequency range.
As AFILS drivers use base band audio signals without additional carrier tones, and so when no input signal is present,
there will be no output signal and so no magnetic field will be generated, ensuring spectrum efficiency.
The present document has been developed in response to Directive 2014/53/EU [i.1] and is the first radio standard that
has been produced for AFILS equipment and has been prepared to allow the assessment of audio frequency induction
loop drivers and receivers for compliance with Directive 2014/53/EU [i.1].
ETSI
---------------------- Page: 6 ----------------------
7 Draft ETSI EN 303 348 V1.2.0 (2021-02)
1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop drivers operating from 10 Hz to 9 kHz used in Audio Frequency Induction Loop System (AFILS) with an upper
limit of 45 A .
rms
NOTE 1: The object of an AFILS is to transmit an audio signal to people with hearing difficulties. The receiver in
this case is normally a hearing aid or cochlear implant with a built in telecoil, both of which are covered
by ETSI EN 300 422-4 [i.11].
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• with (an) output connection(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers induction loop drivers with output connectors. Integral antenna systems are covered by
ETSI EN 300 422-4 [i.11].
NOTE 2: The relationship between the present document and essential requirements of article 3.2 of Directive
2014/53/EU [i.1] is given in annex A.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced document are necessary for the application of the present document.
[1] Void.
[2] CEPT/ERC/Recommendation 74-01E (Siófok 98, Nice 99, Sesimbra 02, Hradec Kralove 05,
Cardiff 11): "Unwanted Emissions in the Spurious Domain".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Directive 2014/53/EU of the European Parliament and of the Council of 16 April 2014 on the
harmonisation of the laws of the Member States relating to the making available on the market of
radio equipment and repealing Directive 1999/5/EC.
[i.2] Void.
ETSI
---------------------- Page: 7 ----------------------
8 Draft ETSI EN 303 348 V1.2.0 (2021-02)
[i.3] Void.
[i.4] IEC 60118-4:2014: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing
aid purposes - Magnetic field strength".
[i.5] Void.
[i.6] Void.
[i.7] Void.
[i.8] Commission Implementing Decision C(2015) 5376 final of 4.8.2015 on a standardisation request
to the European Committee for Electrotechnical Standardisation and to the European
Telecommunications Standards Institute as regards radio equipment in support of Directive
2014/53/EU of the European Parliament and of the Council.
[i.9] Void.
[i.10] Void.
[i.11] ETSI EN 300 422-4: "Wireless Microphones; Audio PMSE up to 3 GHz; Part 4: Assistive
Listening Devices including personal sound amplifiers and inductive systems up to 3 GHz;
Harmonised Standard covering the essential requirements of article 3.2 of Directive 2014/53/EU".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in Directive 2014/53/EU [i.1] and the following apply:
artificial loop: load equal to the nominal resistance and impedance of the loop specified by the manufacturer
audio frequency induction loop driver: audio amplifier designed to drive audio-frequency current in an inductive
loop, thus generating an audio-frequency magnetic field
Audio Frequency Induction Loop System (AFILS): system including induction loop driver(s), microphones and/or
other signal sources, in which a magnetic field is created by the flow of audio-frequency current in a conductor arranged
in the form of a loop or coil
clipping: form of waveform distortion that occurs when an induction loop driver is overdriven and attempts to deliver
an output voltage or current beyond its maximum capability
conducted measurements: measurements that are made using a direct connection to the equipment under test
hearing aid: personal amplification system, worn entirely on the listener, which is designed to enable a person with
impaired hearing to hear more easily
hearing instrument: hearing aid or cochlear implant
hearing loop system: non-technical name for AFILS used by the hard-of-hearing community
in band emissions: emissions on a frequency or frequencies which are inside the necessary bandwidth (10 Hz to 9 kHz)
induction loop: current carrying loop or coil of an AFILS used to create the magnetic field
NOTE: This is equivalent to the term "antenna" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
induction loop driver: audio driver designed to drive an induction loop
NOTE: This is equivalent to the term "transmitter" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
ETSI
---------------------- Page: 8 ----------------------
9 Draft ETSI EN 303 348 V1.2.0 (2021-02)
induction loop listener: portable listening device that is designed to give an audible output in response to signals
produced by an AFILS
induction loop monitor receiver: equipment designed to verify the performance of an AFILS by audio and visual
means:
a) providing visible indication that it is powered and indicating when the strength of the magnetic field produced
by the loop falls within a specified range; and
b) providing an audio-frequency output by which the sound quality of the AFILS transmissions can be assessed
induction loop system: See AFILS.
internal loop: loop designed as a fixed part of the equipment, without the use of an external connector and as such
which cannot be disconnected from the equipment by the user
loop: See induction loop.
loop listener: See induction loop listener.
metal compensation: method of compensating for amplitude and frequency dependant magnetic field losses due to the
interaction of the magnetic field generated by the loop with nearby metal
mobile audio frequency induction loop driver: equipment normally installed in a vehicle (bus, coach, train, etc.)
out of band emissions: emissions on a frequency or frequencies immediately outside the necessary bandwidth (10 Hz
to 9 kHz), but excluding spurious emissions
phased loop array: system of overlapping loops in which the currents are out of phase with each other used to provide
an even field strength and to limit overspill of the magnetic field
portable audio frequency induction loop driver: driver intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: load, stated by the manufacturer, to which the driver output is connected for measurement purposes
-1
reference magnetic field strength level: 0 dB reference for magnetic field strength levels, which is 400 mAm
spurious emissions: emissions on a frequency or frequencies which are outside the necessary bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and
frequency conversion products, but exclude out-of-band emissions.
telecoil: magnetic pickup coil intended to receive signals from an audio frequency induction loop system
NOTE: A telecoil can be part of a hearing aid, cochlear implant, or of any other device for receiving signals from
an audio frequency induction loop system in accordance with IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
A loop area
C correction factor
E electrical field strength
f frequency
f centre frequency in Hz
C
H magnetic field strength
Hf H-field-strength limit
H H-field strength at the centre of the frequency of interest
C
H H-field-strength limit for radiated spurious emissions
S
I audio frequency in band output current
C
ETSI
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10 Draft ETSI EN 303 348 V1.2.0 (2021-02)
I spurious output current
S
λ wavelength
N number of turns for a loop
P power
t time
Ω ohm
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFILS Audio Frequency Induction Loop System
NOTE: Also known as a Hearing Loop.
AMN Artificial Mains Network
CDN Coupling/Decoupling Network
CEPT Conférence Européenne des Postes et Télécommunications
EC European Community
EFTA European Free Trade Association
ERC European Radiocommunications Committee
EU European Union
EUT Equipment Under Test
ISN Impedance Stabilization Network
LISN Line Impedance Stabilization Network
RF Radio Frequency
RFID Radio Frequency Identification Device
rms root mean square
SRD Short Range Device
4 Technical requirements specifications
4.1 Environmental conditions
4.1.1 Environmental profile
The technical requirements of the present document apply under the environmental profile for operation of the
equipment, which shall be in accordance with its intended use. The equipment shall comply with all the technical
requirements of the present document at all times when operating within the boundary limits of the operational
environmental profile defined by its intended use.
4.2 General requirements
4.2.1 Presentation of induction loop driver equipment for testing purposes
Each equipment submitted for testing shall fulfil the requirements of the present document when operated as intended.
The range of operating conditions and power requirements for tests shall be defined based on the supplied technical
documentation and operating manuals.
Drivers shall be supplied with the appropriate test jig incorporating an artificial loop.
Equipment shall be operated at its maximum intended operational current with a
...
SLOVENSKI STANDARD
oSIST prEN 303 348 V1.2.0:2021
01-maj-2021
Gonilniki za avdiofrekvenčne indukcijske zanke do 45 A v frekvenčnem območju
od 10 Hz do 9 kHz - Harmonizirani standard za dostop do radijskega spektra
Audio frequency induction loop drivers up to 45 A in the frequency range 10 Hz to 9 kHz -
Harmonised Standard for access to radio spectrum
Ta slovenski standard je istoveten z: ETSI EN 303 348 V1.2.0 (2021-02)
ICS:
11.180.15 Pripomočki za gluhe osebe in Aids for deaf and hearing
osebe z okvaro sluha impaired people
33.160.50 Pribor Accessories
oSIST prEN 303 348 V1.2.0:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 303 348 V1.2.0:2021
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oSIST prEN 303 348 V1.2.0:2021
Draft ETSI EN 303 348 V1.2.0 (2021-02)
HARMONISED EUROPEAN STANDARD
Audio frequency induction loop drivers up to 45 A
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard for access to radio spectrum
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2 Draft ETSI EN 303 348 V1.2.0 (2021-02)
Reference
REN/ERM-TG17-161
Keywords
cochlear implant, harmonised standard,
hearing aid, inductive
ETSI
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© ETSI 2021.
All rights reserved.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.
3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
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®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
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Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 9
3.3 Abbreviations . 10
4 Technical requirements specifications . 10
4.1 Environmental conditions . 10
4.1.1 Environmental profile . 10
4.2 General requirements . 10
4.2.1 Presentation of induction loop driver equipment for testing purposes . 10
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Driver shut-off facility . 11
4.2.5 No input signal, no output signal . 11
4.2.6 Information from the manufacturer. 11
4.2.7 Test jig . 11
5 Testing for compliance with technical requirements . 11
5.1 Environmental conditions for testing . 11
5.1.1 General requirements . 11
5.1.2 Normal temperature and humidity . 12
5.1.3 Test power source . 12
5.1.3.1 General requirements . 12
5.1.3.2 External test power source . 12
5.1.3.2.0 General . 12
5.1.3.2.1 Mains voltage . 12
5.1.3.2.2 Other power sources . 12
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.0 General . 13
5.2.1.1 Signal input for testing . 13
5.2.2 Loop connections . 13
5.2.2.1 General . 13
5.2.2.2 Artificial Loop . 13
5.3 Induction loop driver . 14
5.3.1 General . 14
5.3.2 In band and out of band emission limits . 14
5.3.2.1 Definition . 14
5.3.2.2 Methods of measurement . 14
5.3.2.3 Values . 14
5.3.3 Spurious domain emission limits . 14
5.3.3.1 Definition . 14
5.3.3.2 Methods of measurement . 15
5.3.3.3 Values . 15
5.4 Interpretation of the measurement results . 15
ETSI
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Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 16
Annex B (informative): Technical overview . 17
B.1 Induction loop drivers . 17
B.1.1 General . 17
B.1.2 Frequency response . 17
B.1.3 Field strength . 17
B.1.4 General performance criteria . 17
B.2 Translation of H-Field values to loop current values . 17
Annex C (informative): The relationship between loop current and H-Field strength . 19
Annex D (informative): How to construct a test fixture incorporating an artificial loop . 21
Annex E (normative): Induction loop driver emission levels and spectrum mask
measurements . 23
Annex F (informative): Maximum Measurement Uncertainty . 24
Annex G (informative): Bibliography . 25
Annex H (informative): Change history . 26
History . 27
ETSI
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Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This draft Harmonised European Standard (EN) has been produced by ETSI Technical Committee Electromagnetic
compatibility and Radio spectrum Matters (ERM), and is now submitted for the combined Public Enquiry and Vote
phase of the ETSI standards EN Approval Procedure.
The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [i.8] to
provide one voluntary means of conforming to the essential requirements of Directive 2014/53/EU on the harmonisation
of the laws of the Member States relating to the making available on the market of radio equipment and repealing
Directive 1999/5/EC [i.1].
Once the present document is cited in the Official Journal of the European Union under that Directive, compliance with
the normative clauses of the present document given in table A.1 confers, within the limits of the scope of the present
document, a presumption of conformity with the corresponding essential requirements of that Directive, and associated
EFTA regulations.
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 18 months after doa
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
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Introduction
Audio Frequency Induction Loop System (AFILS) has been on the market since the middle of the twentieth century,
with the first recognizable patents appearing circa 1938. AFILS are primarily used to facilitate improved
communication to people with impaired hearing and are an important tool in the reduction of discrimination against
disabled people. They are also used in a number of industries including Broadcast and studio.
The present document covers the "drivers" for the loop antenna and represents the performance of equipment which is
currently on the market, which has not previously been subjected to compliance to a "radio" directive.
AFILS are installed in places of worship, places of entertainment, places of education, ticket booths and service
counters, etc. as well as in domestic situations, providing huge benefits to users with impaired hearing.
AFILS provide an audio frequency magnetic field that couples with a receiving coil (telecoil) fitted in hearing aids,
cochlear implants, loop listeners and testing devices. This magnetic field is generated in a wire loop that is fed by an
audio frequency driver which is capable of driving current through the "induction loop" which, in turn, is fed from
external signals such as those generated by microphones, audio-visual equipment and musical instruments.
AFILS operate below 9 kHz and have a very limited range (some few metres) and there is no known evidence of
interference with radio equipment.
2
AFILS are provided in a range of sizes and can cover areas up to approximately 3 000 m . They are also used in
vehicles and lifts and interaction with structural metal means that a complete AFILS can only be tested when fitted in
their final location. This means that the "Loop" is as an external antenna which is not covered by the Radio Equipment
Directive [i.1] and the present document only covers "Drivers".
The market for AFILS is relatively small compared with technologies such as RFID, and is physically separated from
most radio systems, so the opportunity for mutual interference problems is reduced compared to other users of the
spectrum in this frequency range.
As AFILS drivers use base band audio signals without additional carrier tones, and so when no input signal is present,
there will be no output signal and so no magnetic field will be generated, ensuring spectrum efficiency.
The present document has been developed in response to Directive 2014/53/EU [i.1] and is the first radio standard that
has been produced for AFILS equipment and has been prepared to allow the assessment of audio frequency induction
loop drivers and receivers for compliance with Directive 2014/53/EU [i.1].
ETSI
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1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop drivers operating from 10 Hz to 9 kHz used in Audio Frequency Induction Loop System (AFILS) with an upper
limit of 45 A .
rms
NOTE 1: The object of an AFILS is to transmit an audio signal to people with hearing difficulties. The receiver in
this case is normally a hearing aid or cochlear implant with a built in telecoil, both of which are covered
by ETSI EN 300 422-4 [i.11].
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• with (an) output connection(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers induction loop drivers with output connectors. Integral antenna systems are covered by
ETSI EN 300 422-4 [i.11].
NOTE 2: The relationship between the present document and essential requirements of article 3.2 of Directive
2014/53/EU [i.1] is given in annex A.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced document are necessary for the application of the present document.
[1] Void.
[2] CEPT/ERC/Recommendation 74-01E (Siófok 98, Nice 99, Sesimbra 02, Hradec Kralove 05,
Cardiff 11): "Unwanted Emissions in the Spurious Domain".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Directive 2014/53/EU of the European Parliament and of the Council of 16 April 2014 on the
harmonisation of the laws of the Member States relating to the making available on the market of
radio equipment and repealing Directive 1999/5/EC.
[i.2] Void.
ETSI
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[i.3] Void.
[i.4] IEC 60118-4:2014: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing
aid purposes - Magnetic field strength".
[i.5] Void.
[i.6] Void.
[i.7] Void.
[i.8] Commission Implementing Decision C(2015) 5376 final of 4.8.2015 on a standardisation request
to the European Committee for Electrotechnical Standardisation and to the European
Telecommunications Standards Institute as regards radio equipment in support of Directive
2014/53/EU of the European Parliament and of the Council.
[i.9] Void.
[i.10] Void.
[i.11] ETSI EN 300 422-4: "Wireless Microphones; Audio PMSE up to 3 GHz; Part 4: Assistive
Listening Devices including personal sound amplifiers and inductive systems up to 3 GHz;
Harmonised Standard covering the essential requirements of article 3.2 of Directive 2014/53/EU".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in Directive 2014/53/EU [i.1] and the following apply:
artificial loop: load equal to the nominal resistance and impedance of the loop specified by the manufacturer
audio frequency induction loop driver: audio amplifier designed to drive audio-frequency current in an inductive
loop, thus generating an audio-frequency magnetic field
Audio Frequency Induction Loop System (AFILS): system including induction loop driver(s), microphones and/or
other signal sources, in which a magnetic field is created by the flow of audio-frequency current in a conductor arranged
in the form of a loop or coil
clipping: form of waveform distortion that occurs when an induction loop driver is overdriven and attempts to deliver
an output voltage or current beyond its maximum capability
conducted measurements: measurements that are made using a direct connection to the equipment under test
hearing aid: personal amplification system, worn entirely on the listener, which is designed to enable a person with
impaired hearing to hear more easily
hearing instrument: hearing aid or cochlear implant
hearing loop system: non-technical name for AFILS used by the hard-of-hearing community
in band emissions: emissions on a frequency or frequencies which are inside the necessary bandwidth (10 Hz to 9 kHz)
induction loop: current carrying loop or coil of an AFILS used to create the magnetic field
NOTE: This is equivalent to the term "antenna" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
induction loop driver: audio driver designed to drive an induction loop
NOTE: This is equivalent to the term "transmitter" used in other ETSI documents and is used in the present
document as it is the term commonly understood by the AFILS industry.
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induction loop listener: portable listening device that is designed to give an audible output in response to signals
produced by an AFILS
induction loop monitor receiver: equipment designed to verify the performance of an AFILS by audio and visual
means:
a) providing visible indication that it is powered and indicating when the strength of the magnetic field produced
by the loop falls within a specified range; and
b) providing an audio-frequency output by which the sound quality of the AFILS transmissions can be assessed
induction loop system: See AFILS.
internal loop: loop designed as a fixed part of the equipment, without the use of an external connector and as such
which cannot be disconnected from the equipment by the user
loop: See induction loop.
loop listener: See induction loop listener.
metal compensation: method of compensating for amplitude and frequency dependant magnetic field losses due to the
interaction of the magnetic field generated by the loop with nearby metal
mobile audio frequency induction loop driver: equipment normally installed in a vehicle (bus, coach, train, etc.)
out of band emissions: emissions on a frequency or frequencies immediately outside the necessary bandwidth (10 Hz
to 9 kHz), but excluding spurious emissions
phased loop array: system of overlapping loops in which the currents are out of phase with each other used to provide
an even field strength and to limit overspill of the magnetic field
portable audio frequency induction loop driver: driver intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: load, stated by the manufacturer, to which the driver output is connected for measurement purposes
-1
reference magnetic field strength level: 0 dB reference for magnetic field strength levels, which is 400 mAm
spurious emissions: emissions on a frequency or frequencies which are outside the necessary bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
NOTE: Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and
frequency conversion products, but exclude out-of-band emissions.
telecoil: magnetic pickup coil intended to receive signals from an audio frequency induction loop system
NOTE: A telecoil can be part of a hearing aid, cochlear implant, or of any other device for receiving signals from
an audio frequency induction loop system in accordance with IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
A loop area
C correction factor
E electrical field strength
f frequency
f centre frequency in Hz
C
H magnetic field strength
Hf H-field-strength limit
H H-field strength at the centre of the frequency of interest
C
H H-field-strength limit for radiated spurious emissions
S
I audio frequency in band output current
C
ETSI
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I spurious output current
S
λ wavelength
N number of turns for a loop
P power
t time
Ω ohm
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFILS Audio Frequency Induction Loop System
NOTE: Also known as a Hearing Loop.
AMN Artificial Mains Network
CDN Coupling/Decoupling Network
CEPT Conférence Européenne des Postes et Télécommunications
EC European Community
EFTA European Free Trade Association
ERC European Radiocommunications Committee
EU European Union
EUT Equipment Under Test
ISN Impedance Stabilization Netw
...
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