SIST EN 303 348 V1.1.2:2017

HARMONISED EUROPEAN STANDARD
Induction loop systems
intended to assist the hearing impaired
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard covering the essential requirements
of article 3.2 of Directive 2014/53/EU

2 ETSI EN 303 348 V1.1.2 (2017-07)

Reference
DEN/ERM-TG17WG3-16
Keywords
harmonised standard, hearing aid, inductive
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3 ETSI EN 303 348 V1.1.2 (2017-07)
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 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Technical requirements specifications . 11
4.1 Environmental conditions . 11
4.1.1 Environmental profile . 11
4.2 General requirements . 11
4.2.1 Presentation of induction loop amplifier equipment for testing purposes . 11
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Amplifier shut-off facility . 12
4.2.5 Declarations by the manufacturer . 12
4.2.6 Auxiliary test equipment . 12
5 Testing for compliance with technical requirements . 12
5.1 Environmental conditions for testing . 12
5.1.1 General requirements . 12
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 . 13
5.1.3.3 Internal test power source . 13
5.1.3.3.1 General . 13
5.1.3.3.2 Mains voltage . 13
5.1.3.3.3 Valve-regulated lead-acid battery power sources . 13
5.1.3.3.4 Other power sources . 13
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.1 Signal input for testing . 14
5.2.2 Loop connections . 14
5.2.2.1 General . 14
5.2.2.2 Artificial loop . 14
5.2.3 Measuring receiver . 14
5.3 Induction loop amplifier . 15
5.3.1 General . 15
5.3.2 Induction loop amplifier definitions . 15
5.3.2.1 General . 15
5.3.2.2 Product Classes . 15
5.3.3 Audio frequency in band and out of band emission limits . 16
5.3.3.1 Definition . 16
5.3.3.2 Methods of measurement . 16
5.3.3.3 Limits . 17
5.3.4 Spurious domain emission limits . 17
5.3.4.1 Definition . 17
5.3.4.2 Methods of measurement . 17
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4 ETSI EN 303 348 V1.1.2 (2017-07)
5.3.4.3 Limits . 17
5.4 Induction loop receiver . 18
5.4.1 General . 18
5.4.2 Headphone output . 18
5.4.3 Induction loop receiver definitions . 18
5.4.4 Methods of measurement . 18
5.4.5 Limits . 18
5.5 Interpretation of the measurement results . 19
Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 20
Annex B (informative): Technical overview . 21
B.1 Induction loop amplifiers . 21
B.1.1 General . 21
B.1.2 Frequency response . 21
B.1.3 Field strength . 21
B.1.4 General performance criteria . 21
B.2 Induction loop receivers and test equipment . 21
B.2.1 General . 21
B.2.2 Sensitivity . 22
Annex C (normative): Measurement . 23
C.1 Standard test position to be used with internal loop equipment or equipment having a loop
connector . 23
Annex D (normative): The relationship between loop current and H-Field strength . 24
Annex E (informative): Artificial loop. 26
Annex F (normative): Induction loop amplifier emission levels and spectrum mask
measurements . 28
Annex G (informative): Determination and use of the measurement bandwidth . 29
Annex H (informative): Bibliography . 30
Annex I (informative): Change history . 31
History . 32

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5 ETSI EN 303 348 V1.1.2 (2017-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document 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.
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: 17 July 2017
Date of latest announcement of this EN (doa): 31 October 2017
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 April 2018
Date of withdrawal of any conflicting National Standard (dow): 30 April 2019

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.
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6 ETSI EN 303 348 V1.1.2 (2017-07)
Introduction
Audio Frequency Induction Loop Systems (AFILS) have 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.
The present document 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 amplifier 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.
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.
The present document has been developed in response to Directive 2014/53/EU [i.1], which 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 amplifiers and receivers for compliance with Directive 2014/53/EU [i.1].
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7 ETSI EN 303 348 V1.1.2 (2017-07)
1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop amplifiers and receivers operating from 10 Hz to 9 kHz used in audio frequency induction loop systems (AFILS).
NOTE: 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 with a built in telecoil.
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• either with an output connection(s) and dedicated loop(s) or with an internal loop(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers fixed induction loop amplifiers, mobile induction loop amplifiers and portable induction
loop amplifiers.
The present document covers the essential requirements of article 3.2 of Directive 2014/53/EU [i.1] under the
conditions identified in annex A.
2 References
2.1 Normative references
References are specific, identified by date of publication and/or edition number or version number. Only the cited
version 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 documents 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] CEPT/ERC/REC 70-03: "Relating to the use of Short Range Devices (SRD)".
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8 ETSI EN 303 348 V1.1.2 (2017-07)
[i.3] CISPR 16-2-3: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 2-3: Methods of measurement of disturbances and immunity - Radiated disturbance
measurements".
[i.4] IEC 60118-4: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid
purposes - Magnetic field strength".
[i.5] IEC 62489-1 + Amd 1: "Electroacoustics - Audio-frequency induction loop systems for assisted
hearing - Part 1: Methods of measuring and specifying the performance of system components".
[i.6] IEC 61672-1: "Electroacoustics. Sound level meters. Specifications".
[i.7] IEC 60268-10: "Sound system equipment. Methods for specifying and measuring the
characteristics of peak programme level meters".
[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] ETSI TR 100 028 (all parts) (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio
spectrum Matters (ERM); Uncertainties in the measurement of mobile radio equipment
characteristics".
[i.10] ETSI TR 100 028-2 (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio spectrum
Matters (ERM); Uncertainties in the measurement of mobile radio equipment characteristics;
Part 2".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in Directive 2014/53/EU [i.1] and the
following apply:
artificial loop: reduced size radiating dummy load equal to the nominal impedance of the loop specified by the
manufacturer
Audio Frequency Induction Loop System (AFILS): system including induction loop amplifier(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
conducted measurements: measurements that are made using a direct connection to the equipment under test
customized loop: loop built according to manufacturers' loop design rules inside tested limits
dedicated loop: removable loop supplied and type tested with the AFILS equipment, designed as an indispensable part
of the equipment
NOTE: The loop has been designed or developed for one or more specific types of equipment. It is the
combination of dedicated loop and induction loop amplifier that is expected to be compliant with the
regulations.
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: See AFILS.
in band emissions: emissions on a frequency or frequencies which are inside the occupied bandwidth (10 Hz to 9 kHz)
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9 ETSI EN 303 348 V1.1.2 (2017-07)
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 amplifier: audio amplifier 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.
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.
magnetic dipole moment: product of (Number of loop turns) × (loop area) × (loop current)
NOTE: Air loops only.
magnetic field strength level meter: instrument designed to measure magnetic field strength of audio frequency
magnetic fields
NOTE: Two types are in common use; a peak-programme meter (PPM) type having dynamic characteristics
similar to those of the Type II meter as specified in IEC 60268-10 [i.7], and a true rms meter type that
incorporates a true rms rectifier, and meets the relevant requirements for a Class 2 sound level meter as
specified in IEC 61672-1 [i.6]. Full functional specifications for both types of meter can be found in
IEC 60118-4 [i.4].
mobile amplifier: equipment normally installed in a vehicle
out of band emissions: emissions on a frequency or frequencies which are outside the occupied bandwidth (10 Hz to
9 kHz), but for which the levels are in transition to a frequency where the level may be reduced without affecting the
corresponding transmission of information
phased loop array: system of overlapping loops in which the currents are out of phase with each other
portable amplifier: amplifier intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: the load, stated by the manufacturer, to which the amplifier 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 occupied bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
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].
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10 ETSI EN 303 348 V1.1.2 (2017-07)
type designation: manufacturers' marking of the equipment
useful magnetic field volume: volume within which the AFILS provides a hearing-aid user with a signal of acceptable
quality
NOTE: See IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
Ω ohm
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 baseband output current
C
I spurious output current
S
λ wavelength
m magnetic dipole moment
N number of turns for a loop
P power
t time
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFILS Audio Frequency Induction Loop System, also known as a Hearing Loop
AMN Artificial Mains Network
CDN Coupling/Decoupling Network
CEPT Conférence Européenne des Postes et Télécommunications
CISPR Comité International Spécial des Perturbations Radioélectriques
EC European Community
EFTA European Free Trade Area
EMC ElectroMagnetic Compatibility
ERC European Radiocommunications Committee
EU European Union
ISN Impedance Stabilization Network
LISN Line Impedance Stabilization Network
OOB Out Of Band
RF Radio Frequency
RFID Radio Frequency Identification Device
rms root mean square
SRD Short Range Device
THD Total Harmonic Distortion
TR Technical Report
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11 ETSI EN 303 348 V1.1.2 (2017-07)
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 declared by the manufacturer. The equipment shall comply with all the technical
requirements of the present document which are identified as applicable in annex A at all times when operating within
the boundary limits of the declared operational environmental profile.
4.2 General requirements
4.2.1 Presentation of induction loop amplifier equipment for testing
purposes
Each equipment submitted for testing shall fulfil the requirements of the present document when operated as intended.
The manufacturer shall declare the range of operating conditions and power requirements to establish the appropriate
test conditions.
Additionally, technical documentation and operating manuals sufficient to make the test shall be supplied.
For equipment supplied without an internal induction loop, i.e. Product Class 2 defined in clause 5.3.2.2, the
manufacturer shall supply an artificial loop as defined in clause 5.2.2.1.
In the case of equipment supplied with an internal induction loop, i.e. Product Class 1 equipment as defined in
clause 5.3.2.2, it is permissible to supply a sample of the equipment with a temporary connector to facilitate testing.
This shall be used to provide a method to monitor the loop current, or at the manufacturer's discretion, to use an
artificial loop.
The means to access and/or implement the internal permanent or temporary loop connector shall be stated by the
manufacturer with the aid of a diagram. The fact that use has been made of the internal loop connection, or of a
temporary connection to facilitate measurements, shall be recorded in the test report. Such ports shall not affect the
performance of the equipment.
If equipment is designed to operate with different radiated field strengths or power levels, measurement of each
parameter shall be performed on samples of equipment as defined in clause 4.2.2.
4.2.2 Choice of model for testing
Stand-alone equipment shall be supplied by the manufacturer complete with any ancillary equipment needed for testing.
If an equipment has optional features, considered not to affect the RF parameters, then the tests need only to be
performed on the equipment configured with that combination of features considered to be the most complex, as
declared by the manufacturer.
Equipment offered for test shall provide an output connector for conducted RF measurements. For equipment with an
internal loop, this can be a modification for the tests.
The performance of the equipment submitted for testing shall be representative of the performance of the corresponding
production model.
4.2.3 Controls
Controls that may need to be adjusted after installation such as input gain, loop drive, bass, treble, tone or "metal
compensation" may be provided. However, any controls that might increase the interfering potential of the equipment,
if misadjusted, shall not be easily accessible to the user.
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12 ETSI EN 303 348 V1.1.2 (2017-07)
4.2.4 Amplifier shut-off facility
If the amplifier is equipped with an automatic shut-off facility (such as a time-out device, over or under temperature,
voltage or current, etc.) it should be made inoperative for the duration of the test, or be monitored to ensure that the
shut-off facility is not activated during the test.
4.2.5 Declarations by the manufacturer
When submitting equipment for test, the manufacturer shall declare any necessary information which may be required
by an external laboratory.
4.2.6 Auxiliary test equipment
All necessary test signal sources and set-up information shall accompany the equipment when it is submitted for testing
and shall be included in the test report.
5 Testing for compliance with technical requirements
5.1 Environmental conditions for testing
5.1.1 General requirements
Where technical performance varies subject to environmental conditions, tests shall be carried out under a sufficient
variety of environmental conditions (within the boundary limits of the declared operational environmental profile) to
give confidence of compliance for the affected technical requirements.
5.1.2 Normal temperature and humidity
The normal temperature and humidity conditions for tests shall be any convenient combination of temperature and
humidity within the following ranges:
• temperature +15 °C to +35 °C;
• relative humidity 20 % to 75 %.
When it is impracticable to carry out tests under these conditions, a note to this effect, stating the ambient temperature
and relative humidity during the tests, shall be added to the test report.
5.1.3 Test power source
5.1.3.1 General requirements
The equipment shall be tested using the external test power source specified in clause 5.1.3.2 and/or the internal test
power source specified in clause 5.1.3.2. Where equipment can be powered using either external or internal power
sources, then the equipment shall be tested using the external power source specified in clause 5.1.3.2 then repeated
using the internal power source specified in clause 5.1.3.3.
The test power source used shall be stated in the test report.
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13 ETSI EN 303 348 V1.1.2 (2017-07)
5.1.3.2 External test power source
During tests, the power source of the equipment shall be replaced by an external test power source capable of producing
the test voltage specified in clause 5.1.3.3. The internal impedance of the external test power source shall be low enough
for its effect on the test results to be negligible. For the purpose of the tests, the voltage of the external test power source
shall be measured at the input terminals of the equipment. The external test power source shall be suitably de-coupled
(including the use of ferrite beads, inductors, chokes, de-coupling capacitors or networks as required by specific test
methods e.g. AMN, ISN, LISN, CDN, etc.) as close to the equipment input power terminals as practicable.
During tests the test power source voltages shall be within a tolerance of < ±1 % relative to the voltage at the beginning
of each test.
Where it can be shown that internal regulation of power supply rails or output regulation is employed (such as in a
constant-current output design) in such a way as to negate the effects of such power supply variations or fluctuations,
then this tolerance may be relaxed to ± 5 % of nominal and RF emission tests shall be performed at the nominal voltage
only.
5.1.3.3 Internal test power source
5.1.3.3.1 General
Where equipment is designed to operate from an internal power source, for conducted measurements or where a test
fixture is used, an external power supply at the required voltage may replace the supplied or recommended internal
batteries. Use of this shall be stated on the test report.
5.1.3.3.2 Mains voltage
The normal test voltage for equipment to be connected to the mains shall be the nominal mains voltage. For the purpose
of the present document, the nominal voltage shall be the declared voltage, or any of the declared voltages for which the
equipment was designed.
The frequency of the test power source corresponding to the a.c. mains shall be ± 1 Hz of the mains frequency specified
by the manufacturer.
5.1.3.3.3 Valve-regulated lead-acid battery power sources
When the equipment is intended for operation from valve-regulated lead-acid battery power source, the normal test
voltage shall be 1,1 multiplied by the nominal voltage of the battery (e.g. 6 V, 12 V, etc.).
5.1.3.3.4 Other power sources
For operation from other power sources or types of battery (primary or secondary), the normal test voltage shall be that
declared by the manufacturer. Such values shall be stated in the test report.
5.2 General conditions
5.2.1 Normal test signals
For equipment without a connector for an external audio input (i.e. with only an internal microphone), a connector shall
be added to allow testing. This shall be stated in the test report.
The normal test signal is specified as follows:
• 1 kHz sinusoidal tone
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14 ETSI EN 303 348 V1.1.2 (2017-07)
5.2.1.1 Signal input for testing
For the purpose of the measurements with and without an input test signal, there should preferably be a facility to
energize the induction loop amplifier with or without an input signal source. The manufacturer shall describe the
method of achieving this in the documentation and it shall be recorded in the test report. It may involve temporary
internal modifications of the equipment under test.
For the purpose of testing, the normal test signal, see clause 5.2.1, shall be applied to the input of the induction loop
amplifier under test with the normal input device(s) disconnected (e.g. microphone or other audio equipment).
Any 'standby' amplifier modes should be disabled for the duration of test so that the amplifier is not asleep when no
signal is present for long periods.
5.2.2 Loop connections
5.2.2.1 General
For equipment supplied without an internal loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall
supply an artificial loop (reduced radiating load).
For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, the
manufacturer may decide to use the existing internal loop and provide a method to monitor the loop current, or use an
artificial loop. The actual method used shall be stated within the test report.
NOTE: Typical loop impedances are described in IEC 62489-1 [i.5], annex B.
5.2.2.2 Artificial loop
For measurements of induction loop amplifiers (see clause 4.2.1), an artificial loop (reduced radiating load) connected
to the loop output connectors, shall be used as agreed with the test laboratory.
The impedance shall be equal to the nominal load of the equipment specified by the manufacturer.
This method facilitates conducted measurements to be made of the following:
• induction loop amplifier loop in band currents from 10 Hz to 9 kHz;
• induction loop amplifier loop out of band currents from > 9 kHz to 20 kHz; and
• induction loop amplifier spurious loop currents from > 20 kHz to 1 MHz.
A description of the artificial loop shall be stated in the test report.
For equipment supplied with an internal loop, the manufacturer may decide to use the internal loop as the load and
provide a suitable method to monitor the loop current, or use an artificial loop. The actual method used shall be stated
within the test report.
Annex E describes a suitable method of assembling an artificial loop.
5.2.3 Measuring receiver
The term "measuring receiver" refers to a selective voltmeter, spectrum analyser or receiver used in the process of
testing the equipment under test to the appropriate emission limits. The bandwidth and detector type of the measuring
receiver are given in table 1.
Table 1
Frequency Detector type Measurement receiver bandwidth Spectrum analyser bandwidth
rms 200 Hz 300 Hz
9 kHz ≤ f < 150 kHz
rms 9 kHz 10 kHz
150 kHz ≤ f < 1 MHz
If different bandwidths are used, follow the guidance in annex G and record this in the test report.
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15 ETSI EN 303 348 V1.1.2 (2017-07)
5.3 Induction loop amplifier
5.3.1 General
To meet the requirements of the present document, the induction loop amplifier shall be measured whilst operated at the
maximum rated continuous average output level for the load under test, as declared by the manufacturer, with any tone
controls set to a flat response.
When making tests on equipment designed for intermittent operation, the duty cycle of the equipment, as declared by
the manufacturer, shall not be exceeded. The actual duty cycle used shall be stated on the test report.
For equipment supplied without a loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall supply a
reduced radiating load (artificial loop) which is to be used for all tests.
For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, the
manufacturer may decide to use the existing internal loop and provide a method to monitor the loop current, or use an
artificial loop for conducted emission measurements below 1 MHz. The actual method used shall be stated within the
test report.
5.3.2 Induction loop amplifier definitions
5.3.2.1 General
Induction loop amplifiers are divided into Product Classes (see clause 5.3.2.2) depending on the loop type to be used.
Class 1 equipment is provided with an internal loop, whereas Class 2 equipment provides an external connection and
may allow the customer to use his own loop design based on the manufacturer's design guidelines. AFILS
manufacturers will provide written guidance and design tools, or both, to aid with practical and compliant loop design.
5.3.2.2 Product Classes
The equipment is divided into Product Classes depending on the induction loop type used.
The Product Classes according to table 2 are:
Product Class 1:
Induction loop amplifier supplied with an internal loop.
The following restrictions apply to this product class:
- no customization of the internal loop(s) is allowed in the field (or by the end user); and
- the internal loop area shall be < 4 m .
The audio frequency baseband output and spurious emissions are limited by the maxi
...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Induction loop systems intended to assist the hearing impaired in the frequency range 10 Hz to 9 kHz - Harmonised Standard covering the essential requirements of article 3.2 of the Directive 2014/53/EU33.020Telekomunikacije na splošnoTelecommunications in general11.180.15Aids for deaf and hearing impaired peopleICS:Ta slovenski standard je istoveten z:ETSI EN 303 348 V1.1.2 (2017-07)SIST EN 303 348 V1.1.2:2017en01-september-2017SIST EN 303 348 V1.1.2:2017SLOVENSKI
STANDARD
HARMONISED EUROPEAN STANDARD SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 2
Reference DEN/ERM-TG17WG3-16 Keywords harmonised standard, hearing aid, inductive ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00
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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 only prevailing document is the print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat. 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 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.
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DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. oneM2M logo is protected for the benefit of its Members GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 3 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 Definitions, symbols and abbreviations . 8 3.1 Definitions . 8 3.2 Symbols . 10 3.3 Abbreviations . 10 4 Technical requirements specifications . 11 4.1 Environmental conditions . 11 4.1.1 Environmental profile . 11 4.2 General requirements . 11 4.2.1 Presentation of induction loop amplifier equipment for testing purposes . 11 4.2.2 Choice of model for testing . 11 4.2.3 Controls . 11 4.2.4 Amplifier shut-off facility . 12 4.2.5 Declarations by the manufacturer . 12 4.2.6 Auxiliary test equipment . 12 5 Testing for compliance with technical requirements . 12 5.1 Environmental conditions for testing . 12 5.1.1 General requirements . 12 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 . 13 5.1.3.3 Internal test power source . 13 5.1.3.3.1 General . 13 5.1.3.3.2 Mains voltage . 13 5.1.3.3.3 Valve-regulated lead-acid battery power sources . 13 5.1.3.3.4 Other power sources . 13 5.2 General conditions . 13 5.2.1 Normal test signals. 13 5.2.1.1 Signal input for testing . 14 5.2.2 Loop connections . 14 5.2.2.1 General . 14 5.2.2.2 Artificial loop . 14 5.2.3 Measuring receiver . 14 5.3 Induction loop amplifier . 15 5.3.1 General . 15 5.3.2 Induction loop amplifier definitions . 15 5.3.2.1 General . 15 5.3.2.2 Product Classes . 15 5.3.3 Audio frequency in band and out of band emission limits . 16 5.3.3.1 Definition . 16 5.3.3.2 Methods of measurement . 16 5.3.3.3 Limits . 17 5.3.4 Spurious domain emission limits . 17 5.3.4.1 Definition . 17 5.3.4.2 Methods of measurement . 17 SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 4 5.3.4.3 Limits . 17 5.4 Induction loop receiver . 18 5.4.1 General . 18 5.4.2 Headphone output . 18 5.4.3 Induction loop receiver definitions . 18 5.4.4 Methods of measurement . 18 5.4.5 Limits . 18 5.5 Interpretation of the measurement results . 19 Annex A (informative): Relationship between the present document and the essential requirements of Directive 2014/53/EU . 20 Annex B (informative): Technical overview . 21 B.1 Induction loop amplifiers . 21 B.1.1 General . 21 B.1.2 Frequency response . 21 B.1.3 Field strength . 21 B.1.4 General performance criteria . 21 B.2 Induction loop receivers and test equipment . 21 B.2.1 General . 21 B.2.2 Sensitivity . 22 Annex C (normative): Measurement . 23 C.1 Standard test position to be used with internal loop equipment or equipment having a loop connector . 23 Annex D (normative): The relationship between loop current and H-Field strength . 24 Annex E (informative): Artificial loop. 26 Annex F (normative): Induction loop amplifier emission levels and spectrum mask measurements . 28 Annex G (informative): Determination and use of the measurement bandwidth . 29 Annex H (informative): Bibliography . 30 Annex I (informative): Change history . 31 History . 32
ETSI ETSI EN 303 348 V1.1.2 (2017-07) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document 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. 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: 17 July 2017 Date of latest announcement of this EN (doa): 31 October 2017 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
30 April 2018 Date of withdrawal of any conflicting National Standard (dow): 30 April 2019
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. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 6 Introduction Audio Frequency Induction Loop Systems (AFILS) have 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. The present document 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 amplifier 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.
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. The present document has been developed in response to Directive 2014/53/EU [i.1], which 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 amplifiers and receivers for compliance with Directive 2014/53/EU [i.1]. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 7 1 Scope The present document specifies technical characteristics and methods of measurements for audio frequency induction loop amplifiers and receivers operating from 10 Hz to 9 kHz used in audio frequency induction loop systems (AFILS). NOTE: 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 with a built in telecoil. These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range: • either with an output connection(s) and dedicated loop(s) or with an internal loop(s); • for audio frequency baseband transmission (un-modulated and without the use of a carrier). The present document covers fixed induction loop amplifiers, mobile induction loop amplifiers and portable induction loop amplifiers.
The present document covers the essential requirements of article 3.2 of Directive 2014/53/EU [i.1] under the conditions identified in annex A. 2 References 2.1 Normative references References are specific, identified by date of publication and/or edition number or version number. Only the cited version 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 documents 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] CEPT/ERC/REC 70-03: "Relating to the use of Short Range Devices (SRD)". SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 8 [i.3] CISPR 16-2-3: "Specification for radio disturbance and immunity measuring apparatus and methods - Part 2-3: Methods of measurement of disturbances and immunity - Radiated disturbance measurements". [i.4] IEC 60118-4: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid purposes - Magnetic field strength". [i.5] IEC 62489-1 + Amd 1: "Electroacoustics - Audio-frequency induction loop systems for assisted hearing - Part 1: Methods of measuring and specifying the performance of system components". [i.6] IEC 61672-1: "Electroacoustics. Sound level meters. Specifications". [i.7] IEC 60268-10: "Sound system equipment. Methods for specifying and measuring the characteristics of peak programme level meters". [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] ETSI TR 100 028 (all parts) (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Uncertainties in the measurement of mobile radio equipment characteristics". [i.10] ETSI TR 100 028-2 (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Uncertainties in the measurement of mobile radio equipment characteristics; Part 2". 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in Directive 2014/53/EU [i.1] and the following apply: artificial loop: reduced size radiating dummy load equal to the nominal impedance of the loop specified by the manufacturer Audio Frequency Induction Loop System (AFILS): system including induction loop amplifier(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 conducted measurements: measurements that are made using a direct connection to the equipment under test customized loop: loop built according to manufacturers' loop design rules inside tested limits dedicated loop: removable loop supplied and type tested with the AFILS equipment, designed as an indispensable part of the equipment NOTE: The loop has been designed or developed for one or more specific types of equipment. It is the combination of dedicated loop and induction loop amplifier that is expected to be compliant with the regulations. 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: See AFILS. in band emissions: emissions on a frequency or frequencies which are inside the occupied bandwidth (10 Hz to 9 kHz) SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 9 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 amplifier: audio amplifier 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. 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. magnetic dipole moment: product of (Number of loop turns) × (loop area) × (loop current) NOTE: Air loops only. magnetic field strength level meter: instrument designed to measure magnetic field strength of audio frequency magnetic fields NOTE: Two types are in common use; a peak-programme meter (PPM) type having dynamic characteristics similar to those of the Type II meter as specified in IEC 60268-10 [i.7], and a true rms meter type that incorporates a true rms rectifier, and meets the relevant requirements for a Class 2 sound level meter as specified in IEC 61672-1 [i.6]. Full functional specifications for both types of meter can be found in IEC 60118-4 [i.4]. mobile amplifier: equipment normally installed in a vehicle out of band emissions: emissions on a frequency or frequencies which are outside the occupied bandwidth (10 Hz to 9 kHz), but for which the levels are in transition to a frequency where the level may be reduced without affecting the corresponding transmission of information phased loop array: system of overlapping loops in which the currents are out of phase with each other portable amplifier: amplifier intended to be carried or attached radiated measurements: measurements which involve the absolute measurement of a radiated field rated load: the load, stated by the manufacturer, to which the amplifier output is connected for measurement purposes reference magnetic field strength level: 0 dB reference for magnetic field strength levels, which is 400 mAm-1 spurious emissions: emissions on a frequency or frequencies which are outside the occupied bandwidth (10 Hz to 9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information 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]. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 10 type designation: manufacturers' marking of the equipment useful magnetic field volume: volume within which the AFILS provides a hearing-aid user with a signal of acceptable quality NOTE: See IEC 60118-4 [i.4]. 3.2 Symbols For the purposes of the present document, the following symbols apply: Ω ohm A loop area C correction factor E electrical field strength f frequency fC centre frequency in Hz H magnetic field strength Hf H-field-strength limit HC H-field strength at the centre of the frequency of interest HS H-field-strength limit for radiated spurious emissions IC audio frequency baseband output current IS spurious output current λ wavelength m magnetic dipole moment N number of turns for a loop P power t time 3.3 Abbreviations For the purposes of the present document, the following abbreviations apply: AFILS Audio Frequency Induction Loop System, also known as a Hearing Loop AMN Artificial Mains Network CDN Coupling/Decoupling Network CEPT Conférence Européenne des Postes et Télécommunications CISPR Comité International Spécial des Perturbations Radioélectriques EC European Community EFTA European Free Trade Area EMC ElectroMagnetic Compatibility ERC European Radiocommunications Committee EU European Union ISN Impedance Stabilization Network LISN Line Impedance Stabilization Network OOB Out Of Band RF Radio Frequency RFID Radio Frequency Identification Device rms root mean square SRD Short Range Device THD Total Harmonic Distortion TR Technical Report SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 11 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 declared by the manufacturer. The equipment shall comply with all the technical requirements of the present document which are identified as applicable in annex A at all times when operating within the boundary limits of the declared operational environmental profile. 4.2 General requirements 4.2.1 Presentation of induction loop amplifier equipment for testing purposes Each equipment submitted for testing shall fulfil the requirements of the present document when operated as intended. The manufacturer shall declare the range of operating conditions and power requirements to establish the appropriate test conditions. Additionally, technical documentation and operating manuals sufficient to make the test shall be supplied. For equipment supplied without an internal induction loop, i.e. Product Class 2 defined in clause 5.3.2.2, the manufacturer shall supply an artificial loop as defined in clause 5.2.2.1. In the case of equipment supplied with an internal induction loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, it is permissible to supply a sample of the equipment with a temporary connector to facilitate testing. This shall be used to provide a method to monitor the loop current, or at the manufacturer's discretion, to use an artificial loop.
The means to access and/or implement the internal permanent or temporary loop connector shall be stated by the manufacturer with the aid of a diagram. The fact that use has been made of the internal loop connection, or of a temporary connection to facilitate measurements, shall be recorded in the test report. Such ports shall not affect the performance of the equipment. If equipment is designed to operate with different radiated field strengths or power levels, measurement of each parameter shall be performed on samples of equipment as defined in clause 4.2.2. 4.2.2 Choice of model for testing Stand-alone equipment shall be supplied by the manufacturer complete with any ancillary equipment needed for testing. If an equipment has optional features, considered not to affect the RF parameters, then the tests need only to be performed on the equipment configured with that combination of features considered to be the most complex, as declared by the manufacturer. Equipment offered for test shall provide an output connector for conducted RF measurements. For equipment with an internal loop, this can be a modification for the tests. The performance of the equipment submitted for testing shall be representative of the performance of the corresponding production model. 4.2.3 Controls Controls that may need to be adjusted after installation such as input gain, loop drive, bass, treble, tone or "metal compensation" may be provided. However, any controls that might increase the interfering potential of the equipment, if misadjusted, shall not be easily accessible to the user.
ETSI ETSI EN 303 348 V1.1.2 (2017-07) 12 4.2.4 Amplifier shut-off facility If the amplifier is equipped with an automatic shut-off facility (such as a time-out device, over or under temperature, voltage or current, etc.) it should be made inoperative for the duration of the test, or be monitored to ensure that the shut-off facility is not activated during the test. 4.2.5 Declarations by the manufacturer When submitting equipment for test, the manufacturer shall declare any necessary information which may be required by an external laboratory. 4.2.6 Auxiliary test equipment All necessary test signal sources and set-up information shall accompany the equipment when it is submitted for testing and shall be included in the test report. 5 Testing for compliance with technical requirements 5.1 Environmental conditions for testing 5.1.1 General requirements Where technical performance varies subject to environmental conditions, tests shall be carried out under a sufficient variety of environmental conditions (within the boundary limits of the declared operational environmental profile) to give confidence of compliance for the affected technical requirements. 5.1.2 Normal temperature and humidity The normal temperature and humidity conditions for tests shall be any convenient combination of temperature and humidity within the following ranges: • temperature +15 °C to +35 °C; • relative humidity 20 % to 75 %. When it is impracticable to carry out tests under these conditions, a note to this effect, stating the ambient temperature and relative humidity during the tests, shall be added to the test report. 5.1.3 Test power source 5.1.3.1 General requirements The equipment shall be tested using the external test power source specified in clause 5.1.3.2 and/or the internal test power source specified in clause 5.1.3.2. Where equipment can be powered using either external or internal power sources, then the equipment shall be tested using the external power source specified in clause 5.1.3.2 then repeated using the internal power source specified in clause 5.1.3.3. The test power source used shall be stated in the test report. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 13 5.1.3.2 External test power source During tests, the power source of the equipment shall be replaced by an external test power source capable of producing the test voltage specified in clause 5.1.3.3. The internal impedance of the external test power source shall be low enough for its effect on the test results to be negligible. For the purpose of the tests, the voltage of the external test power source shall be measured at the input terminals of the equipment. The external test power source shall be suitably de-coupled (including the use of ferrite beads, inductors, chokes, de-coupling capacitors or networks as required by specific test methods e.g. AMN, ISN, LISN, CDN, etc.) as close to the equipment input power terminals as practicable.
During tests the test power source voltages shall be within a tolerance of < ±1 % relative to the voltage at the beginning of each test. Where it can be shown that internal regulation of power supply rails or output regulation is employed (such as in a constant-current output design) in such a way as to negate the effects of such power supply variations or fluctuations, then this tolerance may be relaxed to ± 5 % of nominal and RF emission tests shall be performed at the nominal voltage only. 5.1.3.3 Internal test power source 5.1.3.3.1 General Where equipment is designed to operate from an internal power source, for conducted measurements or where a test fixture is used, an external power supply at the required voltage may replace the supplied or recommended internal batteries. Use of this shall be stated on the test report. 5.1.3.3.2 Mains voltage The normal test voltage for equipment to be connected to the mains shall be the nominal mains voltage. For the purpose of the present document, the nominal voltage shall be the declared voltage, or any of the declared voltages for which the equipment was designed. The frequency of the test power source corresponding to the a.c. mains shall be ± 1 Hz of the mains frequency specified by the manufacturer. 5.1.3.3.3 Valve-regulated lead-acid battery power sources When the equipment is intended for operation from valve-regulated lead-acid battery power source, the normal test voltage shall be 1,1 multiplied by the nominal voltage of the battery (e.g. 6 V, 12 V, etc.). 5.1.3.3.4 Other power sources For operation from other power sources or types of battery (primary or secondary), the normal test voltage shall be that declared by the manufacturer. Such values shall be stated in the test report. 5.2 General conditions 5.2.1 Normal test signals For equipment without a connector for an external audio input (i.e. with only an internal microphone), a connector shall be added to allow testing. This shall be stated in the test report. The normal test signal is specified as follows: • 1 kHz sinusoidal tone SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 14 5.2.1.1 Signal input for testing For the purpose of the measurements with and without an input test signal, there should preferably be a facility to energize the induction loop amplifier with or without an input signal source. The manufacturer shall describe the method of achieving this in the documentation and it shall be recorded in the test report. It may involve temporary internal modifications of the equipment under test. For the purpose of testing, the normal test signal, see clause 5.2.1, shall be applied to the input of the induction loop amplifier under test with the normal input device(s) disconnected (e.g. microphone or other audio equipment). Any 'standby' amplifier modes should be disabled for the duration of test so that the amplifier is not asleep when no signal is present for long periods. 5.2.2 Loop connections 5.2.2.1 General For equipment supplied without an internal loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall supply an artificial loop (reduced radiating load). For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, the manufacturer may decide to use the existing internal loop and provide a method to monitor the loop current, or use an artificial loop. The actual method used shall be stated within the test report. NOTE: Typical loop impedances are described in IEC 62489-1 [i.5], annex B. 5.2.2.2 Artificial loop For measurements of induction loop amplifiers (see clause 4.2.1), an artificial loop (reduced radiating load) connected to the loop output connectors, shall be used as agreed with the test laboratory. The impedance shall be equal to the nominal load of the equipment specified by the manufacturer. This method facilitates conducted measurements to be made of the following: • induction loop amplifier loop in band currents from 10 Hz to 9 kHz; • induction loop amplifier loop out of band currents from > 9 kHz to 20 kHz; and • induction loop amplifier spurious loop currents from > 20 kHz to 1 MHz. A description of the artificial loop shall be stated in the test report. For equipment supplied with an internal loop, the manufacturer may decide to use the internal loop as the load and provide a suitable method to monitor the loop current, or use an artificial loop. The actual method used shall be stated within the test report. Annex E describes a suitable method of assembling an artificial loop. 5.2.3 Measuring receiver The term "measuring receiver" refers to a selective voltmeter, spectrum analyser or receiver used in the process of testing the equipment under test to the appropriate emission limits. The bandwidth and detector type of the measuring receiver are given in table 1. Table 1 Frequency Detector type Measurement receiver bandwidth Spectrum analyser bandwidth 9 kHz ≤ f < 150 kHz rms 200 Hz 300 Hz 150 kHz ≤ f < 1 MHz rms 9 kHz 10 kHz
If different bandwidths are used, follow the guidance in annex G and record this in the test report. SIST EN 303 348 V1.1.2:2017

ETSI ETSI EN 303 348 V1.1.2 (2017-07) 15 5.3 Induction loop amplifier 5.3.1 General To meet the requirements of the present document, the induction loop amplifier shall be measured whilst operated at the maximum rated continuous average output level for the load under test, as declared by the manufacturer, with any tone controls set to a flat response. When making tests on equipment designed for intermittent operation, the duty cycle of the equipment, as declared by the manufacturer, shall not be exceeded. The actual duty cycle used shall be stated on the test report. For equipment supplied without a loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall supply a reduced radiating load (artificial loop) which is to be used for all tests. For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, the manufacturer may decide to use the existing internal loop and provide a method to monitor the loop current, or use an artificial loop for conducted emission measurements below 1 MHz. The actual method used shall be stated within the test report. 5.3.2 Induction loop amplifier definitions 5.3.2.1 General Induction loop amplifiers are divided into Product Classes (see clause 5.3.2.2) depending on the loop type to be used. Class 1 equipment is provided with an internal loop, whereas Class 2 equipment provides an external connection and may allow the customer to use his own loop design based on the manufacturer's design guidelines. AFILS manufacturers will provide written guidance and design tools, or both, to aid with practical and compliant loop design. 5.3.2.2 Product Classes The equipment is divided into Product Classes depending on the induction loop type used. The Product Classes according to table 2 are: Product Class 1:
Induction loop amplifier supplied with an internal loop.
The following restrictions apply to this product class: - no customization of the internal loop(s) is allowed in the field (or by the end user); and - the internal loop area shall be < 4 m2.
The audio frequency baseband output and spurious emissions are limited by the maximum output loop current multiplied by the loop area, and number of turns as described in annex E and clause 5.3.4.2 and shall comply with the equivalent radiated H-field limits given in clause 5.3.4.2 and clause 5.3.4.3.
Where a manufacturer provides a range of standard internal loops, the equipment shall be tested as Product Class 1. Either each of t
...

SLOVENSKI STANDARD
01-september-2017
Sistemi z indukcijsko zanko v frekvenčnem območju od 10 Hz do 9 kHz za pomoč
slušno prizadetim - Harmonizirani standard, ki zajema bistvene zahteve člena 3.2
direktive 2014/53/EU
Induction loop systems intended to assist the hearing impaired in the frequency range 10
Hz to 9 kHz - Harmonised Standard covering the essential requirements of article 3.2 of
the Directive 2014/53/EU
Ta slovenski standard je istoveten z: ETSI EN 303 348 V1.1.2 (2017-07)
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

HARMONISED EUROPEAN STANDARD
Induction loop systems
intended to assist the hearing impaired
in the frequency range 10 Hz to 9 kHz;
Harmonised Standard covering the essential requirements
of article 3.2 of Directive 2014/53/EU

2 ETSI EN 303 348 V1.1.2 (2017-07)

Reference
DEN/ERM-TG17WG3-16
Keywords
harmonised standard, hearing aid, inductive
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ETSI
3 ETSI EN 303 348 V1.1.2 (2017-07)
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 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Technical requirements specifications . 11
4.1 Environmental conditions . 11
4.1.1 Environmental profile . 11
4.2 General requirements . 11
4.2.1 Presentation of induction loop amplifier equipment for testing purposes . 11
4.2.2 Choice of model for testing . 11
4.2.3 Controls . 11
4.2.4 Amplifier shut-off facility . 12
4.2.5 Declarations by the manufacturer . 12
4.2.6 Auxiliary test equipment . 12
5 Testing for compliance with technical requirements . 12
5.1 Environmental conditions for testing . 12
5.1.1 General requirements . 12
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 . 13
5.1.3.3 Internal test power source . 13
5.1.3.3.1 General . 13
5.1.3.3.2 Mains voltage . 13
5.1.3.3.3 Valve-regulated lead-acid battery power sources . 13
5.1.3.3.4 Other power sources . 13
5.2 General conditions . 13
5.2.1 Normal test signals. 13
5.2.1.1 Signal input for testing . 14
5.2.2 Loop connections . 14
5.2.2.1 General . 14
5.2.2.2 Artificial loop . 14
5.2.3 Measuring receiver . 14
5.3 Induction loop amplifier . 15
5.3.1 General . 15
5.3.2 Induction loop amplifier definitions . 15
5.3.2.1 General . 15
5.3.2.2 Product Classes . 15
5.3.3 Audio frequency in band and out of band emission limits . 16
5.3.3.1 Definition . 16
5.3.3.2 Methods of measurement . 16
5.3.3.3 Limits . 17
5.3.4 Spurious domain emission limits . 17
5.3.4.1 Definition . 17
5.3.4.2 Methods of measurement . 17
ETSI
4 ETSI EN 303 348 V1.1.2 (2017-07)
5.3.4.3 Limits . 17
5.4 Induction loop receiver . 18
5.4.1 General . 18
5.4.2 Headphone output . 18
5.4.3 Induction loop receiver definitions . 18
5.4.4 Methods of measurement . 18
5.4.5 Limits . 18
5.5 Interpretation of the measurement results . 19
Annex A (informative): Relationship between the present document and the essential
requirements of Directive 2014/53/EU . 20
Annex B (informative): Technical overview . 21
B.1 Induction loop amplifiers . 21
B.1.1 General . 21
B.1.2 Frequency response . 21
B.1.3 Field strength . 21
B.1.4 General performance criteria . 21
B.2 Induction loop receivers and test equipment . 21
B.2.1 General . 21
B.2.2 Sensitivity . 22
Annex C (normative): Measurement . 23
C.1 Standard test position to be used with internal loop equipment or equipment having a loop
connector . 23
Annex D (normative): The relationship between loop current and H-Field strength . 24
Annex E (informative): Artificial loop. 26
Annex F (normative): Induction loop amplifier emission levels and spectrum mask
measurements . 28
Annex G (informative): Determination and use of the measurement bandwidth . 29
Annex H (informative): Bibliography . 30
Annex I (informative): Change history . 31
History . 32

ETSI
5 ETSI EN 303 348 V1.1.2 (2017-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document 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.
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: 17 July 2017
Date of latest announcement of this EN (doa): 31 October 2017
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 April 2018
Date of withdrawal of any conflicting National Standard (dow): 30 April 2019

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
6 ETSI EN 303 348 V1.1.2 (2017-07)
Introduction
Audio Frequency Induction Loop Systems (AFILS) have 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.
The present document 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 amplifier 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.
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.
The present document has been developed in response to Directive 2014/53/EU [i.1], which 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 amplifiers and receivers for compliance with Directive 2014/53/EU [i.1].
ETSI
7 ETSI EN 303 348 V1.1.2 (2017-07)
1 Scope
The present document specifies technical characteristics and methods of measurements for audio frequency induction
loop amplifiers and receivers operating from 10 Hz to 9 kHz used in audio frequency induction loop systems (AFILS).
NOTE: 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 with a built in telecoil.
These radio equipment types are capable of operating in the frequency band within the 10 Hz to 9 kHz range:
• either with an output connection(s) and dedicated loop(s) or with an internal loop(s);
• for audio frequency baseband transmission (un-modulated and without the use of a carrier).
The present document covers fixed induction loop amplifiers, mobile induction loop amplifiers and portable induction
loop amplifiers.
The present document covers the essential requirements of article 3.2 of Directive 2014/53/EU [i.1] under the
conditions identified in annex A.
2 References
2.1 Normative references
References are specific, identified by date of publication and/or edition number or version number. Only the cited
version 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 documents 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] CEPT/ERC/REC 70-03: "Relating to the use of Short Range Devices (SRD)".
ETSI
8 ETSI EN 303 348 V1.1.2 (2017-07)
[i.3] CISPR 16-2-3: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 2-3: Methods of measurement of disturbances and immunity - Radiated disturbance
measurements".
[i.4] IEC 60118-4: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid
purposes - Magnetic field strength".
[i.5] IEC 62489-1 + Amd 1: "Electroacoustics - Audio-frequency induction loop systems for assisted
hearing - Part 1: Methods of measuring and specifying the performance of system components".
[i.6] IEC 61672-1: "Electroacoustics. Sound level meters. Specifications".
[i.7] IEC 60268-10: "Sound system equipment. Methods for specifying and measuring the
characteristics of peak programme level meters".
[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] ETSI TR 100 028 (all parts) (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio
spectrum Matters (ERM); Uncertainties in the measurement of mobile radio equipment
characteristics".
[i.10] ETSI TR 100 028-2 (V1.4.1) (12-2001): "Electromagnetic compatibility and Radio spectrum
Matters (ERM); Uncertainties in the measurement of mobile radio equipment characteristics;
Part 2".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in Directive 2014/53/EU [i.1] and the
following apply:
artificial loop: reduced size radiating dummy load equal to the nominal impedance of the loop specified by the
manufacturer
Audio Frequency Induction Loop System (AFILS): system including induction loop amplifier(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
conducted measurements: measurements that are made using a direct connection to the equipment under test
customized loop: loop built according to manufacturers' loop design rules inside tested limits
dedicated loop: removable loop supplied and type tested with the AFILS equipment, designed as an indispensable part
of the equipment
NOTE: The loop has been designed or developed for one or more specific types of equipment. It is the
combination of dedicated loop and induction loop amplifier that is expected to be compliant with the
regulations.
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: See AFILS.
in band emissions: emissions on a frequency or frequencies which are inside the occupied bandwidth (10 Hz to 9 kHz)
ETSI
9 ETSI EN 303 348 V1.1.2 (2017-07)
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 amplifier: audio amplifier 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.
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.
magnetic dipole moment: product of (Number of loop turns) × (loop area) × (loop current)
NOTE: Air loops only.
magnetic field strength level meter: instrument designed to measure magnetic field strength of audio frequency
magnetic fields
NOTE: Two types are in common use; a peak-programme meter (PPM) type having dynamic characteristics
similar to those of the Type II meter as specified in IEC 60268-10 [i.7], and a true rms meter type that
incorporates a true rms rectifier, and meets the relevant requirements for a Class 2 sound level meter as
specified in IEC 61672-1 [i.6]. Full functional specifications for both types of meter can be found in
IEC 60118-4 [i.4].
mobile amplifier: equipment normally installed in a vehicle
out of band emissions: emissions on a frequency or frequencies which are outside the occupied bandwidth (10 Hz to
9 kHz), but for which the levels are in transition to a frequency where the level may be reduced without affecting the
corresponding transmission of information
phased loop array: system of overlapping loops in which the currents are out of phase with each other
portable amplifier: amplifier intended to be carried or attached
radiated measurements: measurements which involve the absolute measurement of a radiated field
rated load: the load, stated by the manufacturer, to which the amplifier 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 occupied bandwidth (10 Hz to
9 kHz) and the level of which may be reduced without affecting the corresponding transmission of information
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].
ETSI
10 ETSI EN 303 348 V1.1.2 (2017-07)
type designation: manufacturers' marking of the equipment
useful magnetic field volume: volume within which the AFILS provides a hearing-aid user with a signal of acceptable
quality
NOTE: See IEC 60118-4 [i.4].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
Ω ohm
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 baseband output current
C
I spurious output current
S
λ wavelength
m magnetic dipole moment
N number of turns for a loop
P power
t time
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFILS Audio Frequency Induction Loop System, also known as a Hearing Loop
AMN Artificial Mains Network
CDN Coupling/Decoupling Network
CEPT Conférence Européenne des Postes et Télécommunications
CISPR Comité International Spécial des Perturbations Radioélectriques
EC European Community
EFTA European Free Trade Area
EMC ElectroMagnetic Compatibility
ERC European Radiocommunications Committee
EU European Union
ISN Impedance Stabilization Network
LISN Line Impedance Stabilization Network
OOB Out Of Band
RF Radio Frequency
RFID Radio Frequency Identification Device
rms root mean square
SRD Short Range Device
THD Total Harmonic Distortion
TR Technical Report
ETSI
11 ETSI EN 303 348 V1.1.2 (2017-07)
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 declared by the manufacturer. The equipment shall comply with all the technical
requirements of the present document which are identified as applicable in annex A at all times when operating within
the boundary limits of the declared operational environmental profile.
4.2 General requirements
4.2.1 Presentation of induction loop amplifier equipment for testing
purposes
Each equipment submitted for testing shall fulfil the requirements of the present document when operated as intended.
The manufacturer shall declare the range of operating conditions and power requirements to establish the appropriate
test conditions.
Additionally, technical documentation and operating manuals sufficient to make the test shall be supplied.
For equipment supplied without an internal induction loop, i.e. Product Class 2 defined in clause 5.3.2.2, the
manufacturer shall supply an artificial loop as defined in clause 5.2.2.1.
In the case of equipment supplied with an internal induction loop, i.e. Product Class 1 equipment as defined in
clause 5.3.2.2, it is permissible to supply a sample of the equipment with a temporary connector to facilitate testing.
This shall be used to provide a method to monitor the loop current, or at the manufacturer's discretion, to use an
artificial loop.
The means to access and/or implement the internal permanent or temporary loop connector shall be stated by the
manufacturer with the aid of a diagram. The fact that use has been made of the internal loop connection, or of a
temporary connection to facilitate measurements, shall be recorded in the test report. Such ports shall not affect the
performance of the equipment.
If equipment is designed to operate with different radiated field strengths or power levels, measurement of each
parameter shall be performed on samples of equipment as defined in clause 4.2.2.
4.2.2 Choice of model for testing
Stand-alone equipment shall be supplied by the manufacturer complete with any ancillary equipment needed for testing.
If an equipment has optional features, considered not to affect the RF parameters, then the tests need only to be
performed on the equipment configured with that combination of features considered to be the most complex, as
declared by the manufacturer.
Equipment offered for test shall provide an output connector for conducted RF measurements. For equipment with an
internal loop, this can be a modification for the tests.
The performance of the equipment submitted for testing shall be representative of the performance of the corresponding
production model.
4.2.3 Controls
Controls that may need to be adjusted after installation such as input gain, loop drive, bass, treble, tone or "metal
compensation" may be provided. However, any controls that might increase the interfering potential of the equipment,
if misadjusted, shall not be easily accessible to the user.
ETSI
12 ETSI EN 303 348 V1.1.2 (2017-07)
4.2.4 Amplifier shut-off facility
If the amplifier is equipped with an automatic shut-off facility (such as a time-out device, over or under temperature,
voltage or current, etc.) it should be made inoperative for the duration of the test, or be monitored to ensure that the
shut-off facility is not activated during the test.
4.2.5 Declarations by the manufacturer
When submitting equipment for test, the manufacturer shall declare any necessary information which may be required
by an external laboratory.
4.2.6 Auxiliary test equipment
All necessary test signal sources and set-up information shall accompany the equipment when it is submitted for testing
and shall be included in the test report.
5 Testing for compliance with technical requirements
5.1 Environmental conditions for testing
5.1.1 General requirements
Where technical performance varies subject to environmental conditions, tests shall be carried out under a sufficient
variety of environmental conditions (within the boundary limits of the declared operational environmental profile) to
give confidence of compliance for the affected technical requirements.
5.1.2 Normal temperature and humidity
The normal temperature and humidity conditions for tests shall be any convenient combination of temperature and
humidity within the following ranges:
• temperature +15 °C to +35 °C;
• relative humidity 20 % to 75 %.
When it is impracticable to carry out tests under these conditions, a note to this effect, stating the ambient temperature
and relative humidity during the tests, shall be added to the test report.
5.1.3 Test power source
5.1.3.1 General requirements
The equipment shall be tested using the external test power source specified in clause 5.1.3.2 and/or the internal test
power source specified in clause 5.1.3.2. Where equipment can be powered using either external or internal power
sources, then the equipment shall be tested using the external power source specified in clause 5.1.3.2 then repeated
using the internal power source specified in clause 5.1.3.3.
The test power source used shall be stated in the test report.
ETSI
13 ETSI EN 303 348 V1.1.2 (2017-07)
5.1.3.2 External test power source
During tests, the power source of the equipment shall be replaced by an external test power source capable of producing
the test voltage specified in clause 5.1.3.3. The internal impedance of the external test power source shall be low enough
for its effect on the test results to be negligible. For the purpose of the tests, the voltage of the external test power source
shall be measured at the input terminals of the equipment. The external test power source shall be suitably de-coupled
(including the use of ferrite beads, inductors, chokes, de-coupling capacitors or networks as required by specific test
methods e.g. AMN, ISN, LISN, CDN, etc.) as close to the equipment input power terminals as practicable.
During tests the test power source voltages shall be within a tolerance of < ±1 % relative to the voltage at the beginning
of each test.
Where it can be shown that internal regulation of power supply rails or output regulation is employed (such as in a
constant-current output design) in such a way as to negate the effects of such power supply variations or fluctuations,
then this tolerance may be relaxed to ± 5 % of nominal and RF emission tests shall be performed at the nominal voltage
only.
5.1.3.3 Internal test power source
5.1.3.3.1 General
Where equipment is designed to operate from an internal power source, for conducted measurements or where a test
fixture is used, an external power supply at the required voltage may replace the supplied or recommended internal
batteries. Use of this shall be stated on the test report.
5.1.3.3.2 Mains voltage
The normal test voltage for equipment to be connected to the mains shall be the nominal mains voltage. For the purpose
of the present document, the nominal voltage shall be the declared voltage, or any of the declared voltages for which the
equipment was designed.
The frequency of the test power source corresponding to the a.c. mains shall be ± 1 Hz of the mains frequency specified
by the manufacturer.
5.1.3.3.3 Valve-regulated lead-acid battery power sources
When the equipment is intended for operation from valve-regulated lead-acid battery power source, the normal test
voltage shall be 1,1 multiplied by the nominal voltage of the battery (e.g. 6 V, 12 V, etc.).
5.1.3.3.4 Other power sources
For operation from other power sources or types of battery (primary or secondary), the normal test voltage shall be that
declared by the manufacturer. Such values shall be stated in the test report.
5.2 General conditions
5.2.1 Normal test signals
For equipment without a connector for an external audio input (i.e. with only an internal microphone), a connector shall
be added to allow testing. This shall be stated in the test report.
The normal test signal is specified as follows:
• 1 kHz sinusoidal tone
ETSI
14 ETSI EN 303 348 V1.1.2 (2017-07)
5.2.1.1 Signal input for testing
For the purpose of the measurements with and without an input test signal, there should preferably be a facility to
energize the induction loop amplifier with or without an input signal source. The manufacturer shall describe the
method of achieving this in the documentation and it shall be recorded in the test report. It may involve temporary
internal modifications of the equipment under test.
For the purpose of testing, the normal test signal, see clause 5.2.1, shall be applied to the input of the induction loop
amplifier under test with the normal input device(s) disconnected (e.g. microphone or other audio equipment).
Any 'standby' amplifier modes should be disabled for the duration of test so that the amplifier is not asleep when no
signal is present for long periods.
5.2.2 Loop connections
5.2.2.1 General
For equipment supplied without an internal loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall
supply an artificial loop (reduced radiating load).
For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 5.3.2.2, the
manufacturer may decide to use the existing internal loop and provide a method to monitor the loop current, or use an
artificial loop. The actual method used shall be stated within the test report.
NOTE: Typical loop impedances are described in IEC 62489-1 [i.5], annex B.
5.2.2.2 Artificial loop
For measurements of induction loop amplifiers (see clause 4.2.1), an artificial loop (reduced radiating load) connected
to the loop output connectors, shall be used as agreed with the test laboratory.
The impedance shall be equal to the nominal load of the equipment specified by the manufacturer.
This method facilitates conducted measurements to be made of the following:
• induction loop amplifier loop in band currents from 10 Hz to 9 kHz;
• induction loop amplifier loop out of band currents from > 9 kHz to 20 kHz; and
• induction loop amplifier spurious loop currents from > 20 kHz to 1 MHz.
A description of the artificial loop shall be stated in the test report.
For equipment supplied with an internal loop, the manufacturer may decide to use the internal loop as the load and
provide a suitable method to monitor the loop current, or use an artificial loop. The actual method used shall be stated
within the test report.
Annex E describes a suitable method of assembling an artificial loop.
5.2.3 Measuring receiver
The term "measuring receiver" refers to a selective voltmeter, spectrum analyser or receiver used in the process of
testing the equipment under test to the appropriate emission limits. The bandwidth and detector type of the measuring
receiver are given in table 1.
Table 1
Frequency Detector type Measurement receiver bandwidth Spectrum analyser bandwidth
rms 200 Hz 300 Hz
9 kHz ≤ f < 150 kHz
rms 9 kHz 10 kHz
150 kHz ≤ f < 1 MHz
If different bandwidths are used, follow the guidance in annex G and record this in the test report.
ETSI
15 ETSI EN 303 348 V1.1.2 (2017-07)
5.3 Induction loop amplifier
5.3.1 General
To meet the requirements of the present document, the induction loop amplifier shall be measured whilst operated at the
maximum rated continuous average output level for the load under test, as declared by the manufacturer, with any tone
controls set to a flat response.
When making tests on equipment designed for intermittent operation, the duty cycle of the equipment, as declared by
the manufacturer, shall not be exceeded. The actual duty cycle used shall be stated on the test report.
For equipment supplied without a loop, i.e. Product Class 2 as defined in clause 5.3.2.2, the manufacturer shall supply a
reduced radiating load (artificial loop) which is to be used for all tests.
For equipm
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