EN 303 348 - V1.1.0 - Induction loop systems intended to assist the

Draft

ETSI EN 303 348

V1.1.0 (2016-02)

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

HARMONISED EUROPEAN STANDARD

ETSI

Draft ETSI EN 303 348 V1.1.0 (2016

02)

Reference

DEN/ERM-TG17WG3-16

Keywords

harmonised standard, hearing aid, inductive

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Contents

Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 5

Introduction ........................................................................................................................................................ 5

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 overview ................................................................................................................................ 11

4.1 Induction Loop Amplifiers ............................................................................................................................... 11

4.1.0 General ........................................................................................................................................................ 11

4.1.1 Frequency response..................................................................................................................................... 11

4.1.2 Field strength .............................................................................................................................................. 11

4.1.3 General performance criteria ...................................................................................................................... 11

4.2 AFILS Receivers and Test Equipment ............................................................................................................. 11

4.3 General ............................................................................................................................................................. 12

4.3.1 Presentation of induction loop amplifier equipment for testing purposes ................................................... 12

4.3.2 Choice of model for testing ........................................................................................................................ 12

4.4 Mechanical and electrical design ...................................................................................................................... 12

4.4.1 Controls ...................................................................................................................................................... 12

4.4.2 Amplifier shut-off facility ........................................................................................................................... 12

4.4.3 Marking (equipment identification) ............................................................................................................ 12

4.4.3.0 General requirements ............................................................................................................................ 12

4.4.3.1 Equipment identification ....................................................................................................................... 13

4.4.3.2 Equipment marking ............................................................................................................................... 13

4.5 Declarations by the provider ............................................................................................................................ 13

4.6 Auxiliary test equipment .................................................................................................................................. 13

4.7 Interpretation of the measurement results ........................................................................................................ 13

5 Test conditions, power sources and ambient temperatures .................................................................... 13

5.1 Normal test conditions ...................................................................................................................................... 13

5.1.0 General requirement ................................................................................................................................... 13

5.1.1 Normal temperature and humidity .............................................................................................................. 13

5.2 Test power source ............................................................................................................................................. 14

5.2.0 General requirements .................................................................................................................................. 14

5.2.1 External test power source .......................................................................................................................... 14

5.2.2 Internal test power source ........................................................................................................................... 14

5.2.2.0 General .................................................................................................................................................. 14

5.2.2.1 Mains voltage ........................................................................................................................................ 14

5.2.2.2 Valve-regulated lead-acid battery power sources .................................................................................. 14

5.2.2.3 Other power sources .............................................................................................................................. 14

5.2.3 Extreme test conditions ............................................................................................................................... 14

5.2.3.1 Extreme test source voltages ................................................................................................................. 14

5.2.3.1.1 Mains voltage .................................................................................................................................. 14

5.2.3.2 Valve-regulated lead-acid battery power sources .................................................................................. 15

5.2.3.3 Power sources using other types of batteries ......................................................................................... 15

5.2.3.4 Other power sources .............................................................................................................................. 15

5.2.3.5 Extreme test temperatures ..................................................................................................................... 15

6 General conditions .................................................................................................................................. 15

6.1 Normal test signals ........................................................................................................................................... 15

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6.2 Loop connections ............................................................................................................................................. 15

6.2.0 General ........................................................................................................................................................ 15

6.2.1 Artificial loop .............................................................................................................................................. 16

6.3 Modes of operation of the induction loop amplifier ......................................................................................... 16

6.4 Measuring receiver ........................................................................................................................................... 16

7 Induction loop amplifier ......................................................................................................................... 16

7.0 General ............................................................................................................................................................. 16

7.1 Induction loop amplifier definitions ................................................................................................................. 17

7.1.0 General ........................................................................................................................................................ 17

7.1.1 Product Classes ........................................................................................................................................... 17

7.2 Induction loop amplifier spurious output levels ............................................................................................... 19

7.2.1 Radiated H-field Limits below 5 MHz ....................................................................................................... 19

7.2.1.1 Definition .............................................................................................................................................. 19

7.2.1.2 Methods of measurement ...................................................................................................................... 19

7.2.1.3 Limits .................................................................................................................................................... 19

7.3 Audio frequency baseband emission limits ...................................................................................................... 20

7.3.1 Definition .................................................................................................................................................... 20

7.3.2 Methods of measurement ............................................................................................................................ 20

7.3.3 Limits .......................................................................................................................................................... 21

7.4 Spurious domain emission limits ...................................................................................................................... 21

7.4.1 Definition .................................................................................................................................................... 21

7.4.2 Measurement conditions ............................................................................................................................. 21

7.4.3 Methods of measurement of Conducted emissions below 5 MHz .............................................................. 21

7.4.4 Limits .......................................................................................................................................................... 21

8 Measurement uncertainty ....................................................................................................................... 21

9 Interpretation of results .......................................................................................................................... 22

9.1 Measurement uncertainty is equal to or less than maximum acceptable uncertainty ....................................... 22

Annex A (normative): Relationship between the present document and the essential

requirements of Directive 2014/53/EU ......................................................... 23

Annex B (normative): Measurement .................................................................................................. 24

B.1 Standard test position to be used with internal loop equipment or equipment having a loop

connector ................................................................................................................................................ 24

B.2 Technical performance of the spectrum analyser or receiver ................................................................. 24

Annex C (normative): Customized loops ........................................................................................... 25

C.1 Antenna loops below 1 MHz .................................................................................................................. 25

C.2 Magnetic field strength at an arbitrary point .......................................................................................... 25

Annex D (informative): Test fixture ..................................................................................................... 26

Annex E (normative): Induction loop amplifier emission levels and spectrum mask

measurements ................................................................................................. 28

Annex F (informative): Determination and use of the measurement bandwidth ............................. 29

Annex G (informative): Bibliography ................................................................................................... 30

History .............................................................................................................................................................. 31

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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 draft Harmonised European Standard (EN) has been produced by ETSI Technical Committee Electromagnetic

compatibility and Radio spectrum Matters (ERM), and is now submitted for the combined Public Enquiry and Vote

phase of the ETSI standards EN Approval Procedure.

The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [4] to

provide one voluntary means of conforming to the essential requirements of Directive 2014/53/EU on the harmonisation

of the laws of the Member States relating to the making available on the market of radio equipment and repealing

Directive 1999/5/EC [i.1].

Once the present document is cited in the Official Journal of the European Union under that Directive, compliance with

the normative clauses of the present document given in table A.1 confers, within the limits of the scope of the present

document, a presumption of conformity with the corresponding essential requirements of that Directive, and associated

EFTA regulations.

Proposed national transposition dates

Date of latest announcement of this EN (doa): 3 months after ETSI publication

Date of latest publication of new National Standard

or endorsement of this EN (dop/e):

6 months after doa

Date of withdrawal of any conflicting National Standard (dow): 18 months after doa

Modal verbs terminology

In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and

"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of

provisions).

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

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.

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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 (see

note), cochlear implants and loop receiving 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.

NOTE: These are covered in ETSI EN 300 422 [2].

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 the Radio Equipment Directive, which reduces the lower limit

for radio equipment from 9 kHz defined in the R&TTE. It 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 the Radio Equipment Directive (RED).

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1 Scope

The present document applies to the following major equipment types:

1) induction loop amplifiers operating from 10 Hz to 9 kHz;

2) induction loop receivers operating from 10 Hz to 9 kHz;

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);

• induction loop receivers.

The present document covers fixed induction loop amplifiers, mobile induction loop amplifiers and portable induction

loop amplifiers.

The present document covers requirements for emissions below, as well as above, 9 kHz.

2 References

2.1 Normative references

References are either specific (identified by date of publication and/or edition number or version number) or

non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the

reference document (including any amendments) applies.

Referenced documents which are not found to be publicly available in the expected location might be found at

http://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] 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".

[2] ETSI EN 300 422 (parts 1 and 2) (V1.5.1) (V1.4.1) (06-2015): "Electromagnetic compatibility and

Radio spectrum Matters (ERM); Wireless microphones in the 25 MHz to 3 GHz frequency range".

[3] BS 7594:2011: "Code of practice for audio-frequency induction-loop systems (AFILS)".

[4] 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.

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

reference 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.

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[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)".

[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] ITU Radio Regulations.

[i.5] IEC 60118-4: "Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid

purposes - Magnetic field strength".

[i.6] 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.7] IEC 61672-1: "Electroacoustics. Sound level meters. Specifications".

[i.8] IEC 60268-10: "Sound system equipment. Methods for specifying and measuring the

characteristics of peak programme level meters".

[i.9] ECC report 208: "Impact of RFID devices using the band at 13.56 MHz on radio services".

3 Definitions, symbols and abbreviations

3.1 Definitions

For the purposes of the present document, the following terms and definitions apply:

artificial loop: reduced size -radiating dummy load equal to the nominal impedance of the loop specified by the

provider

Audio-Frequency Induction-Loop System (AFILS): system including induction loop amplifier(s), microphones

and/or other signal sources, in which magnetic fields are created by the flow of audio-frequency current in a conductor

arranged in the form of a loop or coil

conducted measurements: measurements which 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

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 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 AFILS industry.

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Induction loop listener: portable listening device which 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 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 specified in IEC 60268-10 [i.8], and a true r.m.s. meter type that

incorporates a true r.m.s. rectifier, and meets the relevant requirements for a Class 2 sound level meter

specified in IEC 61672-1 [i.7]. Full functional specifications for both types of meter can be found in

IEC 60118-4 [i.5].

mobile amplifier: equipment normally installed in a vehicle

phased loop array: system of neighbouring loops in which the currents are not in 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 mA/m

spurious emissions: emissions on a frequency or frequencies which are outside the occupied bandwidth 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 in accordance

with IEC 60118-4 [i.5]

NOTE: A telecoil can be part of a hearing aid or of any other device for receiving signals from an audio-

frequency induction-loop system in accordance with IEC 60118-4 [i.5].

type designation: providers' marking of the equipment

useful magnetic field volume: volume within which the AFILS provides a hearing-aid user with a signal of acceptable

quality (see IEC 60118-4 [i.5])

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3.2 Symbols

For the purposes of the present document, the following symbols apply:

ohm

A loop area

C correction factor

E electrical field strength

f frequency

centre frequency in Hz

H magnetic field strength

Hf H-field-strength limit

H-field strength at the centre of the frequency of interest

H-field-strength limit for radiated spurious emissions

audio frequency baseband output current

spurious output current

Wave length

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

NOTE: Also known as Hearing Loop.

AMN Artificial Mains Network

BS British Standard

CDN Coupling/Decoupling Network

CEPT Conférence Européenne des Postes et Télécommunications

CISPR Comité International Spécial des Perturbations Radioélectriques

e.r.p. effective radiated power

EAS Emergency Alert System

EC European Community

ECC Electronic Communication Committee

EFTA European Free Trade Area

EMC ElectroMagnetic Compatibility

ERC European Radiocommunications Committee

EU European Union

HF High Frequency (range)

ISM Industrial, Scientific and Medical

ISN Impedance Stabilization Network

ITU-T ITU-Telecommunication sector

LISN Line Impedance Stabilization Network

NIA Product of N (the number of turns of the loop) x I (current in the loop) x A (the area of the loop)

NRI National Radio Interfaces

R&TTE Radio & Telecommunications Terminal Equipment

r.m.s. root mean square

RED Radio Equipment Directive

RF Radio Frequency

RFID Radio Frequency Identification Device

SRD Short Range Device

TR Technical Report

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4 Technical overview

4.1 Induction Loop Amplifiers

4.1.0 General

Induction loop amplifiers, together with an internal or external induction loop, are used to generate audio-frequency

magnetic fields that may be used by a listener's hearing instrument or AFILS receiver to provide noise-free and

reverberation-free audio directly to the listener. This therefore removes the acoustic gap between talker and listener and

allows what would otherwise be a difficult or unintelligible message for a hearing-impaired listener to become

intelligible.

The majority of hearing instruments are equipped with a small pickup coil (the telecoil) and so no additional equipment

is required by a hearing instrument wearer to use this service. People without hearing instruments wishing to receive the

AFILS signal can use dedicated portable stand-alone receivers called loop listeners.

4.1.1 Frequency response

As an audio frequency baseband transmission system, the output of an AFILS system corresponds precisely with the

bandwidth of the audio. There is no carrier frequency or modulation scheme. A correctly designed and installed AFILS

complying with the requirements of IEC 60118-4 [i.5] has a frequency response within the range 100 Hz to 5 kHz of

± 3 dB with reference to the response at 1 kHz. Wider frequency responses up to 9 kHz may be required for non-hearing

instrument use (e.g. tour guides) and for future developments of hearing instrument technology.

4.1.2 Field strength

A correctly designed and installed AFILS, complying with the requirements of IEC 60118-4 [i.5] and with a 1 kHz sine

wave input signal will produce a magnetic field strength of 400 mA/m when measured with the true r.m.s. meter with

0,125 s averaging time in at least one place within the space where listeners' heads (and therefore hearing instruments)

are expected to be, and should be no more than 3 dB higher for large area AFILS, and no more than 8 dB higher for

small area systems. This is the level also achieved on the highest peaks in the programme material (speech or music).

The average magnetic field strength is much lower and will depend on the programme content.

4.1.3 General performance criteria

For the purpose of the induction loop amplifier performance tests, the amplifier shall be operated as described in

clauses 6 and 7.

4.2 AFILS Receivers and Test Equipment

AFILS receivers, like hearing instruments, are stand-alone battery-powered devices using a telecoil to transduce an

AFILS magnetic field into a voltage, which can be processed and amplified to drive an earphone or headphones.

AFILS field strength meters also sense the magnetic field with a telecoil and often provide a headphone output so that

the measured signal can be assessed by listening.

As there is no heterodyning of signals and no internal intermediate frequency mixer oscillators, etc., the baseband

Audio Frequency magnetic field is transposed directly to an audio frequency baseband output signal. Antenna emissions

tests are therefore not required. EMC standards cover any likely emissions from such equipment, including any internal

loop(s).

Receivers and test equipment are non-critical communication devices, whose failure to operate correctly causes loss of

function which can be overcome by parallel means. This classification is based upon the impact on persons in case the

equipment does not operate above the specified minimum performance level.

Other equipment (e.g. hearing aids, cochlear implants and assistive listening devices) that may be used as AFILS

receivers shall fulfil the standards applicable to that equipment (if any).

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4.3 General

4.3.1 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 provider 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 as defined in clause 7.1.1, the provider

shall supply either a tuned reduced radiating load (see clause 6.2.1) or an artificial loop as defined by annex C.

In the case of equipment supplied with an internal induction loop, i.e. Product Class 1 equipment as defined in

clause 7.1.1, 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 providers 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

provider 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 defined in clause 4.3.2.

4.3.2 Choice of model for testing

Stand-alone equipment shall be supplied by the provider 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 provider.

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.

4.4 Mechanical and electrical design

4.4.1 Controls

Controls that may need to be adjusted after installation such as input gain, loop drive, bass, treble, tone or "metal

compensation" adjustments 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.

4.4.2 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 duration of the test.

4.4.3 Marking (equipment identification)

4.4.3.0 General requirements

The equipment shall be marked in a visible place. This marking shall be legible and durable. Where this is not possible

due to physical constraints, the marking shall be included in the user's manual.

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4.4.3.1 Equipment identification

The marking shall include as a minimum:

• the name of the manufacturer or his trade mark;

• the type designation;

• a reference to allow traceability such as a serial number or works order number.

4.4.3.2 Equipment marking

The equipment shall be marked, where applicable, in accordance with the Directive 2014/53/EU (the RED) [i.1]. Where

this is not applicable the equipment shall be marked in accordance with the National Regulatory requirements.

4.5 Declarations by the provider

When submitting equipment for testing, the provider shall declare any necessary information which may be required by

an external laboratory.

4.6 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.

4.7 Interpretation of the measurement results

The interpretation of the results recorded on the test report for the measurements described in the present document

shall be as follows:

• the measured value relating to the corresponding limit shall be used to decide whether an equipment meets the

requirements of the present document;

• the measurement uncertainty value for the measurement of each parameter shall be included in the test report;

• the recorded value of the measurement uncertainty shall, for each measurement, be equal to, or lower than, the

figures in the table of measurement uncertainty (clause 8).

5 Test conditions, power sources and ambient

temperatures

5.1 Normal test conditions

5.1.0 General requirement

Testing shall be made under normal test conditions.

The test conditions and procedures shall be as specified in clause 5.2.

5.1.1 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.

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5.2 Test power source

5.2.0 General requirements

The equipment shall be tested using the appropriate test power source as specified in clauses 5.2.2 or 5.2.3. Where

equipment can be powered using either external or internal power sources, then the equipment shall be tested using the

external power source as specified in clause 5.2.1 then repeated using the internal power source as specified in

clause 5.2.2.

The test power source used shall be stated in the test report.

5.2.1 External test power source

During tests, the power source of the equipment shall be replaced by an external test power source capable of producing

normal and extreme test voltages as specified in clauses 5.2.2 and 5.2.3. 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.

5.2.2 Internal test power source

5.2.2.0 General

If appropriate, 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. This shall be stated on the test report.

5.2.2.1 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 ac mains shall be +/- 1Hz of the mains frequency specified

by the provider.

5.2.2.2 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.).

5.2.2.3 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 equipment provider. Such values shall be stated in the test report.

5.2.3 Extreme test conditions

5.2.3.1 Extreme test source voltages

5.2.3.1.1 Mains voltage

The extreme test voltages for equipment to be connected to an ac mains source shall be the nominal mains voltage

±10 %. For equipment operating over a range of mains voltages clause 5.3.3.4 applies.

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5.2.3.2 Valve-regulated lead-acid battery power sources

When the equipment is intended for operation from valve-regulated lead-acid battery power sources the extreme test

voltages shall be 1,3 and 0,9 multiplied by the nominal voltage of the battery (6 V, 12 V, etc.).

For float charge applications using "gel-cell" type batteries the extreme voltage shall be 1,15 and 0,85 multiplied by the

nominal voltage of the declared battery voltage.

5.2.3.3 Power sources using other types of batteries

The lower extreme test voltages for equipment with power sources using batteries other than lead-acid shall be as

follows:

• For equipment with a battery indicator, the end point voltage as indicated.

• For equipment without a battery indicator the following end point voltages shall be used:

a) For the Leclanché or the lithium type of battery:

0,85 multiplied by the nominal voltage of the battery.

b) For the nickel-cadmium type of battery:

0,9 multiplied by the nominal voltage of the battery.

• For other types of battery or equipment, the lower extreme test voltage for the discharged condition shall be

declared by the equipment provider.

The nominal voltage is considered to be the upper extreme test voltage in this case.

5.2.3.4 Other power sources

For equipment using other power sources, or capable of being operated from a variety of power sources, the extreme

test voltages shall be those agreed between the equipment provider and the test laboratory. This shall be recorded in the

test report.

5.2.3.5 Extreme test temperatures

Extreme test temperatures are as specified by the provider. As there is no heterodyning of signals and no internal

intermediate frequency mixer oscillators, etc., the baseband audio frequency signal is transposed directly to the

baseband audio frequency magnetic field. Therefore emissions tests are not carried out at extreme temperatures.

6 General conditions

6.1 Normal test signals

For equipment without an external loop connector a connector shall be added to allow testing.

The normal test signal is specified as follows:

• 1 kHz sinusoidal tone

6.2 Loop connections

6.2.0 General

For equipment supplied without an internal loop, i.e. Product Class 2 as defined in clause 7.1.1, the provider shall

supply a tuned reduced radiating load (artificial loop).

Alternatively, for equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 7.1.1,

the provider 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.

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NOTE: Typical loop impedances are described in IEC 62489-1 [i.6], annex B.

6.2.1 Artificial loop

For measurements of induction loop amplifiers, a tuned reduced radiating load (artificial loop) 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 provider.

This method facilitates conducted measurements to be made of the following:

• induction loop amplifier loop currents up to 9 kHz; and

• induction loop amplifier spurious loop currents up to 5 MHz;

A description of the artificial loop shall be stated in the test report.

For equipment supplied with an internal loop, the provider may decide to use the existing 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.

6.3 Modes of operation of the induction loop amplifier

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 method of achieving this shall be

described in the documentation from the provider and shall be recorded in the test report. It may involve suitable

temporary internal modifications of the equipment under test.

For the purpose of testing, the normal test signal, see clause 6.1, 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).

6.4 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: (f)

Detector type

Measurement receiver bandwidth

Spectrum

analyser

bandwidth

9 kHz ≤ f < 150 kHz

Quasi Peak 200 Hz 300 Hz

150 kHz ≤ f < 5 MHz

Quasi Peak 9 kHz 10 KHz

If different bandwidths are used, follow the guidance in annex E and record this in the test report.

7 Induction loop amplifier

7.0 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 provider, 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 provider, 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 7.1.1, the provider shall supply a tuned

reduced radiating load (artificial loop) which is to be used for the full tests which are to be carried out.

For equipment supplied with an internal loop, i.e. Product Class 1 equipment as defined in clause 7.1.1, the provider

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 5 MHz. The actual method used shall be stated within the test report.

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7.1 Induction loop amplifier definitions

7.1.0 General

Induction loop amplifiers are divided into Product Classes (see clause 7.1.1) 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 manufacturers design guidelines. The user's manual

shall include the guidelines for the design of the induction loops.

7.1.1 Product Classes

The equipment is divided into Product Classes depending on the induction loop type used. The different loop types are

referencing CEPT/ERC/REC 70-03 [i.2], as implemented through National Radio Interfaces (NRI) and additional NRI

as relevant.

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

- internal loop area shall be < 4 m

;

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 C and clause 7.3.3 and shall comply

with the equivalent radiated H-field limits given in clauses 7.3.3, 7.2.1.3 and 7.4.2.2.

Where a manufacturer provides a range of standard internal loops, the equipment shall be tested as Product

Class 1. Either each of the loop(s) shall be fitted in turn with an appropriate monitoring connector attached, or

at the provider's discretion, with representative artificial loops used to show compliance when operated with

the minimum and maximum expected loads.

The actual method used shall be stated within the test report.

Product Class 2:

This Product Class is intended for use with external loops which may, or may not, be customized. The

induction loop amplifier is tested by using an artificial loop.

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 C and clause 7.3.3, and shall comply

with the equivalent radiated H-field limits given in clauses 7.3.3, 7.2.1.3 and 7.4.2.2. The manufacturer shall

declare the maximum size of the loop in the user's manual.

Conducted emission measurements, below 5 MHz, shall be carried out with representative artificial loops used

to show compliance when operated with the minimum and maximum expected loads.

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Table 2: Description of product classes

Product

Class

Description of

induction loop

amplifier

Loads to be tested Loop area

Customization of loop

design allowed

Audio frequency baseband and

Spurious emission output limits

Supplied with

Internal Loop(s)

Artificial or internal loop

(with test connector) for all Conducted

measurements below 5 MHz

(see note 1)

For internal loop(s) < 4 m

For equipment with an

external connector(s), as

per class 2

For Internal loop(s) no

customization is allowed.

For equipment with an

external connector(s), the

external loop(s) may be

modified as per class 2

clause 7.3.3

clause 7.2.1.3

clause 7.4.2.2

Supplied with

external Loop

connection

Test using an artificial loop

(see notes 2 and 3)

Not Applicable Yes

clause 7.3.3

clause 7.2.1.3

clause 7.4.2.2

NOTE 1: Where a manufacturer provides equipment with a range of standard class 1 loops, the equipment shall be tested as stated in clause 7.1.4.

NOTE 2: Conducted emission measurements, below 5 MHz, shall be carried out with representative artificial loops used to show compliance when operated with the minimum

and maximum expected loads (loop area).

NOTE 3: Customization is only allowed according to the manufacturer's loop design rules published in the equipment manual.

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7.2 Induction loop amplifier spurious output levels

7.2.1 Radiated H-field Limits below 5 MHz

7.2.1.1 Definition

Spurious emission limits below 5 MHz, are presented here in terms of a reference H-Field at a set distance. This allows

comparison with other standards and international agreements.

7.2.1.2 Methods of measurement

The equipment under test shall operate with a test input signal as specified in clause 6.1, with any tone controls set to a

flat response as stated in clause 7.

7.2.1.3 Limits

The limits presented in the present document are the required field strengths to allow satisfactory operation of Audio

Frequency Induction Loop Systems (AFILS).

The maximum H-field strengths for certain frequency bands are given in table 3. Field-strength limits of National Radio

Interfaces (NRI) apply.

Regulatory information is available in CEPT/ERC/REC 70-03 [i.2], ECC report 208 [i.9] and where applicable ERC or

ECC Decisions as implemented through National Radio Interfaces (NRI) and additional NRI as relevant.

Table 3: H-field limits at 10 m

Frequency range (MHz)

H-field strength limit (H

) dB

A/m at 10 m (note 4)

0,009 ≤ f < 0,090

72 descending 3 dB/octave above 0,03 MHz

or according to note 1

(see note 3)

0,09 ≤ f < 0,119

0,119 ≤ f < 0,135

66 descending 3 dB/octave above 0,119 MHz

or according to note 1

(see note 3)

0,135 ≤ f < 0,140

0,140 ≤ f < 0,1485

37,7

0,1485 ≤ f < 30

-5

0,315 ≤ f < 0,600

-5

3,155≤ f < 3,400

13,5

4,234 9

4,516 7

7,400 ≤ f < 8,800

10,2 ≤ f < 11,00

12,5 f 20 -7

6,765 ≤ f ≤ 6,795

13,553 ≤ f ≤ 13,567

26,957 ≤ f ≤ 27,283

42 (see note 5)

13,410 ≤ f ≤13,553, 13,567 ≤ f ≤ 13,710

13,110 ≤ f ≤ 13,410, 13,710 ≤ f ≤ 14,010

-3,5

12,660 ≤ f ≤ 13,110, 14,010 ≤ f ≤ 14,460

-10

11,810 ≤ f ≤ 12,660, 14,460 ≤ f ≤ 15,310

-16

13,460 ≤ f ≤ 13,553, 13,567 ≤ f ≤ 13,660

13,360 ≤ f ≤ 13,460, 13,660 ≤ f ≤ 13,760

Linear transition from 27 to -3,

13,110 ≤ f ≤ 13,360, 13,760 ≤ f ≤ 14,010

-3,5

12,660 ≤ f ≤ 13,110, 14,010 ≤ f ≤ 14,460

-5

13,553 ≤ f ≤ 13,567

60 (see note 2)

27,095 42

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Frequency range (MHz)

H-field strength limit (H

) dB

A/m at 10 m (note 4)

NOTE 1: For the frequency ranges 9 kHz to 135 kHz, the following additional restrictions apply to limits

above 42 dBµA/m:

- for loops with an area

0,16 m

this table and table 2 with the limitations apply;

- for loops with an area between 0,05 m

and 0,16 m

table 2 applies

with a correction factor. The limit is: table value + 10 × log (area/0,16 m

);

- for loops with an area < 0,05 m

the limit is 10 dB below table 2.

NOTE 2: For RFID and EAS applications only.

NOTE 3: Limit is 42 dBµA/m for the following spot frequencies:

60 kHz ± 250 Hz, 66,6 kHz ± 750 Hz, 75 kHz ± 250 Hz, 77,5 kHz ± 250 Hz,

and 129,1 kHz ± 500 Hz.

NOTE 4: The H-field strength limits (H

) in dBµA/m at 10 m distance of a Wireless Power Transfer

System in the declared working situations.

NOTE 5: The frequency range 6,765 MHz - 6,79 MHz is not a harmonised ISM frequency band

according article 5.138 of the ITU Radio Regulations [i.4]. For the decision scheme in table 3

only Case 2 may therefore be applicable in some countries.

7.3 Audio frequency baseband emission limits

7.3.1 Definition

Audio frequency baseband emission limits are defined as the calculated equivalent emissions produced (see

clause C.1.4 of BS 7594:2011 [3]), for the declared loop size(s), at the furthest point of the useful magnetic field

volume. The manufacturer shall declare the maximum loop size and the distance to the furthest point of the useful

magnetic field volume and this shall be stated in the test report.

7.3.2 Methods of measurement

The equipment shall be set up as follows:

• Class 1 equipment shall be connected either to an appropriate artificial loop(s), see clause 6.2.1 and annex B,

or at the provider's discretion, shall be connected to the internal loop(s), with a suitable method provided to

monitor the loop current.

• Class 2 equipment shall be connected to the artificial loop(s), see clause 6.2.1 and annex B.

The actual method used shall be stated within the test report, along with details of any modifications to the equipment

required to make the measurements possible.

The current delivered to the loop or artificial loop shall be measured up to 9 kHz. The current shall be measured either

by using:

• a derived output from a calibrated artificial loop connected to a measuring receiver, see annex B; or

• a calibrated current probe connected to a measuring receiver; or

• a calibrated non-inductive resistive current sense element, whose value should not significantly affect the

current delivered to the loop, for example the equipment's own internal current sense, connected to a

measuring receiver.

The measuring bandwidth and detector type shall be in accordance with clause 6.4.

The measurements shall be made under normal and extreme test conditions, see clauses 5.3 and 5.3.3.

However, 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 the requirement to test emissions at the extreme voltages shall be removed.

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7.3.3 Limits

The limit for the audio frequency baseband emission for both Product Classes is given in table 4.

Table 4: Equivalent H-Field limits for audio frequency baseband emissions

Frequency range (kHz)

Audio frequency

baseband

emission limit

(

)

10 Hz to 9 kHz

1,005 A/m (see notes 1 and 2)

NOTE 1: This limit is the equivalent H-Field limit, when calculated using the formulae in clause C.1.4 of

BS 7594:2011 [3], and when measured at the furthest point of the useful magnetic field volume, as

declared by the provider. Actual equipment measurements are taken in terms of conducted loop output.

NOTE 2: This is as per the spectrum mask given in annex C.

7.4 Spurious domain emission limits

7.4.1 Definition

Spurious domain emission limits are limits on emissions at frequencies other than those within the normal operational

bandwidth.

7.4.2 Measurement conditions

a) For Class 1 equipment, their current into an artificial loop or at the discretion of the provider, their current into

the actual loop, with a suitable method provided to monitor the loop current.

b) For Class 2 equipment, their current level into an artificial loop.

The level of spurious emissions shall be measured at normal conditions (see clause 5.3).

7.4.3 Methods of measurement of Conducted emissions below 5 MHz

For Class 1 equipment, the induction loop amplifier shall be connected to an artificial loop or at the discretion of the

provider, into the actual loop with a suitable method provided to monitor the loop current (clause 6.2.1).

For Class 2 equipment, the induction loop amplifier shall be connected to an artificial loop (clause 6.2.1).

The measuring receiver shall be connected to the output of the artificial loop, or suitable monitoring point in the case of

Class 1 equipment and the current for the spurious components shall be measured.

For further details of the artificial loop, see annex D.

The currents shall first be measured with the induction loop amplifier energized (operational) with the test signal

applied (clause 6.1) and then repeated with the amplifier energized (operational) with the test signal removed.

7.4.4 Limits

The conducted limits are calculated via the equations given in annex B, and the limits set out in table 3.

This relates the output loop current, declared maximum loop area and number of turns, to the maximum equivalent

radiated H-Field which may be generated.

Emission limits are stated in H-Field terms to allow comparison and interpretation with other standards and

international agreements.

8 Measurement uncertainty

The interpretation of the results recorded in the test report for the measurements described in the present document shall

be as follows:

• The measured value related to the corresponding limit shall be used to decide whether an equipment meets the

requirements of the present document.

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• The value of the measurement uncertainty for the measurement of each parameter shall be separately included

in the test report.

• the value of the measurement uncertainty shall be, for each measurement, equal to or lower than the figures

given below:

- RF frequency ±1 × 10

-7

- RF power, conducted ±1 dB.

- RF power, radiated ±6 dB.

- Temperature ±1 °C.

- Humidity ±5 %.

For the test methods, according to the present document the uncertainty figures shall be calculated according to the

methods described in the ETSI TR 100 028 [1] and shall correspond to an expansion factor (coverage factor) k = 1,96 or

k = 2 (which provide confidence levels of respectively 95 % and 95,45 % in case where the distributions characterizing

the actual measurement uncertainties are normal (Gaussian)).

The measurement uncertainties given above are based on such expansion factors.

The particular expansion factor used for the evaluation of the measurement uncertainty shall be stated.

9 Interpretation of results

9.1 Measurement uncertainty is equal to or less than maximum

acceptable uncertainty

The interpretation of the results when comparing measurement values with specification limits shall be as follows:

a) When the measured value does not exceed the limit value the equipment under test meets the requirements of

the present document.

b) When the measured value exceeds the limit value the equipment under test does not meet the requirements of

the present document.

c) The measurement uncertainty when carrying out the measurement should be recorded in the test report.

d) The measurement uncertainty may be a maximum value for a range of values of measurement, or may be the

measurement uncertainty for the specific measurement untaken. The method used should be recorded in the

test report.

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Annex A (normative):

Relationship between the present document and the

essential requirements of Directive 2014/53/EU

The present document has been prepared under the Commission's standardisation request C(2015) 5376 final [4] 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.

Table A.1: Relationship between the present document and

the essential requirements of Directive 2014/53/EU

Harmonised Standard ETSI

EN 303

348

The following requirements are relevant to the presumption of conformity

under the article 3.2 of Directive 2014/53/EU [i.1]

Requirement

Requirement Conditionality

No Description

Reference:

Clause No

U/C Condition

1 Induction loop amplifier spurious

output

7.2 U

2 Audio frequency baseband emission

limits

7.3 U

3 Spurious domain emission 7.4 U

Key to columns:

Requirement:

No A unique identifier for one row of the table which may be used to identify a requirement.

Description A textual reference to the requirement.

Clause Number Identification of clause(s) defining the requirement in the present document unless another

document is referenced explicitly.

Requirement Conditionality:

U/C Indicates whether the requirement shall be unconditionally applicable (U) or is conditional upon

the manufacturers claimed functionality of the equipment (C).

Condition Explains the conditions when the requirement shall or shall not be applicable for a requirement

which is classified "conditional".

Presumption of conformity stays valid only as long as a reference to the present document is maintained in the list

published in the Official Journal of the European Union. Users of the present document should consult frequently the

latest list published in the Official Journal of the European Union.

Other Union legislation may be applicable to the product(s) falling within the scope of the present document.

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Annex B (normative):

Measurement

B.1 Standard test position to be used with internal loop

equipment or equipment having a loop connector

The standard position for equipment shall be the following:

a) for equipment with an internal loop, it shall be placed in the position closest to normal use as declared by the

provider.

Equipment which is intended to be worn on a person may be tested using a simulated man as support. The simulated

man comprises a rotatable acrylic tube filled with salt water, placed on the ground.

The container shall have the following dimensions:

• Height: 1,7 m ± 0,1 m.

• Inside diameter: 300 mm ± 5 mm.

• Sidewall thickness: 5 mm ± 0,5 mm.

The container shall be filled with a salt (NaCl) solution of 1,5 g per litre of distilled water.

The equipment shall be fixed to the surface of the simulated man, at the appropriate height for the equipment, as

intended in normal use.

NOTE: To reduce the weight of the simulated man it may be possible to use an alternative tube which has a

hollow centre of 220 mm maximum diameter.

B.2 Technical performance of the spectrum analyser or

receiver

It shall be possible, using a resolution bandwidth of 1 kHz, to measure the amplitude of a signal or noise at a level 3 dB

or more above the noise level of the spectrum analyser or receiver, to an accuracy of ±2 dB in the presence of a signal

separated in frequency by 10 kHz, at a level 90 dB above that of the signal to be measured.

The reading accuracy of the frequency marker shall be within ±2 % of the limits.

The accuracy of relative amplitude measurements shall be within ±1 dB.

It shall be possible to adjust the spectrum analyser to allow the separation, on the display, of two components with a

frequency difference of 1 kHz.

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Annex C (normative):

Customized loops

C.1 Antenna loops below 1 MHz

The design formulas given under clauses C.1 and C.2 allow correlation of loop current to equivalent H-Field emissions.

The radiated magnetic field H from a loop in the near field is given by:

A/m (C.1)

where:

N is the number of turns of the induction loop.

I is the current in Ampere in the induction loop.

A is the area in m

of the induction loop.

d is the distance in metre from the induction loop.

The formula is valid at low frequencies under the following conditions:

• Length of the induction loop wire in m:

• Distance from induction loop in m:

The product of NIA is the magnetic dipole moment m of the loop.

The equation for the magnetic moment is:

(Am

) (C.2)

In the present document the reference measuring distances d are 10 m or 30 m.

If 10 m is inserted into (C.2):

(Am

) (C.3)

where:

is the H-field limit at 10 m in A/m

The equation is only valid up to 1 MHz.

For method of measurement for loop current into an artificial loop, see annex D.

C.2 Magnetic field strength at an arbitrary point

See BS 7594:2011 [3], clause C.1.4.

2 d

NIA

l <

λπ

d <

λπ

2 dHNIAm

6283

×== HNIAm

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Annex D (informative):

Test fixture

Test fixture for measuring induction loop amplifier audio frequency baseband and spurious currents by use of an

artificial loop.

The artificial loop may be used for equipment with a loop connector and submitted for testing without a loop. The

radiated fields for the baseband and spurious emissions are proportional to the audio frequency baseband and spurious

currents. Therefore, measurements are made to determine the audio frequency baseband and spurious currents in the

artificial loop.

Figure D.1

Figure D.2

An example of the mechanical layout and the equivalent electric circuit of the components are given in figures D.2 and

D.1 respectively.

If the manufacturer specifies a range of loop dimensions, two artificial loops having maximum and minimum

inductance L should be supplied. This fact should be stated in the test report.

is a low value non-reactive resistor. The voltage across R

is proportional to the conducted audio frequency baseband

and spurious loop currents. These can be measured at the output connector.

in combination with R

ensures that the artificial loop has the same Q as the specified loop.

As the artificial loop does not provide galvanic isolation between the equipment under test and the test receiver,

isolation may be required elsewhere in order to ensure correct and/ or safe operation.

Capacitors C1, C2 are optional components together with L to be used as appropriate by the manufacturer to simulate

the actual loop configuration. Other possible configurations are shown in figure D.3.

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Figure D.3

The test fixture configuration used by the manufacturer should be stated in the test report.

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Annex E (normative):

Induction loop amplifier emission levels and spectrum mask

measurements

The present document allows spectrum measurements to be made. The measurements are relevant for AFILS operating

between 0 Hz to 9 kHz.

NOTE: This limit is the equivalent H-Field limit, when calculated using the formulae in clause C.1.4 of

BS 7594:2011 [3], and when measured at the furthest point of the useful magnetic field volume, as

declared by the provider. Actual equipment measurements are taken in terms of conducted loop output.

Figure E.1

ETSI

Draft ETSI EN 303 348 V1.1.0 (2016

02)

Annex F (informative):

Determination and use of the measurement bandwidth

CISPR 16-2-3 [i.3] specifies a reference bandwidth for the measurement of unwanted emissions by measurement

receivers and spectrum analysers.

The reference bandwidth (BW

REFERENCE

) cannot always be used as the measurement bandwidth (BW

MEASUREMENT

This is particularly the case if the measurement is to be made for example on the slope of a spectrum mask or a receiver

selectivity curve. In such situations the measurement should be made with a sufficiently low bandwidth in order not to

distort the reading.

The actual measured value, A, should be referred back to the reference bandwidth by.

Either:

a) Correcting the measured value, A, for any signal having a flat level spectrum with the following formula:

where:

- B is the measured level, A, transferred to the reference bandwidth.

Or:

b) Use the measured value, A, directly if the measured spectrum is a discrete spectral line.

A discrete spectrum line is defined as a narrow peak with a level of at least 6 dB above the average level inside the

measurement bandwidth.

MEASURED

REFERENCE

AB log10+=

ETSI

Draft ETSI EN 303 348 V1.1.0 (2016

02)

Annex G (informative):

Bibliography

• ERC Report 044 (1997): "Sharing between inductive systems and radiocommunication systems in the band

9 - 135 kHz".

• ERC Report 069: "Propagation model and interference range calculation for inductive systems

10 kHz - 30 MHz".

• ERC Report 092: "Sharing between inductive SRD systems and radio communication systems operating in the

frequency band 10.2 - 11 MHz".

• Council Directive 2004/108/EC of 20 April 2016 on the approximation of the laws of the Member States

relating to electromagnetic compatibility.

• Directive 2014/30/EU of the European Parliament and of the Council of 26 February 2014 on the

harmonisation of the laws of the Member States relating to electromagnetic compatibility.

• ERC Decision of 12 March 2001 on harmonised frequencies, technical characteristics and exemption from

individual licensing of Short Range Devices used for inductive applications operating in the frequency bands

9 - 59.750 kHz, 59.750 - 60.250 kHz, 60.250 - 70 kHz, 70 - 119 kHz, 119 - 135 kHz; (ERC/DEC(01)13).

• Directive 98/34/EC of the European Parliament and of the Council of 22 June 1998 laying down a procedure

for the provision of information in the field of technical standards and regulations.

• ETSI EG 201 399: "Electromagnetic compatibility and Radio spectrum Matters (ERM); A guide to the

production of candidate Harmonized Standards for application under the R&TTE Directive".

• CENELEC EN 55022: "Information technology equipment - Radio disturbance characteristics - Limits and

methods of measurement".

ETSI

Draft ETSI EN 303 3

48 V1.1.0 (2016

02)

History

Document history

V1.1.0 February 2016 EN Approval Procedure AP 20160524: 2016-02-24 to 2016-05-24