IEC_TR_63079-2017.pdf

IEC TR 63079 Edition 1.0 2017-04 TECHNICAL REPORT Code of practice for hearing-loop systems(HLS)IEC T R 63079:2017-04(en)colourinside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2017 IEC,Geneva,Switzerland All rights reserved.Unless otherwise specified,no part of this publication may be reproduced or utilized in any form or by any means,electronic or mechanical,including photocopying and microfilm,without permission in writing from either IEC or IECs member National Committee in the country of the requester.If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,please contact the address below or your local IEC member National Committee for further information.IEC Central Office Tel.:+41 22 919 02 11 3,rue de Varemb Fax:+41 22 919 03 00 CH-1211 Geneva 20 infoiec.ch Switzerland www.iec.ch About the IEC The International Electrotechnical Commission(IEC)is the leading global organization that prepares and publishes International Standards for all electrical,electronic and related technologies.About IEC publications The technical content of IEC publications is kept under constant review by the IEC.Please make sure that you have the latest edition,a corrigenda or an amendment might have been published.IEC Catalogue-webstore.iec.ch/catalogue The stand-alone applica tion for consulting the entir e bibliogr aphical informa tion on IEC International Standar ds,Technical Specifica tions,Technical Reports and other documents.Av ailable for PC,Mac OS,Android Tablets and iPad.IEC publications search-www.iec.ch/searchpub The adv anced sear ch enables to find IEC publications by a var iety of cr iter ia(refer ence number,text,technica l committee,).It also gives infor ma tion on pr ojects,replaced and w ithdraw n publications.IEC Just Published-webstore.iec.ch/justpublished Stay up to da te on all new IEC publications.Just Published details all new publica tions released.Av ailable online and also once a month by email.Electropedia-www.electropedia.org The w or lds leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and Fr ench,w ith equiv alent terms in 16 additional languages.Also know n as the Inter national Electr otechnical Vocabulary(IEV)online.IEC Glossary-std.iec.ch/glossary 65 000 electrotechnical terminology entries in English and Fr ench extracted fr om the Terms and Definitions clause of IEC publica tions issued since 2002.Some entr ies hav e been collected from ear lier publications of IEC TC 37,77,86 and CISPR.IEC Customer Serv ice Centre-webstore.iec.ch/csc If you w ish to giv e us your feedback on this publication or need fur ther assistance,plea se contact the Customer Ser v ice Centre:csciec.ch.IEC TR 63079 Edition 1.0 2017-04 TECHNICAL REPORT Code of practice for hearing-loop systems(HLS)INT ERNAT IONAL ELECT ROT ECHNICAL COMMISSION ICS 17.140.50 ISBN 978-2-8322-4154-7 Registered t rademark of the Internat ional Electrotechnica l Commission Warning!Mak e sure that you obtained this publication from an authorized distributor.colourinside 2 IEC TR 63079:2017 IEC 2017 CONTENTS FOREWORD.7 INTRODUCTION.9 1 Scope.10 2 Normative references.10 3 Terms,definitions,signs and symbols.10 3.1 Terms and definitions.10 3.2 Signs and symbols.12 3.2.1 Symbol for an induction-loop.12 3.2.2 Symbol for multiple loops.12 3.2.3 Sign for display in premises where an HLS is installed and for HLS equipment identification.13 3.2.4 Identification of areas where reception of the HLS is not satisfactory.13 4 General.14 4.1 How to use this document.14 4.1.1 Persons addressed.14 4.1.2 Objectives.14 4.2 Specialist advice.15 4.3 Safety aspects.15 4.4 Conforming to existing performance documents.15 5 Technical advice.15 5.1 Complying with this document.15 5.2 Seeking technical advice.15 5.3 The nature of the advice.16 5.4 Professional(consultancy)advice.16 6 Purpose of the system.16 7 Choosing the system supplier.16 7.1 General.16 7.2 Approaching a contractor.17 7.3 Approaching a manufacturer of HLS equipment.17 7.4 Approaching a specialist consultant.17 8 Contractual provisions.17 8.1 Performance specification.17 8.2 Verifying that the completed system delivers its intended performance.17 8.3 Arbitration.18 9 Classification of systems.18 10 Design.20 10.1 General.20 10.2 Symbols.20 10.3 Basic theory.21 10.3.1 Production of a magnetic field.21 10.3.2 Directional pattern of the magnetic field.22 10.3.3 Uniformity of the magnetic field strength.26 10.3.4 Reference points for magnetic field strength.26 10.3.5 Relationship between the requirements of IEC 60118-4 and the characteristics of hearing aids and speech signals.27 10.3.6 Impedance of the loop.28 IEC TR 63079:2017 IEC 2017 3 10.3.7 Selection of the method of driving the loop.29 10.3.8 Current-driven loop.29 10.3.9 Voltage-driven loop.30 10.3.10 Voltage-driven loop with high-level equalization.31 10.3.11 Voltage-driven loop with low-level equalization.33