Underwater acoustics - Hydrophones - Calibration of hydrophones - Part 1: Procedures for free-field calibration of hydrophones (IEC 60565-1:2020)

This part of IEC 60565 specifies methods and procedures for free-field calibration of
hydrophones, as well as individual electroacoustic transducers that can be used as
hydrophones (receivers) and/or projectors (source transducers). Two general types of
calibration are covered within this document: absolute calibration using the method of threetransducer
spherical-wave reciprocity, and relative calibration by comparison with a reference
device which has already been the subject of an absolute calibration.
The maximum frequency range of the methods specified in this document is from 200 Hz to
1 MHz. The lowest acoustic frequency of application will depend on a number of factors, and
will typically be in the range 200 Hz to 5 kHz depending mainly on the dimensions of the chosen
test facility, The highest frequency of application for the methods described here is 1 MHz.
Procedures for pressure hydrophone calibration at low frequencies can be found in
IEC 60565-2 [1]1. Procedures for hydrophone calibration at acoustic frequencies greater than
1 MHz are covered by IEC 62127-2 [2].
Excluded from the scope of this document are low-frequency pressure calibrations of
hydrophones, which are described in IEC 60565-2 [1]. Also excluded are calibrations of digital
hydrophones and systems, calibration of marine autonomous acoustic recorders, calibration
of acoustic vector sensors such as particle velocity sensors and pressure gradient
hydrophones, calibration of passive sonar arrays consisting of multiple hydrophones, and
calibration of active sonar arrays consisting of projectors and hydrophones.
This document presents a description of the requirements for free-field calibration in terms of
test facility, equipment and instrumentation, signal processing, and frequency limitations. A
description of achievable uncertainty and rules for the presentation of the calibration data are
provided. Also included are informative annexes that provide additional guidance on
• measurement of directional response of a hydrophone or projector,
• measurement of electrical impedance of hydrophones and projectors,
• electrical loading corrections,
• acoustic far-field criteria in underwater acoustic calibration,
• pulsed techniques in free-field calibrations,
• assessment of uncertainty in the free-field calibration of hydrophones and projectors,
• derivation of the formulae for three-transducer spherical-wave reciprocity calibrations,
• calibration using travelling-wave tubes,
• calibration of hydrophones using optical interferometry, and
• calibrations in reverberant water tanks using continuous signals.

Wasserschall - Hydrophone - Kalibrierung von Hydrophonen - Teil 1: Verfahren für die Freifeldkalibrierung von Hydrophonen (IEC 60565-1:2020)

Acoustique sous-marine - Hydrophones - Étalonnage des hydrophones - Partie 1: Procédures d'étalonnage en champ libre des hydrophones (IEC 60565-1:2020)

L'IEC 60565-1:2020 spécifie les méthodes et procédures d'étalonnage en champ libre des hydrophones, ainsi que des transducteurs électroacoustiques individuels qui peuvent être utilisés comme hydrophones (récepteurs) et/ou projecteurs (transducteurs sources). Deux grands types d'étalonnage sont couverts par le présent document: l'étalonnage absolu utilisant la méthode par réciprocité d’onde sphérique à trois transducteurs, et l'étalonnage relatif par comparaison avec un dispositif de référence qui a déjà fait l'objet d'un étalonnage absolu. La plage de fréquences maximale des méthodes spécifiées dans le présent document est comprise entre 200 Hz et 1 MHz. La fréquence acoustique la plus faible de l'application dépend d'un certain nombre de facteurs, et est en général comprise entre 200 Hz et 5 kHz selon les dimensions de l'installation d'essai choisie. La fréquence la plus élevée de l'application pour les méthodes décrites ici est de 1 MHz. Les procédures d'étalonnage de l'hydrophone à pression aux basses fréquences peuvent être consultées dans l'IEC 60565-2 [1] . Les procédures d'étalonnage de l'hydrophone aux fréquences acoustiques supérieures à 1 MHz sont couvertes par l'IEC 62127-2 [2]. Les étalonnages en pression basse fréquence des hydrophones sont exclus du domaine d'application du présent document. Ils sont décrits dans l'IEC 60565-2 [1]. Sont également exclus les étalonnages des hydrophones et systèmes numériques, des enregistreurs acoustiques marins autonomes, des capteurs vectoriels acoustiques (capteurs de vitesse de particules et hydrophones à gradient de pression, par exemple), des réseaux sonars passifs composés de plusieurs hydrophones et des réseaux sonars actifs composés de projecteurs et d'hydrophones. Le présent document donne une description des exigences relatives à l'étalonnage en champ libre en ce qui concerne l'installation, le matériel et les appareils d'essai, le traitement du signal et les limites de fréquence. Une description de l'incertitude pouvant être obtenue et les règles de présentation des données d'étalonnage sont fournies. Sont également incluses des annexes informatives donnant des recommandations supplémentaires • relatives au mesurage de la réponse directionnelle d'un hydrophone ou d'un projecteur, • relatives au mesurage de l'impédance électrique des hydrophones et des projecteurs, • sur les corrections de charge électrique, • relatives aux critères de champ acoustique lointain dans l'étalonnage acoustique sous-marin, • relatives aux techniques par impulsions dans les étalonnages en champ libre, • relatives à l'évaluation de l'incertitude dans l'étalonnage en champ libre des hydrophones et des projecteurs, • sur la déduction des formules pour les étalonnages par réciprocité d'onde sphérique à trois transducteurs, • relatives à l'étalonnage à l'aide de tubes à ondes progressives, • relatives à l'étalonnage des hydrophones par interférométrie optique, et • relatives à l'étalonnage dans des cuves d'eau réverbérées à l'aide de signaux continus. L'IEC 60565-1:2020 avec l’IEC 60565-2:2019, annule et remplace la deuxième édition de l’IEC 60565 parue en 2006. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: 1) suppression de toutes les descriptions des mét

Podvodna akustika - Hidrofoni - Kalibracija hidrofonov - 1. del: Postopki za kalibracijo hidrofonov v odprtem prostoru (IEC 60565-1:2020)

General Information

Status
Published
Publication Date
21-Jul-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jul-2020
Due Date
05-Sep-2020
Completion Date
22-Jul-2020

RELATIONS

Buy Standard

Standard
SIST EN IEC 60565-1:2020 - BARVE na PDF-str 71,86
English language
92 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN IEC 60565-1:2020
01-oktober-2020
Nadomešča:
SIST EN 60565:2008
Podvodna akustika - Hidrofoni - Kalibracija hidrofonov - 1. del: Postopki za
kalibracijo hidrofonov v odprtem prostoru (IEC 60565-1:2020)

Underwater acoustics - Hydrophones - Calibration of hydrophones - Part 1: Procedures

for free-field calibration of hydrophones (IEC 60565-1:2020)

Wasserschall - Hydrophone - Kalibrierung von Hydrophonen - Teil 1: Verfahren für die

Freifeldkalibrierung von Hydrophonen (IEC 60565-1:2020)
Acoustique sous-marine - Hydrophones - Étalonnage des hydrophones - Partie 1:
Procédures d'étalonnage en champ libre des hydrophones (IEC 60565-1:2020)
Ta slovenski standard je istoveten z: EN IEC 60565-1:2020
ICS:
17.140.50 Elektroakustika Electroacoustics
SIST EN IEC 60565-1:2020 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN IEC 60565-1:2020
---------------------- Page: 2 ----------------------
SIST EN IEC 60565-1:2020
EUROPEAN STANDARD EN IEC 60565-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2020
ICS 17.140.50 Supersedes EN 60565:2007 (partially)
and all of its amendments and corrigenda (if any)
English Version
Underwater acoustics - Hydrophones - Calibration of
hydrophones - Part 1: Procedures for free-field calibration of
hydrophones
(IEC 60565-1:2020)

Acoustique sous-marine - Hydrophones - Étalonnage des Wasserschall - Hydrophone - Kalibrierung von

hydrophones - Partie 1: Procédures d'étalonnage en champ Hydrophonen - Teil 1: Verfahren für die Freifeldkalibrierung

libre des hydrophones von Hydrophonen
(IEC 60565-1:2020) (IEC 60565-1:2020)

This European Standard was approved by CENELEC on 2020-05-29. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the

Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 60565-1:2020 E
---------------------- Page: 3 ----------------------
SIST EN IEC 60565-1:2020
EN IEC 60565-1:2020 (E)
European foreword

The text of document 87/708/CDV, future edition 1 of IEC 60565-1, prepared by IEC/TC 87

"Ultrasonics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN IEC 60565-1:2020.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2021-03-01

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2023-05-29

document have to be withdrawn

This document supersedes (partially) EN 60565:2007 and all of its amendments and corrigenda (if

any).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 60565-1:2020 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards

indicated:
IEC 60565-2 NOTE Harmonized as EN IEC 60565-2
IEC 62127-2 NOTE Harmonized as EN 62127-2
---------------------- Page: 4 ----------------------
SIST EN IEC 60565-1:2020
EN IEC 60565-1:2020 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments)

applies.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-801 - International Electrotechnical Vocabulary - - -
Chapter 801: Acoustics and electroacoustics
IEC 60500 2017 Underwater acoustics - Hydrophones - EN 60500 2017
Properties of hydrophones in the frequency
range 1 Hz to 500 kHz
---------------------- Page: 5 ----------------------
SIST EN IEC 60565-1:2020
---------------------- Page: 6 ----------------------
SIST EN IEC 60565-1:2020
IEC 60565-1
Edition 1.0 2020-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Underwater acoustics – Hydrophones – Calibration of hydrophones –
Part 1: Procedures for free-field calibration of hydrophones
Acoustique sous-marine – Hydrophones – Étalonnage des hydrophones –
Partie 1: Procédures d'étalonnage en champ libre des hydrophones
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-8039-3

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN IEC 60565-1:2020
– 2 – IEC 60565-1:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 7

INTRODUCTION ..................................................................................................................... 9

1 Scope ............................................................................................................................ 10

2 Normative references .................................................................................................... 11

3 Terms and definitions .................................................................................................... 11

4 Symbols and abbreviated terms ..................................................................................... 16

5 General procedures for calibration ................................................................................. 17

5.1 General alibration requirements ............................................................................ 17

5.1.1 Types of calibration ....................................................................................... 17

5.1.2 Acoustic field requirements ............................................................................ 18

5.2 Acoustic free-field requirements ............................................................................ 18

5.2.1 Continuous signals ........................................................................................ 18

5.2.2 Time-limited signals ....................................................................................... 18

5.3 Acoustic far-field requirements .............................................................................. 18

5.4 Requirements for steady-state conditions.............................................................. 19

5.5 Equipment requirements ....................................................................................... 20

5.5.1 Calibration facility .......................................................................................... 20

5.5.2 Instrumentation .............................................................................................. 20

5.6 Positioning and alignment ..................................................................................... 22

5.6.1 Coordinate system ......................................................................................... 22

5.6.2 Reference direction ....................................................................................... 22

5.6.3 Transducer mounting and support .................................................................. 22

5.6.4 Alignment ...................................................................................................... 23

5.6.5 Separation distance ....................................................................................... 23

5.7 Representation of the frequency response ............................................................ 23

5.8 Frequency limitations ............................................................................................ 24

5.8.1 High-frequency limit ....................................................................................... 24

5.8.2 Low-frequency limit ........................................................................................ 24

5.9 Checks for acoustic interference ........................................................................... 24

6 Electrical measurements................................................................................................ 25

6.1 Signal type ............................................................................................................ 25

6.2 Electrical earthing ................................................................................................. 25

6.3 Measurement of hydrophone output voltage .......................................................... 25

6.3.1 General ......................................................................................................... 25

6.3.2 Signal analysis .............................................................................................. 26

6.3.3 Electrical loading by measuring instruments .................................................. 26

6.3.4 Electrical loading by extension cables ........................................................... 26

6.3.5 Electrical noise .............................................................................................. 26

6.3.6 Cross-talk ...................................................................................................... 27

6.3.7 Integral preamplifiers ..................................................................................... 27

6.4 Measurement of projector drive current ................................................................. 27

6.4.1 Instrumentation .............................................................................................. 27

6.4.2 Signal analysis .............................................................................................. 27

6.5 Measurement of projector drive voltage ................................................................ 28

6.5.1 Instrumentation .............................................................................................. 28

6.5.2 Signal analysis .............................................................................................. 28

---------------------- Page: 8 ----------------------
SIST EN IEC 60565-1:2020
IEC 60565-1:2020 © IEC 2020 – 3 –

7 Preparation and conditioning of transducers .................................................................. 28

7.1 Soaking ................................................................................................................ 28

7.2 Wetting ................................................................................................................. 28

7.3 Extending the hydrophone cable ........................................................................... 29

7.4 Environmental conditions (temperature and depth) ............................................... 29

8 Free-field three-transducer spherical-wave reciprocity calibration .................................. 29

8.1 General principle .................................................................................................. 29

8.2 Calibration to determine sensitivity modulus (without phase) ................................. 30

8.2.1 Acoustic field requirements ............................................................................ 30

8.2.2 Separation distance ....................................................................................... 30

8.2.3 Transducer preparation, mounting and alignment .......................................... 31

8.2.4 Signal type .................................................................................................... 31

8.2.5 Measurement of electrical transfer impedance ............................................... 31

8.2.6 Calculation of the receive sensitivities ........................................................... 31

8.2.7 Calculation of the transmit sensitivities .......................................................... 32

8.2.8 Repeatability ................................................................................................. 32

8.2.9 Verification and checks .................................................................................. 32

8.2.10 Uncertainty .................................................................................................... 34

8.3 Calibration to determine phase of the hydrophone sensitivity ................................ 34

8.3.1 General principle ........................................................................................... 34

8.3.2 Transducer preparation ................................................................................. 35

8.3.3 Acoustic field requirements ............................................................................ 36

8.3.4 Signal type .................................................................................................... 36

8.3.5 Transducer mounting and alignment .............................................................. 36

8.3.6 Measurement of electrical transfer impedance ............................................... 36

8.3.7 Calculation of sensitivity phase angle ............................................................ 36

8.3.8 Repeatability ................................................................................................. 37

8.3.9 Verification and checking ............................................................................... 37

8.3.10 Uncertainty .................................................................................................... 37

9 Free-field calibration by comparison with an acoustic reference device.......................... 37

9.1 Principles .............................................................................................................. 37

9.2 Types of comparison calibration method ............................................................... 38

9.2.1 Hydrophone calibration using a calibrated reference hydrophone .................. 38

9.2.2 Hydrophone calibration using calibrated reference projector .......................... 38

9.2.3 Projector calibration using a calibrated reference hydrophone ....................... 38

9.3 Hydrophone calibration by comparison with a reference hydrophone .................... 38

9.3.1 Acoustic field requirements ............................................................................ 38

9.3.2 Separation distance ....................................................................................... 38

9.3.3 Transducer preparation, mounting and alignment .......................................... 39

9.3.4 Signal type .................................................................................................... 39

9.3.5 Measurement of electrical voltage ................................................................. 39

9.3.6 Free-field sensitivity ...................................................................................... 39

9.3.7 Repeatability ................................................................................................. 39

9.3.8 Verification and checks .................................................................................. 40

9.3.9 Uncertainty .................................................................................................... 40

9.4 Hydrophone calibration using a calibrated projector .............................................. 40

9.4.1 Acoustic field requirements ............................................................................ 40

9.4.2 Separation distance ....................................................................................... 40

9.4.3 Transducer preparation, mounting and alignment .......................................... 41

---------------------- Page: 9 ----------------------
SIST EN IEC 60565-1:2020
– 4 – IEC 60565-1:2020 © IEC 2020

9.4.4 Signal type .................................................................................................... 41

9.4.5 Measurement of electrical transfer impedance ............................................... 41

9.4.6 Calculation of the receive sensitivities ........................................................... 41

9.4.7 Repeatability ................................................................................................. 41

9.4.8 Verification and checks .................................................................................. 42

9.4.9 Uncertainty .................................................................................................... 42

9.5 Projector calibration using a calibrated hydrophone .............................................. 42

9.5.1 Acoustic field requirements ............................................................................ 42

9.5.2 Separation distance ....................................................................................... 42

9.5.3 Transducer preparation, mounting and alignment .......................................... 42

9.5.4 Signal type .................................................................................................... 43

9.5.5 Measurement of electrical transfer impedance ............................................... 43

9.5.6 Calculation of the transmit sensitivity ............................................................. 43

9.5.7 Verification and checks .................................................................................. 43

9.5.8 Uncertainty .................................................................................................... 44

10 Reporting of results ....................................................................................................... 44

10.1 Sensitivity ............................................................................................................. 44

10.2 Sensitivity level ..................................................................................................... 44

10.3 Calibration uncertainties ....................................................................................... 45

10.4 Auxiliary metadata ................................................................................................ 45

11 Recalibration periods ..................................................................................................... 45

Annex A (informative) Directional response of a hydrophone or projector ............................. 46

A.1 General principle .................................................................................................. 46

A.2 Types of measurement implementation ................................................................. 46

A.3 Coordinate system ................................................................................................ 46

A.4 Acoustic field requirements ................................................................................... 47

A.5 Positioning and alignment ..................................................................................... 47

A.6 Signal type ............................................................................................................ 47

A.7 Measurement of transducer directional response .................................................. 47

A.7.1 Projector ........................................................................................................ 47

A.7.2 Hydrophone ................................................................................................... 47

A.8 Calculation of the directional response level (angular deviation loss) .................... 47

A.9 Uncertainty ........................................................................................................... 48

A.10 Graphic representation ......................................................................................... 48

A.11 Directivity factor .................................................................................................... 49

A.12 Directivity index .................................................................................................... 49

Annex B (informative) Measurement of electrical impedance of hydrophones and

projectors ............................................................................................................................. 50

B.1 General principles ................................................................................................. 50

B.2 Measurement of electrical impedance ................................................................... 50

B.3 Derivation of other electrical impedance parameters ............................................. 51

B.4 Graphical representation ....................................................................................... 52

Annex C (informative) Calculation of electrical loading corrections ....................................... 54

C.1 Electrical loading corrections ................................................................................ 54

C.2 Corrections for amplifier loading using complex electrical impedance ................... 54

C.3 Corrections for loading caused by extension cables (using complex electrical

impedance) ........................................................................................................... 54

C.4 Corrections using only capacitances ..................................................................... 55

Annex D (informative) Acoustic far-field criteria in underwater acoustic calibration .............. 56

---------------------- Page: 10 ----------------------
SIST EN IEC 60565-1:2020
IEC 60565-1:2020 © IEC 2020 – 5 –

D.1 General ................................................................................................................. 56

D.2 The field for piston transducers ............................................................................. 56

D.3 Criteria for far-field conditions ............................................................................... 57

D.4 Far-field criteria in directional response measurements......................................... 58

Annex E (informative) Pulsed techniques in free-field calibrations ........................................ 59

E.1 General ................................................................................................................. 59

E.2 Echo-free time ...................................................................................................... 59

E.3 Minimum separation distance ................................................................................ 61

E.4 Turn-on transients ................................................................................................. 61

E.5 Bandwidth considerations ..................................................................................... 62

E.6 Electrical cross-talk ............................................................................................... 63

E.7 Pulse duration ....................................................................................................... 63

E.8 Reverberation and pulse repetition rate ................................................................ 63

E.9 Typical tank dimensions ........................................................................................ 63

E.10 Spherical-wave conditions .................................................................................... 64

E.11 Reflections from mounting poles and rigging ......................................................... 64

E.12 Analysis methods for tone-burst signals ................................................................ 64

E.13 High-frequency limitations ..................................................................................... 65

E.14 Low-frequency limitations...................................................................................... 66

E.15 Advanced techniques for extending the frequency range beyond the low-

frequency limit ...................................................................................................... 67

Annex F (informative) Assessment of uncertainty in the calibration of hydrophones

and projectors ....................................................................................................................... 69

F.1 General ................................................................................................................. 69

F.2 Type A evaluation of uncertainty ........................................................................... 69

F.3 Type B evaluation of uncertainty ........................................................................... 69

F.4 Reported uncertainty ............................................................................................. 69

F.5 Common sources of uncertainty ............................................................................ 70

Annex G (informative) Derivation of the formulae for three-transducer spherical-wave

reciprocity calibration ............................................................................................................ 72

G.1 General ................................................................................................................. 72

G.2 Calibration to determine the modulus of the sensitivity .......................................... 72

G.3 Calibration to determine the complex sensitivity .................................................... 74

Annex H (informative) Calibration using travelling-wave tubes ............................................. 77

H.1 General ................................................................................................................. 77

H.2 Calibration procedure ............................................................................................ 77

H.3 Limitations of the method ...................................................................................... 77

H.4 Extensions of the method ...................................................................................... 78

Annex I (informative) Calibration of hydrophones using optical interferometry ...................... 79

I.1 General ................................................................................................................. 79

I.2 General principles ................................................................................................. 79

I.3 Procedure ............................................................................................................. 79

I.4 Discussion of method ............................................................................................ 80

Annex J (informative) Calibration in a reverberant water tanks using continuous

signals .................................................................................................................................. 81

J.1 General principle .................................................................................................. 81

J.2 Using a noise signal .............................................................................................. 82

J.3 Using the LFM signal ............................................................................................ 82

J.4 Uncertainties......................................................................................................... 83

---------------------- Page: 11 -------------------
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.