Underwater acoustics - Hydrophones - Calibration of hydrophones - Part 2: Procedures for low frequency pressure calibration

IEC 60565-2:2019 specifies the methods for low frequency pressure calibration of hydrophones at frequencies from 0,01 Hz to several kilohertz depending on calibration method.
IEC 60565-2:2019, together with IEC 60565-1, replaces the second edition of IEC 60565 published in 2006. This edition constitutes a technical revision.
IEC 60565-2:2019 includes the following significant technical changes with respect to the previous edition.
1) IEC 60565 has been divided into two parts:
• Part 1: Procedures for free-field calibration;
• Part 2: Procedures for low frequency pressure calibration (this document).
2) A relative calibration method has been added to Clause 8: Calibration by piezoelectric compensation.
3) A relative calibration method has been added to Clause 11: Calibration by vibrating column.
4) Clause 12: Calibration by static pressure transducer, has been added.
5) Annex A: Equivalent circuit of the excitation system for calibration with a vibrating column, has been deleted.
6) Subclauses 9.6, 9.7 and 9.8 have been moved to form a new Annex A: Advanced acoustic coupler calibration methods.

Acoustique sous-marine – Hydrophones – Étalonnage des hydrophones - Partie 2: Procédures pour l'étalonnage à basse pression de fréquence

L’IEC 60565-2:2019 spécifie les méthodes d’étalonnage à basse pression de fréquence des hydrophones à des fréquences comprises entre 0,01 Hz et plusieurs kilohertz selon la méthode d’étalonnage.
L’IEC 60565-2:2019, avec l’IEC 60565-1, remplace la deuxième édition de l’IEC 60565 parue en 2006. Cette édition constitue une révision technique.
L’IEC 60565-2:2019 inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
1) L’IEC 60565 a été divisée en deux parties:
• Partie 1: Procédures pour l’étalonnage en champ libre;
• Partie 2: Procédures pour l’étalonnage à basse pression de fréquence (le présent document).
2) Une méthode d’étalonnage relatif a été ajoutée à l’Article 8: Étalonnage par compensation piézoélectrique.
3) Une méthode d’étalonnage relatif a été ajoutée à l’Article 11: Etalonnage par colonne vibrante.
4) L’Article 12: Etalonnage par transducteur de pression statique a été ajouté.
5) L’Annexe A: Circuit équivalent du système d’excitation pour l’étalonnage avec une colonne vibrante, a été supprimée.
6) Les paragraphes 9.6, 9.7 et 9.8 ont été déplacés pour constituer une nouvelle Annexe A: Méthodes d’étalonnage par coupleur acoustique évolué.

General Information

Status
Published
Publication Date
18-Sep-2019
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
19-Sep-2019
Ref Project

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IEC 60565-2
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Underwater acoustics – Hydrophones – Calibration of hydrophones –
Part 2: Procedures for low frequency pressure calibration
Acoustique sous-marine – Hydrophones – Étalonnage des hydrophones –
Partie 2: Procédures pour l’étalonnage à basse pression de fréquence
IEC 60565-2:2019-09(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60565-2
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Underwater acoustics – Hydrophones – Calibration of hydrophones –
Part 2: Procedures for low frequency pressure calibration
Acoustique sous-marine – Hydrophones – Étalonnage des hydrophones –
Partie 2: Procédures pour l’étalonnage à basse pression de fréquence
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-7346-3

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: 3 ----------------------
– 2 – IEC 60565-2:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 5

INTRODUCTION ..................................................................................................................... 7

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 Symbols ........................................................................................................................ 12

5 Procedures for calibration .............................................................................................. 13

5.1 Principles .............................................................................................................. 13

5.2 Field limitations ..................................................................................................... 14

5.3 Schematic survey of procedures ........................................................................... 14

5.4 Reporting of results ............................................................................................... 14

5.5 Recalibration periods ............................................................................................ 15

5.6 Temperature and pressure considerations for calibration ...................................... 15

5.7 Preparation of transducers .................................................................................... 15

6 Electrical measurements................................................................................................ 15

6.1 Signal type ............................................................................................................ 15

6.2 Earthing ................................................................................................................ 15

6.3 Measurement of hydrophone output voltage .......................................................... 15

6.3.1 General ......................................................................................................... 15

6.3.2 Electrical loading by measuring instrument .................................................... 15

6.3.3 Electrical loading by extension cable ............................................................. 16

6.3.4 Cross-talk and acoustic interference .............................................................. 16

6.3.5 Integral pre-amplifier ..................................................................................... 16

6.4 Measurement of projector current ......................................................................... 16

7 Calibration by hydrostatic excitation .............................................................................. 16

7.1 General ................................................................................................................. 16

7.2 Principle ............................................................................................................... 16

7.2.1 Determination of the alternating pressure ...................................................... 16

7.2.2 Determination of the correction factor ............................................................ 18

7.2.3 Determination of the equivalent height ........................................................... 18

7.2.4 Calculation of the pressure sensitivity of hydrophone ..................................... 20

7.3 Design of vibration system .................................................................................... 20

7.4 Alternative method for hydrostatic excitation ......................................................... 20

7.5 Uncertainty ........................................................................................................... 21

8 Calibration by piezoelectric compensation ..................................................................... 21

8.1 General ................................................................................................................. 21

8.2 Principle ............................................................................................................... 21

8.2.1 Determination of the sound pressure ............................................................. 21

8.2.2 Determination of the characteristic constant .................................................. 22

8.2.3 Calculation of the pressure sensitivity of hydrophone ..................................... 23

8.3 Design of the calibration chamber ......................................................................... 23

8.3.1 General ......................................................................................................... 23

8.3.2 Low frequency chamber ................................................................................. 23

8.3.3 High frequency chamber ................................................................................ 23

8.4 Practical limitations of the piezoelectric compensation method ............................. 24

8.5 Relative calibration method ................................................................................... 24

---------------------- Page: 4 ----------------------
IEC 60565-2:2019 © IEC 2019 – 3 –

8.6 Uncertainty ........................................................................................................... 25

9 Calibration by acoustic coupler reciprocity ..................................................................... 25

9.1 General ................................................................................................................. 25

9.2 Principle ............................................................................................................... 25

9.2.1 Theory of acoustic coupler reciprocity ............................................................ 25

9.2.2 Procedures for the reciprocity calibration ....................................................... 26

9.2.3 Calculation of transfer impedance .................................................................. 27

9.2.4 Determination of acoustic compliance ............................................................ 27

9.3 Limitation of acoustic coupler reciprocity ............................................................... 27

9.3.1 Frequency limit .............................................................................................. 27

9.3.2 Hydrophone limit............................................................................................ 28

9.4 Measurement ........................................................................................................ 28

9.4.1 General ......................................................................................................... 28

9.4.2 Evidence of interference effects ..................................................................... 28

9.4.3 Reciprocity verification .................................................................................. 28

9.4.4 Linearity verification ...................................................................................... 29

9.5 Uncertainty ........................................................................................................... 29

10 Calibration by pistonphone ............................................................................................ 29

10.1 General ................................................................................................................. 29

10.2 Principle ............................................................................................................... 29

10.2.1 Determination of the sound pressure ............................................................. 29

10.2.2 Determination of the compliance of the medium ............................................. 30

10.2.3 Calculation of the pressure sensitivity ............................................................ 30

10.3 Limitations ............................................................................................................ 30

10.4 Relative calibration ............................................................................................... 31

10.4.1 Comparison with a reference transducer ........................................................ 31

10.4.2 Comparison using air–water pistonphone ...................................................... 31

10.5 Uncertainty ........................................................................................................... 32

11 Calibration by vibrating column ...................................................................................... 32

11.1 General ................................................................................................................. 32

11.2 Principle ............................................................................................................... 32

11.2.1 General ......................................................................................................... 32

11.2.2 Expression for the pressure ........................................................................... 33

11.2.3 Determination of the sensitivity ...................................................................... 34

11.3 Conditions of measurement .................................................................................. 35

11.3.1 Mechanical .................................................................................................... 35

11.3.2 Acoustical ...................................................................................................... 36

11.4 Relative calibration method ................................................................................... 36

11.5 Uncertainty ........................................................................................................... 37

12 Calibration by static pressure transducer ....................................................................... 37

12.1 General ................................................................................................................. 37

12.2 Principle ............................................................................................................... 38

12.2.1 Theory of static pressure calibration .............................................................. 38

12.2.2 Determination of the sensitivity of static pressure transducer ......................... 38

12.2.3 Calculation of the pressure sensitivity ............................................................ 39

12.3 Limitations ............................................................................................................ 39

12.4 Uncertainty ........................................................................................................... 39

Annex A (informative) Advanced acoustic coupler calibration methods ................................. 40

---------------------- Page: 5 ----------------------
– 4 – IEC 60565-2:2019 © IEC 2019

A.1 General ................................................................................................................. 40

A.2 Acoustic-coupler calibration using a reference coupler with two reciprocal
transducers and an auxiliary coupler with the same two transducers and a

hydrophone to be calibrated .................................................................................. 41

A.2.1 General ......................................................................................................... 41

A.2.2 Theory ........................................................................................................... 42

A.3 Acoustic-coupler calibration using a reference coupler with two reciprocal
transducers and an auxiliary coupler with the same two transducers, a

hydrophone to be calibrated, and a sound source ................................................. 43

A.3.1 General ......................................................................................................... 43

A.3.2 Theory ........................................................................................................... 44

A.4 Acoustic-coupler calibration using a coupler, a reciprocal transducer, a
projector, a hydrophone to be calibrated, and a subsidiary body of known

compliance ........................................................................................................... 45

A.4.1 General ......................................................................................................... 45

A.4.2 Theory ........................................................................................................... 45

Annex B (informative) Assessment of uncertainty in the low frequency pressure

calibration of hydrophone .............................................................................................. 48

B.1 General ................................................................................................................. 48

B.2 Type A evaluation of uncertainty ........................................................................... 48

B.3 Type B evaluation of uncertainty ........................................................................... 48

B.4 Reported uncertainty ............................................................................................. 48

B.5 Common sources of uncertainty ............................................................................ 49

Bibliography .......................................................................................................................... 51

Figure 1 – Diagram of calibration by hydrostatic excitation .................................................... 17

Figure 2 – Schematic drawing of calibration by piezoelectric compensation .......................... 22

Figure 3 – Diagram of the chamber for high frequency .......................................................... 24

Figure 4 – Reciprocity coupler with three transducers: a projector P, a reciprocal

transducer T, and a hydrophone H to be calibrated ............................................................... 26

Figure 5 – Comparison calibration using pistonphone with calibrated hydrophone ................. 32

Figure 6 – Diagram of calibration by vibrating column ........................................................... 33

Figure 7 – Diagram of calibration by vibrating column using comparison ............................... 37

Figure 8 –Diagram of comparison calibration using static pressure transducer ...................... 38

Figure A.1 – Reference coupler with two transducers: a projector P and a reciprocal

transducer T ......................................................................................................................... 42

Figure A.2 – Auxiliary coupler with three transducers: a projector P, a reciprocal

transducer T and a hydrophone H to be calibrated ................................................................ 42

Figure A.3 – Auxiliary coupler with four transducers: a projector P, a reciprocal

transducer T, a sound source S and a hydrophone H to be calibrated ................................... 44

Figure A.4 – Schematic drawing of the measuring system ..................................................... 46

---------------------- Page: 6 ----------------------
IEC 60565-2:2019 © IEC 2019 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UNDERWATER ACOUSTICS – HYDROPHONES –
CALIBRATION OF HYDROPHONES –
Part 2: Procedures for low frequency pressure calibration
FOREWORD

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International Standard IEC 60565-2 has been prepared by IEC technical committee 87:

Ultrasonics.

This first edition of IEC 60565-2, together with IEC 60565-1, replaces the second edition of

IEC 60565 published in 2006. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition.
1) IEC 60565 has been divided into two parts:
• Part 1: Procedures for free-field calibration;
• Part 2: Procedures for low frequency pressure calibration (this document).

2) A relative calibration method has been added to Clause 8: Calibration by piezoelectric

compensation.
---------------------- Page: 7 ----------------------
– 6 – IEC 60565-2:2019 © IEC 2019

3) A relative calibration method has been added to Clause 11: Calibration by vibrating

column.
4) Clause 12: Calibration by static pressure transducer, has been added.

5) Annex A: Equivalent circuit of the excitation system for calibration with a vibrating

column, has been deleted.

6) Subclauses 9.6, 9.7 and 9.8 have been moved to form a new Annex A: Advanced acoustic

coupler calibration methods.
The text of this International Standard is based on the following documents:
FDIS Report on voting
87/720/FDIS 87/723/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

NOTE Words in bold in the text are terms defined in Clause 3.

A list of all parts in the IEC 60565 series, published under the general title Underwater

acoustics – Hydrophones – Calibration of hydrophones, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 8 ----------------------
IEC 60565-2:2019 © IEC 2019 – 7 –
INTRODUCTION

The purpose of this document is to establish the procedures for low frequency pressure

calibrations of hydrophones in the frequency range from 0,01 Hz to several kilohertz.

To ensure the correctness of the calibrations, the hydrophones to be calibrated are "rigid"

hydrophones with small size compared to the acoustic wavelength, and are not sensitive to

vibration when calibrated.

Principles, procedures, and uncertainties of physical calibrations such as hydrostatic

excitation, piezoelectric compensation, pistonphone, vibrating column, static pressure

transducer, etc., and reciprocity calibrations in acoustic couplers are given in this document.

Calibrations are carried out using one of these methods, depending on the different principles

to be used, and its limitations to the sound field and the frequency range.
---------------------- Page: 9 ----------------------
– 8 – IEC 60565-2:2019 © IEC 2019
UNDERWATER ACOUSTICS – HYDROPHONES –
CALIBRATION OF HYDROPHONES –
Part 2: Procedures for low frequency pressure calibration
1 Scope

This part of IEC 60565 specifies the methods for low frequency pressure calibration of

hydrophones at frequencies from 0,01 Hz to several kilohertz depending on calibration

method.
2 Normative references

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.

IEC 60050-801, International Electrotechnical Vocabulary – Chapter 801: Acoustics and

electroacoustics (available at http://www.electropedia.org/)

IEC 60500:2017, Underwater acoustics – Hydrophones – Properties of the hydrophone in the

frequency range 1 Hz to 500 kHz
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-801,

IEC 60500:2017 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
...

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