EN IEC 60565-1:2020
(Main)Underwater acoustics - Hydrophones - Calibration of hydrophones - Part 1: Procedures for free-field calibration of hydrophones
Underwater acoustics - Hydrophones - Calibration of hydrophones - Part 1: Procedures for free-field calibration of hydrophones
IEC 60565-1:2020 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 three-transducer 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] . 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. IEC 60565-1:2020 together with IEC 60565-2:2019, cancels and 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) removal of all descriptions of methods for pressure calibrations of hydrophones – these are now included in Part 2; 2) removal of the derivations of formulae for free-field reciprocity calibration (both amplitude sensitivity and phase sensitivity) and placement of these into an informative annex; 3) inclusion within the scope of the calibration of the transmitting response of individual source transducers and hydrophones (but not sonar arrays); 4) re-ordering of the sections within the document such that the more general procedures for calibration such as guidance on obtaining conditions of acoustic free-field, far-field, and stea
Wasserschall - Hydrophone - Kalibrierung von Hydrophonen - Teil 1: Verfahren für die Freifeldkalibrierung von Hydrophonen
Acoustique sous-marine - Hydrophones - Étalonnage des hydrophones - Partie 1: Procédures d'étalonnage en champ libre des hydrophones
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
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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
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
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
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
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
– 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
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
– 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
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
– 6 – IEC 60565-1:2020 © IEC 2020
Bibliography . 84
Figure 1 – Measurement configurations for three-transducer reciprocity . 30
Figure 2 – Measurement framework for supporting in-line the three transducers: a
projector P, a reciprocal transducer T, and a hydrophone H to be calibrated . 35
Figure A.1 – Examples of graphical representations of the level of the directional
response: polar plot (left) and Cartesian plot (right) . 48
Figure B.1 – Examples of plots of transducer electrical impedance for a small
spherical hydrophone of capacitance 3 nF . 53
Figure D.1 – Acoustic pressure as a function of range from the source for a point
source and for a piston source of dimensions ka = 10 . 56
Figure D.2 – Difference in measured acoustic pressure on axis compared to spherical
spreading measured by a point receiver and a piston receiver . 57
Figure E.1 – Schematic diagram of a projector and receiver in a water tank showing
the main sources of reflections . 60
Figure E.2 – Echo arrival time in a 6 m × 6 m × 5 m tank with optimally placed
transducers . 61
Figure E.3 – Hydrophone signals for a pair of spherical transducers (projector: 18 kHz
resonance frequency, Q-factor of 3,5; hydrophone: 350 kHz resonance frequency;
drive frequency: 2 kHz (left) and 18 kHz (right)) . 62
Figure E.4 – Examples of acoustic waveforms showing time-windows for analysis . 65
Figure E.5 – Values for the sound absorption in pure water and sea water, including
contributions due to component factors . 66
Figure I.1 – Configurations for calibration of hydrophones using heterodyne optical
interferometry . 80
IEC 60565-1:2020 © IEC 2020 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UNDERWATER ACOUSTICS – HYDROPHONES –
CALIBRATION OF HYDROPHONES –
Part 1: Procedures for free-field calibration of hydrophones
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60565-1 has been prepared by IEC technical committee 87:
Ultrasonics.
This first edition of IEC 60565-1, together with IEC 60565-2, cancels and 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) removal of all descriptions of methods for pressure calibrations of hydrophones – these are
now included in Part 2;
2) removal of the derivations of formulae for free-field reciprocity calibration (both amplitude
sensitivity and phase sensitivity) and placement of these into an informative annex;
3) inclusion within the scope of the calibration of the transmitting response of individual source
transducers and hydrophones (but not sonar arrays);
4) re-ordering of the sections within the document such that the more general procedures for
calibration such as guidance on obtaining conditions of acoustic free-field, far-field, and
– 8 – IEC 60565-1:2020 © IEC 2020
steady-state, appear before the descriptions of procedures for absolute or relative
calibrations;
5) revision of informative Annex A to include guidance on measurement of directional response
of a hydrophone or projector;
6) addition of a new informative Annex B on measurement of electrical impedance of
hydrophones and projectors;
7) revision of the previous informative annex on electrical loading corrections to include
corrections to account for electrical loading by added cables (now Annex C);
8) addition of a new informative Annex D on acoustic far-field criteria in underwater acoustic
calibration;
9) revision of the previous informative annex on pulsed techniques in free-field calibrations
(now Annex E);
10) revision of the previous informative annex on assessment of uncertainty in the calibration
of hydrophones (now Annex F);
11) deletion of the previous informative annex on equivalent circuit of the excitation system for
calibration with a vibrating column;
12) addition of a new informative Annex G on derivation of the formulae for three-transducer
spherical-wave reciprocity calibration;
13) addition of a new informative Annex H on calibration using travelling-wave tubes;
14) addition of a new informative Annex I on calibration of hydrophones using optical
interferometry.
15) addition of a new informative Annex J on calibration in reverberant water tanks using
continuous signals.
The text of this standard is based on the following documents:
CDV Report on voting
87/708/CDV 87/736/RVC
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 that appear in bold in the text are terms explicitly 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
IEC 60565-1:2020 © IEC 2020 – 9 –
INTRODUCTION
Underwater acoustic measurements are made to provide validation and qualification in a wide
range of ocean applications, including oceanography, defence, fisheries, geophysics and in
developments in the off-shore energy industries. In addition, the increasing concern about the
effect of anthropogenic sound on the marine environment has led to regulation which requires
absolute acoustic measurement of the sound radiated by specific sources, and of the ambient
sound field.
To be meaningful, it is important that measurements be performed in a technically sound
manner, be related to common standards of measurement, and be made using calibrated
sensors. Hydrophones are the most commonly-used sensor to measure sound in the ocean. It
is important that the hydrophones used to measure sound pressure are calibrated using agreed
standard methodologies, with valid uncertainties.
The purpose of this document is to establish procedures for calibration under free-field
conditions of hydrophones used in underwater acoustics for ocean applications. Also covered
are calibration procedures for individual underwater electroacoustic transducers which can
be used as a hydrophone and/or source transducer. Principles, procedures, and sources of
uncertainty are also provided in this document. The calibration methods described include
absolute methods which do not require an acoustic reference transducer, and relative methods
which make use of a calibrated acoustic reference hydrophone or projector. The methods
described cover the frequency range from 200 Hz to 1 MHz.
– 10 – IEC 60565-1:2020 © IEC 2020
UNDERWATER ACOUSTICS – HYDROPHONES –
CALIBRATION OF HYDROPHONES –
Part 1: Procedures for free-field calibration of hydrophones
1 Scope
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 three-
transducer 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] . 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.
___________
Numbers in square brackets refer to the Bibliography.
IEC 60565-1:2020 © IEC 2020 – 11 –
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 refer
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