EN 62127-3:2007

Ultrasonics - Hydrophones - Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz

This part of IEC 62127 specifies relevant hydrophone characteristics. This standard is applicable to: - hydrophones employing piezoelectric sensor elements, designed to measure the pulsed and continuous wave ultrasonic fields generated by ultrasonic equipment; - hydrophones used for measurements made in water; - hydrophones with or without an associated pre-amplifier. IEC 62127-1, IEC 62127-2 and IEC 62127-3 are being published simultaneously. Together these cancel and replace IEC 60866:1987, IEC 61101:1991, IEC 61102:1991, IEC 61220:1993 and IEC 62092:2001.

Ultraschall - Hydrophone - Teil 3: Eigenschaften von Hydrophonen zur Verwendung in Ultraschallfeldern bis zu 40 MHz

Ultrasons - Hydrophones - Partie 3: Propriétés des hydrophones pour les champs ultrasonores jusqu'à 40 MHz

La CEI 62127-3:2007 spécifie les caractéristiques pertinentes de l'hydrophone. La présente norme s'applique aux hydrophones utilisant des capteurs piézoélectriques, conçus pour mesurer les champs ultrasoniques à ondes par impulsions et entretenues générés par les appareils à ultrasons; aux hydrophones utilisés pour les mesures réalisées dans l'eau; et aux hydrophones avec ou sans préamplificateur associé. La CEI 62127-1, la CEI 62127-2 et la CEI 62127-3 ont été publiées conjointement. Ensemble, elles annulent et remplacent la CEI 60866:1987, la CEI 61101:1991, la CEI 61102:1991, la CEI 61220:1993 et la CEI 62092:2001. La version française n'a pas été soumise au vote.

Ultrazvok - Hidrofoni - 3. del: Lastnosti hidrofonov za ultrazvočna polja do 40 MHz (IEC 62127-3:2007)

Ta del standarda IEC 62127 določa ustrezne lastnosti hidrofonov. Ta standard se uporablja za: a) hidrofone, ki uporabljajo piezoelektrične senzorne elemente in so zasnovani za merjenje ultrazvočnih polj z impulznimi in neprekinjenimi valovi, ki jih ustvari ultrazvočna oprema, b) hidrofone, ki se uporabljajo za izvajanje meritev v vodi, ter c) hidrofone s povezanim predojačevalnikom ali brez njega.

General Information

• Status: Published
• Publication Date: 04-Oct-2007
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: CLC/SR 87 - CLC/SR 87
• Drafting Committee: IEC/TC 87 - IEC_TC_87
• Parallel Committee: IEC/TC 87 - IEC_TC_87
• Current Stage: 6060 - Document made available
• Due Date: 05-Oct-2007
• Completion Date: 05-Oct-2007
• Ref Project: SIST EN 62127-3:2008 - Ultrasonics - Hydrophones -- Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz

RELATIONS

• Replaces: EN 62092:2001 - Ultrasonics - Hydrophones - Characteristics and calibration in the frequency range from 15 MHz to 40 MHz
• Effective Date: 13-May-2010
• Replaces: EN 61102:1993/A1:1994 - Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 13-May-2010
• Replaces: EN 61101:1993 - The absolute calibration of hydrophones using the planar scanning technique in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 13-May-2010
• Replaces: EN 61220:1995 - Ultrasonics - Fields - Guidance for the measurement and characterization of ultrasonic fields generated by medical ultrasonic equipment using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 13-May-2010
• Replaces: EN 61102:1993 - Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 13-May-2010
• Revised: EN 62092:2001 - Ultrasonics - Hydrophones - Characteristics and calibration in the frequency range from 15 MHz to 40 MHz
• Effective Date: 07-Sep-2010
• Revised: EN 61220:1995 - Ultrasonics - Fields - Guidance for the measurement and characterization of ultrasonic fields generated by medical ultrasonic equipment using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 07-Sep-2010
• Revised: EN 61102:1993 - Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 07-Sep-2010
• Revised: EN 61102:1993/A1:1994 - Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 07-Sep-2010
• Revised: EN 61101:1993 - The absolute calibration of hydrophones using the planar scanning technique in the frequency range 0,5 MHz to 15 MHz
• Effective Date: 07-Sep-2010
• Amended By: EN 62127-3:2007/A1:2013 - Ultrasonics - Hydrophones - Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
• Effective Date: 27-Sep-2011

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN 62127-3:2008
01-januar-2008
1DGRPHãþD
SIST EN 61101:2002
SIST EN 61102:2002
SIST EN 61102:2002/A1:2002
SIST EN 61220:2002
SIST EN 62092:2002

8OWUD]YRN+LGURIRQLGHO/DVWQRVWLKLGURIRQRY]DXOWUD]YRþQDSROMDGR0+]

,(&

Ultrasonics - Hydrophones - Part 3: Properties of hydrophones for ultrasonic fields up to

40 MHz (IEC 62127-3:2007)

Ultraschall - Hydrophone - Teil 3: Eigenschaften von Hydrophonen zur Verwendung in

Ultraschallfeldern bis zu 40 MHz (IEC 62127-3:2007)
Ultrasons - Hydrophones - Partie 3: Propriétés des hydrophones pour les champs
ultrasonores jusqu'a 40 Mhz (IEC 62127-3:2007)
Ta slovenski standard je istoveten z: EN 62127-3:2007
ICS:
11.040.01
17.140.50
SIST EN 62127-3:2008 en,de

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

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN 62127-3
NORME EUROPÉENNE
October 2007
EUROPÄISCHE NORM

ICS 17.140.50 Partially supersedes EN 61101:1993, EN 61102:1993 + A1:1994, EN 61220:1995 and EN 62092:2001

English version
Ultrasonics -
Hydrophones -
Part 3: Properties of hydrophones
for ultrasonic fields up to 40 MHz
(IEC 62127-3:2007)
Ultrasons - Ultraschall -
Hydrophones - Hydrophone -
Partie 3: Propriétés des hydrophones Teil 3: Eigenschaften von Hydrophonen
pour les champs ultrasonores zur Verwendung in Ultraschallfeldern
jusqu'à 40 Mhz bis zu 40 MHz
(CEI 62127-3:2007) (IEC 62127-3:2007)

This European Standard was approved by CENELEC on 2007-09-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

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

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62127-3:2007 E
---------------------- Page: 2 ----------------------
EN 62127-3:2007 - 2 -
Foreword

The text of document 87/354/CDV, future edition 1 of IEC 62127-3, prepared by IEC TC 87, Ultrasonics,

was submitted to the IEC-CENELEC parallel Unique Acceptance Procedure and was approved by

CENELEC as EN 62127-3 on 2007-09-01.

EN 62127-1, EN 62127-2 and EN 62127-3 are being published simultaneously. Together these European

Standards cancel and replace EN 61101:1993, EN 61102:1993 + A1:1994, EN 61220:1995 and

EN 62092:2001.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-06-01
– latest date by which the national standards conflicting
(dow) 2010-09-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 62127-3:2007 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following note has to be added for the standard indicated:

IEC 60565 NOTE Harmonized as EN 60565:2007 (not modified).
__________
---------------------- Page: 3 ----------------------
- 3 - EN 62127-3:2007
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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 When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
1) 2)
IEC 62127-1 - Ultrasonics - Hydrophones - EN 62127-1 2007
Part 1: Measurement and characterization
of medical ultrasonic fields up to 40 MHz
1) 2)
IEC 62127-2 - Ultrasonics - Hydrophones - EN 62127-2 2007
Part 2: Calibration for ultrasonic fields
up to 40 MHz
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
IEC 62127-3
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
Ultrasonics – Hydrophones –
Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 17.140.50 ISBN 2-8318-9278-3
---------------------- Page: 5 ----------------------
– 2 – 62127-3 © IEC:2007(E)
CONTENTS

FOREWORD...........................................................................................................................3

INTRODUCTION.....................................................................................................................5

1 Scope...............................................................................................................................6

2 Normative references........................................................................................................6

3 Terms, definitions and symbols .........................................................................................6

4 List of symbols..................................................................................................................8

5 Hydrophone characteristics...............................................................................................9

5.1 General ...................................................................................................................9

5.2 Basic information.....................................................................................................9

5.3 Sensitivity................................................................................................................9

5.4 Frequency response ..............................................................................................10

5.4.1 Stated frequency band ...............................................................................10

5.4.2 Frequency dependence..............................................................................10

5.5 Directional response ..............................................................................................11

5.5.1 General .....................................................................................................11

5.5.2 Symmetry of directional response...............................................................11

5.6 Effective radius......................................................................................................11

5.7 Dynamic range, linearity and electromagnetic interference .....................................12

5.8 Electric output characteristics ................................................................................13

5.8.1 General .....................................................................................................13

5.8.2 Hydrophone without pre-amplifier ...............................................................13

5.8.3 Hydrophone assembly................................................................................13

5.8.4 Output lead configuration ...........................................................................14

5.9 Environmental aspects...........................................................................................14

5.9.1 Temperature range ....................................................................................14

5.9.2 Water tightness .........................................................................................14

5.9.3 Water properties and incompatible materials ..............................................14

5.9.4 Exposed material .......................................................................................14

5.10 Guidance manual...................................................................................................14

5.11 List of hydrophone characteristics ..........................................................................14

Annex A (informative) Examples of information on hydrophone properties.............................16

Bibliography ..........................................................................................................................21

Figure A.1 – Frequency response of 0,2 mm needle hydrophone ...........................................17

Figure A.2 – Directional response of 0,2 mm needle hydrophone ...........................................18

Table A.1 – Example of basic information for 0,2 mm needle hydrophone assembly...............16

---------------------- Page: 6 ----------------------
62127-3 © IEC:2007(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – HYDROPHONES –
Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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 62127-3 has been prepared by IEC technical committee 87:

Ultrasonics

IEC 62127-1, IEC 62127-2 and IEC 62127-3 are being published simultaneously. Together

these cancel and replace IEC 60866:1987, IEC 61101:1991, IEC 61102:1991, IEC 61220:1993

and IEC 62092:2001.
The text of this standard is based on the following documents:
Enquiry draft Report on voting
87/354/CDV 87/373/RVC

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

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

---------------------- Page: 7 ----------------------
– 4 – 62127-3 © IEC:2007(E)

A list of all parts of IEC 62127 series, published under the general title Ultrasonics –

Hydrophones, can be found on the IEC website.
NOTE Words in bold in the text are defined in Clause 3.

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

maintenance result date indicated on the IEC website under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
---------------------- Page: 8 ----------------------
62127-3 © IEC:2007(E) – 5 –
INTRODUCTION

The spatial and temporal distribution of acoustic pressure in an ultrasonic field in a liquid

medium is commonly determined using miniature ultrasonic hydrophones. The properties of

these hydrophones have been dealt with in a number of IEC standards in various aspects.

The purpose of this part of IEC 62127 is to bring together all these specifications and to

establish a common standard on the properties of ultrasonic hydrophones. The main

hydrophone application in this context is the measurement of ultrasonic fields emitted by

medical diagnostic equipment in water. Other medical applications are field measurements for

therapy equipment such as that used in lithotripsy, high-intensity focused ultrasound (HIFU)

and physiotherapy. Hydrophones are also used extensively in non-medical applications for both

product development and quality control including:
– mapping of the ultrasound field within ultrasonic cleaning baths;

– characterization of acoustic fields used in transmission measurement systems (e.g.

ultrasonic spectrometers, ultrasonic attenuation meters and velocimeters);

– characterization of acoustic fields used in reflection measurement systems (e.g. Doppler

flowmeters).

While the term "hydrophone" can be used in a wider sense, it is understood here as referring

to miniature piezoelectric hydrophones. It is this instrument type that is used today in various

areas of ultrasonics and, in particular, to quantitatively characterize the field structure of

medical diagnostic instruments. With regard to other pressure sensor types, such as those

based on fibre optics, some of the requirements of this standard are applicable to these as well

but others are not. If in the future these other "hydrophone" types gain more importance in

field measurement practice, their properties will have to be dealt with in a revised version of

this standard or in a separate one.

Underwater hydrophones as covered by IEC 60500 and IEC 60565 are not included in this

standard, although there is an overlap in the frequency ranges. Underwater hydrophones are

used in natural waters, even in the ocean, and this leads to different technical concepts and

requirements. In addition, the main direction of acoustic incidence in underwater applications is

typically at right angles to the hydrophone axis, whereas it is assumed in this standard that it

is in the direction of the hydrophone axis.

In the past, ultrasonic hydrophones have been applied almost exclusively as amplitude

sensors. At present a change can be seen and it is increasingly considered useful to have

additional phase information, which, however, is only possible if the phase characteristics of

the hydrophone have been determined during calibration. In this standard, therefore,

requirements are specified for the amplitude aspect of the hydrophone sensitivity, and

recommendations are provided for the phase aspect, as an option to be considered.

---------------------- Page: 9 ----------------------
– 6 – 62127-3 © IEC:2007(E)
ULTRASONICS – HYDROPHONES –
Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
1 Scope
This part of IEC 62127 specifies relevant hydrophone characteristics.
This standard is applicable to:

– hydrophones employing piezoelectric sensor elements, designed to measure the pulsed

and continuous wave ultrasonic fields generated by ultrasonic equipment;
– hydrophones used for measurements made in water;
– hydrophones with or without an associated pre-amplifier.
2 Normative references

The following referenced documents are indispensable for the application 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 62127-1, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of

medical ultrasonic fields up to 40 MHz

IEC 62127-2, Ultrasonics – Hydrophones – Part 2: Calibration for ultrasonic fields up to 40 MHz

3 Terms, definitions and symbols

For the purposes of this document, the terms and definitions given in IEC 62127-1,

IEC 62127-2 and the following apply.
3.1
directional response

description, generally presented graphically, of the response of a hydrophone, as a function of

direction of propagation of the incident plane sound wave, in a specified plane through the

reference centre and at a specified frequency
NOTE Definition adopted from IEC 60565:2006.
3.2
effective hydrophone radius
a , a , a
h h3 h6

radius of a stiff disc receiver hydrophone that has a predicted directional response function

with an angular width equal to the observed angular width

NOTE 1 The angular width is determined at a specified level below the peak of the directional response function.

For the specified levels of 3 dB and 6 dB, the radii are denoted by a and a respectively.

h3 h6

NOTE 2 The radius is usually the function of frequency. For representative experimental data, see [1].

NOTE 3 The effective hydrophone radius is expressed in metres (m).
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62127-3 © IEC:2007(E) – 7 –
3.3
electric load impedance

complex electric input impedance (consisting of a real and an imaginary part) to which the

hydrophone or hydrophone assembly output is connected or is to be connected
NOTE The electric load impedance is expressed in ohms (Ω).
3.4
end-of-cable

specification that relates to the end of the integral output cable if the hydrophone or

hydrophone assembly is provided with such a cable; if the hydrophone or hydrophone

assembly is not provided with an integral output cable, the specification relates to the output

connector firmly connected with the hydrophone or hydrophone assembly, not to an extra

cable
3.5
end-of-cable loaded sensitivity
end-of-cable loaded sensitivity of a hydrophone or hydrophone assembly

ratio of the instantaneous voltage at the end of any integral cable or output connector of a

hydrophone or hydrophone assembly, when connected to a specified electric load

impedance, to the instantaneous acoustic pressure in the undisturbed free field of a plane

wave in the position of the reference centre of the hydrophone if the hydrophone were

removed
NOTE End-of-cable loaded sensitivity is expressed in volts per pascal (V/Pa).
3.6
end-of-cable open-circuit sensitivity
end-of-cable open-circuit sensitivity of a hydrophone

ratio of the instantaneous, open-circuit voltage at the end of any integral cable or output

connector of a hydrophone to the instantaneous acoustic pressure in the undisturbed free

field of a plane wave in the position of the reference centre of the hydrophone if the

hydrophone were removed

NOTE 1 End-of-cable open-circuit sensitivity is expressed in volts per pascal (V/Pa).

NOTE 2 This corresponds to the free field sensitivity as defined in IEC 60565:2006, 3.15.

3.7
free field

sound field in a homogeneous and isotropic medium in which the effects of boundaries are

negligible
NOTE Definition adopted from IEC 60565:2006, 3.13.
3.8
hydrophone geometrical radius
geometrical radius of a hydrophone active element
radius defined by the dimensions of the active element of a hydrophone
NOTE The hydrophone geometrical radius is expressed in metres (m).
3.9
hydrophone

transducer that produces electric signals in response to waterborne acoustic signals

[IEV 801-32-26]
---------------------- Page: 11 ----------------------
– 8 – 62127-3 © IEC:2007(E)
3.10
hydrophone assembly
combination of hydrophone and hydrophone pre-amplifier
3.11
hydrophone axis
nominal symmetry axis of the hydrophone active element

NOTE Unless stated otherwise (explicitly and quantitatively) by the manufacturer, it is understood for the purposes

of this standard that this is given by the apparent geometrical symmetry axis of the hydrophone.

3.12
hydrophone pre-amplifier

active electronic device connected to, or to be connected to, a particular hydrophone and

reducing its output impedance

NOTE 1 A hydrophone pre-amplifier requires a supply voltage (or supply voltages).

NOTE 2 The hydrophone pre-amplifier may have a forward voltage transmission factor of less than one, i.e. it

need not necessarily be a voltage amplifier in the strict sense.
3.13
reference centre

point on or near a hydrophone about which its acoustic receiving sensitivity is defined

NOTE 1 Unless stated otherwise (explicitly and quantitatively) by the manufacturer, it is understood for the

purposes of this standard that this is given by the geometrical centre of the front surface of the hydrophone active

element.
NOTE 2 Definition adopted from IEC 60565, 3.25.
3.14
uncertainty

parameter, associated with the result of a measurement, that characterizes the dispersion of

the values that could reasonably be attributed to the measurand

NOTE 1 See the ISO Guide to the Expression of Uncertainty in Measurement [2], 2.2.3

NOTE 2 Definition adopted from IEC 62127-1.
4 List of symbols
a hydrophone geometrical radius
a effective hydrophone radius (a , a : with special reference to a 3 dB or 6 dB
h h3 h6
definition, respectively)
c speed of sound in a medium
f frequency

M general symbol for the complex hydrophone sensitivity, M=⏐M⏐ being its modulus and

arg(M) being its argument (= phase angle)
M end-of-cable open-circuit sensitivity
M end-of-cable loaded sensitivity
Z complex electric output impedance of a hydrophone or hydrophone assembly
Z electric load impedance

θ angle of incidence of an ultrasonic wave with respect to the hydrophone axis (θ , θ :

3 6
with special reference to 3 dB and 6 dB defined levels)
---------------------- Page: 12 ----------------------
62127-3 © IEC:2007(E) – 9 –
5 Hydrophone characteristics
5.1 General

For a full characterization of the hydrophone performance in the frequency range of this

standard, the following information is required. Examples of information on hydrophone

characteristics are provided in Annex A.
5.2 Basic information
The following shall be briefly stated:

– the basic physical principles of the transduction process, the type of sensor material

involved, the form and geometrical dimensions (diameter, thickness) of the hydrophone

active element and the needle diameter in case of a needle hydrophone;
– the configuration and design of the hydrophone;

– whether or not a pre-amplifier is associated with the hydrophone; if the pre-amplifier can

be disconnected from the hydrophone, clear information shall be given as to which pre-

amplifier type belongs to which hydrophone type;
– the nominal direction of ultrasonic incidence in relation to the hydrophone.

NOTE The last point is important, as it has been found in the literature [3] that even with membrane

hydrophones, the response might change upon reversal of the ultrasonic propagation direction in relation to the

hydrophone.
The following should be briefly stated:

– the frequency of the fundamental thickness resonance of the hydrophone active element;

– the size and weight of the hydrophone;

– in the case of a membrane hydrophone, the acoustic reflection and transmission factor

(preferably as a function of frequency).

General note relating to 5.3 and 5.4: if phase information is available, the phase angle (which

equals the argument of the complex hydrophone sensitivity) should be stated in addition to the

sensitivity (which equals the modulus of the complex hydrophone sensitivity), as well as the

frequency dependence of the phase angle in addition to the frequency dependence of the

sensitivity.
5.3 Sensitivity

The end-of-cable sensitivity of the hydrophone or hydrophone assembly shall be stated in

V/Pa or in decimal submultiples, or as a logarithmic level in dB with reference to a stated

sensitivity value.

If a pre-amplifier contributes to the sensitivity value given, this shall be stated.

It shall be stated whether the sensitivity value given is understood as the end-of-cable open-

circuit sensitivity or as the end-of-cable loaded sensitivity. In the latter case, the relevant

electric loading conditions shall be stated, i.e. the electric load impedance, in order to obtain

the stated sensitivity.
The uncertainty of the stated sensitivity shall be given.

The frequency interval over which the sensitivity is given and over which the uncertainty

applies shall be stated. For the purposes of this standard, sensitivity and uncertainty values

may be given separately for several frequency intervals.
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– 10 – 62127-3 © IEC:2007(E)

The methods by which the sensitivity and its uncertainty have been obtained shall be

described.

The temperature dependence of the sensitivity shall be given. The hydrophone sensitivity shall

be stated as a function of the water temperature, at least over the temperature range 19 °C to

25 °C, or the particular water temperature to which the stated sensitivity relates, shall be stated

together with the temperature coefficient of the sensitivity.

A recommended calibration period shall be provided in the instructions for use. This

recommendation shall be followed, unless otherwise stated by specific device application

standards.
NOTE 1 A calibration period of one year will be appropriate in most cases.

The reference centre shall be stated if the sensitivity does not relate to the geometrical centre

of the front surface of the hydrophone active element.
NOTE 2 This is particularly important for any phase considerations.

The direction of acoustic incidence shall be stated if the sensitivity does not relate to an

incidence in the direction of the hydrophone axis.
5.4 Frequency response
5.4.1 Stated frequency band

The frequency band claimed for the hydrophone or hydrophone assembly shall be stated by

giving the lower frequency limit and the upper frequency limit. The end-of-cable sensitivity of

the hydrophone or hydrophone assembly shall be constant over the stated frequency band

with a tolerance which shall also be stated.
5.4.2 Frequency dependence

The end-of-cable sensitivity or sensitivity level of the hydrophone or hydrophone assembly

as a function of frequency shall be stated either graphically or as a list of values and over a

frequency range containing at least the frequency band claimed under 5.4.1. If it is given as a

list of values or as discrete points in a graph, the frequency distance between adjacent points

should be low enough so that all important details of the frequency dependence are shown and

the sensitivity level does not vary by more than ±1 dB between adjacent points.

The frequency response may be given in terms of absolute sensitivity values or in a relative

representation, relative with reference to the absolute sensitivity of the hydrophone or

hydrophone assembly at a certain frequency. In the case of the relative representation, the

reference sensitivity and the frequency to which it applies shall be stated.

The statement of the frequency response shall refer to the same conditions (i.e. loaded or

open-circuit output of the hydrophone or hydrophone assembly) as the sensitivity statement

in accordance w
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