kSIST FprEN IEC 62127-3:2022

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

IEC 62127-3:2022 is available as IEC 62127-3:2022 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 62127-3:2022 specifies relevant hydrophone characteristics. This document 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 62127-3:2022 cancels and replaces the first edition published in 2007 and Amendment 1:2013. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition.
a) The upper frequency limit of 40 MHz has been removed.
b) Hydrophone sensitivity definitions have been changed to recognize sensitivities as complex-valued quantities.
c) Procedures to determine the effective hydrophone size have been changed according to the rationale outlined in Annex B.
d) Requirements on the frequencies for which the effective hydrophone size shall be provided have been changed to achieve practicality for increased frequency bands.
e) The new Annex B and Annex C have been added.
f) Annex A has been updated to reflect the changes of the normative parts.

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

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

IEC 62127-3:2022 est disponible sous forme de IEC 62127-3:2022 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.

L'IEC 62127-3:2022 spécifie les caractéristiques pertinentes des hydrophones. Le présent document s'applique:
- aux hydrophones qui utilisent 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 mesurages réalisés dans l'eau;
- aux hydrophones avec ou sans préamplificateur associé.
L'IEC 62127-3:2022 annule et remplace la première édition parue en 2007 et son amendement 1:2013. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente.
a) La limite de fréquence supérieure de 40 MHz a été supprimée.
b) Les définitions de la sensibilité de l'hydrophone ont été modifiées afin de reconnaître les sensibilités comme des grandeurs à valeur complexe.
c) Les procédures de détermination de la taille efficace de l'hydrophone ont été modifiées conformément à la justification donnée à l'Annexe B.
d) Les exigences relatives aux fréquences pour lesquelles doit être fournie la taille efficace de l'hydrophone ont été modifiées afin de tenir compte des bandes de fréquences supérieures.
e) De nouvelles annexes ont été ajoutées (Annexe B et Annexe C).
f) L'Annexe A a été mise à jour afin de refléter les modifications apportées aux parties normatives.

Ultrazvok - Hidrofoni - 3. del: Lastnosti hidrofonov za ultrazvočna polja

General Information

• Status: Not Published
• Public Enquiry End Date: 19-May-2022
• ICS: 11.040.01 - Medical equipment in general
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: I11 - Imaginarni 11
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 19-Oct-2022
• Due Date: 07-Dec-2022
• Completion Date: 24-Nov-2022
• Ref Project: FprEN IEC 62127-3:2022 - Ultrasonics - Hydrophones - Part 3: Properties of hydrophones for ultrasonic fields

Relations

• Revised: SIST EN 62127-3:2008/A1:2013 - Ultrasonics - Hydrophones - Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
• Effective Date: 21-Dec-2021
• Revised: SIST EN 62127-3:2008 - Ultrasonics - Hydrophones -- Part 3: Properties of hydrophones for ultrasonic fields up to 40 MHz
• Effective Date: 22-Dec-2020

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN IEC 62127-3:2022
01-maj-2022
Ultrazvok - Hidrofoni - 3. del: Lastnosti hidrofonov za ultrazvočna polja

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

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

Ultraschallfeldern
Ultrasons - Hydrophoes - Partie 3: Propriétés des hydrophones pour les champs
ultrasoniques jusqu'à 40 MHz
Ta slovenski standard je istoveten z: prEN IEC 62127-3:2022
ICS:
11.040.01 Medicinska oprema na Medical equipment in general
splošno
17.140.50 Elektroakustika Electroacoustics
oSIST prEN IEC 62127-3:2022 en

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

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oSIST prEN IEC 62127-3:2022
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oSIST prEN IEC 62127-3:2022
87/786/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62127-3 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-02-25 2022-05-20
SUPERSEDES DOCUMENTS:
87/751/CD, 87/782/CC
IEC TC 87 : ULTRASONICS
SECRETARIAT: SECRETARY:
United Kingdom Mr Petar Luzajic
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if any, in
this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they

are aware and to provide supporting documentation.
TITLE:

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

PROPOSED STABILITY DATE: 2025
NOTE FROM TC/SC OFFICERS:

Copyright © 2022 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.

You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without

permission in writing from IEC.
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1 CONTENTS

2 1 Scope ............................................................................................................................... 7

3 2 Normative references ....................................................................................................... 7

4 3 Terms, definitions and symbols ........................................................................................ 7

5 4 List of symbols ............................................................................................................... 10

6 5 Hydrophone characteristics ............................................................................................ 11

7 5.1 General ................................................................................................................. 11

8 5.2 Basic information ................................................................................................... 11

9 5.3 Sensitivity ............................................................................................................. 11

10 5.4 Frequency response .............................................................................................. 12

11 5.4.1 Stated frequency band ............................................................................... 12

12 5.4.2 Frequency dependence ............................................................................. 12

13 5.5 Directional response .............................................................................................. 13

14 5.5.1 General ..................................................................................................... 13

15 5.5.2 Determination of the direction response ..................................................... 13

16 5.5.3 Symmetry of directional response .............................................................. 14

17 5.6 Effective hydrophone size ..................................................................................... 14

18 5.6.1 General ..................................................................................................... 14

19 5.6.2 Model of directional response .................................................................... 14

20 5.6.3 Fitting of experimental response to theoretical predictions ......................... 15

21 5.7 Dynamic range, linearity and electromagnetic interference .................................... 16

22 5.8 Electric output characteristics ................................................................................ 16

23 5.8.1 Hydrophone without pre-amplifier .............................................................. 16

24 5.8.2 Hydrophone assembly ............................................................................... 17

25 5.8.3 Output lead configuration .......................................................................... 17

26 5.9 Environmental aspects .......................................................................................... 17

27 5.9.1 Temperature range .................................................................................... 17

28 5.9.2 Water tightness ......................................................................................... 17

29 5.9.3 Water properties and incompatible materials ............................................. 17

30 5.9.4 Exposed material ....................................................................................... 18

31 5.10 Guidance manual .................................................................................................. 18

32 5.11 List of hydrophone characteristics ......................................................................... 18

33 Annex A (informative) Examples of information on hydrophone properties ........................... 19

34 A.1 General ................................................................................................................. 19

35 A.2 Basic information ................................................................................................... 19

36 A.3 Sensitivity and frequency response ....................................................................... 19

37 A.4 Directional response .............................................................................................. 22

38 A.5 Effective dimension ............................................................................................... 23

39 A.6 Dynamic range, linearity and electromagnetic interference .................................... 24

40 A.6.1 Lower dynamic limit ................................................................................... 24

41 A.6.2 Upper dynamic limit ................................................................................... 24

42 A.7 Electric output characteristics ................................................................................ 24

43 A.8 Environmental aspects .......................................................................................... 24

44 Annex B (informative) Rationale........................................................................................... 26

45 B.1 General ................................................................................................................. 26

46 B.2 Changes to the determination of directional response ........................................... 26

47 B.3 Changes to the determination of effective radius ................................................... 26

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48 Annex C (informative) Membrane hydrophone directivity model ........................................... 28

49 C.1 General ................................................................................................................. 28

50 C.2 Details of model .................................................................................................... 28

52 Figure A.1 – Frequency response of 0,2 mm needle hydrophone .......................................... 20

53 Figure A.2 – Directional response of 0,2 mm needle hydrophone .......................................... 22

55 Table A.1 – Example of basic information for 0,2 mm needle hydrophone assembly ............. 19

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58 INTERNATIONAL ELECTROTECHNICAL COMMISSION
59 ____________
61 ULTRASONICS – HYDROPHONES –
63 Part 3: Properties of hydrophones for ultrasonic fields
65 FOREWORD

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

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

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

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

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

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

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

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

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

75 agreement between the two organizations.

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

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

78 interested IEC National Committees.

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

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

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

82 misinterpretation by any end user.

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

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

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

86 the latter.

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

88 equipment declared to be in conformity with an IEC Publication.

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

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

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

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

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

94 Publications.

95 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

96 indispensable for the correct application of this publication.

97 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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

99 This second edition cancels and replaces the first edition published in 2007-08 and its

100 amendment 1 (2013-05). This edition constitutes a technical revision.

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

102 edition:
103 a) The upper frequency limit of 40 MHz has been removed;

104 b) Hydrophone sensitivity definitions have been changed to recognize sensitivities as

105 complex-valued quantities;

106 c) Procedures to determine the effective hydrophone size have been changed according to

107 the rationale outlined in Annex B;

108 d) Requirements on the frequencies for which the effective hydrophone size shall be

109 provided have been changed to achieve practicality for increased frequency bands;

110 e) The new Annexes B and C have been added;
111 f) Annex A has been updated to reflect the changes of the normative parts.
112
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113 International Standard IEC 62127-3 has been prepared by IEC technical committee 87:

114 Ultrasonics.

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

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

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

119 The committee has decided that the contents of the base publication and its amendment will

120 remain unchanged until the maintenance result date indicated on the IEC website under

121 "http://webstore.iec.ch" in the data related to the specific publication. At this date, the

122 publication will be
123 • reconfirmed,
124 • withdrawn,
125 • replaced by a revised edition, or
126 • amended.
127

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 publication using a colour printer.

128
129
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130 INTRODUCTION

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

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

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

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

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

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

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

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

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

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

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

143 ultrasonic spectrometers, ultrasonic attenuation meters and velocimeters);

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

145 flowmeters).

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

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

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

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

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

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

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

153 this document or in a separate one.

154 Underwater hydrophones as covered by IEC 60500, IEC 60565-1, and IEC 60565-2 are not

155 included in this document, although there is an overlap in the frequency ranges. Underwater

156 hydrophones are used in natural waters, even in the ocean, and this leads to different

157 technical concepts and requirements. In addition, the main direction of acoustic incidence in

158 underwater applications is at various angles and often at right angles to the hydrophone

159 axis, whereas this standard it is assumed that the main direction of acoustic incidence is in

160 the direction of the hydrophone axis.

161 Historically, ultrasonic hydrophones were used almost exclusively as amplitude sensors.

162 However, the complex-valued nature of a hydrophone’s system response function is well

163 understood and IEC 62127-1 Ed 2 makes use of this within the deconvolution procedures it

164 contains. In this document, requirements are specified for the amplitude aspect of the

165 hydrophone sensitivity and recommendations are provided for the phase aspect which can

166 be derived either via calibration, or via calculation methods that are discussed in IEC 62127-1

167 Ed 2.
168
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169 ULTRASONICS – HYDROPHONES –
170
171 Part 3: Properties of hydrophones for ultrasonic fields
172
173 1 Scope
174 This part of IEC 62127 specifies relevant hydrophone characteristics.
175 This standard is applicable to:

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

177 and continuous wave ultrasonic fields generated by ultrasonic equipment;
178 – hydrophones used for measurements made in water;
179 – hydrophones with or without an associated pre-amplifier.
180 2 Normative references

181 The following referenced documents are indispensable for the application of this document.

182 For dated references, only the edition cited applies. For undated references, the latest edition

183 of the referenced document (including any amendments) applies.

184 IEC 62127-1, Ultrasonics – Hydrophones – Part 1: Measurement and characterization of

185 medical ultrasonic fields up to 40 MHz

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

187 40 MHz
188 3 Terms, definitions and symbols

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

190 IEC 62127-2 and the following apply.

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

192 addresses:
193 • IEC Electropedia: available at http://www.electropedia.org/
194 • ISO Online browsing platform: available at http://www.iso.org/obp
195 3.1
196 acoustic pulse waveform

197 temporal waveform of the instantaneous acoustic pressure at a specified position in an

198 acoustic field and displayed over a period sufficiently long to include all significant acoustic

199 information in a single pulse or tone-burst, or one or more cycles in a continuous wave

200 Note 1 to entry: Temporal waveform is a representation (e.g. oscilloscope presentation or formula) of the

201 instantaneous acoustic pressure.
202 [SOURCE: IEC 62127-1:2007 and Amendment 1:2013, definition 3.1]
203 3.2
204 directional response

205 description of the response of a hydrophone, as a function of direction of propagation of the

206 incident plane sound wave, in a specified plane through the reference centre and at a

207 specified frequency
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208 NOTE 1 Definition adopted from IEC 60565:2006.

209 NOTE 2 Whilst directional response is a complex-valued function, it is generally the magnitude of directional

210 response that is of most interest and this commonly presented graphically.
211 3.3
212 effective hydrophone size
213 a

214 size of a theoretical receiver hydrophone that has a predicted directional response function

215 with an angular width equal to the observed angular width

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

217 NOTE 2 The effective hydrophone size is expressed in metres (m).

218 NOTE 3 For hydrophones with a circular geometry, the effective hydrophone size is a radius.

219 NOTE 4 For hydrophones with a rectangular geometry, the effective hydrophone size is the half the greatest

220 value of the length or width.
221 3.4
222 electric load impedance
223 Z

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

225 hydrophone or hydrophone assembly output is connected or is to be connected
226 NOTE The electric load impedance is expressed in ohms ().
227 3.5
228 end-of-cable

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

230 hydrophone assembly is provided with such a cable and if the hydrophone or hydrophone

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

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

233 cable
234 3.6
235 end-of-cable loaded sensitivity
236 M (f)
237 quotient of the Fourier transformed

238 hydrophone voltage-time signal (u (t)) at the end of any integral cable or output connector

239 of a hydrophone or hydrophone-assembly, when connected to a specified electric load

240 impedance, to the Fourier transformed acoustic pulse waveform (p(t)) in the undisturbed

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

242 hydrophone were removed
( ( ))
243 Mf = (1)
( )
( ( ))

244 Note 1 to entry: The end-of-cable loaded sensitivity is a complex-valued parameter. Its modulus is expressed

245 in units of volt per pascal (V/Pa), its phase angle is expressed in degrees, and represents the phase difference

246 between the electrical voltage and the sound pressure.
247 3.7
248 end-of-cable open-circuit sensitivity
249 M (f)

250 quotient of the Fourier transformed hydrophone open-circuit voltage-

251 time signal (u (t)) at the end of any integral cable or output connector of a hydrophone to

252 the Fourier transformed acoustic pulse waveform (p(t)) in the undisturbed free field of a

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253 plane wave in the position of the reference centre of the hydrophone if the hydrophone

254 were removed
( ( ))
255 Mf( )= (2)
( ( ))

256 Note 1 to entry: The end-of-cable open-circuit sensitivity is a complex-valued parameter. Its modulus is

257 expressed in units of volt per pascal (V/Pa), its phase angle is expressed in degrees, and represents the phase

258 difference between the electrical voltage and the sound pressure.
259 3.8
260 end-of-cable loaded sensitivity level
( )
261

262 twenty times the logarithm to the base 10 of

263 the quotient of the modulus of the end-of-cable loaded sensitivity |M (f)| to a reference

264 sensitivity M
ref
( )
265 Lf( )= 20log dB (3)
M 10
ref

266 Note 1 to entry: Commonly used values of the reference sensitivity M are 1V/µPa or 1V/Pa.

ref

267 Note 2 to entry: The end-of-cable loaded sensitivity level is expressed in decibels (dB).

268 3.9
269 free field

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

271 negligible
272 Note 1 to entry: Definition adopted from IEC 60565:2006, 3.13.
273 3.10
274 hydrophone geometrical size
275 geometrical size of a hydrophone active element
276 a
277 size defined by the lateral extents of the active element of a hydrophone
278 Note 1 to entry: The hydrophone geometrical size is expressed in metres (m).

279 Note 2 to entry: For hydrophones with a circular geometry, the hydrophone geometrical size is a radius.

280 Note 3 to entry: For hydrophones with a rectangular geometry, the hydrophone geometrical size is a half the

281 greatest value of the length or width.
282 3.11
283 hydrophone

284 transducer that produces electric signals in response to waterborne acoustic signals

285 SOURCE: IEV 801-32-26
286 3.12
287 hydrophone assembly
288 combination of hydrophone and hydrophone pre-amplifier
289 3.13
290 hydrophone axis
291 nominal symmetry axis of the hydrophone active element

292 Note 1 to entry: Unless stated otherwise (explicitly and quantitatively) by the manufacturer, it is understood for

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

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294 3.14
295 hydrophone pre-amplifier

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

297 reducing its output impedance

298 Note 1 to entry: A hydrophone pre-amplifier requires a supply voltage (or supply voltages).

299 Note 2 to entry: The hydrophone pre-amplifier may have a forward voltage transmission factor of less than one,

300 i.e. it need not necessarily be a voltage amplifier in the strict sense.
301 3.15
302 reference centre

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

304 Note 1 to entry: Unless stated otherwise (explicitly and quantitatively) by the manufacturer, it is understood for

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

306 active element.
307 Note 2 to entry: Definition adopted from IEC 60565:2006, 3.25.
308 3.16
309 uncertainty

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

311 the values that could reasonably be attributed to the measurand

312 Note 1 to entry: See the ISO Guide to the Expression of Uncertainty in Measurement [2], 2.2.3

313 Note 2 to entry: Definition adopted from IEC 62127-1.
314
315
316 4 List of symbols
317 a hydrophone geometrical size
318 a effective hydrophone size
319 c speed of sound in a medium

320 D model function used during the determination of effective hydrophone size from

321 a measured directional response of a hydrophone
322 f frequency
323 k wavenumber = 2π / λ
( )
L end-of-cable loaded sensitivity level
324
325 M general symbol for the complex hydrophone sensitivity, M =M being its
326 modulus and arg(M) being its argument (= phase angle)
327 M end-of-cable open-circuit sensitivity
328 M end-of-cable loaded sensitivity
329 Z complex electric output impedance of a hydrophone or hydrophone assembly
330 Z electric load impedance

331  angle of incidence of an ultrasonic wave with respect to the hydrophone axis

332
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333 5 Hydrophone characteristics
334 5.1 General

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

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

337 characteristics are provided in Annex A.
338 NOTE Determination methods are covered in IEC 62127-2.
339 5.2 Basic information
340 The following shall be briefly stated:

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

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

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

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

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

347 amplifier type belongs to which hydrophone type;

348 – the nominal direction of ultrasonic incidence in relation to the hydrophone.

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

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

351 hydrophone.
352 The following should be briefly stated:
353 – the lateral and thickness dimensions of the hydrophone active element;

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

355 – the size and weight of the hydrophone;

356 – the recommended directional response model (see clause 5.6.2) appropriate for the

357 hydrophone;
358 – in the case of a membrane hy
...