This part of IEC 60565 specifies methods and procedures for free-field calibration of hydrophone<\/b>s, as well as individual electroacoustic transducer<\/b>s that can be used as hydrophone<\/b>s (receivers) and\/or projector<\/b>s (source transducer<\/b>s). Two general types of calibration are covered within this document: absolute calibration using the method of threetransducer spherical-wave reciprocity, and relative calibration by comparison with a reference device which has already been the subject of an absolute calibration.<\/p>\n
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.<\/p>\n
Procedures for pressure hydrophone<\/b> calibration at low frequencies can be found in IEC 60565-2 [1]1<\/sup>. Procedures for hydrophone<\/b> calibration at acoustic frequencies greater than 1 MHz are covered by IEC 62127-2 [2].<\/p>\n Excluded from the scope of this document are low-frequency pressure calibrations of hydrophone<\/b>s, which are described in IEC 60565-2 [1]. Also excluded are calibrations of digital hydrophone<\/b>s and systems, calibration of marine autonomous acoustic recorders, calibration of acoustic vector sensors such as particle velocity sensors and pressure gradient hydrophone<\/b>s, calibration of passive sonar arrays consisting of multiple hydrophone<\/b>s, and calibration of active sonar arrays consisting of projectors and hydrophone<\/b>s.<\/p>\n This document presents a description of the requirements for free-field calibration in terms of test facility, equipment and instrumentation, signal<\/b> 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<\/p>\n measurement of directional response of a hydrophone<\/b> or projector,<\/p>\n<\/li>\n measurement of electrical impedance of hydrophones<\/b> and projectors,<\/p>\n<\/li>\n electrical loading corrections,<\/p>\n<\/li>\n acoustic far-field<\/b> criteria in underwater acoustic calibration,<\/p>\n<\/li>\n pulsed techniques in free-field calibrations,<\/p>\n<\/li>\n assessment of uncertainty in the free-field calibration of hydrophones<\/b> and projectors,<\/p>\n<\/li>\n derivation of the formulae for three-transducer<\/b> spherical-wave reciprocity calibrations,<\/p>\n<\/li>\n calibration using travelling-wave tubes,<\/p>\n<\/li>\n calibration of hydrophone<\/b>s using optical interferometry, and<\/p>\n<\/li>\n calibrations in reverberant water tanks using continuous signal<\/b>s.<\/p>\n<\/li>\n<\/ul>\n Underwater acoustics. Hydrophones. Calibration of hydrophones – Procedures for free-field calibration of hydrophones<\/b><\/p>\n\n
PDF Catalog<\/h4>\n
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\n PDF Pages<\/th>\n PDF Title<\/th>\n<\/tr>\n \n 2<\/td>\n undefined <\/td>\n<\/tr>\n \n 5<\/td>\n Annex ZA(normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n \n 7<\/td>\n English
CONTENTS <\/td>\n<\/tr>\n\n 12<\/td>\n FOREWORD <\/td>\n<\/tr>\n \n 14<\/td>\n INTRODUCTION <\/td>\n<\/tr>\n \n 15<\/td>\n 1 Scope <\/td>\n<\/tr>\n \n 16<\/td>\n 2 Normative references
3 Terms and definitions <\/td>\n<\/tr>\n\n 21<\/td>\n 4 Symbols and abbreviated terms <\/td>\n<\/tr>\n \n 22<\/td>\n 5 General procedures for calibration
5.1 General calibration requirements
5.1.1 Types of calibration <\/td>\n<\/tr>\n\n 23<\/td>\n 5.1.2 Acoustic field requirements
5.2 Acoustic free-field requirements
5.2.1 Continuous signals
5.2.2 Time-limited signals
5.3 Acoustic far-field requirements <\/td>\n<\/tr>\n\n 24<\/td>\n 5.4 Requirements for steady-state conditions <\/td>\n<\/tr>\n \n 25<\/td>\n 5.5 Equipment requirements
5.5.1 Calibration facility
5.5.2 Instrumentation <\/td>\n<\/tr>\n\n 27<\/td>\n 5.6 Positioning and alignment
5.6.1 Coordinate system
5.6.2 Reference direction
5.6.3 Transducer mounting and support <\/td>\n<\/tr>\n\n 28<\/td>\n 5.6.4 Alignment
5.6.5 Separation distance
5.7 Representation of the frequency response <\/td>\n<\/tr>\n\n 29<\/td>\n 5.8 Frequency limitations
5.8.1 High-frequency limit
5.8.2 Low-frequency limit
5.9 Checks for acoustic interference <\/td>\n<\/tr>\n\n 30<\/td>\n 6 Electrical measurements
6.1 Signal type
6.2 Electrical earthing
6.3 Measurement of hydrophone output voltage
6.3.1 General <\/td>\n<\/tr>\n\n 31<\/td>\n 6.3.2 Signal analysis
6.3.3 Electrical loading by measuring instruments
6.3.4 Electrical loading by extension cables
6.3.5 Electrical noise <\/td>\n<\/tr>\n\n 32<\/td>\n 6.3.6 Cross-talk
6.3.7 Integral preamplifiers
6.4 Measurement of projector drive current
6.4.1 Instrumentation
6.4.2 Signal analysis <\/td>\n<\/tr>\n\n 33<\/td>\n 6.5 Measurement of projector drive voltage
6.5.1 Instrumentation
6.5.2 Signal analysis
7 Preparation and conditioning of transducers
7.1 Soaking
7.2 Wetting <\/td>\n<\/tr>\n\n 34<\/td>\n 7.3 Extending the hydrophone cable
7.4 Environmental conditions (temperature and depth)
8 Free-field three-transducer spherical-wave reciprocity calibration
8.1 General principle <\/td>\n<\/tr>\n\n 35<\/td>\n 8.2 Calibration to determine sensitivity modulus (without phase)
8.2.1 Acoustic field requirements
8.2.2 Separation distance
Figures
Figure 1 \u2013 Measurement configurations for three-transducer reciprocity <\/td>\n<\/tr>\n\n 36<\/td>\n 8.2.3 Transducer preparation, mounting and alignment
8.2.4 Signal type
8.2.5 Measurement of electrical transfer impedance
8.2.6 Calculation of the receive sensitivities <\/td>\n<\/tr>\n\n 37<\/td>\n 8.2.7 Calculation of the transmit sensitivities
8.2.8 Repeatability
8.2.9 Verification and checks <\/td>\n<\/tr>\n\n 39<\/td>\n 8.2.10 Uncertainty
8.3 Calibration to determine phase of the hydrophone sensitivity
8.3.1 General principle <\/td>\n<\/tr>\n\n 40<\/td>\n 8.3.2 Transducer preparation
Figure 2 \u2013 Measurement framework for supporting in-line the three transducers: a projector P, a reciprocal transducer T, and a hydrophone H to be calibrated <\/td>\n<\/tr>\n\n 41<\/td>\n 8.3.3 Acoustic field requirements
8.3.4 Signal type
8.3.5 Transducer mounting and alignment
8.3.6 Measurement of electrical transfer impedance
8.3.7 Calculation of sensitivity phase angle <\/td>\n<\/tr>\n\n 42<\/td>\n 8.3.8 Repeatability
8.3.9 Verification and checking
8.3.10 Uncertainty
9 Free-field calibration by comparison with an acoustic reference device
9.1 Principles <\/td>\n<\/tr>\n\n 43<\/td>\n 9.2 Types of comparison calibration method
9.2.1 Hydrophone calibration using a calibrated reference hydrophone
9.2.2 Hydrophone calibration using calibrated reference projector
9.2.3 Projector calibration using a calibrated reference hydrophone
9.3 Hydrophone calibration by comparison with a reference hydrophone
9.3.1 Acoustic field requirements
9.3.2 Separation distance <\/td>\n<\/tr>\n\n 44<\/td>\n 9.3.3 Transducer preparation, mounting and alignment
9.3.4 Signal type
9.3.5 Measurement of electrical voltage
9.3.6 Free-field sensitivity
9.3.7 Repeatability <\/td>\n<\/tr>\n\n 45<\/td>\n 9.3.8 Verification and checks
9.3.9 Uncertainty
9.4 Hydrophone calibration using a calibrated projector
9.4.1 Acoustic field requirements
9.4.2 Separation distance <\/td>\n<\/tr>\n\n 46<\/td>\n 9.4.3 Transducer preparation, mounting and alignment
9.4.4 Signal type
9.4.5 Measurement of electrical transfer impedance
9.4.6 Calculation of the receive sensitivities
9.4.7 Repeatability <\/td>\n<\/tr>\n\n 47<\/td>\n 9.4.8 Verification and checks
9.4.9 Uncertainty
9.5 Projector calibration using a calibrated hydrophone
9.5.1 Acoustic field requirements
9.5.2 Separation distance
9.5.3 Transducer preparation, mounting and alignment <\/td>\n<\/tr>\n\n 48<\/td>\n 9.5.4 Signal type
9.5.5 Measurement of electrical transfer impedance
9.5.6 Calculation of the transmit sensitivity
9.5.7 Verification and checks <\/td>\n<\/tr>\n\n 49<\/td>\n 9.5.8 Uncertainty
10 Reporting of results
10.1 Sensitivity
10.2 Sensitivity level <\/td>\n<\/tr>\n\n 50<\/td>\n 10.3 Calibration uncertainties
10.4 Auxiliary metadata
11 Recalibration periods <\/td>\n<\/tr>\n\n 51<\/td>\n Annex A (informative)Directional response of a hydrophone or projector
A.1 General principle
A.2 Types of measurement implementation
A.3 Coordinate system <\/td>\n<\/tr>\n\n 52<\/td>\n A.4 Acoustic field requirements
A.5 Positioning and alignment
A.6 Signal type
A.7 Measurement of transducer directional response
A.7.1 Projector
A.7.2 Hydrophone
A.8 Calculation of the directional response level (angular deviation loss) <\/td>\n<\/tr>\n\n 53<\/td>\n A.9 Uncertainty
A.10 Graphic representation
Figure A.1 \u2013 Examples of graphical representations of the level of the directional response: polar plot (left) and Cartesian plot (right) <\/td>\n<\/tr>\n\n 54<\/td>\n A.11 Directivity factor
A.12 Directivity index <\/td>\n<\/tr>\n\n 55<\/td>\n Annex B (informative)Measurement of electrical impedance of hydrophones and projectors
B.1 General principles
B.2 Measurement of electrical impedance <\/td>\n<\/tr>\n\n 56<\/td>\n B.3 Derivation of other electrical impedance parameters <\/td>\n<\/tr>\n \n 57<\/td>\n B.4 Graphical representation <\/td>\n<\/tr>\n \n 58<\/td>\n Figure B.1 \u2013 Examples of plots of transducer electrical impedance for a small spherical hydrophone of capacitance 3 nF <\/td>\n<\/tr>\n \n 59<\/td>\n Annex C (informative)Calculation of electrical loading corrections
C.1 Electrical loading corrections
C.2 Corrections for amplifier loading using complex electrical impedance
C.3 Corrections for loading caused by extension cables (using complex electrical impedance) <\/td>\n<\/tr>\n\n 60<\/td>\n C.4 Corrections using only capacitances <\/td>\n<\/tr>\n \n 61<\/td>\n Annex D (informative)Acoustic far-field criteria in underwater acoustic calibration
D.1 General
D.2 The field for piston transducers
Figure D.1 \u2013 Acoustic pressure as a function of range from the source for a point source and for a piston source of dimensions ka = 10 <\/td>\n<\/tr>\n\n 62<\/td>\n D.3 Criteria for far-field conditions
Figure D.2 \u2013 Difference in measured acoustic pressure on axis compared to spherical spreading measured by a point receiver and a piston receiver <\/td>\n<\/tr>\n\n 63<\/td>\n D.4 Far-field criteria in directional response measurements <\/td>\n<\/tr>\n \n 64<\/td>\n Annex E (informative)Pulsed techniques in free-field calibrations
E.1 General
E.2 Echo-free time <\/td>\n<\/tr>\n\n 65<\/td>\n Figure E.1 \u2013 Schematic diagram of a projector and receiver in a water tank showing the main sources of reflections <\/td>\n<\/tr>\n \n 66<\/td>\n E.3 Minimum separation distance
E.4 Turn-on transients
Figure E.2 \u2013 Echo arrival time in a 6 m x 6 m x 5 m tank with optimally placed transducers <\/td>\n<\/tr>\n\n 67<\/td>\n E.5 Bandwidth considerations
Figure E.3 \u2013 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)) <\/td>\n<\/tr>\n\n 68<\/td>\n E.6 Electrical cross-talk
E.7 Pulse duration
E.8 Reverberation and pulse repetition rate
E.9 Typical tank dimensions <\/td>\n<\/tr>\n\n 69<\/td>\n E.10 Spherical-wave conditions
E.11 Reflections from mounting poles and rigging
E.12 Analysis methods for tone-burst signals <\/td>\n<\/tr>\n\n 70<\/td>\n E.13 High-frequency limitations
Figure E.4 \u2013 Examples of acoustic waveforms showing time-windows for analysis <\/td>\n<\/tr>\n\n 71<\/td>\n E.14 Low-frequency limitations
Figure E.5 \u2013 Values for the sound absorption in pure water and sea water, including contributions due to component factors <\/td>\n<\/tr>\n\n 72<\/td>\n E.15 Advanced techniques for extending the frequency range beyond the low-frequency limit <\/td>\n<\/tr>\n \n 74<\/td>\n Annex F (informative)Assessment of uncertainty in the calibration of hydrophones and projectors
F.1 General
F.2 Type A evaluation of uncertainty
F.3 Type B evaluation of uncertainty
F.4 Reported uncertainty <\/td>\n<\/tr>\n\n 75<\/td>\n F.5 Common sources of uncertainty <\/td>\n<\/tr>\n \n 77<\/td>\n Annex G (informative)Derivation of the formulae for three-transducer spherical-wave reciprocity calibration
G.1 General
G.2 Calibration to determine the modulus of the sensitivity <\/td>\n<\/tr>\n\n 79<\/td>\n G.3 Calibration to determine the complex sensitivity <\/td>\n<\/tr>\n \n 82<\/td>\n Annex H (informative)Calibration using travelling-wave tubes
H.1 General
H.2 Calibration procedure
H.3 Limitations of the method <\/td>\n<\/tr>\n\n 83<\/td>\n H.4 Extensions of the method <\/td>\n<\/tr>\n \n 84<\/td>\n Annex I (informative)Calibration of hydrophones using optical interferometry
I.1 General
I.2 General principles
I.3 Procedure <\/td>\n<\/tr>\n\n 85<\/td>\n I.4 Discussion of method
Figure I.1 \u2013 Configurations for calibration of hydrophones using heterodyne optical interferometry <\/td>\n<\/tr>\n\n 86<\/td>\n Annex J (informative)Calibration in a reverberant water tanks using continuous signals
J.1 General principle <\/td>\n<\/tr>\n\n 87<\/td>\n J.2 Using a noise signal
J.3 Using the LFM signal <\/td>\n<\/tr>\n\n 88<\/td>\n J.4 Uncertainties <\/td>\n<\/tr>\n \n 89<\/td>\n Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" \n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n BSI<\/b><\/a><\/td>\n 2020<\/td>\n 96<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":239611,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[270,2641],"product_tag":[],"class_list":{"0":"post-239608","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-17-140-50","7":"product_cat-bsi","9":"first","10":"instock","11":"sold-individually","12":"shipping-taxable","13":"purchasable","14":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/239608","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/239611"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=239608"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=239608"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=239608"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}