BS ISO 4366-2007 Hydrometry Echo sounders for water depth measurements《液体比重测定法 水深测量用回声测深仪》.pdf

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1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58ICS 17.120.20Hydrometry Echo sounders for water depth measurementsBRITISH STANDARDBS ISO 4366:2007B

2、S ISO 4366:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 June 2007 BSI 2007ISBN 978 0 580 52947 4Amendments issued since publicationAmd. No. Date CommentsThis publication does not purport to include all the necessary provisions of a

3、contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 4366:2007.The UK participation in its preparation was entrusted

4、 by Technical Committee CPI/113, Hydrometry, to Subcommittee CPI/113/5, Measuring instruments and equipment.A list of organizations represented on this committee can be obtained on request to its secretary.INTERNATIONALSTANDARDISO4366Second edition2007-05-15Reference numberISO 4366:2007(E)Hydrometry

5、 Echo sounders for water depth measurementsHydromtrie Sondeurs cho pour le mesurage de la profondeur de leauBS ISO 4366:2007iiiiiContents Page1 Scope 12 Normative references 13 Terms and definitions 14 Units of measure 15 Principles of operation 15.1 General . 15.2 Theory of operation . 25.3 System

6、components . 25.4 Non-recording echo sounders . 35.5 Analog recording echo sounders 35.6 Digital echo sounders . 46 Selection of instrument . 66.1 General . 66.2 Effect of operating frequency . 66.3 Effect of beamwidth 76.4 Type of data display 86.5 Accuracy 86.6 Type of transducer system . 87 Instr

7、uments performance criteria . 97.1 General . 97.2 Information to be specified by the user 97.3 Information to be specified by the manufacturer . 97.4 Housing 107.5 Additional features 108 Field use of echo sounders 118.1 Calibration 118.2 Interpretation of data 128.3 Precautions 129 Operations manua

8、l 12Bibliography . 13BS ISO 4366:2007ivForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies(ISO member bodies). The work of preparing International Standards is normally carried out through ISOtechnical committees. Each member body i

9、nterested in a subject for which a technical committee has beenestablished has the right to be represented on that committee. International organizations, governmental andnon-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnica

10、l Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standardsadopted by the tech

11、nical committees are circulated to the member bodies for voting. Publication as anInternational Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patentrights. ISO sha

12、ll not be held responsible for identifying any or all such patent rights.ISO 4366 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 5, Instruments,equipment and data management.This second edition cancels and replaces the first edition (ISO 4366:1979), which has been techni

13、cally revised.BS ISO 4366:20071Hydrometry Echo sounders for water depth measurements1ScopeThis International Standard provides information concerning the principles of operation, selection andperformance criteria for echo sounders used in depth measurements for open-channel flow (and related)measure

14、ments. The use of standard terminology is promoted.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies. For undated references, the latest edition of the referenced document(including any

15、 amendments) applies.ISO 772, Hydrometric determinations Vocabulary and symbolsISO 6420, Liquid flow measurement in open channels Position fixing equipment for hydrometric boats3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 772 and the following appl

16、y.3.1 tracking windowvertical distance of limited size that follows and automatically centres itself on the depth indicated by the lastreceived echoNOTE If the next echo falls within the window, the signal is accepted as correct; if it does not, the signal is rejected. Thepurpose of a tracking windo

17、w is to screen out erroneous readings caused by reflecting materials in the water (fish, debris,etc.).4 Units of measureThe units of measurement used in this International Standard are SI units and decibels.5 Principles of operation5.1 GeneralThe state-of-the-art of echo sounders is well advanced, a

18、nd sounders have been put into widespread use formany different applications. Consequently, a variety of specialized echo sounders have evolved to best meet thespecific requirements of the application. A digital echo sounder with an integrated analog chart generated by athermal or inkjet print head

19、is the most common echo sounder used for open-channel applications. Multiple-transducer systems are in common use by many professional surveyors and the use of single-transducer,multibeam-swath systems is expanding rapidly.BS ISO 4366:200725.2 Theory of operationThe echo sounder is an electroacousti

20、c instrument that determines the depth of water by measuring the timerequired for a burst of acoustic energy to travel from a transducer to the streambed and reflect back to thetransducer (Figure 1). The travel time of the reflected wave can be converted to distance by use of the followingequation:(

21、1)whereis the distance from the reference water surface to the streambed;is the average velocity of sound in the water column;is the travel time of the acoustic energy from the transducer to the bottom and back to thetransducer;is the system index constant;is the distance from the reference water su

22、rface to the transducer (draft).NOTE All distance units are consistent.The velocity of sound varies with the density and elastic properties of the water, which are primarily a functionof the water temperature and suspended or dissolved constituents (i.e. salinity). Large variations in temperatureand

23、/or salinity with depth are not uncommon. For practical depth measurement with an echo sounder, thevelocity of sound is usually determined by calibration (see 8.1), since measuring and correcting for the actualvariation at each depth interval is difficult.The travel time of the acoustic energy is re

24、corded either electronically by a digital echo sounder or graphicallyby an analog chart echo sounder. The shape, or sharpness, of the reflected acoustic energy pulse plays asignificant role in the accuracy of a depth measurement (Figure 1). The shape and magnitude of the reflectedenergy pulse is a f

25、unction of the acoustic attenuation, background noise and acoustic reflectivity characteristicsof the target.The system index constant ( ) contains all electrical and/or mechanical delays inherent in the measuringsystem, including return signal threshold detection variations. The system index consta

26、nt also contains anyconstant correction due to the change in the velocity of sound between the upper surface level and the averagevelocity used for the site. Therefore, the draft ( ), set during calibration, is not necessarily the actual draft of thetransducer that would be obtained by a physical me

27、asurement from the water surface to the transducer, but alsoincludes corrections for the system index constant determined during on-site calibration.5.3 System componentsThe echo sounder consists of two elements: the electronic assembly, which usually includes a display and/orrecording device, and t

28、he acoustic assembly commonly called the transducer. The electronic circuitry generateshigh frequency electrical energy and provides regulated bursts of this energy to the transducer. When a burst ofenergy is released, time is measured until the reflected energy is received, then Equation (1) is sol

29、ved and thedepth is displayed or recorded.The transducer is an electroacoustic assembly that acts as a two-way energy conversion device. Duringtransmission, it converts pulses of electrical energy into pulses of acoustic energy that travel through the waterto the bottom. During reception, it receive

30、s the reflected acoustic energy (echo) from the streambed andconverts it into electrical energy for processing by the electronic circuits.d =vt2+ k + drdvtkdrkdrBS ISO 4366:200735.4 Non-recording echo soundersThe most common type of non-recording echo sounder has a liquid crystal display (LCD) that

31、displays the depthnumerically. Many of these echo sounders also display the return echo graphically and are commonly used asfish finders by fishermen. The numerical depth determination requires the same processing as a digital echosounder (see 5.6). The non-recording echo sounders typically have wid

32、er beamwidth transducers and nocalibration adjustments, resulting in a lower accuracy than survey-grade digital echo sounders. Some of thenon-recording echo sounders digitally output the depth to an external device through a serial communicationsport.5.5 Analog recording echo soundersTraditionally,

33、analog recording echo sounders have used an electric timing motor to rotate a stylus at a constantspeed across heat-sensitive paper. When the stylus passes over the zero contact, it burns a mark on the paperand simultaneously triggers the release of acoustic energy. The stylus continues to move unti

34、l reflected acousticenergy is received at the transducer generating an electrical current that is applied to the stylus to cause it toburn a mark on the chart again. The stylus continues to rotate until it reaches the zero contact and the cycle isrepeated. As the stylus rotates, the chart is being m

35、oved by another motor and the resulting succession ofKey1 depthsounder transducer2draft3 signal4 time acoustic pulse is transmitted5 reduced energy6 acoustically reflective bottom7 time reflected pulse is received, 8timeFigure 1 Illustration of an acoustic depth measurement2(2v)(depth k dr)BS ISO 43

36、66:20074marks made by the stylus creates a time-time graph. The stylus speed is adjusted through calibration to equalthe speed at which the acoustic energy travels to the streambed and back, thus the distance between the zeromark and other marks on the chart are proportional to the distance between

37、the transducer and the streambed.The speed at which the chart moves is arbitrary so that the chart transit does not necessarily indicate thedistance the boat travelled.Modern analog recorders, which are often combined with a digital display and output (see 5.6), use a fixedthermal or inkjet printing

38、 head in place of the rotating stylus. This helps reduce the potential synchronizationerror and allows electronic filters and processing algorithms to be applied to the data to compensate for thevelocity of sound and allows electronic annotation of the chart. The mass, dimensions and power consumpti

39、onof the fixed-head recorders are less than the rotating stylus design.5.6 Digital echo sounders5.6.1 GeneralIn the digital echo sounder, acoustic pulses are released at set intervals. When an acoustic pulse is released, acounter is started and counts the output of an oscillator. When the reflected

40、acoustic energy is received, theoscillator counts are used to measure the elapsed time and the depth is computed using Equation (1). Theaccuracy of the depth measurement is highly dependent on the digitization techniques and filters that are usedto determine what oscillator count represents the stre

41、ambed.Digital echo sounders are the most common echo sounders available. They range from non-recording LCDunits to survey-grade echo sounders that usually combine an analog recorder with a numerical display anddigital output.5.6.2 Digitization techniquesTwo digitization techniques are commonly used

42、to screen erroneous data and improve the reliability of theacoustic data. The most common technique is threshold detection. Threshold detection measures the time fromtransmission of the acoustic signal until the energy of the reflected energy exceeds a predetermined thresholdor strength. The remaini

43、ng acoustic energy is not analysed. The threshold value may be adjusted by the user onadvanced echo sounders, but it is often fixed and not user selectable. A more robust technique, employed onsome survey-grade echo sounders, is peak value detection. Peak value detection analyses all of the reflecte

44、denergy and computes the time from acoustic release to the peak of the reflected energy or strongest signal.Figure 2 illustrates the difference between the two techniques on a sloping bed. The peak value detectiontechnique produces a measured depth more representative of the centre of the acoustic f

45、ootprint of thetransducer. The peak value technique can significantly reduce the effective beamwidth of the transducer,providing a more accurate representation of the streambed directly below the transducer.Any material such as fish, debris or air bubbles between the transducer and the streambed can

46、 reflect acousticenergy. Peak value detection is less sensitive to these unwanted reflections than threshold detection; however,nearly all survey-grade echo sounders employ techniques to reduce or eliminate erroneous readings caused byreflectors in the water column. A tracking window that rejects al

47、l signals except those within a given tolerance ofthe preceding depth is commonly provided. These reflections from objects in the water column are recorded onthe analog chart in addition to the bottom echo. The analog chart is very valuable for verifying the accuracy ofthe digitized depth. Despite t

48、he techniques employed in digital echo sounders, erroneous readings are stillcommon, particularly around obstructions such as bridge piers and sea walls. Depth measurement in suchareas without an analog presentation of the data is not recommended.BS ISO 4366:200755.6.3 Multiple-transducer systemsA v

49、ariety of multiple-transducer channel sweep systems have been used since the mid-1970s. These systemsare designed to provide a broad area of coverage, rather than a single line, for each pass of the vessel. Channelsweep systems are simply a series of standard transducers mounted on a vessel and/or on booms attached tothe vessel. Sweep systems may use any number of transducers. The spacing between the transducers isdetermined by the nominal water depth, transducer beamwidth, and desired overlap of the transducersac