Verification Regulation of Standard Hydrophones in the Frequency Range 1 Hz to 2 kHz
Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG1018—2007
Standard Hydrophones in the Frequency Range1 Hz to 2 kHz
2007 0228 Issued
2007-05-28 Implementation
General Administration of Quality Supervision, Inspection and Quarantine
JJG1018--2007
Verification Regulation of StandardHydrophones in the Frequency Range1 Hz to 2 kHz
JJG1018—2007
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine on February 28, 2007, and came into effect on May 28, 2007.
Responsible unit: National Technical Committee on Acoustic Metrology Main drafting unit: 715th Institute of China Shipbuilding Industry Corporation Participating drafting units: Institute of Acoustics, Chinese Academy of Sciences China Institute of Testing Technology
This regulation entrusts the National Technical Committee on Acoustic Metrology to be responsible for the interpretation of this regulation Main drafters
JJG1018—2007
Zhao Han (715th Institute of China Shipbuilding Industry Corporation) Fei Teng (715th Institute of China Shipbuilding Industry Corporation) Yuan Wenjun (715th Institute of China Shipbuilding Industry Corporation) Participating drafters:
Zhu Houqing (Institute of Acoustics, Chinese Academy of Sciences) Shang Guohua (China Institute of Testing Technology) 1
2 References
3 Terms and measurement units
3.1 Open circuit voltage of hydrophone||t t||3.2 Sound pressure sensitivity of hydrophone
3.3 Sound pressure sensitivity level
3.4 Vibrating liquid column
3.5 Piezoelectric compensation cavity….
Overview
5 Metrological performance requirements
5.1 Normal operation
5.2 Sound pressure sensitivity level
5.3 Sound pressure sensitivity level frequency response
6 General Technical requirements
6.1 General requirements
6.2 Materials and structure
6.3 Marking and factory calibration data
7 Control of measuring instruments
7.1 Verification conditions
7.2 Verification items
7.3 Verification methods
7.4 Processing of verification results
7.5 Verification cycle
JJG 1018—2007
Appendix A Measurement method of characteristic constant K of piezoelectric compensation transducer Appendix B Inner page format of verification certificate and verification result notice Appendix C Measurement uncertainty assessment example
(4))
JJG 1018--2007
1Hz2kHz standard hydrophone verification procedure
This procedure refers to the piezoelectric compensation method calibration and vibrating liquid column method calibration in the International Electrotechnical Commission IEC60565Ed.2:2006 "Calibration of underwater acoustic hydrophones in the frequency range of 0.01Hz to 1MHz". 1 Scope
This procedure is applicable to the initial verification, subsequent verification and in-use inspection of standard hydrophones in the frequency range of 1Hz to 2kHz.
2 References
This procedure refers to the following documents:
GB/T 3102.7—-1993
GB/T 3947—1996
GB/T 4128--1995
GB/T 4130--2000
GJB/J 3803—1999
JJF 1001 ---1998
JJF 10342005
JJF1059-1999
“Acoustic Quantities and Units”
“Acoustic Terminology”
“Acoustic Standard Hydrophone”
“Low-frequency Calibration Method for Acoustic Hydrophone”
“Verification Procedure for Low-frequency Primary Standard Hydrophone”
“General Metrological Terms and Definitions”
“Acoustic Metrological Terms and Definitions”
“Evaluation and Expression of Measurement Uncertainty”
IEC 60565 Ed.2: 2006, Underwater acoustics-Hydrophones-Calibration in the fre-quency range 0.01 Hz to 1 MHz When using this procedure, attention should be paid to using the currently valid versions of the above-mentioned references. 3: Terms and measurement units
This specification adopts the relevant terms and definitions in GB/T 3947~-1996, JJF1001-1998, and JJF 1034-2005.
This specification adopts the quantities and units specified in GB/T3102.7-1993. 3.1 Open-circuit voltage at hydrophone: The voltage present at the output end of a hydrophone when no current flows through it. Unit: V.
3.2 Pressure sensitivity of a hydrophone: The ratio of the output voltage of a hydrophone to the actual sound pressure acting on the receiving surface of the hydrophone. Symbol: Mp.
Unit: V/Pa.
3.3 Pressure sensitivity level The logarithm of the ratio of the hydrophone pressure sensitivity M to the reference pressure sensitivity Mre multiplied by 20. Symbol: M.
Unit: decibel, dB.
1. Usually Mrr = 1 VlμPaa
JJG 1018—2007
2. At low frequencies far from the resonance frequency, the pressure sensitivity level is equal to the free field sensitivity level. 3.4 Vibrating column The liquid column formed by the liquid injected into the open rigid cylindrical container generates a depth-related sound pressure in the liquid column when it vibrates.
3.5 Piezoelectric compensation water-filled chamber is a rigid closed water chamber composed of piezoelectric compensation transducer, piezoelectric zero displacement detector, source transducer and upper and lower rigid cover plates. When the source transducer is excited, it can generate a known uniform sound pressure field in the closed water chamber. 4 Overview
Standard hydrophone is used to calibrate and measure hydrophones and measure sound pressure in water. Standard hydrophone consists of sensitive elements of piezoelectric or other transducer materials and corresponding structures, preamplifiers, etc., and can generate an open circuit voltage value proportional to the sound pressure value under the action of sound waves.
5 Metrological performance requirements
5.1 Normal operation
5.1.1~ For standard hydrophones without preamplifiers, the insulation resistance measured at the cable end should be greater than 100M2 (test voltage 100V), and the measured capacitance value should not differ from the value provided in the instruction manual by more than 20%. 5.1.2 For standard hydrophones with preamplifiers, when the vibration signal is transmitted to the hydrophone sensitive element, there should be a corresponding voltage output at the cable end.
5.2 Sound pressure sensitivity [level]
The sound pressure sensitivity level or low-frequency free field sensitivity level of the standard hydrophone should not be less than -215dB (reference value: 1 VlμPa).
Note: Sound pressure sensitivity refers to the average value of the flat part of the sensitivity frequency response curve. 5.3 Sound pressure sensitivity level frequency response
In the entire operating frequency range, the unevenness of the sound pressure sensitivity level shall not exceed 2.0dB. Note: The calibration frequency is based on 1/3 octave, or as specified by the customer. 6 General technical requirements
6.1 General requirements
6.1.1 The characteristics and structure of the standard hydrophone should be suitable for measurement under environmental conditions of water temperature (5~30)℃ and water depth (0~10)m.
6.1.2 The surface of the standard hydrophone in contact with water should be smooth, non-porous and wettable by water. 6.2 Materials and structure
JJG 1018—-2007
6.2.1 The materials and structure used for the standard hydrophone should ensure its long-term stability in use, and all parts of the hydrophone exposed to water should be made of corrosion-resistant materials. 6.2.2 High impedance sensitive components should have electrostatic shielding, which should be connected to the cable shielding and insulated from the metal casing exposed to water; the metal casing exposed to water of the standard hydrophone with preamplifier should be connected to the cable shielding.
6.3 Marking and factory calibration data
6.3.1 The standard hydrophone should have the following clear and durable markings: 1) Manufacturer's name;
2) Product model;
3) Product serial number.
6.3.2 Each standard hydrophone should be accompanied by a separate factory calibration document. The factory calibration document should include the sound pressure sensitivity level frequency response of the standard hydrophone and the identification of the signal line, ground line and shielding line. The standard hydrophone with preamplifier should also have the power supply line marked and indicate the power supply voltage value: For the standard hydrophone without preamplifier, the cable length when in use should be consistent with that during calibration.
6.3.3 Parts not for operator use shall be protected by sealing or marking to avoid affecting the accuracy of the standard hydrophone.
7 Control of measuring instruments
Control of measuring instruments includes initial calibration, subsequent calibration and inspection during use. 7.1 Calibration conditions
7.1.1 Environmental conditions
Room temperature: 10℃30℃;
Relative humidity: .30%~～90%;
Water temperature: 5℃～30℃.
7.1.2 Measurement standards and main supporting equipment
Measurement standards and main supporting equipment include electronic instruments, compensation chambers and vibrating liquid column containers. 7.1.2.1 Electronic instruments
1) Signal source
Piezoelectric compensation method: It should have a dual output channel of sinusoidal signal with independently adjustable frequency, amplitude and phase: the working frequency range is 1Hz-2kHz, the frequency indication error does not exceed ±0.5%; the maximum output voltage is not less than 10V peak, and the voltage indication error does not exceed ±1%: the adjustable phase range is not less than 0°～359.9°, and the minimum adjustment step is not greater than 0.1
Vibrating liquid column method: the working frequency range is 20Hz～1kHz, the frequency indication error does not exceed ±0.5%; the maximum output voltage is not less than 10V peak, and the voltage indication error does not exceed 1%. 2) Phase-locked amplifier: the working frequency range is 1Hz～2kHz, the sensitivity is better than 10μV, the dynamic range is not less than 90dB, the maximum allowable error of voltage measurement is ±1%, and the maximum allowable error of phase measurement is 0.5°. 3) Preamplifier: Working frequency range 1Hz~2kHz, input impedance value should be at least 100 times higher than the impedance of zero displacement detector and detected hydrophone, gain error should not exceed 0.1dB. 4) Programmable switch: Working frequency range 1Hz~2kHz, crosstalk between channels should be less than -80dB. 5) Power amplifier
Piezoelectric compensation method: Working frequency range 1Hz~2kHz, output impedance matches the source transducer impedance, output waveform distortion (THD+N) is not more than 2%;
Vibration liquid column method: Working frequency range 20Hz~1kHz, output impedance matches the exciter impedance in the vibration table, output waveform distortion (THID+N) is not more than 2%. 6) Filter
Piezoelectric compensation method: working frequency range 1Hz~2kHz, bandwidth can be adjusted arbitrarily, attenuation slope is not less than 48dB/octave;
Vibration liquid column method: working frequency range 20Hz1kHz, 1/3 or 1/1 octave. 7) Measuring amplifier: working frequency range 1Hz~2.kHz, amplification factor is not less than 40dB; nonlinearity of amplification factor does not exceed ±0.1 dB.
8) Digital voltmeter: maximum allowable error of voltage measurement is 0.5%. 9) Accelerometer (including adaptive amplifier): sensitivity is not less than 1mVl (ms~2), maximum allowable error is ±2%. 10) Vibration table: dynamic driving force is not less than 10 times the load mass of the water-filled container, vertical resonance frequency is greater than 5kHz, vibration waveform distortion (THD+N) is not more than 2%. 11) Oscilloscope: dual channel.
12) Megaohmmeter: test voltage 100V, maximum allowable error of insulation resistance measurement ±10%. 13) Capacitance meter: capacitance value measurement range not less than 100μF; maximum allowable error of capacitance measurement ±5%. 14) Computer: with instrument control interface. 7.1.2.2 Piezoelectric compensation cavity
1) The piezoelectric compensation cavity is a rigid structure composed of piezoelectric compensation transducer, piezoelectric zero displacement detector, source transducer and upper and lower rigid cover plates. The maximum linear dimension in the cavity should be less than one tenth of the wavelength of the sound wave in the liquid in the cavity. The cavity wall should have sufficient thickness and the entire compensation cavity should be electromagnetically shielded; 2) Take effective vibration isolation measures to prevent the vibration of the source transmitter from being directly coupled to the compensation transducer, zero position detector and hydrophone through the structure;
3) The cavity is filled with clean fresh water that has been degassed, and the structure of the cavity should facilitate the exhaustion of residual air in the cavity; 4) The characteristic constant K of the compensation transducer in the compensation cavity (measured according to Appendix A). The measurement uncertainty of the value shall not exceed 0.2 dB.
7.1.2.3 Vibrating liquid column container
1) The wall of the vibrating liquid column container should be rigid; 2) The height of the liquid column (clean fresh water that has been degassed) in the liquid column container should be greater than the diameter of the liquid column and less than one-fourth of the wavelength of the sound wave in the liquid corresponding to the highest measuring frequency; 3) The diameter of the liquid column should be at least times greater than the diameter of the standard hydrophone under test. 7.2 Verification Items
The initial verification, subsequent verification and in-use inspection items of standard hydrophones are shown in Table 1.4
JJG 1018--2007
Table 1 List of initial verification, subsequent verification and in-use inspection items of standard hydrophones Item
Appearance inspection
Insulation resistance
Sound pressure sensitivity [level]
Sound pressure sensitivity level Frequency response
Initial verification
Subsequent verification
1. For standard hydrophones with preamplifiers, insulation resistance and voltage are not verified. 2. "+" indicates items to be inspected
7.3 Verification method
7.3.1 Appearance inspection
Indicates items not to be inspected.
Standard hydrophones should have clear markings
, etc. The appearance should be intact
including the manufacturer's name. The product
has no mechanical damage that affects normal operation. The factory calibration data should meet the requirements of 6.3.2. 7.3.2 Insulation resistance!
Connect the standard hydrophone without preamplifier to the soft end of the component. The insulation resistance value measured should meet the requirements of 5.1.7.3.3 Capacitance
Inspection during use
Serial number of the product
Connect the cable end to the megohmmeter
Put it in water, 1
Connect the cable of the standard hydrophone without preamplifier to the capacitance meter, and meet the requirements of 5.1.1.
The measured capacitance value shall comply with
7.3.4 Sound pressure sensitivity [level]
First calibration and subsequent calibration: When the structure and size of the standard hydrophone to be tested are suitable for the honey compensation cavity, the piezoelectric compensation method shall be used for calibration; when the standard hydrophone to be tested is inconvenient to be placed in the compensation building control body,
1kHz, the vibrating liquid column method shall be used for calibration.
In-use inspection: When the piezoelectric compensation method is used for calibration, follow 7.3.4.1.2 1) 6 and 7.3.4, 2.2 1) 9)
7.3.4.1 Voltage compensation method
7.3.4.1.1 Calibration device
The block diagram of the piezoelectric compensation method calibration device is shown in Figure 1. 7.3.4.1.2 Verification steps
Since the frequency range is only 20 Hz~
Implementation: When using the vibrating liquid column method for verification
1) Make the following preparations before verification: Measure the characteristic constant K of the compensation transducer in the compensation cavity. The measurement method is shown in Appendix A; Fill the compensation cavity with clean fresh water that has been degassed and remove the bubbles in the cavity; Scrub the surface of the standard hydrophone to be tested with a non-corrosive detergent, soak it in water for at least 1 hour, and then fix it in the compensation cavity through a connector, with its symmetry axis located on the axis of the compensation cavity.
2) Connect the measuring instruments, the various parts of the compensation cavity and the standard hydrophone to be tested as shown in Figure 1. 5
Program-controlled switch
Hydrophone
Source transducer
National amplifier
JJG 1018--2007
Computer
Filter
Shielding layer
Zero displacement detector
Elastic filler
Compensation transducer
Elastic filler
Lock-in amplifier
Oscilloscope
Power amplifier
Figure 1 Block diagram of the piezoelectric compensation method verification device 3) Turn on all instruments and equipment and preheat for 15 minutes. 4) Adjust the amplification of the power amplifier to an appropriate value. Signal source
5) Under the actual working state, by exciting and stopping the excitation source transducer, check the signal-to-noise ratio of the open-circuit output voltage U of the zero detector and the open-circuit output voltage U of the standard hydrophone under test, and its value should be no less than 30dB. 6) Set the working frequency of the calibration device to 500Hz, and the output waveform of the hydrophone under test should have no obvious distortion. 7) Operate the computer, call up the corresponding measurement program from the hard disk, and input the frequency sequence to be measured. 8) Control and measure according to the flowchart shown in Figure 2. When the program-controlled instrument is adjusted to the panel control state, manual point-by-point measurement can also be performed.
Instrument initialization
Signal source A output, (1)
The program-controlled switch is set to "1\
Signal source B output, ()
Adjust the B output amplitude and phase
The value read by the phase-locked amplifier
is the minimum
Read the compensation voltage U.
The program-controlled switch is set to "2"
The phase-locked amplifier reads U, value
Calculate the sensitivity level M(i)
Is it completed?
Measurement flow chart of piezoelectric compensation method
9) Record the relevant measurement data.
JJG1018-—2007
10) Calculate the sound pressure sensitivity [level] (dB) according to formula (1). M = 20 lg(U/U.) -- 20 lgK. - 120 Where; M is the sound pressure sensitivity level, dB;
U.--the open circuit voltage value of the standard hydrophone under test: V: U is the compensation voltage value, V;
K. The characteristic constant of the compensation transducer, Pa/V; Repeat the measurement 6 times and calculate the sound pressure sensitivity level at different frequencies. The result should meet the requirements of 5.3. 7.3.4.2 Vibration liquid column method
7.3.4.2.1 Calibration device
The block diagram of the vibration liquid column method calibration device is shown in Figure 3. Suspension Bracket
Tested hydrophone
Accelerometer
Vibration table
Power amplifier
7.3.4.2.2 Verification steps
Adaptive amplifier
Signal source
Measuring amplifier
Filter
Preamplifier
Programmable switch
Figure 3 Block diagram of the vibration liquid column method verification device Digital voltmeter
Oscilloscope
Computer
1) Make the following preparations before calibration: firmly fix the liquid column container to the center of the vibration table, and adjust the table to ensure that the liquid column vibrates vertically; slowly pour clean fresh water that has been degassed into the container, scrub the surface of the hydrophone to be tested with a non-corrosive detergent, and immerse it in water for at least 1 hour before hanging it on the central axis of the liquid column container. The design of the suspension mechanism should avoid direct coupling between the vibration source and the standard hydrophone to be tested. 2) By adjusting the water immersion depth of the hydrophone and the liquid level position of the liquid column, the liquid column height L and the water immersion depth h of the hydrophone reach appropriate values (usually L is 20cm~~30cm, h is 10cm15cm), and the measurement uncertainty should not exceed 1.5%.
3) Rigidly fix the accelerometer to the outer bottom of the container by appropriate means. 4) Connect the measuring instrument and the standard hydrophone to be tested as shown in Figure 3. 5) Turn on all instruments and equipment and preheat for 15 minutes. 6) Adjust the output of the power amplifier so that the vibration of the vibration table has a suitable longitudinal acceleration. JJG 1018-2007
7) Adjust the adaptive amplifier to output an appropriate voltage signal. 8) Under the actual working state, check the signal-to-noise ratio of the output open-circuit voltage of the hydrophone under test by moving the hydrophone in and out of the liquid column. The value should be no less than 30dB. 9) Set the working frequency of the calibration device to 500Hz. The output waveform of the hydrophone under test should not be significantly distorted. 10) Start the computer and run the sound velocity measurement program in the tube according to the flow chart shown in Figure 4. Determine the resonant frequency of the liquid column under the current state and calculate the sound velocity C according to the relationship that the height of the liquid column is equal to one-quarter of the wavelength at the resonant frequency. Instrument initialization
Press and read the U. value
The program-controlled switch is adjusted to
5 minimum?
Signal source edit and store ()
Calculate and output the flow chart of the measurement program
11) Input the frequency sequence to be measured by the computer. According to the program in the figure, when the program-controlled instrument is adjusted to the panel control state, the instrument can be initialized
Input various parameters
The program-controlled switch is adjusted to
The digital voltmeter reads the U value
The program-controlled switch is adjusted to "2\
The digital voltmeter reads the U value
Show the flow chart and run the hydrophone sensitivity measurement point measurement.
Calculate M ())
Store and output
Figure 5 Vibration liquid column method measurement flow chart2 Verification steps
Adaptive amplifier
Signal source
Measuring amplifier
Filter
Preamplifier
Program-controlled switch
Figure 3 Block diagram of the vibration liquid column method verification device Digital voltmeter
Oscilloscope
Computer
1) Make the following preparations before verification: Fix the liquid column container firmly on the center of the vibration table surface, and adjust the table surface to ensure that the liquid column vibrates vertically; slowly pour degassed clean fresh water into the container, scrub the surface of the hydrophone to be tested with a non-corrosive detergent, and after soaking in water for at least 1 hour, suspend it on the central axis of the liquid column container. The design of the suspension mechanism should avoid direct coupling between the vibration source and the standard hydrophone to be tested. 2) By adjusting the water depth of the hydrophone and the position of the liquid column, the height of the liquid column L and the depth of the hydrophone in the water h reach appropriate values (usually L is 20cm~~30cm, h is 10cm15cm), and the measurement uncertainty should not be greater than 1.5%.
3) Rigidly fix the accelerometer to the outer bottom of the container by appropriate means. 4) Connect the measuring instrument and the standard hydrophone under test as shown in Figure 3. 5) Turn on all instruments and equipment and preheat for 15 minutes. 6) Adjust the output of the power amplifier so that the vibration table has appropriate longitudinal acceleration. JJG 1018-2007
7) Adjust the adaptive amplifier so that it has appropriate voltage signal output. 8) Under actual working conditions, by moving the hydrophone under test in and out of the liquid column, check the signal-to-noise ratio of the output open-circuit voltage of the hydrophone under test, and its value should be no less than 30dB. 9) Set the working frequency of the calibration device to 500Hz. The output waveform of the hydrophone under test should not be significantly distorted. 10) Start the computer and run the sound velocity measurement program in the tube according to the flow chart shown in Figure 4. Determine the resonant frequency of the liquid column under the current state and calculate the sound velocity C according to the relationship that the height of the liquid column is equal to one quarter of the wavelength at the resonant frequency. Instrument initialization
Press and read U. value
The program-controlled switch is adjusted to
5 minimum?
Signal source edit and store ()
Calculate and output the flow chart of the measurement program
11) Input the frequency sequence to be measured by the computer. According to the program in the figure, when the program-controlled instrument is adjusted to the panel control state, the instrument can be initialized
Input various parameters
The program-controlled switch is adjusted to
The digital voltmeter reads the U value
The program-controlled switch is adjusted to "2\
The digital voltmeter reads the U value
Show the flow chart and run the hydrophone sensitivity measurement point measurement.
Calculate M ())
Store and output
Figure 5 Vibration liquid column method measurement flow chart2 Verification steps
Adaptive amplifier
Signal source
Measuring amplifier
Filter
Preamplifier
Program-controlled switch
Figure 3 Block diagram of the vibration liquid column method verification device Digital voltmeter
Oscilloscope
Computer
1) Make the following preparations before verification: Fix the liquid column container firmly on the center of the vibration table surface, and adjust the table surface to ensure that the liquid column vibrates vertically; slowly pour degassed clean fresh water into the container, scrub the surface of the hydrophone to be tested with a non-corrosive detergent, and after soaking in water for at least 1 hour, suspend it on the central axis of the liquid column container. The design of the suspension mechanism should avoid direct coupling between the vibration source and the standard hydrophone to be tested. 2) By adjusting the water depth of the hydrophone and the position of the liquid column, the height of the liquid column L and the depth of the hydrophone in the water h reach appropriate values (usually L is 20cm~~30cm, h is 10cm15cm), and the measurement uncertainty should not be greater than 1.5%.
3) Rigidly fix the accelerometer to the outer bottom of the container by appropriate means. 4) Connect the measuring instrument and the standard hydrophone under test as shown in Figure 3. 5) Turn on all instruments and equipment and preheat for 15 minutes. 6) Adjust the output of the power amplifier so that the vibration table has appropriate longitudinal acceleration. JJG 1018-2007
7) Adjust the adaptive amplifier so that it has appropriate voltage signal output. 8) Under actual working conditions, by moving the hydrophone under test in and out of the liquid column, check the signal-to-noise ratio of the output open-circuit voltage of the hydrophone under test, and its value should be no less than 30dB. 9) Set the working frequency of the calibration device to 500Hz. The output waveform of the hydrophone under test should not be significantly distorted. 10) Start the computer and run the sound velocity measurement program in the tube according to the flow chart shown in Figure 4. Determine the resonant frequency of the liquid column under the current state and calculate the sound velocity C according to the relationship that the height of the liquid column is equal to one quarter of the wavelength at the resonant frequency. Instrument initialization
Press and read U. valuebzxZ.net
The program-controlled switch is adjusted to
5 minimum?
Signal source edit and store ()
Calculate and output the flow chart of the measurement program
11) Input the frequency sequence to be measured by the computer. According to the program in the figure, when the program-controlled instrument is adjusted to the panel control state, the instrument can be initialized
Input various parameters
The program-controlled switch is adjusted to
The digital voltmeter reads the U value
The program-controlled switch is adjusted to "2\
The digital voltmeter reads the U value
Show the flow chart and run the hydrophone sensitivity measurement point measurement.
Calculate M ())
Store and output
Figure 5 Vibration liquid column method measurement flow chart
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