BRUEL & KJAER 9737 User Manual
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BRUEL & KJAER 9737 User Manual

BRUEL & KJAER 9737 User Manual

Portable impedance meter system
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USER MANUAL
Portable Impedance Meter System
Type 9737
BE 1839 – 13
English

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Summary of Contents for BRUEL & KJAER 9737

  • Page 1 USER MANUAL Portable Impedance Meter System Type 9737 BE 1839 – 13 English...
  • Page 3 Portable Impedence Meter System Type 9737 User Manual BE 1839 – 13 December 2019 www.bksv.com...
  • Page 4 Health and Safety Considerations Electrical Hazards This apparatus has been designed and tested in accordance Warning: Any adjustment, maintenance and Safety with IEC/EN 61010 – 1 ANSI/UL 61010 – 1 repair of the open apparatus under voltage must Requirements for Electrical Equipment for Measurement, be avoided as far as possible and, if unavoidable, Control and Laboratory Use .
  • Page 6 Brüel & Kjær has made every effort to ensure the accuracy of Brüel & Kjær and all other trademarks, service marks, trade the information contained in this document. No responsibility names, logos and product names are the property of is accepted for any errors or omissions herein. It is the Brüel &...

  • Page 7: Table Of Contents

    Contents CHAPTER 1 Introduction..........................1 CHAPTER 2 System Overview and Setup ....................3 System Layout........................... 3 Software Installation and Getting Started ................4 CHAPTER 3 User Interface for Impedence Testing ..................7 Graphical User Interface (GUI)....................7 Impedance Meter Control ......................7 CHAPTER 4 Project Setup ...........................
  • Page 8 CHAPTER 8 Data Export/Import ....................... 37 General ........................... 37 Export to Excel........................37 Export/Import Results ......................40 Post-processing ........................40 Saving the Project........................40 CHAPTER 9 Troubleshooting and Tips for Efficient Testing ............... 41 General ........................... 41 CHAPTER 10 Specifications ........................43 INDEX ................................

  • Page 9: Introduction

    Chapter 1 Introduction Portable Impedance Meter System Type 9737 (Fig.1.1) represents the state of the art in normal incidence impedance measurement for the aerospace industry. Increasingly stringent aerospace environmental regulations are demanding acoustic lining attenuation improvements, which are driving ever-improved installed acoustic liner impedances. As a result, fully bonded curved panels must now be assessed for their true effective acoustic behaviour in their final condition, and acoustic measurements are now superseding the traditional geometric and DC flow methods.
  • Page 10 Portable Impedence Meter System Type 9737 – User Manual...

  • Page 11: System Overview And Setup

    Chapter 2 System Overview and Setup System Layout Fig.1.1 and Fig.2.1 show the system hardware components and connections. Fig.2.1 Portable impedance meter system – LAN-XI front end Type 3160-A-042, with Front Panel UA-2104 (left) and Power Amplifier WB-3592 in double LAN-XI casing (right) Microphone Signal 1 Microphone Signal 2 No connection...

  • Page 12: Software Installation And Getting Started

    Portable Impedence Meter System Type 9737 – User Manual Fig.2.2 Rear connectors of LAN-XI combination PC LAN Mains Voltage Selector ⚠ Make sure the correct voltage is set on the Mains Voltage Selector BEFORE you connect WARNING: the module to mains power (either 115 or 230 V), see Fig.2.2. Failure to do this will cause damage to the equipment.
  • Page 13 CHAPTER 2 System Overview and Setup Settings Control Panel Control 4) Set the IP address – from the Start menu, click (or just Panel Network Connections Local Area Connection depending on your setup) > > Properties Internet Protocol (TCP/IP) Use the following IP >...
  • Page 14 Portable Impedence Meter System Type 9737 – User Manual...

  • Page 15: User Interface For Impedence Testing

    Chapter 3 User Interface for Impedence Testing Graphical User Interface (GUI) After connecting all the cables and powering up the LAN-XI data acquisition unit and the power amplifier, the next step is to go through the Measurement task on the GUI in sequential order. The sequence follows a natural progression, starting with the task at the top of the Measurement task bar (left of the display), then filling in details in the window(s) to the right of that task, and then moving down to the next task, and so on.
  • Page 16 Portable Impedence Meter System Type 9737 – User Manual ⚠ This equipment can generate intense sound pressure levels that could seriously damage WARNING: or destroy a person’s hearing. It is recommended that the speaker is not powered on unless the meter is placed on a sample. Under no circumstances should the meter be pointed towards individuals.

  • Page 17: Project Setup

    Chapter 4 Project Setup Project Setup The Project Setup task allows input of all information describing the tube, the acquisition parameters, the initial test broadband OASPL, and the reference ambient conditions. Click the Project Setup task button. The Material Testing Control window appears to the right of the task bar, together with the associated task note (if displayed).
  • Page 18 Portable Impedence Meter System Type 9737 – User Manual ✐ The default distances for the microphone closest to the sample (9.9 cm), and the distance Please note: between the microphones (2 cm), will be updated following the Acoustic Center task (see section 5.5).
  • Page 19 CHAPTER 4 Project Setup Fig.4.3 Generator tab Generator Active checkbox is checked as default. 4.1.4 Environment Tab: Recording the Ambient Conditions Environment tab allows you to input the ambient temperature, pressure and relative humidity (Fig 4.4). Using these inputs, the speed of sound, density and the characteristic impedance of the air are calculated.
  • Page 20 Portable Impedence Meter System Type 9737 – User Manual Fig.4.4 Environment tab 4.1.5 Options Tab: Units, Warning Tolerances, and Transfer Function Type Options tab (Fig 4.5) allows you to set warnings for signal-to-noise ratio, the dynamic range and the transfer function calibration factors (amplitude and phase) of a measurement. The default values are 10 dB, 60 dB, and 2 dB/2 degrees, respectively.
  • Page 21 CHAPTER 4 Project Setup Fig.4.5 Options tab 4.1.6 Front-end Tab: Setting the Microphone and Channel Inputs Front-end tab (Fig 4.6) provides information on the microphones used, along with their slot, channel and serial numbers. ✐ The Slot Number values will always be set to ‘1’. Please note: This tab also provides a button for activation of the signal connections and a drop-down list for selecting different generator signals, if required.
  • Page 22 Portable Impedence Meter System Type 9737 – User Manual Fig.4.6 Front-end tab...

  • Page 23: Calibration

    The calculation of the microphone acoustic centre is also described. Brüel & Kjær Type 4187 microphones, which are used in Type 9737, are highly stable. As such, they do not require individual sensitivity calibration unless there appears to be a problem with them.

  • Page 24: Transfer Function Calibration

    Portable Impedence Meter System Type 9737 – User Manual Fig.5.1 Typical microphone autospectra (noise < 60 dB) In order to perform an SNR test, position the meter on an acoustic sample (preferably the ‘Reference’ sample), and select the Signal Measurement radio button. Click Start and immediately hold down the button on the tube handle to measure the signal.

  • Page 25: Reference Panel - Recommended For Overall System Calibration Procedures

    CHAPTER 5 Calibration recorded by the wall microphones. When using the fixed reference sample, any changes to the coherence spectrum may be a sign of some leakage in the microphone bedding in the tube, whereupon the microphones should be removed and re-inserted. Fig.5.2 Transfer Function Calibration task –...

  • Page 26: Acoustic Centre Measurement

    Portable Impedence Meter System Type 9737 – User Manual Acoustic Center Measurement This task (Fig 5.3) is used to calculate the acoustic centre of the 1/4 microphones. It is very important to know this distance accurately, as the measurement error in impedance is very sensitive to the accuracy in the measurement of the distance to the sample, and the distance between the microphones.

  • Page 27: Channel Calibration

    CHAPTER 5 Calibration Channel Calibration The Channel Calibration task allows you to perform simple calibrations of the individual measurement channels quickly and easily. As mentioned previously, a microphone calibration is seldom needed, as the Brüel & Kjær microphones are accurately calibrated on supply and are very stable.
  • Page 28 Portable Impedence Meter System Type 9737 – User Manual...

  • Page 29: Sample Holder Correction

    Sample Holder Correction General Portable Impedance Meter Type 9737 is supplied with a screw-on Sample Holder (WA-1706). The holder allows samples to be cut to fit exactly into the 29 mm tube diameter, accommodating samples of a depth up to 20 cm. The sample holder is ideal for testing non-locally reacting materials (for example, foams, slotted core, etc.), as it restricts lateral sound propagation.
  • Page 30 Portable Impedence Meter System Type 9737 – User Manual Fig.6.1 Example measurements with flanged tube and sample holder Fig.6.2 Example of flanged in- tube correction The flanged tube to sample holder correction can be applied to future flanged tube Test...

  • Page 31: Measurements

    Chapter 7 Measurements General Type 9737 can perform both broadband and pure tone measurements, and it can measure at sound pressure levels exceeding 150 dB. ⚠ This equipment can generate intense sound pressure levels that could seriously damage WARNING: or destroy a person’s hearing. It is recommended that the speaker is not powered on unless the meter is placed on a sample.
  • Page 32 Portable Impedence Meter System Type 9737 – User Manual Fig.7.1 Naming and adding a measurement in the Measurements task The remainder of this section describes the measurement options. Single level broadband measurements, broadband and pure tone non-linear measurements, quality control measurements, and measurements with a user-defined source, can be performed.
  • Page 33 CHAPTER 7 Measurements Fig.7.2 Subset Control tab With the meter positioned on the sample, click Start (in the software, or via the Measurement Measurement done Control Unit) and hold the loudspeaker button down until the message appears. The measured impedance spectra can be displayed by checking the checkboxes next to the Results individual impedance results in the list on the tab (see Fig.7.3).
  • Page 34 Portable Impedence Meter System Type 9737 – User Manual Fig.7.3 Results tab Plots of other relevant parameters can also be displayed by checking the appropriate checkbox Results on the tab. The scale of the axes can also be adjusted by right-clicking on the axis in question, and setting the desired minimum and maximum values (see Fig.7.3).
  • Page 35 CHAPTER 7 Measurements frequency steps are good default values. The use of a search range ensures the desired reactance zero crossing is found. The range and/or the number of frequency steps may be varied to maximise accuracy of the measured varying resonance frequency. The example in Fig.7.4 shows a centre frequency of 2800 Hz, with a span of 800 Hz, giving a resonance frequency search range between 2400 Hz and 3200 Hz.
  • Page 36 Portable Impedence Meter System Type 9737 – User Manual Fig.7.5 Subset Control tab: Pure Tone – Fixed Frequency • Broadband Quality Control single OASPL – see section 7.3.1 Broadband test with increasing OASPL • (Fig.7.6) – this option allows you to perform a resistance non-linearity test with an increasing random OASPL.
  • Page 37 CHAPTER 7 Measurements Fig.7.6 Subset Control tab: Broadband test with increasing OASPL User-defined Signal (Wave-file) • – Broadband noise (Fig.7.7). This option performs broadband tests with an increasing OASPL, for a waveform defined by you and imported in a .wav file. This may be, for example, a source representative of an engine with a fundamental tone and harmonics superimposed on a broadband spectrum.
  • Page 38 Portable Impedence Meter System Type 9737 – User Manual Fig.7.7 Subset Control tab: User-defined Signal (Wave -file) For each test using the SPL automation, the acoustic velocity is calculated. For pure tone tests, the facing sheet impedance and pressure are determined. The latter uses the tube standing wave equation and the tube wall microphone measurements.
  • Page 39 CHAPTER 7 Measurements Fig.7.8 Pure tone R vs V displayed on screen and in the plots Fig.7.8 shows an example of the impedance variation with OASPL.
  • Page 40 Portable Impedence Meter System Type 9737 – User Manual Fig.7.9 Impedance variation with increasing broadband OASPL 7.2.4 Handle Indicator Lights An amber ready light on the handle indicates the meter is ready to measure. Measurement initiation may either be set to ‘Autostart’, where the meter just waits for the button on the handle to be pressed, or to ‘Trigger’.

  • Page 41: Quality Control Measurements

    CHAPTER 7 Measurements Quality Control Measurements 7.3.1 General The portable impedance meter includes the option to insert upper and lower impedance tolerances, when using the broadband impedance measurement. When this option is activated and a test is made, the meter will signal whether the tolerances have been passed, or failed, at each test point, and for each frequency for which the tolerances are set.
  • Page 42 Portable Impedence Meter System Type 9737 – User Manual Fig.7.11 Example of resistance and reactance tolerances 7.3.2 Quality Control Test procedure Autostart next measurement Apply Quality Control limits 1) Select on the Subset Control tab. 2) Set the test OASPL parameters on the Measurement Control tab. Enter the number of test positions, name the test and click Add.
  • Page 43 CHAPTER 7 Measurements Fig.7.12 On-screen plotting of successive test impedances and tolerances 7.3.3 Quality Control Test Results ® Word Report The quality control test results can be exported to Microsoft Word using the task on the Measurements Task Bar. Fig.7.14 shows an example of a quality control Word output. Word reports can be generated simply by selecting the required test outputs, and clicking Create Report.
  • Page 44 Portable Impedence Meter System Type 9737 – User Manual Fig.7.13 Exporting quality control data to Word Fig.7.14 shows an example page from a quality control output file. The file contains test, part, and operator details, and whether the part has passed or failed the set quality control impedance limits.

  • Page 45: Chapter 8 Data Export/Import

    Chapter 8 Data Export/Import General The portable impedance meter allows you to not only make fast acoustic measurements, in situ, ® ® at high SPLs, but also offers immediate export of the data to Microsoft Excel or Word. This allows the acoustic engineer to analyse the data as soon as possible. Export to Excel ®...
  • Page 46 Portable Impedence Meter System Type 9737 – User Manual Fig.8.1 Excel export task – exporting single OASPL parameters 8.2.1 Broadband Measurements at User-defined OASPL The test parameters for these single position, single OASPL tests are output by selecting the single OASPL parameters. Fig.8.1 shows an example where all of the available test parameters are exported.
  • Page 47 CHAPTER 8 Data Export/Import Fig.8.2 Excel export task – exporting OASPL Loop parameters 8.2.3 Quality Control Tests In addition to the Word quality control report, with a scrollable impedance plot, the quality ® control data can also be exported to Excel .

  • Page 48: Export/Import Results

    Portable Impedence Meter System Type 9737 – User Manual Fig.8.3 Excel export task – export of three quality control test locations Export/Import Results The Export Results and Import Results tasks on the Results task bar allow you to save measured data in dedicated files, and retrieve data (for use in another project, for example).

  • Page 49: Troubleshooting And Tips For Efficient Testing

    Chapter 9 Troubleshooting and Tips for Efficient Testing General This section gives some troubleshooting advice and hints and tips for efficient use of the portable impedance meter. 9.1.1 Reference Panel – Overall System Check As stated in section 5.4, you are advised to assign a flat reference panel for use with the meter. A back-up sample is also recommended.
  • Page 50 Portable Impedence Meter System Type 9737 – User Manual 9.1.4 Curved Flange Design It is important to design a flange to obtain the closest possible fit to the test panel. If the panel curvature varies across its surface, it is recommended to manufacture a flange to fit the mean curvature obtained by averaging a number of CATIA sections.

  • Page 51: Chapter 10 Specifications

    Chapter 10 Specifications Specifications – Portable Impedance Tube WA-1599-W-070 FREQUENCY RANGE ENVIRONMENTAL SENSORS Tube: 500 Hz to 6.4 kHz Integrated sensors measure temperature pressure and relative humidity ZERO ABSORPTION (calculated in 1/3-octave bands) LOUDSPEAKER Max. RMS Power: 50 W at 20 C (68 F) 50 Hz to 4 kHz: <...
  • Page 52 Portable Impedence Meter System Type 9737 – User Manual • Measurement with broadband, pure-tone, or user- • Extraction of 1/n-octave centre frequency information defined source • Acoustic pressure and acoustic velocity spectra at sample • Automated pass/fail impedance quality control routine...
  • Page 53 CHAPTER 10 Specifications Compliance with Standards - Type 9737 The CE marking is the manufacturer's declaration that the product meets the requirements of the applicable EU directives. RCM mark indicates compliance with applicable ACMA technical standards – that is, for EMC and EME in Australia.
  • Page 54 Portable Impedence Meter System Type 9737 – User Manual...

  • Page 55: Index

    Index Numerics 4187 ............... 15 Front-end Tab ............13 Acoustic Center Measurement ......18 Generator Tab ............10 Acoustic Center Task ..........41 GUI ................7 Add New Measurements Panel ......23 Importing Data ............37 Background Noise Measurement Radio Interchanged Microphone Positions Radio Button ..............
  • Page 56 Portable Impedance Meter System ....1, 3, 4 SNR (Signal-to-Noise Ratio) ........15 Post-processing ............. 40 Software Installation ..........4 Power Amplifier (WB-3592) ........7 Specifications ............43 Project Setup ............9 System Layout ............3 Project Setup Task ........... 9 System Overview .............
  • Page 58 © Brüel & Kjær. All rights reserved. www.bksv.com...

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