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FFT Analysis Software BZ-7230

1. s o a number is retained The analyzer also conforms to these EN Standards DETECTORS Parallel Detectors on every measurement A or B weighted switchable broadband detector channel with Fast time weighting one linearly averaging detector and one peak detector C or Z weighted switchable as for A or B weighted Overload Detector Monitors the overload outputs of all the frequency weighted channels MEASUREMENTS X frequency weightings A or B Y frequency weightings C or Z V frequency weightings A B C or Z For Display and Storage Start Time Stop Time Overload Elapsed Time LxXeq Lyeq LxFmax LyFmax LxFmin LYFmin Lxieq Lyleq LAFTeq Lvpeak Only for Display as Numbers LxF Lyf Weather Data requires connection to a weather station Wind Dir avg Wind Dir min Wind Dir max Wind Speed avg Wind Speed min Wind Speed max Amb Temperature Amb Humidity Amb Pressure Amb Rain Gauge FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Instantaneous Weather Data Wind Dir Wind Speed Instantaneous GPS Data Latitude Longitude MEASURING RANGES When using Microphone Type 4189 Dynamic Range From typical noise floor to max level for a 1 kHz pure tone signal A weighted 16 6 to 140 dB Primary Indicator Range In accordance with IEC 60651 A weighted 23 5 dB to 123 dB Linearity Range In accordance with IEC 60804 A weighted 21 4 dB to 140 dB L
2. APPENDIX A Setup Parameters 105 Table A 3 Cont Frequency setting parameters Parameter Values Comment Frequency Correction On Determines whether the frequency correction is to Off be applied to the cursor readout While measuring a pure tone a peak may lie between two lines In this case the energy from that peak will be distriouted between these two lines Therefore the exact level and frequency will not be shown if the Frequency Correction parameter is set to Off For a tone that coincides with an FFT line the corrected and uncorrected values will be very similar These corrected levels and frequency values are displayed with the prefix c A 4 Measurement Control Parameters Table A 4 Measurement control parameters Parameter Values Comment Measurement Mode Manual Determines whether the measurement is manual or Triggered triggered Averaging Type Linear Determines the way in which the spectra are Exponential averaged Note Averaging Type is automatically set to Linear when measurement mode is set to Triggered and cannot be changed Average Spectra 1 to 8388607 Linear 1 to 999 Exponential Determines the the number of spectra to be averaged Note If triggered mode is selected it is set to the number of spectra resulting from the setting of Triggers and Spectra per Trigger parameters Signal Type Continuous Determines the type of signal to
3. CHAPTER 2 Getting Started 7 2 2 Overview An overview of the measurement screen is provided in Fig 2 2 Accelerometer Type 4397 A has been selected as the current transducer Fig 2 2 Typical FFT spectrum display showing the various fields Select template from here FFT ANALYZER Transducer Icon Measurement Time Cursor Selection Panel Graph Panel Ava A Frequency Readout MAX 0 000 FET Level Readout Parameter Panel Act R tiz F Averaging a PR Frequency Correction Scaling Ai 160 Main Cursor Post Weighting un ae Y Axis X frequency Axis Noise Floor This range may contain spurious noise lines Value Panel 2 3 Tutorial Measurements on a Stationary Signal To work through this tutorial you will need the following equipment Hand held Analyzer Type 2270 or Type 2250 with e Microphone Type 4189 e Accelerometer Type 4397 A e Sound Calibrator Type 4231 e Calibrator Exciter Type 4294 e Earphones HT 0015 or equivalent This tutorial provides a step by step guide on how to perform FFT measurements on a stationary source including familiarisation with the important features of BZ 7230 Note If you do not have the Signal Recording option BZ 7226 installed please skip section 2 3 7 1 Fit the supplied microphone onto the Hand Held Analyzer 2 Turn the analyzer on 8 Fig 2 3 FFT and MAX spectra being measured are displayed on screen 2 3 1 FFT Analysis Software BZ 72
4. Calibration Exciter Type 4294 onto the accelerometer turn on Type 4294 and tap ST the Start button on the screen to start the calibration The rest of the procedure is similar to the microphone calibration procedure Various mountings are available depending on the type of accelerometer you are using please refer to the User Manual for Calibration Exciters Types 4294 and 4294 002 36 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 4 Measuring Random Signals 4 1 Random Signals Fig 4 1 Random signals Stationary signals Non stationary signals Frequency Frequency Frequency A random signal is a continuous stationary signal whose properties can only be described using statistical parameters Random signals have a frequency spectrum that is continuously distributed with frequency Acousticians would generally call random signals noise Examples of random signals are background noise in the environment such as rain and the effects of cavitations and turbulence a 4 2 4 2 1 4 2 2 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Preparing for Measurement This section will guide you in choosing suitable start values for measurement of random signals Configuring the Input Configuring the input is a three step process 1 Choosing the correct transducer 2 Setting the signal source and type 3 Calibra
5. TEMPERATURE IEC 60068 2 1 amp IEC 60068 2 2 Environmental Testing Cold and Dry Heat Operating Temperature 10 to 50 C 14 to 122 F lt 0 1 dB Storage Temperature 25 to 70 C 13 to 158 F HUMIDITY IEC 60068 2 78 Damp Heat 90 RH non condensing at 40 C 104 F Effect of Humidity lt 0 1 dB for 0 lt RH lt 90 at 40 C 104 F and 1 kHz MECHANICAL Environmental Protection IP44 Non operating IEC 60068 2 6 Vibration 0 3 mm 20 m s2 10 500 Hz IEC 60068 2 27 Shock 1000 m s IEC 60068 2 29 Bump 4000 bumps at 400 m s WEIGHT AND DIMENSIONS 650 g 23 oz including rechargeable battery 300 x 93 x 50 mm 11 8 x 3 7 x 1 9 including preamplifier and microphone USERS Multi user concept with login Users can have their own settings with jobs and projects totally independent of other users PREFERENCES Date Time and Number formats can be specified per user LANGUAGE User Interface in Catalan Chinese People s Republic of China Chinese Taiwan Croatian Czech Danish English Flemish French German Hungarian Japanese Italian Korean Polish Portuguese Romanian Russian Serbian Slovenian Spanish Swedish and Turkish CHAPTER 8 Specifications HELP Concise context sensitive help in English French German Italian Japanese Korean Polish Portuguese Romanian Serbian Slovenian and Spanish UPDATE OF SOFTWARE Update to any version using BZ 5
6. The parameter is enabled when Trigger Type is set to External or Tacho is set to On 58 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Slope The slope parameter determines the trigger slope on the external trigger It is enabled when Trigger Type is set to External or Tacho is set to On You can choose to trigger on the Rising or Falling slope of the external trigger signal CCLD Pull Up For instruments with serial number 2630266 and above this parameter is named CCLD Use this parameter to switch on or off a CCLD power supply depending on the requirements of the equipment connecting to the trigger input Note Laser Tachometer Probe MM 0360 requires CCLD set to On For instruments with serial numbers below 2630266 the parameter is named Pull up Use this parameter to pull up the external trigger input to 5 V via a 7 5 kQ resistor The CCLD or Pull Up parameter is enabled when Trigger Type is set to External or Tacho is set to On Internal External Level The Internal Level parameter determines the level of the incoming measurement signal that will cause a trigger This parameter is enabled when Trigger Type is set to Internal The maximum value you can enter depends on the full scale level The External Level parameter determines the level of the signal applied on the trigger input that will cause a trigger This parameter is enabled when Trigger Type is set to External or Tacho is set t
7. different usage scenarios day night etc Backlight Adjustable level and on time USER INTERFACE Measurement Control Using pushbuttons on keyboard Setup and Display of Results Using stylus on touch screen or pushbuttons on keyboard Lock Keyboard and touch screen can be locked and unlocked VOICE ANNOTATIONS Voice annotations can be attached to measurements so that verbal comments can be stored together with the measurement Playback Playback of voice annotations or signal recordings can be listened to using an earphone headphones connected to the headphone socket Gain Adjustment 60 dB to 60 dB TEXT ANNOTATIONS Text annotations can be attached to measurements so that written comments can be stored with the measurement IMAGE ANNOTATIONS TYPE 2270 ONLY Image annotations can be attached to measurements Images can be viewed on the screen GPS ANNOTATIONS A text annotation with GPS information can be attached Latitude Longitude Altitude and position error Requires connection to a GPS receiver DATA MANAGEMENT Metadata Upto 10 Metadata annotations can be set per project text from keyboard or text from pick list number from keyboard or auto generated number Project Template Defines the display and measurement setups Setups can be locked Project Measurement data stored with the Project Template Job Projects are organised in Jobs Explorer facilities for easy management of data copy cut paste dele
8. eeeeceeceeseeeeeeeeeteeeeeeeeeeneeeeees 105 FALINGS fo ennaa ANAE 104 Spectra per Trigger H MNQGGSMS vectscsciictssevecoviseccevesevusaeductavlenscdesVicvetiodsoase 105 Numerics Acceleration Display cceceecceeeeeeeeeeeeeeeeeeeee 55 Accelerometers Audibility and Penalty cece eee eeeeeeeeeeee 74 Auto Peak Find cccsececsscssesessesseesseceesenseneesneeeees 15 Auto Save 4 Automatic Gain Control 110 Average Number and Elapsed Time cee 46 Average RPM ee eeeeeeceeeeeeeeeees Average Spectra Parameter ssec 39 51 Averaged Spectra eececceseseseeceeeeeeeeeeeeeeeeeeeeeeeaees 39 Averaging T Averaging TiMe ccccscsesessscesessesseesteceseseesseesseesees 39 Averaging Time Parameter 39 B Bandwidth ninne N Bottom Frequency Broadband Parameters Cc Cable Break Short Detection ccseeeseeeeee 45 Calibration aan ele de Hie Weick 35 75 Caption CB Constant Bandwidth ce ceeceeseeeeeeeeeeeeeeeeeeees 3 Cementing Studs Centre Frequency eceeseeeeseeseeseeeeeeeeaeeees Choosing a Mounting Position CONFIQUIE oe eee eeceeteeeeceeeeneceeeteeeeaeteeeeeeaeeeeeaeeeeeas Configuring the Input Constant Bandwidth CB Constant Percentage Bandwidth CPB n se 3 Continues a aa paa EREE S Continuous Correct Scaling of Deterministic Signals 65 CPB Constant Percentage Ban
9. no damage for signals up to 20 Vpeak Source Impedance lt 1 kQ CCLD Input Max input voltage 7 07 Vpeak no indication for violation of this level no damage for signals in the range 10 to 25 VPeak CCLD Current Voltage 4 mA 25 V CCLD Cable Break Short Indication Checked before and after measurements TRIGGER SOCKET Connector Triaxial LEMO Max Input Voltage 20 Vpeak no damage for signals up to 50 Vpeak Input Impedance gt 47 kQ CCLD Current Voltage 4 mA 25 V OUTPUT SOCKET Connector Triaxial LEMO Max Peak Output Level 4 46 V Output Impedance 50 Q Load Impedance gt 15 kQ lt 1 nF for lt 0 2 dB attenuation from DC to 20 kHz short circuit proof without affecting the measurement results Max DC Offset 15 mV Source Input conditioned gain adjustment 60 dB to 60 dB so J HEADPHONE SOCKET Connector 3 5 mm Minijack stereo socket Max Peak Output Level 1 4 V no load Output Impedance 32 in each channel short circuit proof without affecting the measurement results Sources Input conditioned gain adjustment 60 dB to 60 dB playback of voice annotations and signal recordings gain adjustment 60 dB to 0 dB and playback of recordings gain adjustment 60 dB to 60 dB however max gain is 0 dB for 16 bit wav files MICROPHONE FOR COMMENTARY Microphone which utilises Automatic Gain Control AGC is incorporated in underside of instrument Used to create voice
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11. 3 1 4 Recommended Accelerometers Table 3 1 Recommended DeltaTron accelerometers Type Description Frequency Range Hz Nominal Sensitivity 4397 Miniature 1 25000 1 mV ms 4513 4514 General Purpose 1 10000 1 mV ms 4513 001 4514 001 General Purpose 1 10000 10 mV ms 4513 002 4514 002 General Purpose 1 10000 50 mV ms 8341 Industrial 0 3 10000 10 mV ms 3 2 Configuring the Input DeltaTron accelerometers should be connected to the Rear Input socket of the Hand held Analyzer this is used for Direct or CCLD inputs Also called Rear Socket in the software Use Cable AO 0702 D 030 to connect accelerometers with a 10 32 UNF connector or charge converter to the Rear Input socket of the Hand held Analyzer For accelerometers with a smaller M3 connector use cable AO 0701 D 030 For Type 8341 use cable AO 0722 D 050 Other Accelerometers If you have chosen to use a charge accelerometer you need to incorporate a charge converter in the signal chain For example two charge converters that are compatible are e Type 2647 A Charge to DeltaTron Converter 1 mV pC e Type 2647 B Charge to DeltaTron Converter 10 mV pC Notice that the only difference between the two is the gain re 1 pC Recommended charge accelerometer Type 8324 for Industrial use e Frequency range 1 10000 Hz e Nominal Sensitivity 1 pC ms Use Type 2647 D 004 Charge to Deltatron c
12. 4 Observe the spectra 5 Change Signal Type to Continuous 6 Window Type changes to Hanning 7 Observe the spectra 8 Change Window Type to Rectangular 9 Signal Type changes to Transient 10 Observe the spectra Fig 4 4 Left Selecting Window Type from the Setup Page Right Selecting signal type from the Setup Page 4 2 6 Measurement Control Measurement Mode Triggered Signal Type Continuous Window Type Frequency Settings Units Sound Recording Quick Full 13 41 07 Post weighting CHAPTER 4 Measuring Random Signals Measurement Control d Measurement Mode Triggered Transient Rectangular Signal Type Window Type Frequency Settings Units Sound Recording BZ 7230 has two kinds of post weighting A Weighting and Z Weighting A weighting attenuates frequencies where the human ear is less sensitive Note Although A weighting was designed to be used during the measurement of sound you can also apply it when using vibration or direct transducers Z weighting Zero weighting means that no frequency weighting is applied 1 Tap and select Setup from the list of options 2 On the Full view tab select Frequency Settings and then Post Weighting 3 Select A or Z see Fig 4 5 Note Setting the post weighting will disable the pre weighting a a Fig 4 5 Selecting Post weighting from the Setup menu FFT Analysis Software BZ 7230 and Tone
13. 64 bit versions and Microsoft NET Recommended PC Pentium III or equivalent processor 2048 Mbyte RAM SVGA graphics display adaptor sound card DVD drive mouse USB Windows 7 CHAPTER 8 Specifications Ordering Information 2250 H D01 Hand held Analyzer Type 2250 with BZ 7230 FFT Analysis Software Included with 2250 H D01 e AO 1476 USB Standard A to USB Mini B Interface Cable for hardware versions 1 3 1 8 m 6 ft AO 1494 USB Standard A to USB Micro B Interface Cable for hardware version 4 1 8 m 6 ft BZ 5298 Environmental Software including BZ 5503 Measurement Partner Suite BZ 7230 FFT Analysis Software DD 0594 Protection Plugs for Top Socket FB 0679 Hinged Cover for Hand held Analyzer e KE 0459 Shoulder Bag QB 0061 Battery Pack e UA 1654 5 Extra Styli e UA 1673 Adaptor for Standard Tripod Mount e ZG 0426 Mains Power Supply 2270 H D02 Hand held Analyzer Type 2270 with BZ 7222 Sound Level Meter and BZ 7230 FFT Analysis Software 2250 H D02 Hand held Analyzer Type 2250 with BZ 7222 Sound Level Meter and BZ 7230 FFT Analysis Software Included with 2270 H D02 and 2250 H D02 Type 4189 Prepolarized Free field 1 2 Microphone ZC 0032 Microphone Preamplifier BZ 7222 Sound Level Meter software BZ 7230 FFT Analysis Software KE 0440 Travel Bag KE 0441 Protective Cover for Type 2250 DH 0696 Wrist Strap e UA 1650 90 mm dia Windscreen with A
14. 7230 and Tone Assessment Option BZ 7231 User Manual If you purchased a separate software application for your Hand held Analyzer then you have to install the license on the instrument This is done using Utility Software for Hand held Analyzers BZ 5503 Please consult the on line help included with the BZ 5503 software for instructions on how to install a license Introduction to Tone Assessment When assessing noise it is generally recognised that noise containing audible pure tones is more annoying than noise with the same A weighted broadband level that does not contain audible tones The first evaluation of audible tones in noise is most often carried out by the human ear But for comparative analysis results and documentation an objective analysis may be needed Tone Assessment may be performed using either a 1 3 octave method or an FFT based method ISO 1996 2 2007 Determination of environmental noise levels includes two informative annexes dealing with objective Tone Assessment e Annex C Objective method for assessing the audibility of tones in noise Reference method This method uses FFT analysed measurements e Annex D Objective method for assessing the audibility of tones in noise Simplified method This method uses 1 3 octave analysed measurements The selection of the method to be used when assessing tones in noise is dependent on local legislation The local legislation may refer to ISO 1996 2
15. Fig 2 21 Note This will not turn off the feature that checks for limits this is done by setting the Check parameter to Off under Tolerance Windows Setup menu see Fig 2 19 61 With a saved measurement you may adjust the tolerance windows and see the corresponding results However the latched indicator remains unchanged FFT ANALYZER indication md oc FFT dd 687 500 Hz Off Delta Sum Rather than checking all FFT lines against the top and bottom frequencies of the tolerance window for upper and lower limit compliance you can check the sum of FFT lines for limit compliance Select Setup gt Tolerance Windows and check Values Checked Delta Sum Delta Sum is based on the measured FFT lines however it takes Spectrum Display and Post weighting into account The summation principle is as described in Table 4 1 The Delta Sum parameter is displayed using the same units as the FFT spectrum In Linear averaging the calculation and check of Delta Sum and FFT Lines are made on the available FFT spectrum You can change the frequency range and limits for the tolerance windows before during and after the measurement the tolerance results are re calculated except the Latched Result which is updated during measurement only CHAPTER 2 Getting Started 21 In Exponential averaging the Delta Sum is calculated periodically e g every 100 ms during the measurement and checked against the limits In addition to the Tolerance R
16. Resolution and Span e X axis scaling compress expand e Corrected Frequency 5 1 4 Measurement Control To measure transient signals you need initially to set the analyzer to triggered mode 3 Tap and select Setup from the list of options 4 On the Quick setup tab locate the Measurement Control group and change the Measurement Mode to Triggered see Fig 5 2 Fig 5 2 Setting Triggered mode Signal Type Continuous Window Type Hanning Triggers i Spectra Per Trigger il Trigger and Tacho Input Frequency Settings Quick p t Time Windows The purpose of a time window is to minimise the effects of the discontinuity which occurs when only a section of a continuous signal is measured When measurement is manual the Time window parameter is always set to Hanning In the triggered mode you can change the CHAPTER 5 Measuring Transient and Continuous Signals 51 Window Type from Hanning to Rectangular and vice versa You can also change the Window Type by changing the Signal Type see Fig 5 3 Fig 5 3 S Left Selecting Hanning as a Mase raIrantGanial Measurement Control the window type from Measurement Mode Triggered Measurement Mode Triggered Im Setup menu Right Selecting Transient as signal type from Setup Signal Type Continuous Signal Type Continuous menu Window Type eHanning Window Type Transient Rectangular Frequency Settings Frequency Settings Uni
17. SOUICE a nont 112 SPAN sieni drdi ieii 104 Specifications n a 87 Spectra at Time for Max Delta Sum 119 Spectra per Trigger 60 Spectrum Compress Expand cccceceeeseeeeeeeees 45 Spectrum Display 55 109 Statina aiaea hei ena Siang 37 Status Codes Smileys ccceceeeseeeeseeseeseeeeeees 83 Stud MOUNTING 0 ceceeeeeceeeeeeseeneeeeeeeeeeeeeaeeeeeeaeeanes 31 Summary of Summation Principles 44 Summation Principle ceeeeseeeeseeteeeeeeteeeeeneeeees 44 Symmetric Delta Cursor eeeeceeeeceeeeeeeeeteeeeeeeeeees 16 T MAGI o oo O Seal eta cee ES Mens E PAD eet enter aids ented iin alee eh The Noise Floor 0 0 The Threshold of Hearing The Tone Cursor The Tone Parameter Panel i e INDEX 125 Time Window ccccceee 5 8 40 50 60 64 105 Tolerance Exceeded onaniar n s 21 Tolerance LAF Parameters cccccccsssseeeeeeees 119 Tolerance Results Tolerance RPM ParameterS cccccccssssseeeeeeees 118 Tolerance Window Off c cccccsccccssseeecssseeesseeeeeesee 20 Tolerance WiINdOWS cccccccessceceeeeesssstseeeees 18 67 Tolerances For sani nea eaa sea EEE Tone Assessment Frequency Settings eececceeeeeeeeeeeeeeeeeeneees ETTE e rn Measuring Rating Level Result Display Setting Up esses carte ecte evened Setting up the Instrument c ceeceeeeeeeeeeeee Tone Assessment Calc
18. Signal Tone Assessment lr Tone Assessment 7 Tone Assessment On Tone Standard ISO 1996 2 2007 Tone Seek Criterion Tone at Cursor n Tone at Cursor Quick 15 17 59 E a 15 16 17 Select the Tone Standard as required The Tone Seek Criterion is set to 1 dB by default Increasing the criterion will make the tone seek algorithm less sensitive when searching the FFT spectrum for tone candidates Increasing the Tone Seek Criterion may be relevant for analysing irregular spectra mainly spectra with short averaging times The Tone Seek Criterion can be varied between 0 5 and 4 dB 7 4 2 Setting up the Measurement Using the Default Setup The Tone Assessment option offers two ways of setting up the FFT measurement for tone assessment calculations The default method will be covered first Please refer to section 7 4 3 for a description of how to set up the measurement manually Start the FFT measurement by pressing the Start Pause Pushbutton If the selected setup parameters do not comply with the recommendations in the selected Tone Standard the following pop up window will be displayed Fig 7 3 Pop up window for the Measurement Setup Check Settings are not as per standard Do you want to restore default settings O Do not ask again call 15 21 27 CHAPTER 7 Tone Assessment Option BZ 7231 77 From the pop up window for the measurement setup check see Fig 7 3 you can set the parameters relevant for Tone Assessment to
19. Signal Recording Option BZ 7226 RECORDING Recording Option BZ 7226 is enabled with a separate license Recording requires a CF or SD Card for data storage AUTOMATIC GAIN CONTROL The average level of the signal is kept within a 40 dB range or the gain can be fixed SAMPLING RATE AND PRE RECORDING The signal is buffered for the pre recording of the signal This allows the beginnings of events to be recorded even if they are only detected later Maximum Maximum Sampling Pre recording s Pre recording s Memory Memory Rate 16 bit 24 bit KB s KB s kHz 16 bit 24 bit HW 1 3 HW G4 HW 1 3 HW G4 8 100 470 70 310 16 24 16 50 230 30 150 32 48 24 30 150 16 96 48 72 48 10 70 3 43 96 144 Manual Control of Recording Recording can be manually started and stopped during a measurement using a pushbutton Automatic Control of Recording Start of recording when measurement is started Minimum and Maximum recording time can be preset Tolerance Level Recording is started when the tolerance limits are violated PLAYBACK Playback of signal recordings can be listened to using the earphone headphones connected to the headphone socket RECORDING FORMAT The recording format is 24 bit or 16 bit wave files extension wav attached to the data in the project easily played back afterwards on a PC using BZ 5503 or 7820 Calibration information is stored in the wav file allowing PULS
20. We recommend that DeltaTron accelerometers be used with Hand held Analyzer FFT Analysis Software BZ 7230 and this will be assumed in this manual unless otherwise stated Choosing an Accelerometer Fig 3 1 shows two typical groups of accelerometers with typical specifications Two typical groups of accelerometers with typical specifications a 1 10 pC ms 0 1 0 3 pC ms ECHO Weight 10 50 gram IR Weight 0 5 3 g ms 250 000 20 000 100 000 0 003 0 01 0 0001 0 001 Frequency Di 4 5 12k 15 30k Hz 070081 Notice that accelerometer responses extend to considerably lower frequencies than sound measurements You can also see that the output of the accelerometers is given in pC ms This is in recognition of the fact that fundamentally they are charge based devices However the charge to voltage converters incorporated in accelerometers are usually designed to give nice number conversions For example if an accelerometer supplies 1 pC ms the charge converter output might typically be 1 mV ms With a ratio of 9 81 1 of SI units ms to US UK units g this means that you may also get accelerometers with specified sensitivities like 98 1 mV g Sensitivity and Frequency Range All accelerometers will give a constant output signal for a constant acceleration from very low frequencies up to a limit set by the increase in output due to resonance of the accelerometer In general however the accelerometer is not used cl
21. and accessories without notice 100 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Appendix A Setup Parameters This appendix lists and explains the various parameters that you can choose when perform ing FFT and Tone Assessment measurements A 1 Input Parameters Table A 1 Input parameters 101 Parameter Values Comment Input Top Socket Determines whether the input is taken from the top Rear Socket socket or the Rear Input socket of the instrument Connect your transducer to one of these sockets Transd Used Direct Determines which transducer is currently connected Accelerometer to the Hand held Analyzer and once selected the Microphone hardware of the analyzer will be automatically set up to fit the transducer If Direct is selected it means voltage is being measured from the input socket this can be either Top Socket or Rear Socket whichever is selected This parameter is part of the instrument setup and is common to all setups It can also be set from the Transducers option of the Main Menu Sound Field Correction Free field Select a correction matching the sound field Diffuse field conditions of your measurements If your sound source can be positioned facing the microphone exactly that is it s sound comes mainly from one direction then use the Free field correction otherwise use the Diffuse field correction 102 FFT Analysis Softw
22. averaging time as well as running exponential averaging Please refer to section 4 2 2 where Measurement Control is explained 7 4 4 Signal Recording If a valid license for the Signal Recording Option is present it is possible to record the signal while measuring the FFT spectrum Refer to the User Manual for Hand held Analyzers Types 2270 and 2250 Chapter 13 for information about the Signal Recording Option Note 1 When Hand held Analyzer recordings are used for re analysis on a PC be sure to set Automatic Gain Control to Off under the Sound Recording parameters and set the Recording Quality to High and Resolution to 24 bit Note 2 You may find the Template Explorer accessed from useful to save your own measurement setup Please find more information about using templates in the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 7 5 Measuring When the measurement is done the preset measurement time for a linear measurement has finished or the Start Pause Pushbutton is pressed the Hand held Analyzer carries out the tone assessment calculation A typical ISO 1996 2 Annex C calculation using 6400 lines FFT will take 4 to 5 seconds 7 6 Result Display 7 6 1 The Tone Cursor Choose the Tone cursor from the Cursor drop down menu accessed when you tap on the cursor see Fig 7 5 80 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Fig 7 5 Selecting the Tone c
23. axis scaling selected Linear or Logarithmic e The type of transducer selected Microphone Accelerometer Direct e The Unit System used SI US UK e How the Vibration is displayed Acceleration Velocity or Displacement The displayed Y axis can also be scaled in terms of the display range We shall cover this in the Y axis operations section Table 5 1 shows the physical units that are available when an accelerometer is selected Physical units available for display SI US UK Acceleration m s dB ref 1 m s g dB ref 1 ug Velocity m s dB ref 1 nm s nm s dB ref 10 nm s Displacement m dB ref 1 pm mil dB ref 1 umilt Sound dB dB ref 20 uPa dB dB ref 20 uPa Direct Volts dB ref 1 u V Volts dB ref 1 u V These units are traditionally used in the US and UK t 1 mil 0 001 inch Scaling of Transient Signals Power has no meaning in relation to transient signals since the signal only exists for a short period of time What is of interest for a transient signal is the energy The energy is the main factor to take into consideration for a transient signal This is obtained from the measured power by multiplying it with the observation time The measurement should be normalised with respect to the filter bandwidth since transients have continuous spectra resulting in energy spectral density ESD ESD is measured in units seconds Hz Therefore for transient signals use ESD scal
24. curves show IEC 61260 limits Response 20 dB 0 20 40 60 80 0 1 1 10 Multiple of Center Frequency PEET A real time CPB analysis is characterised by a continuous stream of results with averaging controlled exponentially for example Fast or Slow or linearly Leg The BZ 7223 application for Types 2270 and 2250 is an example of a 1 3 or 1 l octave real time analyzer capable of simultaneous linear and exponential averaging Constant Bandwidth Analysis Constant Bandwidth analysis is included with FFT Analysis Software BZ 7230 and is performed using the FFT algorithm With this kind of analysis the filters are placed evenly on a linear frequency axis where each filter has a constant bandwidth making FFT a constant bandwidth method of analysis FFT analysis is characterised by producing results stepwise from time blocks records of acquired data though with modern digital processors and overlapping the blocks of data the FFT analysis appears almost as continuous as CPB measurements The other characteristic of FFT analysis is the narrow bandwidth relative to the measured frequency span providing the common synonym for the FFT analyzer the narrowband frequency analyzer A common reason to use a narrowband analyzer is to identify features of stationary signals such as resonance frequencies and rotational harmonics The constant bandwidth spacing is ideal for identifying the harmonic and sideband compon
25. ete a aaan aE aE 112 Gear Rato a ea e r eaae e Tani 106 Generation of Tone at CUrSOT sesseeeeceeee 84 GlOSSal ts ieee a a Staal 121 GraphiPanel cies s ccasshovescasatscstacsacoasseaustasasstanes 7 80 H Hand held Probe cccsceeeecceeeseeeeeeeeeeeeeeeeeeeaee 31 Harmonic Cursor eccesceeseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeaee 16 Hold Off eee 57 106 Hysteresis inn aiene iaee iadaa 57 107 l INPUTS aieu eatin yoann 33 101 Instantaneous RPM eee eee eeeeeeneeeeeeeeaes 121 Instantaneous Time weighted Sound Levels 120 Internal LOVE cceessecceeessssseeeeeeesesseaeeees 58 106 Internal TrIQQON eects cessevcesaeascoeesresveerdeecesecheeevesteass 56 Introduction to Fourier FFT Signal Analysis 3 Introduction to Tone Assessment sai Isolated MOUNTING cee ee ee eee eeeeeeeeeeteeeeneeteeeens 31 L LeVelissinvaiiensaiaie Ghia A Renata Level of Trigger Linear Averaging Exponential Averaging eeeeeeeeeeeeeees 105 Linear AVEFAGING sceceeesstesssceeserseseessecesneenseeetoreees 20 Linear Y axis 93 Lines 104 Listening to a Mixed Signal 85 Logarithmic Y axis eee eee eeeeeeneeeeeeeeaeee 53 Lower Limit s 0c cecvsternendiessenietieesnceseenceene 108 M Main GUurSOF ees esse eas nerian eiaeia eea 46 Masking Noise Level 0 00 0 eee eeeeeeeeeeeeeeeeee 122 Max Delta Sum Parameters c ccccscccssseceeeseees 118 Maximu
26. for surveying vibration in various locations beeswax can be used for mounting the accelerometer Because beeswax becomes soft at high temperatures the method is restricted to about 40 C Isolated Mounting In places where it is desirable to isolate the accelerometer from the test object an isolated stud and a mica washer should be used This could be either because the potential of the test object is different from the ground potential of the test instrumentation or because direct stud mounting will create a ground loop which could affect the measurement The latter is the most common reason for use of an isolated mounting Mounting with the Aid of a Magnet An easy and fast method of mounting the accelerometer is by using a permanent magnet which can very easily be shifted from one position to another This is especially useful for surveying The method is restricted to use on ferromagnetic surfaces and the dynamic range is limited due to the limited force of the magnet To obtain the maximum frequency range and dynamic range the ferromagnetic surface must be clean and flat By fitting a self adhesive disc on the magnet it will provide electrical isolation between the accelerometer and the surface to which it is attached Use of a Hand held Probe A hand held probe with the accelerometer mounted on top is very convenient for quick look survey work but can give gross measuring errors because of the low overall stiffness Mechanical Filte
27. how many batches of records will be averaged together to make the final result 7riggers parameter Spectra per Trigger For continuous measurements each time a trigger occurs the software will linearly average together the number of spectra per trigger Spectra per Trig parameter that you have set see Fig 5 14 and Fig 5 15 You can consider this number to be the number of records in a batch Graphical explanation of what happens to records when measuring triggered continuous signals using the set up described in section 5 2 2 Time Signal Time Pre Trigger 1 Pre Trigger 2 Record 1 Record 2 Record 3 Triggers 02 wees Record 4 Spectra per Trigger 05 D Overlap 67 Recordio _ n Record 1 lt Record 2 mu Record 3 mus Record 4 mus Record 5 Partial Average 1 khan Partial Average 2 kham Final Average 010183 CHAPTER 5 Measuring Transient and Continuous Signals 61 Set the value of Spectra per Trig to give an average time measurement period that is long enough to be sure that the signal you are measuring is fully captured in each batch of records Fig 5 15 Entering the number of Input spectra per trigger for a Measurement C triggered measurement Measurement Mo Averaging Type Ayo age Spectr Signal Type Window Type Triggers Spectra Per Trig Total Averaging Time Trigger and Tacho Trigger Type External Quick Measu
28. is a local maximum with a 3 dB bandwidth smaller than 10 of the bandwidth of the critical band The tone level is the energy sum of all lines within 6 dB of the local maximum level corrected for the influence of the Hanning window Critical Bands The critical band the frequency range that can mask the tone is centred on the tone and its width is 100 Hz below 500 Hz and 20 of the tone frequency above 500 Hz Note that above 500 Hz this is close to the bandwidth of 1 3 octave filters 23 while it is progressively wider at lower frequencies If more than one tone is found within a critical band the critical band is placed symmetrically around the tones in the critical band centring on the sum of frequencies divided by the number of tones Only tones with levels within 10 dB of the highest tone level are included in the positioning of the critical band Note For Tone Standard Denmark 1984 1991 all tones are included in the positioning of the critical band If not all tones can be included in the critical band that placement of the critical band is selected which yields the highest difference between tone level and masking noise level Tone Level and Noise Level Usually the frequency of a tone does not coincide precisely with one line in the FFT spectrum Instead its energy is spread over two or more lines In such cases the tone level is the level sum of all lines within 6 0 dB of the local maximum corrected for the applied Hanni
29. operation do the following 83 Tap on the Y axis 84 Select Zoom in from the resulting drop down menu and observe the display Zoom in for Engineering Scale This operation works like an object moving towards a half length mirror As the object gets closer a more and more partial view of the object is seen in the mirror Similarly on performing a zoom in the range of the Y axis is reduced from the top of the scale only giving the impression that you are zooming in on the bottom of an expanding Y axis scale For example if you zoom in on the default range of the Y axis which has a range of 100 um s that is a scale from 0 to 100 uum s and after the Zoom in operation it changes to a scale from 0 to 50 um s then the range has reduced to 50 um s see Fig 2 28 FFT ANALYZER 7 7 T7 7 i 40k 8 0k 12 0k 16 0k 20 0k Perform the following steps 85 Change Y axis parameter to Engineering Tap gt Setup gt Units gt Engineering 86 Tap on the Y axis 87 A drop down is displayed Select Zoom In The other operations you can perform are listed in Table 2 2 CHAPTER 2 Getting Started 27 Table 2 2 Y axis Operations Operation Principal Function Zoom In This operation works just like the zoom lens of a camera but in one dimension The range of the Y axis is reduced each time you zoom in so you get a zoomed in view of your data Zoom Out This operation is the exact revers
30. or some local method The ISO 1996 2 Annex C method provides measurement procedures that are used to verify the presence of audible tones The method is based on the psychoacoustic concept of critical bands The definition of a critical band is that noise outside the band does not contribute significantly to the audibility of the tones inside the critical band The implementation of the ISO 1996 2 Annex C method in Hand held Analyzer FFT based Tone Assessment BZ 7231 includes procedures for steady tones narrow band noise low frequency tones and the result is a graduated adjustment K to the rating level calculated from Leg The tone corrected rating level is obtained by adding the adjustment K to the L Aeq level ISO 1996 2 Annex C describes how to deal with time varying tones Tones may be varying either in level or in frequency Tone Assessment Option BZ 7231 does not support automatic features for dealing with time varying tones Find more information about rating level and assessment of environmental noise in ISO 1996 2 and in Briiel amp Kjer s Environmental Booklet Tone Standard Denmark 1984 1991 is identical to ISO 1996 2 2007 except for a few details mentioned in the following sections Tone Assessment Calculations BZ 7231 follows the rules given in ISO 1996 2 Annex C Please refer to Fig 7 1 for a graphical overview of terms and definitions explained in this section CHAPTER 7 Tone Assessment Option BZ 72
31. pin 7 16 27 UNS connection Accelerometer Industrial with 10 2 mV ms sensitivity and Mil C 5015 top connection Accelerometer cable LEMO to M3 length 3 m 10 ft Accelerometer cable LEMO to 10 32 UNF length 3 m 10 ft Beeswax for mounting accelerometer Tube of Cyanoacrylate Adhesive Mounting magnet for accelerometer 10 32 UNF mounting Mounting magnet for accelerometer M3 mounting Signal cable LEMO to BNC length 1 5 m 5 ft Microphone Extension Cable 10 pin LEMO length 1 5 m 5 ft Microphone Extension Cable 10 pin LEMO length 3 m 10 ft Microphone Extension Cable 10 pin LEMO length 10 m 33 ft Accelerometer cable LEMO to MIL C 5015 length 5 m 16 ft Cable for Laser Tachometer Probe MM 0360 LEMO to SMB length 5 m 16 ft Signal cable LEMO to BNC Female length 1 5 m 5 ft MM 0360 UA 0801 UA 1317 UL 1009 UL 1013 Laser Tachometer Probe Small Tripod Microphone Holder SD Memory Card CF Memory Card for Hand held Analyzers for hardware versions 1 3 UL 1016 UL 1017 ZG 0444 CHAPTER 8 Specifications 99 10 100 Ethernet CF Card for hardware versions 1 3 SDHC Memory Card Charger for QB 0061 Battery Pack Bruel amp Kj r supplies a wide range of accelerometers Please contact your local Briel amp Kj r office for more information regarding the different types and their use or visit the website at www bksv com Bruel amp Kj r reserves the right to change specifications
32. ro TETA ao PAE oe cast eds Ada ee A Ae os Ih sti Be tte Sed 22 FeferenGe SpectfUM rrii deueni flue nes cesecte aeaaaee aeaaea aaae de Saee einai adai 24 Y axis Opora ONS e ar are de aeae ce a ol hed eel as ee ed dea 25 CHAPTER 3 Using Accelerometers for Vibration Measurement sssssssssssnnssnnnsnnunnnnnnnnn 29 SU MFOdUC ON an ea r a r a a pa a a E a aa aa EE a A S AE 29 Choosing an Accelerometel esccsessceeeeceseereseenereeresneeeseanessenerseneeesaeeeneners 30 The Importance of Correct MOUNTING 0 00 0 eee cece eeneeeeneeeeeeeeeeeeeteeeeteaeeseaeeeeeees 31 Choosing a Mounting Position ee eee eeeseeeseeeeeeeeeeeeeseaeeeeaeeseeeeessneeeeeeeeeees 32 Recommended Accelerometers esscceesceesseeceseeeeseeeesaeeesaeeseaeesseeeeseeeesaeeesaes 33 3 2 Configuring the H UT e ste eet ah teats a raea a r aa a ae tied A EAE Aa 33 Transducer Database 2 2 ie ar aa aeaea aa aa aaae Ea ar aa Aa EA a aa N aaae 34 Adding an Accelerometel eseccsscecesneceseereeneeeseeeesenecsenesseneseeneneneeeesaeesneners 34 3 3 Calpa OT ae a aa a a tases a E a aa A e EA ea Aaaa pan aae 35 CHAPTER 4 Measuring Random Signals ccsccccseseeeeeeseeeceeeeseneeeeeeseeeeeeseeeeeeeseseeeeeeeeeees 37 4 1 Random Signals en ee eae aa aaea aaa aa aeae aa aa tabe aaa aaaeaii 37 4 2 Preparing for Measurement ees eeeeeceseecesneceeneeeseceseeeseanersanerecsaeeseanereenerens 38 Configuring the AMPUt eeaeee aeea ea
33. see Fig 4 7 Fig 4 7 Selecting Pre weighting by tapping on the Wgt parameter FFT ANALYZER 0 0 40k 2 0k 12 0k 16 0k 20 0k 20 kHz 400 ad 14 20 57 4 2 8 Scaling Scaling the Level in the FFT Graph You can select from the following scales that are available with FFT Analysis Software BZ 7230 for amplitude measurement RMS root mean square value of the FFT line spectrum Peak RMS value x V2 Peak Peak RMS value x 2V2 PWR Power RMS value PSD Power Spectral Density RMS value2 NBW ESD Energy Spectral Density RMS value NBW x observation time The observation time for manual and continuous measurements is the elapsed averaging time and for transient measurements it is the record length Scaling for Different Signals When considering amplitude scaling For deterministic signals use the Power scaling PWR RMS For random signals use Power Spectral Density scaling PSD PWR Bandwidth For transient signals use Energy Spectral Density scaling ESD PSD x observation time Note Your choice of scaling will not affect the appearance of the displayed spectrum It is the units and values in the display that will reflect your choice 44 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Summation Principle Table 4 1 summarises the summation principle for each type of scaling relative to the total level or sum for Delta Cursors T
34. should be mounted so that the desired measuring direction coincides with the main sensitivity axis Accelerometers are slightly sensitive to vibrations in the transverse direction but this can normally be ignored as the maximum transverse sensitivity is typically only a few percent of the main axis sensitivity The reason for measuring vibration will normally dictate the position of the accelerometer In Fig 3 2 the reason is to monitor the condition of the shaft and bearing The accelerometer should be positioned to maintain a direct path for the vibration from the bearing YL SSSLLLSLLL TT LLY y ZA G al a PTT ennai B9 rD Namm GF Accelerometer A detects the vibration signal from the bearing predominant over vibrations from other parts of the machine but accelerometer B receives the bearing vibration modified by transmission through a joint mixed with signals from other parts of the machine Likewise accelerometer C is positioned in a more direct path than accelerometer D CHAPTER 3 Using Accelerometers for Vibration Measurement 33 It is very difficult to give general rules about placement of accelerometers as the response of mechanical objects to forced vibrations is a complex phenomenon so that one can expect especially at high frequencies to measure significantly different vibration levels and frequency spectra even at adjacent measuring points on the same machine element
35. signal if Automatic Gain Control is On or if Resolution is 24 bit or if Peak Recording Level is set to its maximum value Peak Recording Level Depends on the current transducer type selected For Automatic Gain Control Off and Resolution 16 bit the recorded wave file has a dynamic range of up to 96 dB When playing back on the Hand held Analyzer the dynamic range of the output is approx 75 dB When playing back on a PC it might be even lower Set Peak Recording Level to fit the signal The values for Peak Recording Level take the sensitivity of the attached transducer into account Note This parameter is enabled only if Automatic Gain Control is set to Off Pre recording Time 0 to 470s Recording is started the Pre recording Time before the trigger conditions are fulfilled for example 5 s means the recording will be started 5 s before you hit the Manual Event pushbutton This is possible because the recording is done continuously in an internal buffer ready to be saved as a wave file The Pre recording Time is limited by this buffer size and the Recording Quality and Resolution Quality Pre recording Pre recording Time limit 16 bit Time Limit 24 bit HW1 3 HW4 HW1 3 HW4 Low 110s 470s 70s 310s Fair 50s 230 s 30s 150s Medium 30s 150s 16s 96 s High 10s 70s 3s 43s Post recording Time 0 to 300s Use this parameter to specify how much extra you want to be recorded after the trigger conditions are no longer
36. stylus to tap the cursor selector between the Ka and gt buttons Select Delta cursor from the cursor selection drop down 38 Use the pushbutton to navigate down until the main cursor is active Fig 2 12 FFT ANALYZER The cursor selection drop down menu 40k 2 0k 12 0k 16 0k Ik 20 kHz 400 7 19 50 13 39 Use the or pushbuttons to place the main together with the delta cursor at a position to the left of the calibrator tone 40 Use the Eg or gt buttons to move the delta cursor to a position further to the right of the calibrator tone 41 Observe the cursor reading see Fig 2 13 Note The delta cursor reading indicates the frequency difference between the main and delta cursor as well as the sum of all FFT lines between them CHAPTER 2 Getting Started 15 Fig 2 13 Delta cursor reading FFT ANALYZER Reference Cursor and Auto Peak Find 42 Use your stylus to tap the cursor selector again Select Reference cursor from the cursor selection drop down 43 Use the Ed or gt buttons to navigate the reference cursor to a position close to the calibrator tone 44 Observe the cursor readout see Fig 2 14 Note The reference cursor readout displays the amplitude difference between the main cursor and the reference cursor Fig 2 14 Reference cursor reading 12 0k 16 0k 20 ok 20 kHz 400 m 19 53 45 Use your stylus to tap the cursor selector and select the Auto Peak function This will
37. you want to align the 6 4 6 4 1 CHAPTER 6 Measuring Deterministic Signals 67 FFT ANALYZER WARNING Transducers are different spectrum Reference spectrum cannot 12 0k 16 0k 20 ok 20 kHz 400 14 06 55 20 kHz 400 ad 14 05 53 Tolerance Windows Exponential Averaging During a measurement using exponential averaging you can use Tolerance Windows to calculate whether the Delta Sum complies with limits see Delta Sum on page 20 The Delta Sum is based on the measured FFT lines within the specified frequency range however it takes Spectrum Display Scaling and Post weighting into account The summation principle is as described in Table 4 1 The Delta Sum is calculated periodically every 100 ms for up to 1600 lines and every 1 s for more than 1600 lines during the measurement and checked against the limits In addition to the Tolerance Result parameters a number of other parameters are updated e Delta Sum e Max Delta Sum e RPM at time for Max Delta Sum requires Tacho set to On e LAF at time for Max Delta Sum e FFT Spectrum at time for Max Delta Sum To ensure the integrity of the measured parameters listed above changing frequency range or limits for the tolerance windows during or after the measurement cannot be done without resetting the measurement This also applies to changing some of the display parameters Scaling Spectrum Display Unit System Y axis and Post weighting One exam
38. 0 pms 75 Ms peax 1 25 6 3 Hz 10 kHz 8341 10 mV ms 300 ums 710 ms peax 30 pms 7 5 ms pea 0 7 6 3 Hz 10 kHz The lower limit of the measurement range is influenced by self generated random noise and self generated tones called spurious signals The influence of the random part can be reduced to a level below the spurious signals by selecting a small analysis bandwidth small span and many lines Therefore the lower limit is specified as the maximum Peak level of the spurious signal lines BZ 7230 has only one measuring range but the spurious level depends on the peak level of the signal Therefore two specifications are given One for high levels where the upper limit is the overload limit and one for low levels The Typical Frequency Response shows the 1 dB limits for Direct Input and microphones and the 10 limits for accelerometers RPM MEASUREMENT RPM is measured on the signal connected to Trigger input when Tacho is set to On Range 1 to 6000000 RPM Instantaneous RPM Instantaneous RPM is only displayed and not stored Average RPM Displayed and stored together with each Spectrum result In Linear Averaging it is an average over the same time as the spectrum In Exponential averaging it is the last measured RPM Gear Ratio 10 5 to 1038 The displayed RPM are the measured RPM divided by the RPM Gear Ratio OVERLOAD Instantaneous Overload Instantaneous Overload is dis
39. 032 Nominal Preamplifier Attenuation 0 25 dB Connector 10 pin LEMO Extension Cables Up to 100 m in length between the microphone preamplifier and the Hand held Analyzer without degradation of the specifications Note EMC is only tested with a 10 m cable AO 0441 D 100 Accessory Detection Windscreen UA 1650 can be automatically detected when fitted over ZC 0032 MICROPHONE POLARIZATION VOLTAGE Selectable between 0 V and 200 V TRANSDUCER DATABASE Transducers are described in a transducer database with information on Serial Number Preamplifier ID No Nominal Sensitivity and CCLD required For microphones Polarization Voltage Free field Type and Capacitance are also included For Accelerometers Weight is also included The analogue hardware is set up automatically in accordance with the selected transducer CORRECTION FILTERS For Microphone Types 4189 4190 4191 4193 4950 and 4952 BZ 7230 is able to correct the frequency response to compensate for sound field and accessories Sound Field Free field or Diffuse field for Type 4952 only 0 Top reference direction and 90 Side reference direction Accessories Type 4189 only None Windscreen UA 1650 or Outdoor Microphone Kit UA 1404 Accessories Types 4191 and 4193 only None or Windscreen UA 1650 Accessories Type 4950 only None or Windscreen UA 0237 CALIBRATION For accelerometer Types 4397 A 4513 4513 001 4513 002 4514 4514 001 4514 002 8
40. 25 3 125 Note The NBW Noise Bandwidth equals the Frequency Resolution for the Rectangular window Hanning weighting makes the NBW of the filters 1 5 x Frequency Resolution The Record Length is 1 Frequency Resolution The resolution also determines the length of time it takes for the analyzer to gather a block of data This time or record length is equal to the reciprocal of the resolution So for example if the resolution is 5 Hz then the record length will be 0 20 seconds Note that with narrower resolutions the record length will be longer meaning the response time for the analysis can be slower For example if we choose a 100 Hz frequency span with 6400 lines of analysis our record length will be over a minute 1 0 015625 64 seconds With continuous signals we use an overlap of the time records of 67 so the second update of the frequency spectrum will occur just 22 seconds later With continuous signals the time recorded signal is shaped by a time window to reduce the transients caused by the start and end of each time record This shaping is called a Hanning window and the overlap of 67 matches the Hanning window so that no time data is lost All the time data is then equally weighted If the signal type is set to transient that is its length is less than the record length no shaping or overlap is required and the type of window reverts to rectangular 6 FFT Ana
41. 30 and Tone Assessment Option BZ 7231 User Manual 3 Select the FFT ANALYZER template 4 Mount Sound Calibrator Type 4231 and switch it on 5 Press Start Pause to start a measurement 6 Observe the spectrum 7 Using the stylus move the cursor to any other line 8 Observe the spectra and the readings see Fig 2 3 MAX Spectrum FFT Spectrum Frequency Correction For a single tone to be measured correctly it has to fall exactly at the frequency of one line in the FFT spectrum In practice tones falls between two lines and their energy are shared between these two lines The Corrected Frequency facility analyses the FFT lines adjacent to a peak of energy and determines where the actual energy peak is to an accuracy approximately 10 times greater that the FFT line spacing and determines the corresponding level Frequency correction is available for main as well as auxiliary cursor readouts but for spectra measured with Hanning time windows only 9 Select Auto Peak from the Cursor Selection Panel 10 Observe the frequency and level values 11 Turn Frequency Correction on by tapping directly on FC Off on the Spectrum Display see Fig 2 4 and choose On from the resulting drop down menu CHAPTER 2 Getting Started 9 Fig 2 4 Setting Frequency Correction Left before Right after g g g i g i i i 8 0k 12 0k 16 0 0 40k 80k 12 0k 16 0k 20 0k 12 Observe the corrected values for frequency a
42. 31 73 Fig 7 1 Graphic overview of terms 5 Ly related to FFT based tone 4 ey LN assessment RR K 3 dB l l m d Tonal energy o li Noise level a Linear regression Sound pressure level per analysis bandwidth dB Neither Tone nor noise Tone Critical Band CB l 0 75 of CB gt Frequency Hz 020007 1 Detecting the Tone Candidates First the calculation algorithm looks for noise pauses in the measured FFT spectrum Tone Standard ISO 1996 2 2007 requires the A weighted spectrum Tone Standard Denmark 1984 1991 requires the Z weighted spectrum A noise pause is a local maximum in the spectrum with a probability of containing a tone The Tone Seek Criterion in the Setup menu is the threshold for the algorithm that looks for noise pauses in the spectrum i e differences between successive line levels The criterion may be interpreted as the maximum variation in levels between neighbouring lines in the parts of the FFT spectrum where no tone candidate is present In general this criterion should be set to 1 dB For irregular spectra mainly spectra with short averaging time values up to 4 dB may give better results 74 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual When a noise pause is detected the tone seek algorithm seeks for tones or narrow bands of noise at local maxima inside the noise pauses A tone or narrow band of noise
43. 341 and 8324 the lower frequency limit will be optimized to match the specifications for the accelerometer Initial calibrations for each transducer are stored for comparison with later calibrations Acoustic Using Sound Calibrator Type 4231 or custom calibrator The calibration process automatically detects the calibration level when Sound Calibrator Type 4231 is used Mechanical Using Calibrator Exciter Type 4294 or custom calibrator Direct Electrical Using an external Voltage Reference Electrical Uses internally generated electrical signal combined with a typed in value of the sensitivity Calibration History Up to 20 of the last calibrations made are listed and can be viewed on the instrument KEYBOARD Pushbuttons 11 keys with backlight optimised for measurement control and screen navigation ON OFF BUTTON Function Press 1 s to turn on press 1s to enter standby press for more than 5s to switch off TRAFFIC LIGHT Red yellow and green LEDs show measurement status and instantaneous overload as follows Yellow LED flashing every 5s stopped ready to measure Green LED flashing slowly awaiting trigger or cal ibration signal Green LED on constantly measuring Yellow LED flashing slowly paused measurement not stored Red LED flashing quickly intermittent overload calibration failed DISPLAY Type Transflective back lit colour touch screen 240 x 320 dot matrix Colour Schemes Five different optimised for
44. 503 through USB or update via Internet Hardware versions 1 3 the latest version only Hardware version 4 any version from 4 0 and up WEB PAGE Connect to the instrument using an Internet Browser supporting Java script The connection is password protected Two levels of protection e Guest level for viewing only e Administrator level for viewing and full control of the instrument NOTIFICATIONS Sends an SMS or e mail if an alarm condition is fulfilled Alarm Conditions e Disk Space below set value Trig Input Voltage below set value Internal Battery enters set state Change in Measurement State Reboot of instrument Software Specifications FFT Analysis Software BZ 7230 Specifications for FFT analysis are given for the Hand held Analyzer with software BZ 7230 installed and fitted with one of the recommended transducers see Table 8 1 FFT ANALYSIS Sampling Frequency Downsampling from 51 2 kHz Frequency Span 100 Hz 200 Hz 500 Hz 1 kHz 2 kHz 5 kHz 10 kHz 20 kHz Lines 100 200 400 800 1600 3200 6400 Zoom Centre Frequency Can be set so that the Frequency Span is placed in the range 0 to 20 kHz Spectrum Averaged and Maximum Pre weighting Z none A B or C MEASUREMENT CONTROL Manual Start Measurements can be manually started and stopped using a pushbutton or an external signal The actual number of lines is one more than stated to provide symmetry aro
45. 6 2 Preparing for Measurement uu eee eee eeeeeceeeeeeeeeeteaeeeeaeeeeeeseeseseeeeeeaeeeeaeees 64 Configuring the INDUt ee eee esse eeeeeeeeeeeeaeeeeaeeeeseeeeaeeseaeeseaeeseeeeeeaeeeeeeeeaeees 64 Configuring the AnalyZer eee eeceeseeeseeeeneeeeeeeeeeeeeseeeseaeeeeaeeseeeeesaeeeeaeeeeaeees 64 Measurement Control 0 0 0 0 eeeseeesecesserecenereeneeseneeeseeesnanessanereeeeeseeeessenesteneres 64 Correct Scaling of Deterministic Signals eee eeeeeeeeeeeeeseeeneeeeeeeeeeneeeeeees 65 Turning Frequency Correction On Off eee eeseeeeseeeeeeeeeeeeeseaeeeeaeeeeneeeneees 65 RPM Measurement eeececeeeeseeneceseeeeseeeeseeecsaneceanersseeeeaeeeseeessanersenereenenenaes 65 6 3 Reference Spectra xenp oneri ee e e e a e e GE 65 6 4 Tolerance WiNdows esseesseeeesseesreesrnesrnsrnssrnsttnnttantnnstnatnarrnarrnactnertneeeneennnena 67 Exponential Averaging ssesssessreesrsesrsrrsrnesrnnsrnnsrnnsrnnsrnestnsstnettnsenanenanenasenanenae 67 CHAPTER 7 Tone Assessment Option BZ 7231 scccceceseeceeeeeeeeeseeeeeeeeeeneeseneeeneeseneeeeeeees 71 TA General iec cccssec id sdev a seen a aE see Aaa E E ai ia 71 7 2 Introduction to Tone Assessment eseeseeeeseeriesiresrierirerrierrnsrrnerrnerrnsrreereene 72 Tone Assessment Calculations eeceeeseeeseeeeneeeeneeseseeeeeeeeeeaeeeeaeeeeeeeeeees 72 7 3 Calibration e he seetteee che Save EA A aaa a ETEA E iE 75 7 4 Setting up the InstrUMent ee eee e cen
46. Assessment Option BZ 7231 User Manual Measurement Control d Trigger and Tacho Input Frequency Settings Span 20 kHz Lines 400 Centre Freq 10000 0 Hz Post Weighting Frequency correction Limit Level Units Output Socket Signal Quick Full Note Another way to select Post weighting is to tap on the Wgt parameter label on the measurement screen and select Post A or Z from the drop down list that appears see Fig 4 7 4 2 7 Pre weighting There are four different pre weighting parameters that can be used A B C or Z 1 Tap and select Setup from the list of options 2 On the Full view tab select Frequency Settings and then Pre Weighting 3 Select A B C or Z see Fig 4 5 A B weighting is determined when you set the Broadband excl Peak parameter under Frequency Weightings in the Setup menu Note Setting the post weighting will disable the pre weighting Fig 4 6 Selecting Pre weighting from the Setup menu Input Frequency Weightings Frequency Settings Span 20 kHz Lines 400 Centre Freq 10000 0 Hz Post Weighting Z Frequency Correction Off Pre Weighting A Measurement Control fe Trigger and Tacho ez Limit Level Quick t CHAPTER 4 Measuring Random Signals 43 Note Another way to select Pre weighting is to tap on the Wgt parameter label on the measurement screen and select Pre A Pre B Pre C or Z from the drop down list that appears
47. Delta Sum for Tolerance Window 8 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 9 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 10 B 1 3 For Tone Assessment Option BZ 7231 Parameters e K Prom Tone Ala Lin g Loti mo Toe e Critical Band e Critical Band f 120 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual B 1 4 Instantaneous Measured Parameters Not Stored with Measurement Instantaneous Time weighted Sound Levels Instantaneous Weather Data e Wind Dir e Wind Speed Instantaneous GPS Data e Latitude e Longitude Appendix C Glossary This Appendix is a continuation of the Glossary in Appendix E of User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 Gal FFT Parameters Current Average Number Current Average Time Total Averaging Time Total of FFT Spectrum Total of MAX Spectrum Total of Ref Spectrum Instantaneous RPM Average RPM When measuring the average of several spectra the Current Average Number parameter shows the number of spectra averaged so far When measuring the average of several spectra the Current Average Time parameter shows the averaging time elapsed so far When measuring the average of several spectra the Total Averaging Time parameter shows the time for the complete measurement The Total of FFT Spectrum is the sum of the levels of all the lines in the displayed FFT spe
48. Deterministic Random Transient Jy jh Frequency Frequency Frequency A transient signal is a signal which only exists for a short period of time Examples of transient signals are impacts caused at industrial sites combustion in a reciprocating machine or the opening or closing of a valve A transient signal produces continuous spectra To measure transient signals you need to be able to trigger at or just before the start of the signal and be sure to capture the transient within the length of a single FFT record Note If the transient cannot be captured within the length of a single FFT record the technique for measuring continuous signals described in section 5 2 can be used Preparing for Measurement This section will guide you in choosing suitable start values for the measurement of transient signals 50 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 5 1 2 Configuring the Input Configuring the input is a two step process 1 Choosing the correct transducer 2 Calibrating the system using Calibrator Type 4294 These steps are covered in detail in Chapter 3 and should be done before proceeding 5 1 3 Configuring the Analyzer The following parameters discussed in Chapter 2 are also applicable for transient measurements You should check each one in turn before you begin measurements to make sure they are set correctly in relation to your expected input signal e Frequency
49. E to analyse the recordings RECORDED SIGNAL The Z weighted signal from the measurement transducer Software Specifications Measurement Partner Suite BZ 5503 BZ 5503 is included with the Hand held Analyzer for easy synchronisation of setups and data between PC and Analyzer BZ 5503 is supplied on CD ROM BZ 5298 ON LINE DISPLAY OF TYPE 2270 2250 DATA Measurements on the analyzer can be controlled from the PC and displayed on line with the PC using the same user interface on the PC as on the analyzer DATA MANAGEMENT Explorer Facilities for easy management of analyzers users jobs projects and project templates copy cut paste delete rename create Data Viewer View measurement data content of projects Template Editor Editor for changing setups in Project Templates Synchronisation Project Templates and Projects for a specific user can be synchronised between the PC and Type 2250 2270 USERS Users of the analyzer can be created or deleted EXPORT FACILITIES Excel FFT Projects can be exported to Microsoft Excel Type 7820 FFT Projects can be exported to Evaluator Type 7820 HAND HELD ANALYZER SOFTWARE UPGRADES AND LICENSES Utility software controls the analyzer software upgrades and licensing of the analyzer applications INTERFACE TO HAND HELD ANALYZER USB ver 1 1 or Hayes compatible GSM or standard analogue modem PC REQUIREMENT Operating System Windows 7 XP or Windows Vista 32 and
50. Hand held Analyzer Select Overall Tolerance between Off and Input signal for monitoring Result purposes Latched Tolerance Choose between Overall Tolerance Result and Result Latched Tolerance Result to get 3 3 V DC out if an upper limit is exceeded 3 3 V DC out if signal is below one of the lower limits or alternating between 3 3 V and 3 3 V if signal is both above and below Note If you do not want to output the signal then set this parameter to Off to save power Gain 60 dB to 60 dB Key in a gain value 0 1 dB resolution for the input signal Use to assign the new value for immediate response at the output or use the up down navigation keys to increment decrement the value in steps of 1 dB Note 1 0dB means 1 V output for 1 V input Note 2 This parameter is enabled only if the Source parameter is set to nput APPENDIX A Setup Parameters A 10 Tone Assessment Parameters Table A 10 Tone assessment parameters Parameter Values Comment Tone Assessment On Off Turn this parameter On to enable Tone Assessment Note Tone Assessment will be enabled providing a valid BZ 7231 license is available Tone Standard ISO 1996 2 2007 Denmark 1984 1991 Determines the standard on which tone assessment is based Tone Seek Criterion 0 1 dB to 4 0 dB Determines if a classified line is a noise pause A noise line is classified as a noise pause if the differ
51. ISO 1996 2 or Briiel amp Kj r s Environmental Noise booklet for more detailed information about the rating level While using the Hand held Analyzer with FFT Analysis Software BZ 7230 it is possible to access the wide range of broadband parameters from Sound Level Meter Software BZ 7222 by selecting them in the Status field see Fig 7 8 Tap on the panel and select the parameter to be displayed CHAPTER 7 Tone Assessment Option BZ 7231 83 Fig 7 8 FFT ANALYZER Selecting Broadband parameters lt M Status field 7 6 5 Status Codes Smileys When the Hand held Analyzer has finished the Tone Assessment Calculation a quality indicator or smiley may appear Tap on a smiley to get an explanation of the status code and for a tip on how to remedy or improve the settings on the instrument see an example in Fig 7 9 Fig 7 9 FFT ANALYZER Explanation of status codes FC Off Lin 4 0k Kt Prom Tone 14 44 46 For an overview of all the remedies associated to the various smileys please refer to Table 7 2 a FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Table 7 2 Overview of Smiley Indicators and Associated Remedies Smiley Colour Explanation Remedy Tip for Solution Red Noise bandwidth too high Effective analysis bandwidth must be less than 5 of minimal critical bandwidth Increase the number of lines or reduce the analysed frequency span Red A w
52. PEAK parameter W frequency weightings A B C or Z controlled by SETUP FREQUENCY WEIGHTINGS SPECTRUM parameter 115 116 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual B 1 Total Measurement B 1 1 For FFT Analysis Software BZ 7230 FFT Parameters Spectrum Parameters e FET Spectrum e MAX Spectrum FFT Parameters e Current Average Number e Current Average Time e Total Averaging Time e Total of FFT Spectrum e Total of MAX Spectrum e Total of Ref Spectrum e Instantaneous RPM e Average RPM Broadband Parameters The following parameters are measured within the Elapsed Time Equivalent Continuous Sound Levels LxXeq e Lyeq Peak Sound Level Ly peak Maximum Time weighted Sound Levels LyFmax e LyFmax Minimum Time weighted Sound Levels LxFmin Lypmin General Parameters e Overload in e Start time e Stop Time e Elapsed Time excl pauses Special Parameters LxIeq Lyteq LaFteq also called LAFTm5 Weather Data Requires connection to a weather station Wind Dir avg Wind Dir min Wind Dir max Wind Speed avg Wind Speed min Wind Speed max Amb Temperature Amb Humidity Amb Pressure Amb Rain Gauge Tolerance Results Tolerance Window 1 Tolerance Window 2 Tolerance Window 3 Tolerance Window 4 Tolerance Window 5 Tolerance Window 6 Tolerance Window 7 Tolerance Window 8 Tolerance Window 9 Tolerance Window 10 Tolerance Lap Tole
53. Technical Documentation FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 For use with Hand held Analyzer Types 2270 and 2250 User Manual Bruel amp Kj r gt FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 For use with Hand held Analyzer Types 2270 and 2250 User Manual Valid for all hardware versions and from software versions 4 1 BE 1778 16 October 2012 Do not dispose of electronic equipment or batteries as unsorted municipal waste e Itis your responsibility to contribute to a clean and healthy environment by using the appropriate local return and collection systems e Hazardous substances in electronic equipment or batteries may have detrimental effects on the environment and human health The symbol shown to the left indicates that separate collection systems must be used for any discarded equipment or batteries marked with that symbol e Waste electrical and electronic equipment or batteries may be returned to your local Briiel amp Kj r representative or to Briiel amp Kj r Headquarters for disposal Trademarks Microsoft Windows and Excel are registered trademarks of Microsoft Corporation in the United States and or other countries Pentium is a registered trademark of Intel Corporation or its subsidiaries Copyright 2007 2012 Briel amp Kj r Sound amp Vibration Measurement A S All rights reserved No part of this publication may be reproduced
54. Total Reading The cursor gives the frequency and amplitude value of the FFT line it is aligned with However if you wish to know the total level of the displayed spectra you should read the displayed total at the right hand end of the graph panel Linear Averaging The initial exploratory measurement used exponential averaging This was chosen to allow you to see any changes in the average signal For detailed analysis and qualified measurement of a random signal you should choose linear averaging The main difference between exponential and linear averaging is that with linear averaging all the energy gathered during the averaging time is used to build up the final spectrum whereas for exponential averaging only the full energy from the latest record is used Previous records only partially contribute to the total with the penultimate record being given a lot more emphasis than the very first one The duration of the measurement is set by you but should be long enough to build up a good representation of the random signal CHAPTER 4 Measuring Random Signals 47 Setting Linear Averaging Parameters The values used for Linear averaging are set using the Meas Ctrl parameters on the Setup menu Change averaging to linear and set the Average spectra parameter to the number you require Note e Set the value of Avg Spectra to give an average time measurement period that is long enough to be sure that the signal you are me
55. a default setup that complies with the selected Tone Standard To reset all relevant parameters to the preset defaults described in Table 7 1 tap on the OK button To measure with the manual setup tap on the Cancel button The pop up window can also be deactivated for the rest of the measurement session by checking the Do not ask again checkbox To activate the tone assessment setup check again you will have to restart the FFT ANALYZER template or restart your instrument The measurement setup check is also deactivated when the Tone Assessment parameter is set to Off in the Setup menu Table 7 1 Default Parameters used by the Measurement Setup Check Default Setup Tone Frequency Measurement Units Assessment Settings Control Tone Seek 1 dB Span 20 kHz Averaging Linear Scaling RMS Criterion Type Lon 0 75xCB Lines 6400 Average 600 Regression Spectra Range Centre 10 kHz Window Hanning Freq Type Pre AorZ Total 00 01 04 2132 weighting Averaging Time 1 Cannot be controlled by the user 2 Calculated by the Hand held Analyzer 3 A weighting for Tone Standard ISO 1996 2 2007 Z weighting for Tone Standard Denmark 1984 1991 7 4 3 Setting up the Measurement Manually Rating Level The result of the FFT based tone assessment is the adjustment K which needs to be added to the Laeg measurement to calculate the rating level according to the selected tone stand
56. able a AO Total Level or sum for Delta cursors Summation principles Scaling Hanning Window Rectangular Window i included FFT lines T observation time RMS V Zipf 5 V 2p PWR gt pri 5 Lp PSD zp i 5 zp ESD p N 5 x T pA x T Peak N A N A Peak Peak N A N A The default scaling for FFT Analysis Software BZ 7230 is RMS Changing the scaling will result in change in units and values on the display Different levels of scaling can be used for different signals for example for random signals use PSD Power Spectral Density scaling Note Depending upon which scaling is selected the relevant values of Total level and sum are modified 1 Click the RMS parameter label on the measurement display 2 Select PSD from the drop down list that is displayed see Fig 4 8 Fig 4 8 FFT ANALYZER FFT ANALYZER Left Changing scaling t from measurement display Right Resulting measurement display 150 gp 100 50 T D g g i D i i 0 0 40k 8 0k 12 0k 16 0k 20 0k 12 0k 16 0k 20 0k Note Alternatively on the Quick view tab of the Setup menu select Units then Scaling and then PSD CHAPTER 4 Measuring Random Signals 45 Frequency Correction The use of frequency correction was covered earlier section 2 3 1 For the initial measurement set the Frequency Correction parameter to Off Spectrum Compress Expand If you want to view the signal in more detail expand the display to the range o
57. ak Sound Level 116 Physical Units iiron aria 52 Post Weighting 104 Post recording Time cscsccsscccsceneceescessersseeeneseees 111 Post weighting essesseessesrissnesreeresrearenrinereerranensenaes 41 Pre and Post weighting of the Frequency 78 Pre Weighting 0 0 cece eee eeeeeeeees 104 Preparing for Measurement eee eee tenets 38 R Random Signals Level sassone RIES OHE AEE Recalling Saved Measurements 0 eseeees 85 Recommended Accelerometers s s s 33 Record Length seess 104 Recording a s iiesiiiseeranierisiniiiianirsdaiiereti aiai 21 Recording Control cesseceeseecseseseeeeeeseeeenereeeeaees 110 Recording ParameterS cccsscseeeseeseeeeeeees 110 Recording Quality Reference Cursor Save Pushbutton Sealing sararem aai Scaling the Level in the FFT Graph sesse 43 Sensitivity and Frequency Range ceeeeeeenees 30 Set aS Ref ceeeeceseeseeeeeeseteeeeeeeaees Setting Linear Averaging Parameters Setting the Measurement Control Parameters 38 Setting up the Measurement Manually 77 Setting up the Tone Assessment Option 75 5S 910 71m 0 ree Signal Type s wi4s schtaeeviwevacansreeediveadied Slope Of Trigger eecseceeeseeeseseeeeeeeeeeeeeeee Sound Field Correction Sound Recording cccceeceeeeeeteeseeeeeeeeseeeeeeesteeeees 79
58. alue under Nominal Sensitivity whether or not to use the CCLD power supply and the weight of the accelerometer see Fig 3 3 4 Enter the name of the accelerometer under Name up to 10 characters can be used The name of the accelerometer will be displayed in the Transd used title of the status field appended with the serial number of the accelerometer 5 You can also enter the serial number and edit the description of the accelerometer if required Fig 3 3 Transducer used parameters 4513 01234 43974 0 Serial No in Name 43974 Description CCLD Preamplifier ID No Family Accelerometer Accelerometer Type 43974 Weight 249 Calibration History gt CHAPTER 3 Using Accelerometers for Vibration Measurement 35 Calibration After you have configured the input you need to calibrate your Hand held Analyzer The calibration procedure is very similar to that for acoustically calibrating a microphone using Sound Calibrator Type 4231 please refer to Chapter 5 of User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 if you are not familiar with this procedure The only difference between this procedure and the acoustic calibration procedure already mentioned is that you attach Calibration Exciter Type 4294 to the accelerometer you have just connected and configured Proceed as follows 1 Tap HBH and select Calibration from the list of options the initial calibration screen appears 2 Mount
59. ameter Values Comment MATRON Handswitch Voltage Level Tacho Trigger Trigger Input This parameter should be set to match the equipment connected to the Trigger Input Socket on the connector panel of the analyzer Set it to Tacho Trigger if it is not used or if External Triggering is used or if a Tacho is connected to the Trigger Input Note Set CCLD Pull Up as required by the equipment Set it to MATRON Handswitch if you want to start or stop the measurement using a MATRON Handswitch Please contact your local Briiel amp Kj r representative for further information Set it to Voltage Level if you want to start stop a measurement by a voltage level generated by external equipment The Voltage Level should generate at least 2 V for a start and less than 1 V for a stop The duration of the steady level should be at least 1 s so it can be recognised by the analyzer Note Start Stop of measurement using Trigger Input cannot be combined with using it for tacho or trigger signal A 2 Frequency Weightings Table A 2 Frequency weighting parameters Parameter Values Comment Broadband excl Peak AC All broadband parameters except Lpeak are AZ measured simultaneously with two different BC frequency weightings select the weightings here BZ Broadband Peak One broadband peak parameter Lpeak is measured select the frequency weighting here Note X frequency weighting A or B A req
60. and giving the highest total audibility 7 3 7 4 7 4 1 CHAPTER 7 Tone Assessment Option BZ 7231 75 The most prominent tone is the tone in the decisive band with the highest audibility Penalty for Tone Standard ISO 1996 2 2007 is determined from the audibility as If the audibility is less than 4 dB no adjustment is incurred If the audibility is over 10 dB the adjustment is 6 dB Between 4 and 10 dB the adjustment is AL 4 dB Note the adjustment is not restricted to integer values Penalty for Tone Standard Denmark 1984 1991 is determined from the audibility as If the audibility is less than or equal to 4 5 dB no adjustment is incurred If the audibility is greater than 4 5 dB the adjustment is 5 dB Analysing Very Low Tone Levels The basic aim for objective tone assessment is to give objective indicators for perceived annoyance from tones in noise Objective tone assessment must be used with great care when the level of the detected tone s is close to either the threshold of hearing or the noise floor in the equipment used for analysing and calculating the objective parameters The Noise Floor The noise floor of the Hand held Analyzer may include spurious signal noise that will cause the calculation to give an adjustment K greater than 0 dB On the Hand held Analyzer s display the level of the noise floor in the FFT application is indicated with a red line on the y axis This indication may be us
61. annotations for attaching to measurements CAMERA 2270 ONLY Camera with fixed focus and automatic exposure is incorporated in underside of instrument Used to create image annotations for attaching to measurements Image Size Hardware versions 1 3 640 x 480 pixels Hardware version 4 2048 x 1536 pixels Viewfinder Size 212 x 160 pixels Format jpg with exif information EXTERNAL DC POWER SUPPLY REQUIREMENTS Used to charge the battery pack in the instrument Voltage 8 24 V DC ripple voltage lt 20 mV Current Requirement min 1 5A Power Consumption lt 2 5 W without battery charging lt 10 W when charging Cable Connector LEMO Type FFA 00 positive at centre pin EXTERNAL AC MAIN SUPPLY ADAPTOR Part No ZG 0426 Supply Voltage 100 120 200 240 VAC 47 63 Hz Connector 2 pin IEC 320 BATTERY PACK Part No QB 0061 Rechargeable Li lon battery Voltage 3 7 V Capacity 5200 mAh nominal Typical Operating Time e Single channel gt 11 h screen backlight dimmed gt 8 5 h full screen backlight e Dual channel gt 7 5 h full screen backlight Use of external interfaces LAN USB WLAN will decrease battery operating time Battery Cycle Life gt 500 complete charge discharge cycles Battery Aging Approximately 20 loss in capacity per year FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Battery Indicator Remaining battery capacity and expe
62. apo aei aae aaaea Mac daea aea ei ade ae te Taaka 38 Measurement Controli eiii iieii aiaei eiaei iaieineea 38 Full Scale Value cccccccccccccccceececceceeeeeeeeceeeeeceeeueeseeeesseeuaeeseeeeeeseeeueueeseeseeeeaes 39 Frequency Resolution Span ccccccccceeeeeeceeeeseeeeeeeeeeeeeecaeeesesaeeeeeseneeeesenaees 39 THM WINdOWS ieinter onen an aeiae Ja ede gies 40 POSt WOIQHTING 2 2 eeeceeecceeeeeeeseeeceecereeneneeeeneeeesnenessenenssnenesseneneeesseeesseneneenenenees 41 Pre WeOiQhting iinan en eaea i e Ta eaea aas Saa aa 42 SCAlING nas ta i a panes Sa tie ne ad ee 43 4 3 M aSUNING i s3 fcket Atcnged Aisin an een i 45 Measurement Start 0 0 0 seseecesnceescecseceseneeesneeeseeeesenessanesseneseseeeesanesneneseenerees 45 Overload Indication 0 eee eee cece eeenee tence eeeeeeseneeteaeeeeaeeseaeeseaeeeeaeeseaeeeeaeeseaeees 45 Cable Break Short Detection 2 00 eeceeceeesceeeseeeeeneeeeeeeeeaeeseaeeseseeessneeseeeeeeees 45 Measurement Pause Continue Save eeceecceeeseeeeseeeeeeeeeeeeeeeneeseaeeenseeeeeeeeee 45 Main CUrSOP hies eae sein BA A aa ee 46 Total REAGING ic setts ci seg tie eee See aston oe A te Ae ol ad 46 Linear Averaging yoini e ee Ee ate Es I ae ate 46 ALA SIRS TUNING EAP AAE AE T A E 47 ZOOMING ne A E A EA 47 CHAPTER 5 Measuring Transient and Continuous Signals ccssseeesseeeeeeeeeseeeeeees 49 51 Transient Signal cvec ssa aa bee erie i eed 49 Preparing for Measurement
63. ard While using the Hand held Analyzer with FFT Analysis Software BZ 7230 it is possible to access the wide range of broadband parameters for example Laeg from Sound Level Meter Software BZ 7222 Please refer to the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 for more information about broadband parameters Frequency Settings According to ISO 1996 2 Annex C the effective analysis bandwidth shall be less than 5 of the bandwidth of critical bands with the tonal components The bandwidth of the critical bands Fig 7 4 Selecting the frequency range FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual is 100 Hz if the centre frequency is less than 500 Hz and 20 of the centre frequency if the frequency is more than 500 Hz This 5 criterion is fulfilled for the range from 20 Hz to 20 kHz if Span is set to 20 kHz Lines to 6400 and Centre Freq to 10000 Hz In this case the effective analysis bandwidth is 4 7 Hz You are allowed to select other combinations of frequency range and lines see Fig 7 4 these parameters are found in the Setup menu under Frequency Settings parameters Selecting a lower number of lines will make the tone assessment calculation faster If the 5 bandwidth criterion is violated within the measured frequency range an error indication will be generated in the status codes smileys Frequency Settings Measurement Control Tone Settings Ton
64. are BZ 7230 and Tone Assessment Option BZ 7231 User Manual Table A 1 Cont Input parameters Parameter Values Comment Windscreen Auto On Turn this parameter on to automatically detect Detect Off UA 1650 windscreen when mounted on the ZC 0032 microphone preamplifier and compensate for the impact on the overall frequency response of the analyzer Turn this parameter off to enable manual setting of windscreen correction Note 1 The preamplifier should be connected to the top socket if necessary using a microphone extension cable Note 2 Windscreen detection cannot be performed while measuring so if the instrument detects a change in windscreen status i e the windscreen has been removed or a windscreen has been fitted during the measurement a warning message box will appear This message box gives you the opportunity to reset the measurement by tapping the OK button If you want to save the measurement tap the Cancel button and then save the measurement as normal Windscreen Correction None If Windscreen Auto Detect is set to Off you can UA 1650 manually select a windscreen correction suitable for UA 1404 the windscreen in use Extended Low Off Use this parameter to extend the low frequency of the Frequency On measurement down to approximately 1 Hz determined by the transducer used and the CCLD circuit Table A 1 Cont Input parameters APPENDIX A Setup Parameters 103 Par
65. asuring is fully represented For example when measuring environmental noise some standards require that you measure for at least two minutes to be sure that a good representative sample is taken e The Avg Time field is computed by the FFT software The value depends upon the frequency span see section 4 2 4 and the number of spectra to be averaged e Changing the Averaging Type parameter will reset the measurement buffer and start a new measurement 4 4 Fine Tuning In section 4 3 the initial exploratory measurement was dealt with The setup was designed to allow you to quickly home in on the general characteristics of the random signal This section deals with how to make more qualified measurements on the signal as a whole or on specific parts of the signal 4 4 1 Zooming in Whether you are using exponential or linear averaging you may see parts of the measured spectra that require closer inspection a finer resolution You may do this by changing the span centre frequency and the x axis scaling The initial span and centre frequency were entered as part of the measurement set up see section 4 2 4 The x axis scaling was set to be in Compress mode 48 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 5 Measuring Transient and Continuous Signals 5 1 Fig 5 1 Transient signals 5 1 1 Transient Signals Stationary signals Non stationary signals
66. be measured Transient Note If manual mode is selected Signal Type is automatically set to Continuous by default Window Type Hanning Determines the type of Time Window to be applied Rectangular on the measured signal Note If manual mode is selected Window Type is automatically set to Hanning by default Triggers 1 to 32767 Determines the number of triggers for which the measurement will run Note This parameter is disabled in manual mode 106 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Table A 4 Cont Measurement control parameters Parameter Values Comment Spectra per Trigger 1 to 32767 Determines the number of spectra that will be averaged per trigger Note This parameter is disabled in the manual measurement mode Auto Save On Off Choose On to save the measurement automatically when the measurement pauses either automatically or manually A 5 Trigger and Tacho Parameters Table A 5 Trigger and tacho parameters Parameter Values Comment Trigger Type Internal Determines whether the trigger input is internal or External external Internal trigger is used to trigger on the incoming time signal External trigger is used to trigger on a signal applied through the trigger input Delay Permissible delays for Determines the delay from the trigger to the start of the respective spans the record 20KHz 0 64s to 300 s When the de
67. by the FFT software The value depends upon the frequency span see section 2 3 3 and section 4 2 4 and the number of spectra to be averaged Full Scale Value The full scale value is the maximum signal level that the analyzer will accept before overload occurs with the current input type setting This is specific to the transducer used and cannot be changed Frequency Resolution Span Frequency Span For sound measurements in the audio range a span of 20 kHz centred on 10 kHz and 400 lines gives a good overview This enables you to see the sound in almost real time The frequency resolution is set by the frequency span and the number of FFT lines which in turn governs the record length for each captured spectrum and the effective noise bandwidth of each FFT line Therefore you need to initially set these parameters to values that suit the signal type you are testing The Frequency Span is set to a value that you expect will encompass the frequency range of your signal The centre frequency decides the frequency around which the frequency span will be distributed equally The span parameters are found under Frequency Settings Setup menu set the required Span Lines or Centre Freq value by selecting them in the Frequency Settings parameters see Fig 4 3 Fig 4 3 Setting the frequency span 4 2 5 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Centre Freq Post Weighting F
68. ce eeneeeeaeeeeeeeeeeeeeeeaeeseaeeeeaeeeeeeeeeeneeeaes 75 Setting up the Tone Assessment Option ee eeeeeeseeseeeeeeseeeeeeeeeeneeeeneeeeneees 75 Setting up the Measurement Using the Default Setup ee eeeeeeeeees 76 Setting up the Measurement Manually ee ce eeeeeeeseeeeeeeeeeeeeeeeeeeeneeeeaeeeneees 77 Signal Recording iecssc sscgectec ceed ceeeeee cetbe ees iten ceibes aa reeves gunmen 79 7 55 M aSuring veces sche eet at ee ee ee ee a a 79 76e ReSult DISPlaY sie ess taiegi ss ee eel hs eet eeieek OS eed lostin eed eel aoe ecsacdebea 79 TING OMe CUS On iiest pet coh hate tn bes tees a ar Yael das at ees a leat ght 79 TheTone Parameter Panels crei ane leak Sauiees eniee ant dus let eel ata dit eae 81 WICWEATC Gh cites EE arta Lakes et EE E igees el gas Mead decs aud so Wot tes Ls 81 Broadband Parameters ciscicics techy sae ides eet aa a a Shs Leal bes dd ebb Sock as dab aah 82 Status Godes SMileys ix fvidecigatiecs soe contac ea ei a a edges able eel sea ek leeks 83 7 7 Generation of Tone at Cursor ccccceccceceeeeceeeeeeaeeeeeeeeeeeeaeeeeeeneeeeesneeeeeeenaees 84 Adjusting the LEVE krere e a a r r aata aaa ara ra a aan fail a ar aea ara eaaa 85 Navigating the Frequency s ssseesssssrsssrsrensrensrnnsrnesraesrnestnsrnneetnrennrenarenarenanenne 85 Listening to a Mixed Signal inntir oper noti ot ep raretat enten iaia aei 85 7 8 Recalling Saved Measurements ce eeeeeeceee
69. city or displacement If Direct is selected under Trans Used this parameter is set by default to Voltage and cannot be edited Unit System SI Determines which unit system is used for the US UK measured signal Y axis dB Determines whether the Y axis will be displayed in Engineering decibel values dB or Engineering units Unit Determines the current unit of measurement It is dependent on all the above parameters 110 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual A 8 Signal Recording Parameters Manual Event Tol Exceed Table A 8 Signal Recording parameters Parameter Values Comment Recording Control Off Determines how recording of the measured signal is controlled Automatic Set to Automatic to start the recording when the measurement starts and record throughout the measurement only limited by the Maximum Duration Set to Manual Event to start recording manually while measuring when the Manual Event pushbutton is pressed and record until pressing the pushbutton again however take Maximum and Minimum Duration into account Set to Tol Exceed to start recording whenever the signal exceeds one of the set upper limits or gets below one of the set lower limits and stop when the signal is within all tolerance limits Recording Quality Low 3 3kHz Fair 6 6 kHz Medium 10 kHz High 20 kHz This setup determines the quality of the recording by adjust
70. cted working time may be read out in and in time Battery Fuel Gauge The battery is equipped with a built in fuel gauge which continuously measures and stores the actual battery capacity in the battery unit Charge Time In analyzer typically 10 hours from empty at ambient temperatures below 30 C To protect the battery charging will be terminated completely at ambient temperatures above 40 C At 30 to 40 C charging time will be prolonged With External Charger ZG 0444 optional accessory typically 5 hours Note It is not recommended to charge the battery at temperatures below 0 C 32 F or over 50 C 122 F Doing this will reduce battery lifetime CLOCK Back up battery powered clock Drift lt 0 45 s per 24 hour period Storage INTERNAL FLASH RAM NON VOLATILE For user setups and measurement data Hardware versions 1 3 20 MB e Hardware version 4 512 MB EXTERNAL SECURE DIGITAL MEMORY CARD SD and SDHC Card For store recall of measurement data EXTERNAL COMPACT FLASH MEMORY CARD Hardware Versions 1 3 Only CF Card For store recall of measurement data USB MEMORY STICK Hardware version 4 only For store recall of measurement data REAL TIME CLOCK Back up battery powered clock Drift lt 0 45 s per 24 hour period WARM UP TIME After reaching equilibrium with the ambient environment and switching on power From Power Off lt 2 minutes From Standby lt 10 seconds for prepolarized microphones
71. ctrum The Total of MAX Spectrum is the sum of the levels of all the lines in the displayed MAX spectrum The Total of REF Spectrum is the sum of the levels of all the lines in the displayed REF spectrum The Instantaneous RPM is the current RPM value For Linear averaging the Average RPM is the average RPM over theTotal Averaging Time For Exponential averaging it is the latest RPM of the measurement 121 122 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual C 2 Tone Assessment Parameters Tone Level Lp Level Loti Masking Noise Level Lpn Audibility AL Critical Band Critical Band f Adjustment Kj Level of all tones in the critical band containing the selected tone Level of the selected tone Masking noise is the sound which does not belong to the tone and which limits masks the audibility of the tone It is the total level of the masking noise in the band containing the selected tone Audibility is difference between the tone level and the masking noise level It refers to the audibility of all tones found in the same critical band as the selected tone Start of Critical Band and end of Critical Band containing the selected tone Centre frequency of Critical Band containing the selected tone The size of the adjustment in dB The adjustment is calculated from the decisive band and refers to the total spectrum Index Symbols Average Spectra
72. dwidth 3 Critical Band ve Critical Band fC eee eeeeeeceeeeeeeeeeeeeeeeeeeeeeeneeees Critical Bands ierse ane nay Current Average Number Current Average Time D Default Parameters Used by the Measurement Setup Check 77 Delay oe eeeeececeecneeeeeneeeeeeaeeeeenaeeeeeaaeeseenaeeeeeaeeees 57 106 Delta Cursor w 14 17 Delta Sum Parameters s e 118 Detecting the Tone Candidates 0 cceeee 73 Deterministic ss cite sins eine eat 63 DiSplaCeMent cccsccccseerscctsseceseesseesseeeeseesensesseeees 55 Duration Limiten eii ete cena 111 E Engineering Display cee cece eee eeeeeeeneeeeeees ES Durrani patair Expanding the Display Exponential Averaging 123 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Exponential averaging ccceeceeeeeeeeseeneeeeees 21 Exponential Y AXiS ccecsccssscsesteeeseesteeeeseenseeseeeees 53 Extended Low Frequency ccscsssesseesseeseeeees 102 External Level i External lev liinoris ngina External TriQQer sccccsccsscssssccessrsessecssesosnsesseeseenes 56 F Falling FFT Parameters 7 Fine TUNING i iaaiaee ieie areia For Deterministic Signals eeeeeeeeeeee Frequency Correction Frequency Resolution Span Frequency Span seses k Frequency Weighting Parameters 103 Full Scale Value tass centre niono dti 39 G G e hase
73. e to restart the measurement not needed if an exponential average measurement was running 30 Observe the spectrum the number of averages display and the elapsed time Observe that the measurement automatically goes to the paused state after the pre configured number of averages has been reached default setup is 10 averages 31 You can also select averaging from the setup page see Fig 2 11 32 Tap and select Setup from the list of options On the Quick setup tab locate the Average Spectra and change the value to 20 33 Return to the measurement display 34 Press Start Pause to continue the measurement 35 Observe the spectrum the number of averages display and the elapsed time Note The measurement continues for another 20 averages making the total number of averages in your measurement up to 30 36 To set the measurement in free run mode again select Exponential averaging by tapping directly on the measurement display 14 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 2 3 5 Cursors FFT Analysis Software BZ 7230 provides a range of cursors to assist in making various measurements Until now you have been working solely with the main cursor which is used to read the data for a single line Now you will also work with various auxiliary cursors such as delta reference harmonic and symmetric delta and with the auto peak find function Delta Cursor 37 Use your
74. e drop down menu see Fig 7 10 This activates the generation of a pure tone with a frequency corresponding to the frequency of the main cursor The tone is generated from the headphone socket The actual output level in the headphones is dependent of the sensitivity of the headphones used for listening CHAPTER 7 Tone Assessment Option BZ 7231 85 Fig 7 10 Generation of a tone at the cursor 9 Tot 83 6 ALta 14 6 dB gt FC Off Lin 50 4 gt 35k 37k 40k Kt Prom Tone Lines 12 44 19 When tone generation is on the display shows the speaker on KE icon When tone generation is off it shows the speaker off 4 icon 7 7 1 Adjusting the Level When generation of tone at cursor is on the level can be controlled from the drop down menu accessed by tapping on the KE icon see Fig 7 10 Tap on Level Up or Level Down or control the level by navigating to the Setup menu and setting the Level under the Tone At Cursor parameters 7 7 2 Navigating the Frequency The frequency of the generated tone follows the position of the main cursor The lt gt buttons will jump the main cursor between the detected tones and in this way you can select the generated frequency 7 7 3 Listening to a Mixed Signal Tone At Cursor generation can be mixed with the signal from the microphone so if you want to be able to listen to the input signal then navigate to Headphone Settings under Preferences a
75. e 2270 Traceable Calibration of Type 2270 Conformance Test of Type 2270 with certificate Accredited Initial Calibration of Type 2250 Accredited Calibration of Type 2250 Traceable Calibration of Type 2250 Conformance Test of Type 2250 with certificate IEPE Accelerometer Accredited Calibration IEPE Accelerometer Traceable Calibration PC SOFTWARE BZ 5503 Type 7820 Measurement Partner Suite supplied as standard with Type 2250 Evaluator data viewing and calculation software FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual MEASUREMENT ACCESSORIES Type 2647 D 004 Charge to DeltaTron Converter with Type 4513 4514 Type 4513 001 4514 001 Type 4513 002 4514 002 Type 4397 A Type 8324 Type 8341 AO 0701 D 030 AOQ 0702 D 030 YJ 0216 QS 0007 UA 0642 UA 1077 AOQ 0440 D 015 AO 0697 015 AO 0697 030 AO 0697 100 AOQ 0722 D 050 AOQ 0726 D 050 AO 0727 D 015 integrated cable and connectors for Type 8324 Accelerometer Accelerometer general purpose with 1 mV ms sensitivity and 10 32 UNF connection Accelerometer suitable for low level measurement 10 mV ms and 10 32 UNF connection Accelerometer suitable for very low level measurement 50 mV ms 2 and 10 32 UNF connection Accelerometer with 1 mV ms sensitivity suitable for high frequency and high level measurement with M3 connection Charge Accelerometer Industrial with 1 pC ms sensitivity and 2
76. e Assessmen Tone Standard Tone Seek Criter You can speed up the tone assessment calculation without violating the 5 bandwidth criterion by selecting a smaller span and a corresponding smaller number of lines But be sure that the range with the audible tones is analysed In rare cases where a complex tone has many closely spaced components a finer resolution may be necessary to determine the level of the masking noise correctly The setting of frequency correction FC to On or Off only affects the results read from the main cursor the tone assessment calculation is not affected by the setting of the frequency correction Pre and Post weighting of the Frequency In the default setup the pre weighting is set to A in accordance with ISO 1996 2 2007 or set to Z in accordance with Denmark 1984 1991 The Hand held Analyzer gives you the freedom to choose pre weighting as A B C or Z and the post weighting as A or Z Please note that to avoid errors from double weighting the Hand held Analyzer automatically deactivates the post weighting feature when the pre weighting differs from Z Please refer to section 4 2 4 where Frequency Settings are explained CHAPTER 7 Tone Assessment Option BZ 7231 79 Measurement Control According to ISO 1996 2 Annex C tone assessment must be performed using linear averaging for at least 1 minute But the Hand held Analyzer gives you the freedom to choose various combinations of linear
77. e User Manual for Types 2270 and 2250 BE 1713 This manual assumes that you are familiar with the concepts of measuring sound using a microphone and some form of sound level meter analyzer Summary of Contents e Chapter 1 Introduction e Chapter 2 Getting Started includes a general description of FFT Signal Analysis followed by a step by step tutorial which allows you to familiarise yourself with how FFT Analysis Software BZ 7230 together with your Hand held Analyzer performs FFT measurements e Chapter 3 Using Accelerometers for Vibration Measurement a guide to choosing and mounting your accelerometer configuring the instrument s input for vibration measurements and information on calibration e Chapter 4 Measuring Random Signals gives a brief description of random signals including examples tells you how to prepare for measurement how to measure random signals and how to fine tune e Chapter 5 Measuring Transient and Continuous Signals gives a brief description of transient and continuous signals including examples tells you how to prepare for measurement and how to measure transient and continuous signals ee 1 3 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual e Chapter 6 Measuring Deterministic Signals gives a brief description of deterministic signals including examples tells you how to prepare for measurement how to measure deterministic signals and describ
78. e of the Zoom in operation User can zoom out only up to the maximum range however and not beyond that Auto Zoom This operation zooms in on the data in such a way that the data of the highest and the lowest values is visible on the screen Scale Up This operation moves the area currently being displayed on the Y axis up by a fixed value up to the maximum limit This is only possible after the first zoom in operation on the Y axis Scale Down This operation moves the area currently being displayed on the Y axis down by a fixed value up to the maximum limit This is only possible after the first zoom in operation on the Y axis Auto Scale This operation scales the Y axis up or down in such a way that the maximum value in the data is visible on screen While doing this it maintains the current range Congratulations you ve finished with the Getting Started guide 28 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 3 3 1 Using Accelerometers for Vibration Measurement Introduction For a good introduction to accelerometers consult Briiel amp Kjer s Piezoelectric Accelerometers and Vibration Preamplifiers Theory and Application Handbook order number BB 0694 The piezoelectric accelerometer is today accepted as the standard vibration transducer for most general purpose vibration measurement situations The reason for the high degr
79. ectrum use one of the two following methods 1 Tap on the spectrum display on the measurement screen 2 Select Acc Vel or Dis from the drop down list that appears see Fig 5 10 56 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Fig 5 10 Left Changing spectrum display from measurement page Right Resulting measurement page Fig 5 11 Left Changing spectrum display from Setup menu Right Resulting measurement page Scaling Spectrum Display Unit System Y axis Sound Recording Lines 400 5 1 11 Averaging You cannot switch between linear and exponential averaging in triggered mode Averaging is set to Linear and cannot be toggled 5 1 12 Trigger Values When Measurement Mode is set to Triggered the BZ 7230 software will only begin a measurement when either an internal or an external trigger has occurred However you must still prime the analyzer by pressing Start Pause To set the trigger state use the Trigger and Tacho parameters on the Setup menu see Fig 5 12 CHAPTER 5 Measuring Transient and Continuous Signals 57 Fig 5 12 Setting the trigger and Kod tacho parameters Bfree E Trigger Type External Delay 0 0 psg Hold Off 0 0 ps Tacho off External Level 24 V Hysterisis 50 mY Slope Rising Pull Up off Frequency Settings Quick Full 14 07 42 Trigger Type This parameter det
80. ed as a guide when judging the source of a tone signal For more details of the noise floor of the Hand held Analyzer please refer to the specifications The Threshold of Hearing When tones appear at low levels it is up to you to check whether the total tone level in the critical band is above the threshold of hearing If the total tone level in a critical band does not exceed the threshold of hearing this critical band should be disregarded Special care has to be taken when tones appear at low frequencies where the threshold of hearing is elevated Calibration ISO 1996 2 Annex C recommends that the measurement setup including the frequency analyzer is calibrated for sound pressure measurements dB re 20 Pa Refer to Chapter 5 of the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 for more information about acoustic calibration Setting up the Instrument Setting up the Tone Assessment Option Tap and select Setup from the list of options Under the Tone Settings parameters on the full list of options tap on the Tone Assessment option and select On see Fig 7 2 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Fig 7 2 Left Selecting the Tone Frequency Settings k Frequency Settings Assessment option Measurement Control Measurement Control Right Setting the Tone Trigger and Tacho g Seek Criterion Limit Level Units Sound Recording Output Socket
81. ee Fig 2 10 A logarithmic X axis can be useful for sound measurements Tap on the frequency axis once more to select linear X axis again Fig 2 10 Left Drop down list showing Logarithmic X axis option Right Logarithmic X axis displ gt 27 1 Tot a s displayed Wgt z FC Off Exp FFT ANALYZER FFT ANALYZER terna 55 1 Tot 90 2 27 1 Tot 71 6 FC Off Exp 21 16 12 CHAPTER 2 Getting Started 13 2 3 4 Averaging Exponential averaging which has been used up to now is typically used to find the signal of interest using the setup zoom and display facilities To make a well defined measurements of stationary signals you should switch to Linear averaging In a triggered mode of measurement averaging type is set to Linear by default and cannot be changed to Exponential 28 Select Linear averaging by tapping directly on the measurement display see Fig 2 11 Fig 2 11 Left Setting Linear F Ci Project 002 B Measurement Control averaging directly 4 3 04 a Measurement Mode Right Setting Linear 0 Main r i Averaging Type averaging via the 5 i sitot Average Spectra Setup menu nal Type Frequency Settings F Units Sound Recording ok 2 de 2 kHz 400 19 48 01 29 If the measurement is in Running Paused state a message box will be displayed similar to the one shown in Fig 2 7 Tap OK to allow the measurement to be reset This has to be done since FFT analysis is being restarted Press Start Paus
82. ee of acceptance is that the piezoelectric accelerometer offers the following properties e Linear amplitude response across a wide dynamic range limited only by built in electronics e Wide and flat frequency response with proper mounting e Self generating piezoelectric element which simplifies power supply and signal conditioning e No moving parts a rugged transducer that will not wear out e High stability in most test environments temperature humidity dust and fluids e Compact often very low weight so easy to mount in any orientation One limitation is the very high output impedance of the piezoelectric element Therefore most modern accelerometers include a charge to voltage converter circuit in the housing To distinguish them from traditional piezoelectric devices these accelerometers are known generically as Integrated Electronics Piezoelectric IEPE accelerometers or commercially as DeltaTron or ISOTRON accelerometers The circuit in a DeltaTron accelerometer is powered from an input with Constant Current Line Drive CCLD power supply The Hand held Analyzer is able to deliver such a power supply on its Rear Input Socket when CCLD is selected The Hand held Analyzer then receives an input signal in the form of a modulated voltage on the input which is proportional to the acceleration measured gt 3 1 1 Fig 3 1 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual
83. eeeeeseneeeneeeeaeeeeseeeeeeeeseaeeeeneeeeeees 85 CHAPTER 8 Specificato S e aa ee eae r ea ae Aaaa aaan chan Eae ap Aaea daei 87 APPENDIX A Setup Parameters aaa ee SBS or ap ie SoBe e mee srs te nanne nnmnnn BBE 101 A 1 Input Parameters iseci araia A a aE ia 101 A 2 Frequency WeigQhtingS 0 0 0 0 ceeeeeeceeeeneeeeneeeeeeeeesneeseaeeesaeeenaeeseeeeeeneeseeeeeeees 103 A 3 Frequency Setting Parameters 0 ce ecceeeseeeeceeeeeeeeeeeeeeaeeeeaeeeeeeeeesneeseneeeeaeees 104 A 4 Measurement Control Parameters eecceeeceeeseeeeeeeeeneeeeeeseseeeeeneeeeeeeeaeees 105 A 5 Trigger and Tacho Parameters cecceesseeseeeeeeeeeeeeeeneeseaeeseeeseeeeteeeeeeeeeees 106 A 6 Tolerance Window Parametels ccccccecceeeeeceeeeeeeeeeeeeeeeeeeeeeeeeeseneeeeeesneeees 107 A 7 Parameters Related to Units 0 eee eee e eee tees eeeeeeeeaeeeeaeeeeeeeeeaeeseeeeeaeees 109 A 8 Signal Recording Parameters eee ceseeeseeeeeeeeeeeeeeeeeseeeeeeeeeeeeeesneeseneeeeeees 110 A 9 Output Socket Signal Parameters eecceeseeeeeeeeneeeeneeeeseeeeeeeeeeneeseeeeeeees 112 A 10 Tone Assessment Parameters cceecceesseeeeeeeeeeeeeeeeseeeeeeeeeeneeteaeeseneeeeeees 113 A 11 Tone at Cursor Parameters iriseora re raa e eae a lao 113 APPENDIX B Measurement Parameters cccccccesssseecseceeeeenssseeeeceeesesesseneeneeeeseseesenssenoees 115 B 1 Total Measurement ccccccceeeeceeeeeeneeeeeeeeeeeeseaeeeeesaaeeeeecaeee
84. eenetnrenne Triggered Triggers oe eee ee ceeeeeee eee eeeeeeeee 51 57 60 Turning Corrected Frequency ON seceeeeeeeeeeee 65 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual U Unit SYSt6M ca nanea 52 54 109 Upper Limit Using Accelerometers for Vibration Measurement 29 V Valle Panelis tasses ann 7 46 80 Valles Checked iss cca Ai iindainiaiessthentals 108 Velocity Display View Area Volatile Memory WwW Window TY Pe sssi ciccareesceevsregseenestinertdaveneesteadereesrevsee 105 Windscreen Auto Detect 102 Windscreen Correction Parameter 102 Y Y axis yoe tapa he 25 53 109 Z Zooming in on Display 0 eee eeeeeeeeeeeeeees 9 25 Zooming in on Frequency Span 10 47 HEADQUARTERS Briel amp Kj r Sound amp Vibration Measurement A S DK 2850 N rum Denmark Telephone 457741 2000 Fax 45 4580 1405 www bksv com info bksv com Local representatives and service organisations worldwide
85. eesneeeeeesneeeesenaees 116 For FFT Analysis Software BZ 7230 eecceesseeeseeeeneeeeseeeeseeeeeeeeeeeeseneeeeaeees 116 Parameters for Tolerance Windows with Check on Delta Sum ee 118 For Tone Assessment Option BZ 7231 ooo eeceeseeeeeeeneeeeeeeeeeeeeteneeseneeeeeees 119 Instantaneous Measured Parameters Not Stored with Measurement 120 APPENDIX C MIO SSARY A ciol a caesar a seach teed La aaa 121 Gali JPET Parameters ieee Se eee ee ER 121 C 2 Tone Assessment ParaMeters ccccccccccccccccceeeeeeceeeeeeeeeeeeeeeesaeeeeueeeeeeeeeeeaes 122 INDEX Chapter 1 1 1 1 2 Introduction Personal Preparation FFT Analysis Software BZ 7230 and the Tone Assessment Option BZ 7231 are just two of the application packages available for Hand held Analyzers Types 2270 and 2250 If you are newcomer to the world of Type 2270 and Type 2250 you are strongly advised to study the User Manual for Hand held Analyzers Types 2270 and 2250 before reading this manual By doing this you will get a better understanding of the platform concept and how the BZ 7230 and BZ 7231 application packages fit into the portfolio You will also become familiar with some terms used in this manual that apply to the Hand held Analyzers in general This manual instructs you on how to set up your Hand held Analyzer for FFT measurements how to measure and how to look at your results Anything that is independent of BZ 7230 or BZ 7231 will be found in th
86. eighting needed Set Pre weighting to A for Tone Standard ISO 1996 2 2007 Red Z weighting needed Set Pre weighting and Post weighting to Z for Tone Standard Denmark 1984 1991 Red Hanning window needed Select Hanning Window Yellow Total Averaging Time short Increase Total Average Time to a total of more than one minute Yellow Linear averaging missing Set Linear Averaging Yellow Closely spaced Tones Need better frequency resolution refer to ISO 1996 2 Annex C Note 3 page 27 Yellow Tone too close to border Adjust the analysed frequency span Yellow Assessment is performed on Reselect Tone Cursor or change the graph MAX spectrum manually to FFT Yellow Assessment is performed on Reselect Tone Cursor or change the graph Reference spectrum manually to FFT 7 7 Note Special care has to be taken when assessing tones at low levels For more information please refer to Analysing Very Low Tone Levels on page 75 Generation of Tone at Cursor Generation of Tone at Cursor is a useful feature for comparing the results of the objective FFT based tone assessment to the actual noise and may be used to verify the consistency between the subjective evaluation of the noise and the objective calculation It is also useful for identifying a tonal noise source and may be used in dialogue with a complainant From the Measurement Display tap the loudspeaker icon KI and then choose Turn On from th
87. ence between its dB level and the dB levels of immediate neighbouring lines is greater than or equal to the Tone Seek Criterion Available for Tone Assessment Option BZ 7231 only A 11 Tone at Cursor Parameters Table A 11 Tone at cursor parameters Parameter Values Comment Level re 1 V 70 dB to 10 0 dB This sets the level of a tone sine wave at the cursor frequency The tone is output at the headphone socket Available for Tone Assessment Option BZ 7231 only 113 114 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Appendix B Measurement Parameters This appendix describes the measurement parameters They are measured in accordance with the setup parameters Please refer to the Glossary in Appendix E of the User Manual for Hand held Analyzer Types 2250 and 2270 BE 1713 and the Glossary in Appendix C of this manual for a descrip tion of the parameters The following letters are substituted in the parameters that follow to represent the wide range of frequency weightings time weightings and percentile levels available V frequency weightings A B C or Z controlled by SETUP FREQUENCY WEIGHTINGS BROADBAND PEAK parameter X frequency weightings A or B controlled by SETUP FREQUENCY WEIGHTINGS BROADBAND EXCL PEAK parameter Y frequency weightings C or Z controlled by SETUP FREQUENCY WEIGHTINGS BROADBAND EXCL
88. ency Correction parameter to On or Off as required Frequency correction will work with any measurement mode that is manual transient or continuous 6 2 6 RPM Measurement RPM is measured on the signal that is connected to the trigger input To measure RPM the Tacho parameter should be set to On Two types of RPM can be displayed either instantaneous or average RPM Instantaneous RPM is only displayed as it is being measured at the trigger input whereas Average RPM is displayed and stored together with each spectrum result It is an average over the same time as the spectrum if Linear Averaging is selected as Averaging Type If Exponential is selected no averaging is done The result is the last measured RPM 6 3 Reference Spectra FFT Analysis Software BZ 7230 has a buffer to store a reference spectrum The spectrum saved in this buffer can be the current measurement or it can be a recalled measurement In the case of turbines a perfectly balanced turbine s vibrations can be used as the reference spectrum Volatile Memory Data in the reference spectrum buffer is not saved and is therefore lost during power off The only way to save a spectrum that you can use in the future as a reference spectrum is to save it from the measurement screen This means that either you need to plan in advance which spectra you want to use as a reference or save every measurement 66 FFT Analysis Software BZ 7230 and Tone Assessment Op
89. ents of a signal when displayed on the FFT analyzer s linear frequency axis CHAPTER 2 Getting Started 5 FFT Analysis Software BZ 7230 is actually a zoom type of FFT analysis where the baseband is achieved by setting the centre frequency to half of the frequency span With this software if one of the lines of analysis falls on 0 Hz it will not be displayed this is because the hardware does not go down to DC In modern frequency analyzers the operator can select the frequency span and the number of narrowband filters or lines of analysis With the Hand held Analyzer s FFT Analysis Software you can select frequency spans from 100 Hz to 20000 Hz in a 1 2 5 sequence while selecting the number of lines of analysis from 100 to 6400 in a binary sequence Dividing the frequency span by the number of lines provides the resolution of the analyzer s spectrum analysis Table 2 1 shows the available resolutions in FFT Analysis Software BZ 7230 Table 2 1 Frequency resolutions available in FFT Analysis Software BZ 7230 Frequency Resolution Hz 100 200 500 1000 2000 5000 10000 20000 100 1 2 5 10 20 50 100 200 200 0 5 1 2 5 5 10 25 50 100 g 400 0 25 0 5 1 25 2 5 5 12 5 25 50 800 0 125 0 25 0 625 1 25 2 5 6 25 12 5 25 1600 0 0625 0 125 0 3125 0 625 1 25 3 125 6 25 12 5 3200 0 03125 0 0625 0 15625 0 3125 0 625 1 5625 3 125 6 25 6400 0 015625 0 03125 0 078125 0 15625 0 3125 0 78125 1 56
90. eraging the analyzer will continue to measure until you press Start Pause This pauses the measurement and displays the last spectrum in the measurement buffer a 4 3 5 4 3 6 4 3 7 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Continue Since pausing the measurement does not clear the measurement buffer pressing the key again continues a measurement from where it left off Save When you have completed your measurement you need to save it Check that the data path at the top of the screen displays the project where you want to save the measurement and press the Save pushbutton amp Average Number Elapsed Time Current Averaging Time and Total Averaging Time For exponential averaging you set a number of spectra to be averaged together Until this number of spectra have been recorded the software will display the current record number in the form Avg n on the status panel When the set number has been exceeded you will see Avg gt n Similarly the elapsed measurement time is shown on the status panel The current and total averaging time can be seen on the value panel on the bottom of the screen Main Cursor Whether the measurement is running or paused the frequency and amplitude of the FFT line at the main cursor for both graphs is shown on the respective graph panels if applicable You can scroll the main cursor using the pushbuttons or the lt gt buttons
91. ermines whether the trigger input is internal or external Choose Internal to trigger on the incoming time signal applied through the Rear Input or Top socket and External to trigger on an external signal applied through the Trigger Input socket Delay The delay parameter determines the delay from the trigger point to the start of the record When the delay is positive the record starts the specified duration after the occurrence of the trigger point When the delay is negative the record starts the specified duration before the occurrence of the trigger point Hold Off The hold off value determines the time that the trigger circuit is held off after the occurrence of a trigger A new trigger is only accepted after this time You can use this to prevent false triggering e Ifa transient trigger condition you are not interested in occurs shortly after the one you are interested in e If your transient is longer than the record length and energy in the signal causes re triggering before the transient has decayed records will be overlaid incoherently If the repetition rate of the transient signal allows it is wise to set a hold off time longer than two record lengths Hysteresis This parameter determines the hysteresis on the external trigger Hysteresis refers to the safety margin you should take into account when setting the trigger level and will stop interference from noise signals around that level
92. es how to use reference spectra and tolerance windows e Chapter 7 Tone Assessment Option BZ 7231 describes how to perform FFT based tone assessment measurements and includes a general introduction how to set up and measure with your Hand held Analyzer and how to view and recall your measurements e Chapter 8 Specifications technical specifications for FFT Analysis Software BZ 7230 and FFT based Tone Assessment Software BZ 7231 e Appendix A Setup Parameters lists and explains the various parameters that you can choose when performing FFT measurements e Appendix B Measurement Parameters lists the various parameters that you can choose when viewing FFT measurements e Appendix C Glossary contains descriptions of FFT and Tone Assessment parameters and is a continuation of the Glossary in the User Manual for Hand held Analyzers Types 2270 and 2250 e Index Conventions Used in this Manual Instructions and descriptions that refer to Hand held Analyzer pushbuttons are shown with the pushbutton icons as seen on the instrument See the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 Chapter 2 for a list of pushbutton icons and their functions Menu Items and Buttons tabs used on the Screen Indicated by bold type face for example select Calibration from the list of options Parameter Text Appearing on the Screen Parameters instructions and descriptions appearing on the screen are indicated by italic
93. esult parameters a number of other parameters are updated e Delta Sum e Max Delta Sum e RPM at time for Max Delta Sum requires Tacho set to On e LAF at time for Max Delta Sum e FFT Spectrum at time for Max Delta Sum Refer to section 6 4 for details regarding the use of Delta Sum and exponential averaging 2 3 7 Signal Recording Note This section is only applicable if you have Signal Recording Option BZ 7226 If not please proceed directly to section 2 3 8 As well as recording sound Signal Recording Option BZ 7226 can also be used to record signals during FFT analysis It has special relevance in conjunction with the tolerance windows The recording can be set to start whenever the set tolerance is exceeded allowing you to record the signal only during the incident that caused the tolerance to be exceeded 62 Tap and select Setup from the list of options 63 Tap Quick tab tap Sound Recording and set Recording Control to Tol Exceed Fig 2 22 Fig 2 22 Left Selecting Tolerance Units Exceedance in Sound is Recording Recording Recording Control Right Tolerance Recording Quality indications Automatic Gain Contr Resolution Peak Rec Level Pre recording Time Post recording Time Duration Limit Minimum Duration Maximum Duration Output Socket Signal Quick i J 40k 80k 16 58 13 64 Repeat the measurement described in the previous Tolerance Windows section steps 53 t
94. f your choice Reference Spectrum Display If you have stored a reference spectrum see section 2 3 9 you can show or hide it on the measurement display by clicking the graph selection panel 4 3 Measuring If you have been through the screens mentioned in section 4 2 you should be in a position to make an initial exploratory measurement The parameters should have been set to allow you to quickly find out what parts of the spectrum you are interested in analysing further When you have found what you really want to measure then you can fine tune the setup 4 3 1 Measurement Start 1 Close all the other screens and view the measurement display 2 Press Start Pause to start the measurement Pressing this clears the measurement buffer any spectrum shown will be erased 3 If you don t see the proper signal apply the Y axis operations section 2 3 10 to view the signal clearly 4 3 2 Overload Indication During measurements you may see the instantaneous Overload warning or the textual feedback on the overload situation on the status panel These indicate that the input signal amplitude is or has been too high 4 3 3 Cable Break Short Detection Cable breaks and shorts are detected at the start and the end of a measurement and indicated by a message box Intermittent cable breaks and shorts during a measurement will not be detected 4 3 4 Measurement Pause Continue Save Pause When using exponential av
95. fulfilled Duration Limit On Off Use this parameter to enable the Minimum Duration and Maximum Duration parameters for overruling the duration of the signal recording determined by the trigger condition parameters Note This parameter is enabled only if Recording Control is set to Manual Event or Limit Level 112 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Table A 8 Cont Signal Recording parameters Parameter Values Comment Minimum Duration 00 00 00 to When Duration Limit is On then Minimum Duration 01 00 00 will determine the minimum recording time regardless of the trigger conditions The total record length will then as a minimum be the sum of Minimum Duration Pre recording Time and Post recording Time Maximum Duration 00 00 00 to When Duration Limit is On then Maximum Duration 01 00 00 will determine the maximum recording time regardless of the trigger conditions The total record length will then as a maximum be the sum of Maximum Duration Pre recording Time and Post recording Time Note If Maximum Duration 00 00 00 then it is disabled and doesn t limit the duration Requires license for Signal Recording Option BZ 7226 A 9 Output Socket Signal Parameters Table A 9 Output socket signal parameters Parameter Values Comment Source Off Determines the source of the input signal for the Input output socket of the
96. he spectrum on the display is displayed at a higher resolution You can expand the display until only 20 FFT lines are displayed 16 Using the stylus tap the frequency axis Select No Expand from the drop down menu see Fig 2 6 17 Observe the spectra and the frequency axis Note The frequency axis now displays the full frequency range 0 Hz to 20 kHz and the spectrum is now at the default resolution again Zooming In The default frequency span of the FFT Analysis Software BZ 7230 is 20 kHz with a centre frequency of 10 kHz The zoom function is used to change this frequency range to provide a more detailed FFT analysis of a narrower frequency band Unlike the expand function the zoom function actually changes the frequencies included in the FFT analysis the expand function is purely a display tool The zoom function can be activated either by drag and release on the spectrum this gives you a graphical method to zoom around an interesting area or through the setup page this method allows you to configure frequency span and centre frequency precisely 18 Use the stylus to drag and release across the calibrator tone 19 Select Zoom from the resulting drop down menu see Fig 2 7 CHAPTER 2 Getting Started 11 Fig 2 7 Left Spectrum before zoom operation Right Message box for measurement reset Ik Span Hz Lines o0 ae y 10 01 17 12 19 40 49 20 If the measurement is in Ru
97. ig 2 26 a Fig 2 26 Waiting for Trigger indication on measurement display 2 3 9 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual g g 40k 80k 76 Tap the rim of the porcelain cup with your pencil 77 The Hand held Analyzer should trigger and measure a spectrum Reference Spectrum In many measurement scenarios you want to compare one spectrum to another you measured previously The Hand held Analyzer with BZ 7230 provides a quick and easy way to do this through the reference spectrum 78 Save the current spectrum from the porcelain cup above directly from the measurement display and use this as a reference You do this by tapping FFT on the primary cursor line with your stylus and selecting Set as Ref from the drop down list 79 Now fill the porcelain cup with tea or coffee and repeat the measurement described in section 2 3 8 steps 72 to 75 80 The display now shows the spectrum for the full porcelain cup on the primary cursor line 81 Select Ref on the secondary cursor line 82 Observe the spectrum Note the two spectra one for a full porcelain cup and one for an empty cup CHAPTER 2 Getting Started 25 2 3 10 Y axis Operations By clicking on the Y axis you can perform the following operations Zoom In Zoom Out e Auto Zoom e Scale Up e Scale Down e Auto Scale Additionally if the Y axis is using an engineering scale you can also
98. inear Operating Range In accordance with IEC 61672 A weighted 1 kHz 24 8 dB to 140 dB Peak C Range In accordance with IEC 61672 42 3 dB to 143 dB Broadband parameters for Accelerometer inputs When Type 2270 2250 Hand held Analyzer is fitted with an accelerometer the following broadband parameters can be displayed in engineering units Lxeq Lyeq LxFmax LyFmax LxFmin LYFmin LVpeak LxF Lyf CHAPTER 8 Specifications Software Specifications Tone Assessment Option BZ 7231 LICENSE Tone Assessment Option BZ 7231 is enabled with a separate license and can be used with the FFT template STANDARD Tone assessment is based on the measured FFT spectrum in accordance with ISO 1996 2 2007 Acoustics Description assessment and measurement of environmental noise part 2 Determination of environmental noise levels Annex C informative Objective method for assessing the audibility of tones in noise Reference method or with Denmark 1984 1991 Vejledning nr 6 1984 fra miljastyrelsen M ling af ekstern st j fra virksomheder Orientering nr 13 1991 fra milj styrelsens referencelaboratorium for st jm linger M ling af h rbare toner i st j SPECTRA ASSESSED Any displayed sound FFT spectrum FFT Ref MAX or spectrum obtained at Max Delta Sum may be assessed Assessment is made as post processing i e when measurement is paused or stopped SETUP ACCORDING TO STANDARD Default Set
99. ing Y axis Unit Display Change the units of the Y axis from the dB to the engineering scale by 1 Selecting Units and then Y axis from the Setup menu CHAPTER 5 Measuring Transient and Continuous Signals 53 2 Select Engineering see Fig 5 5 and Fig 5 6 Fig 5 5 SETU Left The Y axis with dB Measurement Control units displayed Frequency Settings Units Scaling Spectrum Display Unit System Y axis Right Selecting engineering units from the Setup menu Sound Recording 160 0 0 4 0k 8 0k Full 5 01 00 Fig 5 6 The Y axis with engineering units displayed 1 40k 8 0k 5 1 8 Linear to Log Conversion When Y axis displays an engineering scale the scale can be chosen to be either linear or logarithmic On a linear scale the selection values on the Y axis are divided linearly while on a logarithmic scale they are divided exponentially Also while measuring vibrations the structural responses vary over a wide dynamic range so select logarithmic scaling To change from Linear to Logarithmic 1 Tap on the Y axis 2 Select Log from the drop down list that appears see Fig 5 7 54 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Fig 5 7 FFT ANALYZER FFT ANALYZER Left Switching between linear and log scale Right Log scale displayed 10F A i 0 0 40k 80k 5 1 9 Unit System W
100. ing the sampling rate The amount of space required for the recording will depend on the selected quality Quality Sampling Upper Memory Memory freq freq 16 bit 24 bit Low 8 kHz 3kHz 16 KB s 24 KB s Fair 16 kHz 6kHz 32 KB s 48 KB s Medium 24kHz 10kHz 48 KB s 72 KB s High 48kHz 20kHz 96 KB s 144 KB s Automatic Gain Control On Off To ease identification of sound sources the gain can be automatically adjusted to keep the average level within a 40 dB range When playing back the recorded signal you will then hear clearly the whole signal content whether the level has been 20 dB or 140 cB Set Automatic Gain Control to On to convert the recorded signal The recorded signal is stored as a 16 bit wav file Set Automatic Gain Control to Off for recording the signal with a fixed gain then set Resolution 24 bit recommended to cover the full 120 dB dynamic range from max input level and down or select Resolution 16 bit and specify the Peak Recording Level to fit the signal Note If the sound contains very high levels at low frequency then a fixed gain is recommended APPENDIX A Setup Parameters Table A 8 Cont Signal Recording parameters Parameter Values Comment Resolution 24 bit Set Resolution to 24 bit to cover the full dynamic 16 bit range Set Resolution to 16 bit to cover up to 96 dB from Peak Recording Level and down Note You will only be warned about overload in the recorded
101. ith FFT Analysis Software BZ 7230 you can view the acceleration in SI units or in US UK units To change the unit system 1 Click Units on the Setup menu and then Unit System 2 Select US UK see Fig 5 8 and Fig 5 9 Fig 5 8 Left SI units displayed Right Changing to US UK units from Setup menu Scaling Spectrum Display Unit System Y axis FC OFF Exp Sound Recording 10 29 2 15 13 09 CHAPTER 5 Measuring Transient and Continuous Signals 55 Fig 5 9 US UK units displayed 5 1 10 Spectrum Display The vibration spectrum can be displayed in terms of Acceleration Velocity or Displacement Acceleration Displays These are used where forces loads and stresses must be analysed and where force is proportional to acceleration Velocity Displays These are used e Where vibration measurements are to be correlated with acoustic measurements since sound pressure is proportional to the velocity of the vibrating surface e In measurements on machinery where velocity spectrum usually is more uniform than either displacement or acceleration spectra Displacement Displays These are used e Where amplitude of displacement is particularly important for example where vibrating parts must not touch or where displacement beyond a given value results in equipment damage e Where the magnitude of displacement may be an indication of stresses to be analysed To change the display of the sp
102. l Trigger Rising Falling See Table 8 1 the Pull up has been changed to a CCLD power supply MEASUREMENT RANGE Table 8 1 Measurement ranges with the recommended transducers Typical Frequency Teansduieer Nominal Spurious Free Dynamic Spurious Free Dynamic Response Extended Sensitivity Range for High Levels Range for Low Levels Low Frequency On Off Direct Input 1 V V 3 uV 14 1 VPeak 300 nV 75 MVpeak 1 5 6 3 Hz 20 kHz 4189 50 mV Pa 10 dB 143 dBpeak 10 dB 97 5 dBpeak 6 8 7 8 Hz 20 kHz 4190 50 mV Pa 10 dB 143 dBpeak 10 dB 97 5 dBpeak 4 0 6 7 Hz 20 kHz 4191 12 5 mV Pa 22 dB 155 dBpeak 2 dB 109 5 dBpeak_ 3 6 6 6 Hz 20 kHz 4193 12 5 mV Pa 22 dB 155 dBpeak 2 dB 109 5 dBpeak 0 56 6 3 Hz 20 kHz 4950 50 mV Pa 10 dB 143 dBpeak 10 dB 97 5 dBpeak 4 3 6 3 Hz 19 kHz 4952 31 6 mV Pa 14dB 146 dBpeak 6 dB 101 5 dBpeak 4 3 6 3 Hz 14 kHz 4397 A 1 mV ms 3 mm s 7 1 km s peax 300 m s 75 m s peak 1 25 6 3 Hz 20 kHz 4513 4514 1 mV ms 3 mm s 7 1 km s peak 300 m s 75 m s peak 1 25 6 3 Hz 10 kHz 4513 001 4514 001 10 mV ms 300 ums 710 ms peak 30 ums 7 5 ms peak 1 25 6 3 Hz 10 kHz 4513 002 4514 002 50 mV ms 60 ums 141 ms p 4 6 ums 1 5 ms peak 1 25 6 3 Hz 10 kHz 8324 2647 D 1mV ms 3 mms 7 1 kms peax 30
103. l parameters 70 Open the keyboard panel for configuring the Trigger Level by tapping on the value next to the Internal Level parameter see Fig 2 24 If the Internal Level parameter is greyed out check that the Trigger Type parameter is set to Internal Set the level to 70 dB then press the Accept pushbutton y or tap the button on the screen to enter the level Tap on the X button on the screen or outside the number keyboard to cancel the change of value CHAPTER 2 Getting Started 23 Fig 2 24 Setting the Trigger level Trigger Type Delay Hold Off Internal Level Tacho Not Triggered Quick q y x 19 19 57 71 Keep the keyboard panel open Hold the porcelain cup 10 cm from your microphone and hit the rim of the cup with your pencil 72 If the keyboard panel indicates a trigger see Fig 2 25 then all is fine and you have successfully set your Hand held Analyzer up for a triggered measurement If not try to adjust the level down in 3 dB steps until you get a trigger when hitting the rim Fig 2 25 Successful setup of the Trigger level Measurement Control Trigger Type Delay Hold Off Internal Level Tacho RPM Ge 73 Return to the measurement display tap on the X button on the screen or outside the number keyboard to close the keyboard 74 Start a measurement by pressing Start Pause 75 The Hand held Analyzer should indicate Waiting for Trigger see F
104. lay is positive the record starts the 10KHz 1 28s to 300s specified duration after the occurrence of the trigger 5KHz 2 56s to 300 s point 2KHz 6 4s to 300s When the delay is negative the record starts the 1KHz 12 8s to 300s specified duration before the occurrence of the 500Hz 25 6s to 300s trigger point 200Hz 64s to 300s 100Hz 128s to 300 s Hold Off 0 to 300s Determines the time that the trigger circuit is held off after the occurrence of a trigger A new trigger is only accepted after this time Internal Level Maximum you can enter depends on full scale level Determines the level of the incoming measurement signal that will cause a trigger This parameter is enabled when Trigger Type is set to Internal Tacho On Off When Tacho is On RPM measurements are done on the signal connected to Trigger input The parameters for External Level Hysteresis Slope and Pull Up are used for finding the tacho pulses these are used to measure the RPM When Tacho is Off no RPM is measured RPM Gear Ratio 10 to 10 8 The displayed RPM are the measured RPM divided by the RPM Gear Ratio APPENDIX A Setup Parameters 107 Table A 5 Cont Trigger and tacho parameters Parameter Values Comment External Level 20 V to 20 V Determines the level of the signal applied on the trigger input that will cause a trigger This parameter is enabled
105. lysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual A side effect of the Hanning weighting is that the noise bandwidth of the filters is forced to be wider than the line spacing of the analysis Normally this of little consequence to the user however when summing the levels of a span of filters such as when we display a total or delta cursor total of level this 50 increase in filter noise bandwidth is automatically corrected for To average time variations in the signal either linear or exponential spectrum averaging is used In linear averaging all averaged spectra are weighted equally The operator specifies a number of spectra to be included in the linear average and after this number of spectra has been averaged the measurement is completed In exponential averaging all spectra are averaged with a weight based on order the most recent spectrum weighted the most significantly with earlier spectra weighted in an exponentially decaying fashion Exponential averaging proceeds indefinitely until stopped by the user and is useful in evaluating non stationary signals or surveying potential measurement positions A maximum hold display sometimes called peak averaging is also available when using FFT Analysis Software BZ 7230 to capture the highest value in any frequency band during the measurement The Noise Bandwidth NBW is the bandwidth of an ideal box shape filter passing the same noise power
106. m Duration ccccccccccccsesssseeeeeesessssseeeeees 112 Measurement Control cc cccccsseceesseeeeeseeeeees 38 79 Measurement Control Parameters Setting Of isoine 38 50 60 64 Setting Ofrena nan a 105 Measurement Mode cc cccccccccssssseeeeeceesssessteeeeeees 56 Measurement Mode Parameter ccccccsesseeeees 105 Measurement Parameters zi Measurement Partner Suite BZ 5503 c 96 Measurement Pause Continue cccccccceeseeeeees 45 Measurement Start c ccccccccssseccessseceeseeeeeseeeeees 45 Measuring 45 61 Mechanical Filter c cccceceeeseeeeeeseeeeeeeeeeeeeeeetes 31 Minimum Duration cccccccccccesssssseeeeeesesesssaeeeeees 112 Mounting with the Aid of a Magnet 0 ee 31 Mounting with the Aid of Beeswax eee 31 N Noise Bandwidth ccccccccccccssssteeeeeeesenseneee 5 6 39 NOIA mela PAES EA 7 80 Number of LiIn S cccccccccscsssseeceesesssseeeeeeeesesseas 40 0 Other Accelerometers 2 c cccceceeteeeeeeeeteeseeeeeeees 33 Output Socket Signal Parameters cee 112 Ovarl ad s Nio k ai OU Overload Indication OVEIVIEW cisco iene ied eere nate velar MAE E Overview of Options Available During a Typical Enhanced Logging Task Overview of Quality Indicators Overview of Smiley Indicators P Peak Recording Level sesseseeerrerrerrrerrerrnerrers 111 Pe
107. mplate Note 2 Under Tolerance Windows Setup menu you can fine tune the settings for upper and lower limit and for top and bottom frequency for each tolerance window You can also define a name Caption for each tolerance window See Fig 2 19 Note 3 Under Tolerance Windows Setup menu you can also define tolerances for four single values two instantaneous values Lgr and Instantaneous RPM and two average values Lag and Average RPM Note 4 The FFT Spectrum and single values are compared to the set limits with an indication of above upper limit within limits below lower limit above and below limits Note 5 The background colours for the displayed results are different depending on the result see Note 4 Fig 2 19 Tolerance Window settings Trigger and Tacho Tolerance Windows Tolerance For Configure Check Upper Limit Lower Limit Top Frequency Bottom Frequency Caption Units Sound Recording Output Socket Signal Quick CHAPTER 2 Getting Started 55 Make a measurement and observe the spectrum and the status field see Fig 2 18 Note 1 The tolerance window indication is visible on the display 19 Note 2 Two indicators are displayed in the status field 1 Overall Result for instan taneous tolerance window exceedance blue text indicating that there is a tolerance window exceedance now and 2 Latched Result for latched tolerance wi
108. nd level When a frequency or amplitude is corrected it is preceded by a c see Fig 2 4 2 3 2 Expanding the Display The Hand held Analyzer with BZ 7230 can measure FFT spectra with line resolutions of up to 6400 lines It is impossible to have 6400 pixels resolution on the display however so in the default mode every line displayed on screen will contain more than one measured value the amplitude on the displayed line is determined by the maximum of the underlying FFT lines Expanding the display allows you to expand around a specific area on the screen to see more details for that particular area 13 Using the stylus tap and hold the stylus on the spectra display to the left of the calibrator tone then drag it across the calibrator tone to a position on the other side and release This will be referred to as drag and release See Fig 2 5 Fig 2 5 Expanding the display Left before Right after MAX M 1 150 kHz FFT a 1 RMS 120 gp g on g r 1 g 12 0k 16 0k Ok 4 gt 250 0 650 0 1 4k 15k 13k 2 3k 20 kHz Span 20 kHz 400 Lines 400 19 24 53 t 9 25 58 Fig 2 6 Performing a No Expand operation Left before Right after 2 3 3 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 14 Select Expand from the resulting drop down menu 15 Observe the spectra and the frequency axis Note The frequency axis now displays a narrower frequency range and t
109. nd set the Listen to signal parameter to Input If the Tone At Cursor parameter is enabled then input signal will now be mixed with the generated tone 7 8 Recalling Saved Measurements Saved FFT measurements can be opened and the Tone Assessment can be applied Please refer to the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 on how to save and recall FFT measurements 86 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 8 Specifications Unless otherwise stated values are given as typical values under Reference Environmental Conditions with nominal sensitivities for the microphones and accelerometers a FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Specifications Type 2270 and 2250 Platforms These specifications refer to Types 2270 and 2250 unless otherwise stated DUAL CHANNEL MEASUREMENTS TYPE 2270 Two independent measurement channels are available on Type 2270 to enable you to measure various acoustic parameters subject to having a dual channel application license REFERENCE ENVIRONMENTAL CONDITIONS Air Temperature 23 C Static Pressure 101 325 kPa Relative Humidity 50 SUPPLIED MICROPHONE Type 4189 Prepolarized Free field 2 Condenser Microphone Nominal Open circuit Sensitivity 50 mV Pa corresponding to 26 dB re 1 V Pa 1 5 dB Capacitance 14 pF at 250 Hz MICROPHONE PREAMPLIFIER ZC 0
110. ndication of Max Delta Sum and Upper and Lower Limits For engineering units the axis on Bar Graph can be logarithmic or Linear and can be zoomed Sound Level Meter Parameters Sound level meter broadband parameters are measured simultaneously with the FFT parameters however their measurement starts when the the Start Pause pushbutton is pressed and it ends at the nearest whole second after the end of the FFT measurement Specifications for the Sound Level Meter parameters apply to Type 2270 2250 Hand held Analyzer fitted with Microphone Type 4189 and Microphone Preamplifier ZC 0032 SELF GENERATED NOISE LEVEL Typical values at 23 C for nominal microphone open circuit sensitivity Weighting Microphone Electrical Total A 14 6 dB 12 4dB 16 6 dB B 13 4 dB 11 5dB 15 6 dB C 13 5 dB 12 9dB 16 2 dB g 5 Hz 20 kHz 15 3 dB 18 3dB 20 1 dB g 3 Hz 20 kHz 15 3 dB 25 5dB 25 9 dB Conforms with the following National and International Standards IEC 61672 1 2002 05 Class 1 IEC 60651 1979 plus Amendment 1 1993 02 and Amendment 2 2000 10 Type 1 IEC 60804 2000 10 Type 1 DIN 45657 1997 07 ANSI 1 4 1983 plus ANSI S1 4A 1985 Amendment Type 1 ANSI 1 43 1997 Type 1 Note The International IEC Standards are adopted as European standards by CENELEC When this happens the letters IEC are replaced with EN and the
111. ndow exceedance a blue icon indicating that there has been at least one tolerance window exceedance during the measurement Note 3 The status of one of the indicators may be selected as a signal at the Output Socket please refer to the Specifications for information Note 4 The status indicators or the result for each single tolerance window can be selected and displayed in the two value panels below the graph By selecting the FFT ANALYZER ADVANCED template an extra Results tab is available which displays all your results and status indications useful for checking a number of results see Fig 2 20 Fig 2 20 Advanced FFT Analyzer Result tab FFT ANALYZER ADVANCED Desa Wid High LAeq 74 8 dB TolLAeq Overall Result Latched Result Start Time 26 05 2009 13 37 26 Stop Time 26 05 2009 13 41 13 Overload 0 Span 20 kHz Total of FFT Spectrum 74 0 dB Result Fig 2 21 Setting tolerance window FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 56 Start the calibrator again 57 Observe the spectrum and the status field see Fig 2 18 58 Turn off the calibrator again 59 Observe the spectrum Note The indication for instantaneous tolerance window exceedance disappears while the indicator for latched tolerance window exceedance remains 60 Turn the indication of tolerance window off by clicking on the Y axis and selecting Tolerance Window Off see
112. ndow 5 e RPM at time for Max Delta Sum for Tolerance Window 6 e RPM at time for Max Delta Sum for Tolerance Window 7 e RPM at time for Max Delta Sum for Tolerance Window 8 e RPM at time for Max Delta Sum for Tolerance Window 9 e RPM at time for Max Delta Sum for Tolerance Window 10 APPENDIX B Measurement Parameters Tolerance LAF Parameters Exponential Averaging Only e LXF at time for Max Delta Sum for Tolerance Window 1 e LXF at time for Max Delta Sum for Tolerance Window 2 e LXF at time for Max Delta Sum for Tolerance Window 3 e LXF at time for Max Delta Sum for Tolerance Window 4 e LXF at time for Max Delta Sum for Tolerance Window 5 e LXF at time for Max Delta Sum for Tolerance Window 6 e LXF at time for Max Delta Sum for Tolerance Window 7 e LXF at time for Max Delta Sum for Tolerance Window 8 e LXF at time for Max Delta Sum for Tolerance Window 9 e LXF at time for Max Delta Sum for Tolerance Window 10 Spectra at Time for Max Delta Sum Exponential Averaging Only e FFT Spectrum at time for Max Delta Sum for Tolerance Window 1 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 2 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 3 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 4 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 5 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 6 e FFT Spectrum at time for Max Delta Sum for Tolerance Window 7 e FFT Spectrum at time for Max
113. ng window function Several tones may be found within one critical band The resulting level for every tone see above is added on an energy basis The tone assessment evaluates all the tones found and the possible associated critical bands The decisive critical band that yields the highest audibility is reported as the final result The most prominent tone is the tone with the highest audibility within the decisive critical band The results for tones in other bands are also shown In some special spectra you might find a tone with higher audibility than that of the decisive critical band this is because the tone level is very low a tone can be disregarded if its level is more than 10 dB below the tone with the highest level in the critical band The noise level in a critical band L is found by linear regression of the spectrum in a range 0 75 xcritical band from the centre of the critical band When determining the noise level all maxima resulting from tones are disregarded The noise level is calculated from the part of the regression line within the critical band placed symmetrically around the tone s Audibility and Penalty The total audibility AL is frequency dependent and calculated from the difference between the total tone level Lo and the masking noise level Lon in a critical band The penalty K is referring to the total analyzed FFT spectrum and is calculated from the decisive band The decisive band is the critical b
114. nning Paused state a message box will be displayed see Fig 2 7 Tap OK to allow the measurement to be reset This has to be done since FFT analysis is being restarted Press Start Pause to restart the measurement 21 Observe the spectrum and the frequency axis see Fig 2 8 Note The axis now has a new span and centre frequency Fig 2 8 Spectrum after zoom operation FFT 100 gp g 750 0 1 1k 22 Tap and select Setup from the list of options 23 On the Quick setup tab locate the Centre Frequency and Frequency Span 24 Change the frequency span to 20 kHz see Fig 2 9 This will automatically set your centre frequency to 10 kHz Note It is also possible to unzoom by tapping the frequency axis and selecting Unzoom from the drop down menu see Fig 2 9 12 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Fig 2 9 Left Drop down list showing selectable frequency spans Right Alternative method of unzooming Centre Freq Post Weighting Frequency correction Limit Level Units Output Socket Signal Quick 19 46 17 25 Return to the measurement display 26 Observe the spectrum and frequency axis Note The frequency axis now covers the full 0 Hz to 20 kHz range again and the measurement has restarted 27 Instead of a linear X axis frequency axis you can select a logarithmic X axis by tapping on the frequency axis and selecting Logarithmic X axis s
115. o 60 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 65 Observe the display Note The T icon is displayed in the status field while the tolerance is exceeded and after the tolerance exceedance stops a paper clip icon appears indicating that there is an annotation to the project 66 Tap the paper clip icon and play back the recording Note When measuring in Triggered mode trigger points are indicated in the recorded file However this function only works with the highest recording quality so set the Recording Quality to High 20 kHz 2 3 8 Triggering So far we have been measuring a stationary signal a calibrator tone however there are many signals that are not stationary Some exist for only a short duration so the triggered measurement mode assists in measuring non stationary and intermittent signals For this measurement demonstration you need an empty porcelain cup a pencil and a jug of tea coffee 67 Tap and select Setup from the list of options 68 On the Full setup tab locate the Measurement Control group and change the Measurement Mode to Triggered see Fig 2 23 Fig 2 23 Setting Triggered mode l Measurement Control Measurement Mode Signal Type Continuous Window Type Hanning Triggers 1 Spectra Per Trigger 1 f Trigger and Tacho ie Input Frequency Settings Quick 69 Set the Signal Type to Transient under Measurement Contro
116. o On It can be set to any value from 20 V to 20 V By default it is set to 2 4 V In practice a good way to set the trigger level and to avoid false triggering is to 1 Open the keyboard panel for configuring the Trigger Level by tapping on the value next to the Internal Level or External level parameter under Trigger and Tacho in the Setup menu See Fig 2 25 Type in the required value 2 Tap on the keyboard panel to apply the value You can now check whether triggering occurs or not by watching the keyboard panel It will display Triggered or Not Triggered depending on the situation 3 Set the trigger level so that no triggers occur when only the background noise is present 4 Check that triggering occurs when the signal and background are present 5 To confirm the level you ve set click outside the keyboard panel or tap X 5 2 CHAPTER 5 Measuring Transient and Continuous Signals 59 Continuous Signals Fig 5 13 Continuous signals Stationary signals Non stationary signals 5 2 1 Frequency Frequency Frequency Continuous non stationary signals have some similarities with both transient and stationary signals During analysis continuous non stationary signals should normally be treated as random signals see Chapter 4 or separated into their individual transients and treated as transients see section 5 1 An example of a continuous signal is a pneumatic drill where there are rand
117. om components from the air supplied by the compressor and the transients are produced when the drill bit is applied to a material Continuous signals normally need to be measured over a period of time that is longer than one record but starting with some form of trigger Thus you can consider them to be an extended measurement of a transient signal which is measured one record at a time You should note that the transient signal is measured with a rectangular window in BZ 7230 while continuous signals use Hanning windows with overlap Configuring the Analyzer The following parameters discussed in previous sections are also applicable for continuous measurements You should check each one in turn before you begin measurements to make sure they are set correctly in relation to your expected input signal e Frequency Resolution and Span e Y axis e X axis Scaling compress expand e Corrected Frequency Trigger Values 60 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 5 2 2 Fig 5 14 Measurement Control To measure continuous signals you need to set the analyzer initially for a triggered measurement start with continuous signals Select Measurement Control from the Setup menu and then the following parameters Time Window The time window is automatically set to Hanning when you set the Signal Type parameter to Continuous Triggers The number of triggers that you set determines
118. on the Value Panel marks the most prominent tone in the decisive band In accordance with ISO 1996 2 the tone frequency is the frequency of the line with the highest level and the tone frequency is not corrected for the influence of the window function If you want to read the tone frequency corrected for the influence of the window function please turn Frequency Correction on by tapping directly on FC Off on the Spectrum Display and choose On from the resulting drop down menu You can then read the value from the main cursor Find more information about frequency correction in section 2 3 1 of this manual e ALa the audibility of all tones found in the same critical band as the selected tone When the selected tone is the Prom Tone AL is the total audibility of all tones in the decisive band To step between the detected tones tap the Ka and gt buttons The lt gt buttons will jump the main cursor between the detected tones and in this way you can select the generated frequency View Area The results that relate to the total FFT analysis are shown on the Value Panel see Fig 7 6 Two selectable parameters are displayed and the parameters shown may be changed by tapping on them As default the following parameters will be shown on the Value Panel e Kis the size of the adjustment in dB e Lpris the total tone level in dB of all tones in the decisive band By tapping one of the parameters it is possible to acce
119. onverter 1 mV pC for direct connection to the rear input socket of the Hand held Analyzer See relevant accelerometer data sheet for complete specifications 34 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 3 2 1 Transducer Database Any transducer used by the Hand held Analyzer whether it is a microphone for acoustic signals or an accelerometer for vibration signals must be entered in the transducer database This enables easy switching between transducers and allows a calibration history to be maintained for each transducer Entering microphone transducers is discussed in the User Manual for Hand held Analyzers Types 2270 and 2250 BE 1713 Instructions for adding an accelerometer are described in the next section 3 2 2 Adding an Accelerometer 1 Tap and select Transducers from the list of options 2 Tap on the Add New Transducer icon ox and select Accelerometer from the dropdown that appears The entry defaults to a general purpose DeltaTron Accelerometer Type 4397 A though other accelerometer names and types can be used The transducer you have chosen now appears in the Transd Used title of the status field If you have chosen an accelerometer the field below automatically changes to Rear Socket 3 Enter the type number of the accelerometer you are using under the Accelerometer Type parameter or select Unknown if you don t know For unknown accelerometers you should enter a v
120. or distributed in any form or by any means without prior written consent from Briiel amp Kj r Sound amp Vibration Meas urement A S N rum Denmark Contents CHAPTER 1 IntrodU tiON ssania naear renion py Oren mer repre Ere eee T Cert per reer ce reer 1 Tir Personal Preparations i 2 sucesso ok Meio ek oath cs ae eed aa 1 1 2 Summary Of Contents oaie acces seca sag iiie iir aaae a aA h E AEA 1 1 3 Conventions Used in this Manual 0 eee eeeeeeeeeeeeeeeeeeeeeeeaeeeeaeeseeeseeeeeeeaeeeeaes 2 CHAPTER 2 GeOHING Started aE sii rete eee eee eee tee eee 3 2 1 Introduction to Fourier FFT Signal Analysis 0 0 0 0 eeeeeeeeeeeeeeeeneeseneeeeneeeeneees 3 CBiOn CPB eluea ee a Malet ade eth dedi Jd aug dates ac oe dase us atau deus 3 22 OVCWWIOW se otee e aeta eet Se ast Ne eos ees hd Ries tad ch Nei ad couse 7 2 3 Tutorial Measurements on a Stationary Signal 7 Frequency Correction rieien aiiai eiei daina sci is Jenene edo ec do dese 8 Expanding the Displays irigat dennin idee ates Sd aise Re ee ees 9 ZOOMING Misses tase et iees ests ae aes dele a ad che eae doen eee Ses ets eee dees de 10 AVGlAOQING AEE E E EEE EEEE A eh hak Ad ish Bek Ss 13 GUIS OFS re 2 secs if ose 1522 evaded ik Sid cok ted Sie dad ck Aetaepehcdid coke de deateh feud ook denen sdg ent acy 14 Tolerance WiIndOWS 3i5citi 86 Mia eee a ieee ad cists Shik aun 18 Signal RECOPGING aA e itch ede okt eed ek de a aea aaea dene ed oes denen aces cad 21 MEATO
121. ose to its resonance as this will result in a big error in the measured signal as the sensitivity at the mounted resonance is often 10 to 30 times the transducer s specified sensitivity As a rule of thumb the accelerometer s useful frequency is limited to one third of its resonance frequency This will then ensure that the error at that frequency does not exceed approximately 12 or 1 dB The sensitivity and frequency range of an accelerometer are related in general the bigger the accelerometer the higher its sensitivity and the lower its useful frequency range and vice versa CHAPTER 3 Using Accelerometers for Vibration Measurement 31 3 1 2 The Importance of Correct Mounting Bad mounting of the accelerometer can spoil vibration measurements by severely reducing the usable frequency range The main requirement is for close mechanical contact between the accelerometer base and the surface to which it is to be attached Stud Mounting Mounting the accelerometer with the aid of a steel stud is the best mounting method and should be used wherever possible Cementing Studs In places where it is not wished to drill and tap fixing holes a cementing stud can be fixed onto the machine with the aid of an epoxy or cyanoacrylate cement The frequency response will be nearly as good as that obtained using a plain stud Soft glues must be avoided Mounting with the Aid of Beeswax For quick mounting of the accelerometers for example
122. pe 3 Calibrating the system These steps are covered in detail in Chapter 3 and should be done before proceeding Configuring the Analyzer The following parameters discussed in Chapter 4 are also applicable for deterministic measurements You should check each one in turn before you begin measurements to make sure they are set correctly in relation to your expected input signal e X axis Scaling compress expand e Corrected Frequency Measurement Control To measure deterministic signals you need to set the analyzer initially for a manual measurement start with exponential averaging Select Measurement Control from the Setup menu set Measurement Mode to Manual Averaging Type to Exponential and then check the following parameters Time Window The time window Window Type parameter is automatically set to Hanning when you set Measurement Mode to Manual Frequency Resolution Span Deterministic signals will in general be generated by rotating machinery There is likely to be a fundamental frequency related to the base rpm In a system involving gears meshed or chain driven there will also be harmonics related to the fundamental The gearing ratio and number of teeth involved give frequencies related to the fundamental So you should choose the frequency resolution and span to encompass what you expect to be in the signal For vibration measurements a span of 10 times the fundamental frequency is suitable Then yo
123. place your main cursor on the highest peak in the spectrum Unless you are working in a very noisy environment this should be the calibrator tone 16 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Harmonic Cursor 46 Use your stylus to tap the cursor selector again Select the Harmonic cursor from the cursor selection drop down This cursor assists in identifying harmonics see Fig 2 15 47 Use the Ka or EJ buttons to navigate to the third harmonic 48 Use the 7 pushbutton to navigate down until the main cursor is active 49 Use the or gt pushbuttons to move the third harmonic Note The other harmonics are also adjusted This allows you to align your harmonics based on a high order harmonic You can set the Frequency Correction parameter On tap directly on FC Off on the Spectrum Display to more easily match peaks with harmonics Fig 2 15 Harmonic cursor reading Symmetric Delta Cursor 50 Use your stylus to tap the cursor selector Select Sym Delta symmetric delta cursor from the cursor selection drop down You can also drag and release on the spectrum to select the symmetric delta cursor This gives you a graphical method to position the symmetric delta cursor around an interesting area You will find that the symmetric cursors are drawn at the start and end point of the drag line The main cursor will be equidistant from both the symmetric cursors 51 Use the EJ button to increase
124. played as an icon on the display and is also indicated by the Traffic Light Spectrum Overload Displayed and stored together with each Spectrum result DISPLAY SPECTRA Two spectra superimposed Scaling RMS Peak Peak to Peak Power PSD ESD Reference Spectrum Compare spectrum to stored measured reference Axis Logarithmic or Linear Y axis Logarithmic or Linear X axis X axis Display full frequency range or expand the X axis until only 20 FFT lines are displayed Scroll available Y axis Display Range 5 10 20 40 60 80 100 120 140 160 180 or 200 dB Auto zoom or Auto scale available Digital Post weighting Z none or A weighting DISPLAY PARAMETERS Sound Sound Pressure Level in dB Vibration Acceleration velocity or displacement in dB or physical units SI units m s m s or m or US UK units g m s or Mil Direct Voltage in dB or V CURSORS Readings Total level within the spectrum Frequency Correction For spectra measured with a Hanning Window spectral peaks are interpolated to a higer precision Main Reads level versus frequency Symmetrical Delta and Delta Defines lower and upper frequency limit for any part of the spectrum and calculates the level sum within that frequency range Harmonic Identifies fundamental frequency and harmonics in the spectrum and calculates the Total Harmonic Distortion THD Reference Reads the difference between the main cursor Y value and the reference curso
125. ple of usage is checking if the vibration level within a specified frequency range exceeds a certain limit during a run up of an engine 1 Set the Span Lines and Centre Freq as required 2 Set Averaging Type to Exponential Average Spectra 1 Tolerance for FFT Check On Values Checked Delta Sum and Upper Lower Limits and Top and Bottom Frequency as required 68 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 3 Start the measurement when you speed up the engine 4 Stop the measurement when the engine has reached the required speed During the measurement a Max Delta Sum will have been measured together with the spectrum present at the time for the Max Delta Sum The parameters for display can be selected in the Tolerance Delta Sum group Tap any parameter then More gt Tolerance Delta Sum gt Delta Sum Parameters Fig 6 4 FFT ANALYZER ADVANCED Delta Sum Parameters submenu The parameters can also be displayed in the bar graph in the XL View see Fig 6 5 Fig 6 5 FFT ANALYZER ADVANCED XL View tab TolWin1A Tm 0 rowms 5 311mM ms rowna 34 74M mis CHAPTER 6 Measuring Deterministic Signals 69 The Delta Sum parameters can be selected for display in the bar graph tap on the parameter in first line within the bar graph The upper limit is indicated red line on the bar graph together with the Max Delta Sum a single white line The Delta Sum parameter is displayed
126. r As mentioned earlier in section 3 1 1 when vibration energy is present at or near the resonance peak of an accelerometer the resonance can cause a 10 to 30 times boost in the signal level This can give strange overload indications on the Hand held Analyzer if there are vibrations near the mounted resonance frequency of the accelerometer even though the upper Sy 3 1 3 Fig 3 2 Examples of different accelerometer mounting positions on the bearing of a drive shaft FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual frequency of the analysis is set to a lower frequency In practice you can to some extent use the wide dynamic range of the Hand held Analyzer to reduce this problem by selecting a less sensitive accelerometer and still measure the vibration of interest If you would like to reduce the effect of the mounted resonance on an accelerometer s measured response it can be accomplished with the aid of a mechanical filter which is mounted between the accelerometer and the test object The mechanical filter prevents energy from exciting the resonance protecting the whole measurement chain The mechanical filter can also provide electrical isolation between the accelerometer base and the mounting point Note that the attenuation achieved depends upon the mass of the accelerometer so not all accelerometers are compatible with mechanical filters Choosing a Mounting Position The accelerometer
127. r Y value TOLERANCE CHECK Tolerance Window Determines the upper and lower levels and the top and bottom frequency at which the spectrum is checked The check can either be made on all the FFT Lines within the specified range or on the Delta Sum of the lines The following parameters are measured for check on Delta Sum with exponential averaging Delta Sum Max Delta Sum RPM at time for Max Delta Sum LAF at time for Max Delta Sum FFT Spectrum at time for Max Delta Sum Up to 10 tolerance windows can be specified per template Single Values Check Tolerances can be set for the parameters Lar Instantaneous RPM Laeg and Average RPM Indication Results for each tolerance window and for the four single values can be displayed An Overall Result combination of all results and a Latched Total Harmonic Distortion THD is the sum in of all the harmonics relative to the sum of the fundamental and all the harmonics CHAPTER 8 Specifications Result latched during measurement can be displayed and are indicated in the status panel When tolerance limits are violated a recording can be started license for BZ 7226 required and a 3 3 V DC signal above upper limit a 3 3 V DC below lower limit or a signal alternating between 3 3 V and 3 3 V both above and below limits can be output to the Output Socket BAR GRAPH LAF LZF Total of Spectrum and Delta Sum can be displayed on a bar graph with i
128. rance Laeg Tolerance Instantaneous RPM Tolerance Average RPM Overall Tolerance Result Latched Tolerance Result APPENDIX B Measurement Parameters 117 118 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual B 1 2 Parameters for Tolerance Windows with Check on Delta Sum Delta Sum Parameters e Delta Sum for Tolerance Window 1 e Delta Sum for Tolerance Window 2 e Delta Sum for Tolerance Window 3 e Delta Sum for Tolerance Window 4 e Delta Sum for Tolerance Window 5 e Delta Sum for Tolerance Window 6 e Delta Sum for Tolerance Window 7 e Delta Sum for Tolerance Window 8 e Delta Sum for Tolerance Window 9 e Delta Sum for Tolerance Window 10 Max Delta Sum Parameters Exponential Averaging Only e Max Delta Sum for Tolerance Window 1 e Max Delta Sum for Tolerance Window 2 e Max Delta Sum for Tolerance Window 3 e Max Delta Sum for Tolerance Window 4 e Max Delta Sum for Tolerance Window 5 e Max Delta Sum for Tolerance Window 6 e Max Delta Sum for Tolerance Window 7 e Max Delta Sum for Tolerance Window 8 e Max Delta Sum for Tolerance Window 9 e Max Delta Sum for Tolerance Window 10 Tolerance RPM Parameters Exponential Averaging Only e RPM at time for Max Delta Sum for Tolerance Window 1 e RPM at time for Max Delta Sum for Tolerance Window 2 e RPM at time for Max Delta Sum for Tolerance Window 3 e RPM at time for Max Delta Sum for Tolerance Window 4 e RPM at time for Max Delta Sum for Tolerance Wi
129. requency Correction Output Socket Signal Sound Recording Quick t Note The frequency span can also be set by dragging the stylus across the desired frequency range on the display It s up to you which method you choose However to set the precise frequency range more accurately use the Measurement Control parameters from the Setup menu Number of Lines The FFT Analyzer allows you to perform up to 6400 line measurements Since there isn t enough space to display all of the lines at the same time the FFT analyzer displays a group of them in 1 pixel with the value of the one with the maximum amplitude being displayed The greater the number of lines the more precise the frequency resolution becomes but the longer it takes to get a result Time Windows The purpose of a time window is to minimise the effects of the discontinuity that occurs when a section of continuous signal is measured When the measurement is manual the Window Type is always set to Hanning In the Triggered mode you can change the Window Type from Hanning to Rectangular and vice versa You can also change the Window Type by changing the Signal Type Transient Signal Type always corresponds to rectangular window Continuous Signal Type always corresponds to Hanning Window see example displays in Fig 4 4 Perform the following steps 1 Set the Measurement Mode to Triggered 2 Select Rectangular as the Window Type 3 Signal Type changes to Transient
130. ring See Measuring on page 45 62 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 6 Measuring Deterministic Signals 6 1 Deterministic Signals Fig 6 1 Deterministic signals Stationary signals Non stationary signals Time Time Continuous Deterministic Transient Frequency Frequency Frequency Deterministic signals are made up entirely of sinusoidal components at discrete frequencies When the spectral lines show a harmonic relationship the signal is described as being periodic Examples of a periodic signals are vibration from a rotating shaft the sound vibration from meshing gearwheels or more theoretically a square wave To measure deterministic signals successfully you need to use multiple cursors to explore the relationships of the discrete frequencies For machine diagnostics it is also useful to be able to compare two spectra for example a known reference generated by measuring an optimally set up machine compared to the current state of the machine 6 2 6 2 1 6 2 2 6 2 3 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Preparing for Measurement This section will guide you in choosing suitable start values for measurement of deterministic signals Configuring the Input Configuring the input is a three step process 1 Choosing the correct transducer 2 Setting the signal source and ty
131. s for example Measurement Mode Path Denotations Indicated by capitals for example SETUP BZ7230 Chapter 2 2 1 2 1 1 Getting Started This chapter starts with an introduction to FFT Signal Analysis which gives you a better understanding of some of the methods and terms used when making this kind of measurement This should be very useful for those of you who are not familiar with FFT and vibration measurements and serve as a refresher to those of you who are familiar with these measurements An overview of a typical FFT measurement screen is provided for reference The rest of the chapter is presented as a tutorial to familiarise you with the important features of FFT Analysis Software BZ 7230 in relation to measurements on a stationary signal If you need information on how to perform FFT measurements on other types of signal for instance random or transient signals please refer to the relevant chapter listed under Contents Introduction to Fourier FFT Signal Analysis The object of frequency analysis is to break down a complex signal into its components at various frequencies and in order to do this the practical engineer needs to understand the frequency analysis parameters and how to interpret the results of spectrum measurements CB or CPB There are primarily two common spectrum analysis techniques Constant Bandwidth CB and Constant Percentage Bandwidth Analysis CPB CPB Analysis can be implemen
132. ss all the detailed parameters that are available for the FFT analysis Tone Assessment and Broadband Parameters Tap on More and then Tone Parameters on the drop down to get the list with the tone parameters see Fig 7 7 a Fig 7 7 Selecting different tone FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual FFT ANALYZER parameters 7 7 6 4 FFT adi Prom Tone Select between the following parameters from the drop down list e K the size of the adjustment in dB The adjustment is calculated from the decisive band and refers to the total spectrum e ALa the audibility of all tones found in the same critical band as the selected tone Lyn the Total level of the masking noise in the band containing the selected tone Lpa the Level of the selected tone Lpe the Level of all tones in the critical band containing the selected tone e Critical Band the start and end of the critical band containing the selected tone e Critical band f the centre frequency of the critical band Broadband Parameters The result of the FFT based tone assessment is the adjustment K which should be added to the Laeg Measurement to calculate the rating level L according to ISO 1996 2 The tone corrected rating level is calculated from the following equation L Laeq K The rating level L may be subject to other adjustments for example impulsive noise time of day etc please refer to
133. switch between linear and logarithmic scales Change current transducer to Type 4397 A and calibrate it using Calibration Exciter Type 4294 see Chapter 3 Zoom In This operation works differently when using the dB scale or engineering scale for the Y axis Select these scales from the Y axis parameters found in the Units parameters of the Setup menu Zoom in on dB Scale This operation works just like the zoom lens of a camera but in one dimension On performing a Zoom in the range of the Y axis is reduced giving the impression that you are zooming in on an expanding Y axis scale For example if you zoom in with the default range of the Y axis selected which has a range of 200 dB from 160 dB to 40 dB and after the Zoom in operation the range changes to 150 dB to 30 dB then the range has reduced to 180 dB see Fig 2 27 Thus we get a zoomed in view of our data after successive Zoom in operations Fig 2 27 Left Performing a Zoom in operation on the dB scale before zoom in Right after zoom in These zoom in and zoom out operations should not be confused with the zoom operations available for the frequency or x axis covered in section 2 3 3 a Fig 2 28 Left Performing a Zoom in operation on the engineering scale before zoom in Right after zoom in FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual To perform a zoom in
134. t Option BZ 7231 User Manual 2 3 6 Tolerance Windows When you need an indication that your measured level is above or below a certain value in particular frequency ranges of your choice use the Tolerance Windows feature You can set the values on the setup page as well as the measurement display Then either the FFT lines within the specified frequency range are all checked against the limits or the Delta Sum of the lines within the specified frequency range is checked See Delta Sum on page 20 In addition to tolerance windows on the FFT spectrum you can specify tolerances for the single values Lap Leg Instantaneous RPM and Averaged RPM The system can also be configured to start recording automatically when data are beyond the tolerances Check FFT Lines 53 Using your stylus drag and release a rectangle somewhere between the noise floor and the calibrator tone s maximum level 54 Select Tolerance Window and then TolWin1 from the resulting drop down menu see Fig 2 18 After selecting TolWin1 select to check FFT Lines Fig 2 18 Left Selecting the tolerance window Right Tolerance window vg gt Avgi indications Overall T 687 500 Hz s 3 3 013 kHz 31 1 Tot 93 8 Result instantaneous ee FS a AL O RMS WgtZ FCO Exp blue gt Limit or Latched Lid Ace Result blue arrow Note 1 In addition to the tolerances for the single values you can have up to 10 tolerance windows active at the same time per te
135. tandard Tripod Mount QB 0061 Battery Pack ZG 0426 Mains Power Supply AO 1476 USB Standard A to USB Mini B Interface Cable for hardware versions 1 3 1 8 m 6 ft AO 1494 USB Standard A to USB Micro B Interface Cable for hardware version 4 1 8 m 6 ft HT 0015 Earphones BZ 5298 Environmental Software including BZ 5503 Measurement Partner Suite UL 1009 SD Memory Card for Hand held Analyzers FB 0679 Hinged Cover for Hand held Analyzer os a SOFTWARE MODULES AVAILABLE SEPARATELY BZ 7230 BZ 7231 BZ 7222 BZ 7222 UPG BZ 7223 BZ 7224 BZ 7225 BZ 7225 UPG BZ 7226 BZ 7227 BZ 7228 BZ 7229 BZ 7232 CALIBRATION Type 4294 Type 4231 Type 4226 Type 4228 2270 CAl 2270 CAF 2270 CTF 2270 TCF 2250 CAl 2250 CAF 2250 CTF 2250 TCF 4513 CAF 4513 CTF FFT Analysis Software Tone Assessment Option Sound Level Meter Software Upgrade to allow SLM based applications to run on Type 2250 Frequency Analysis Software Logging Software Enhanced Logging Software Upgrade from Logging Software BZ 7224 to Enhanced Logging Software BZ 7225 does not include memory card Signal Recording Option Reverberation Time Software Building Acoustics Software Dual channel Building Acoustics Software Type 2270 only Noise Monitoring Software Calibration Exciter Sound Calibrator fits in KE 0440 Multifunction Acoustic Calibrator Pistonphone Accredited Initial Calibration of Type 2270 Accredited Calibration of Typ
136. te rename view data open project create job set default project name USB INTERFACE Hardware Versions 1 to 3 USB 1 1 OTG Mini B socket Hardware Version 4 USB 2 0 OTG Micro AB and USB 2 0 Standard A sockets MODEM INTERFACE Connection to Internet through GPRS EDGE HSPA modem connected through e the Compact Flash slot hardware versions 1 3 e the USB Standard A Socket hardware version 4 Supports DynDNS for automatic update of IP address of host name CHAPTER 8 Specifications PRINTER INTERFACE PCL printers Mobile Pro Spectrum thermal printer or Seiko DPU S245 S445 thermal printers can be connected to USB socket COMPACT FLASH SOCKET Hardware Version 1 to 3 only Connection of CF memory card CF modem CF to serial interface CF Ethernet interface or CF WLAN interface SECURE DIGITAL SOCKET e 1 x SD socket for hardware versions 1 3 e 2 x SD sockets for hardware version 4 Connect SD and SDHC memory cards LAN INTERFACE SOCKET Hardware Versions 1 to 3 Type 2270 only Connector RJ45 MDI Speed 10 Mbps e Protocol TCP IP Hardware Version 4 Types 2250 and 2270 Connector RJ45 Auto MDIX e Speed 100 Mbps e Protocol TCP IP REAR INPUT SOCKET TYPE 2270 HAS TWO Connector Triaxial LEMO used for Direct input as well as input with Constant Current Line Drive CCLD power supply Input Impedance gt 1 MQ Direct Input Max input voltage 14 14 Vpeak 10 Vrms for sinusoidal input signals
137. ted with analog or digital signal processing while CB analysis is usually implemented using the digital FFT Fast Fourier Transform technique Constant Percentage Bandwidth Analysis Traditionally the frequency analysis of sound and occasionally vibration is made using constant percentage bandwidth CPB filters The filters may be 1 3 octave approximately 21 or 1 1 octave approximately 70 band pass filters Sometimes CPB analyzers are called Octave analyzers for this reason The constant percentage bandwidth matches human perception of sound and the filters are well defined by international standards ensuring consistent results Fig 2 1 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Constant Percentage Bandwidth frequency analysis is appropriate where the frequency scaling is logarithmic and where octave analysis is specified such as in acoustic or human vibration measurements or in quality control measurements of rotating machinery where you need to compare spectra when there are minor fluctuations in running speed Fig 2 1 shows the Hand held Analyzer s 1 3 octave filters used in BZ 7223 Frequency Analysis Software They all approximate to the same filter shape relative to their respective centre frequencies The shapes of the 1 3 octave band filters from 0 to 80 dB The innermost and outermost
138. the measurement and checked against the limits In addition to the Tolerance Result parameters a number of other parameters are updated e Delta Sum e Max Delta Sum e RPM at time for Max Delta Sum requires Tacho set to On e LAF at time for Max Delta Sum e FFT Spectrum at time for Max Delta Sum Upper Limit Lower Limit to Full Determines the upper limit for the selected window Scale or parameter Lower Limit Lowest Y value to Determines the lower limit for the selected window Upper Limit or parameter Top Frequency 0 0 Hz to 20000 Hz Determines the upper limit of the tolerance window Bottom Frequency 0 0 Hz to 20000 Hz Determines the lower limit of the tolerance window Caption 1 10 characters A name caption for the selected tolerance window or parameter APPENDIX A Setup Parameters A 7 Parameters Related to Units 109 Table A 7 Parameters related to units Parameter Values Comment Scaling Pwr Determines the scaling to be applied to the RMS measured signal and accordingly modifies the ESD Y axis range the spectrum and the units of PSD measurement Peak Peak Peak Spectrum Display Acceleration If a microphone is selected under Trans Used this Velocity parameter is set by default to Snd Sound and Displacement cannot be edited Sound If an accelerometer is selected this parameter Voltage determines whether the measured signal is displayed in terms of acceleration velo
139. the delta span 52 Observe the spectrum and cursor reading see Fig 2 16 Note The two cursors are positioned symmetrically around the main cursor The difference in frequency and the sum of the delta span can be seen in the cursor reading Fig 2 16 Symmetric Delta cursor reading CHAPTER 2 Getting Started 17 FFT ANALYZER Selecting Cursors by Dragging the Stylus Over the Spectrum You can also select a cursor by dragging the stylus over part of the spectrum When you drag the cursor from left to right the cursors are placed as follows Fig 2 17 Left Dragging stylus over part of spectrum to select Main cursor Right Example of left and right symmetric delta cursors placed on the left and right ends of a drag and release line Main cursor in the centre Main cursor positioned at left end of the drag and release line Delta cursor Main cursor on left end and delta cursor on right end of the drag and release line Reference cursor Main cursor on left end and reference cursor on right end of the drag and release line Harmonic cursor Main cursor on left end and the first harmonic cursor on right end of the drag and release line Symmetric Delta cursor Left symmetric delta cursor on the left end right symmetric delta cursor on the right end and main cursor adjusted exactly in between these two 0 0 4 0k 8 0k 12 0k 16 0k 20 0k 20 kHz 18 FFT Analysis Software BZ 7230 and Tone Assessmen
140. ting the system These steps are covered in detail in Chapter 3 and should be done before proceeding Measurement Control To measure random signals you initially need to set the analyzer up for a manual measurement start with exponential averaging see Setting the Measurement Control Parameters on page 38 Because of their nature triggered measurements with random signals are not suitable since there is no specific event to trigger on Selecting exponential averaging in the first instance allows you to judge if the random signal is truly random or if it varies with time a continuous signal Linear averaging will mask time variations Setting the Measurement Control Parameters The measurement control parameters are found under Measurement Control tap and select Setup from the list of options Set Measurement Mode to Manual and Averaging Type to Exponential see Fig 4 2 Fig 4 2 q amp Setting the measurement control parameters Measurement Mode Manual Averaging Type Exponential Average Spectra 10 4 2 3 4 2 4 CHAPTER 4 Measuring Random Signals 39 Trigger and Tacho Input Frequency Settings Averaged Spectra If you enter a value of 10 for the Average Spectra parameter the analyzer will iron out any very short term changes in the random signal but is still fast enough for you to see the general trend of the signal Averaging Time The Averaging Time readout is computed
141. tion BZ 7231 User Manual Note The reference spectrum can only be displayed if the parameters frequency Span Centre Freq number of Lines and Trans Used match the currently displayed measurement Set as Ref Use the Set as Ref option to save the currently displayed spectrum in the measurement buffer as a reference spectrum you do this by tapping FFT on the primary cursor line and selecting Set as Ref from the drop down list see Fig 6 2 Fig 6 2 Saving the reference spectrum i D 0 0 4 0 8 0k 12 0k 16 0k 20 0k Span 20 kHz Lines 400 f x 14 04 05 Show Hide You can show or hide the reference spectrum using the Graph Panel see Fig 2 2 The reference spectrum can be shown as a line graph or a bar graph depending on whether you select it from the first or second line of the Graph Panel Align When the current setup with respect to Span Centre Frequency and number of Lines is different from the setup in which the reference spectrum is stored you will be asked if you want to align the measurement this means aligning the current measurement setup to that of the reference spectrum setup see Fig 6 3 However if the transducer used is different you cannot display the reference spectrum even if the above three parameters are the same also see Fig 6 3 Fig 6 3 Message boxes that appear Left when parameters of spectrum are different Right when the transducers are different 3 Do
142. to Select which one of the 10 windows to display the Window10 tolerances for Note Only selectable if Tolerances For parameter is set to FFT Check Off Determines whether the tolerance check is made for On the selected window parameter or not 108 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Table A 6 Cont Tolerance window parameters Parameter Values Comment Values Checked FFT Lines Select FFT Lines to check whether all the FFT lines Delta Sum within Bottom and Top Frequencies of the Window are within the Upper and Lower Limits of the window or not Select Delta Sum to check whether the sum of the FFT lines within Bottom and Top Frequencies of the Window are within the Upper and Lower Limits of the window or not Delta Sum is based on the measured FFT lines however it takes Spectrum Display and Post weighting into account The summation principle is as described in Table 4 1 The Delta Sum parameter is displayed using the same units as the FFT spectrum In Linear averaging the calculation and check of Delta Sum and FFT Lines are made on the available FFT spectrum You can change the frequency range and limits for the tolerance windows before during and after the measurement the tolerance results are re calculated except the Latched Result which is updated during measurement only In Exponential averaging the Delta Sum is calculated periodically e g every 100 ms during
143. tput of the Hand held Analyzer for comparison to the actual noise BZ 7231 works as an add on to BZ 7230 and allows assessment of tones on site The result of the tone assessment is the adjustment K to the rating level as described in ISO 1996 2 The Lagg and other broadband parameters are measured simultaneously by the Hand held Analyzer and the tone corrected rating level can be calculated on site Additionally the Generate tone at cursor feature is a useful tool that can be used in dialogue for identifying a tonal noise source BZ 7231 works with Sound Recording Option BZ 7226 and together with BZ 7230 provides the complete solution for on site objective FFT based tone assessment and recording BZ 7231 gives you results on site as well as preparing for post processing and reporting back at the office Documentation can be prepared using Utility Software for Hand held Analyzers BZ 5503 or the measured data can be exported for post processing by Evaluator Type 7820 or other post processing software such as Microsoft Excel Check the About Menu to see whether you have the right license to run the Tone Assessment Option The About Menu is accessed from built in help tap gg on the shortcut bar then select About If you have purchased a Hand held Analyzer together with the software application s then the relevant license s comes pre installed on the instrument 7 2 7 2 1 FFT Analysis Software BZ
144. ts Units Sound Recording Sound Recording Quick Full Quick ee 13 41 07 1 Set the Measurement Mode to Triggered 2 Set Signal Type to Transient Window Type automatically changes to Rectangular 3 Observe the spectra Note Transient signals always correspond to rectangular windows and continuous signals always correspond to Hanning windows Triggers The number of triggers that you set determines how many records will be averaged together to make the final result see Fig 5 4 You can get a statistical average of several occurrences when measuring if you trigger more than once Fig 5 4 How spectra are averaged Time Signal in triggered mode when signal is transient Time Trigger 1 Trigger 2 Tigger 3 rigger 4 Trigger 5 Record 1 Record 2 Record 3 Record 4 Record 5 ldam ldon ldam lm dh 7 Final Average 010186 52 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual 5 1 5 Table 5 1 5 1 6 5 1 7 One consequence of increasing the number of triggers is that the duration of the measurement increases you need to wait longer to get the final result Another consequence is that random components in the measurement will also be averaged Setting Up the Y axis The Y axis can be set up by selecting the scaling and the units for display Setting the units for the Y axis depends on the following factors e The type of Y
145. u will be able to see harmonics up to the ninth If the fundamental frequency is above 2 kHz then you must set the span to maximum Similarly if you cannot guess what the fundamental frequency is or if there are many then maximum span can be used to get an overview Remember you can always zoom in later CHAPTER 6 Measuring Deterministic Signals 65 For example consider a 1 2 gear system running at 600 rpm input with 40 teeth on the input gear and 20 on the output gear set the RPM Gear Ratio parameter to 2 This will give frequencies of 10 Hz 20 Hz and 400 Hz so you might set the initial span to 1 kHz and centre frequency close to 500 Hz 6 2 4 Correct Scaling of Deterministic Signals Deterministic signals are normally described in terms of their mean square or their root mean square amplitude RMS as a function of frequency The RMS value U is the square root of the mean square RMS is measured in the appropriate units Mean square is measured in units Mean square is often also called power U which strictly speaking is not correct since impedance is missing so it is assumed that the impedance has a numerical value of unity For Deterministic Signals Measure Power PWR in U 2 or RMS amplitude RMS in U 6 2 5 Turning Frequency Correction On Off You can turn the frequency correction algorithm on and off at any time select Measurement Control from the Setup menu then under Frequency Settings set the Frequ
146. uires that the Broadband excl Peak parameter is set to AC or AZ B requires that the Broadband excl Peak parameter is set to BC or BZ 104 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual A 3 Frequency Setting Parameters Table A 3 Frequency setting parameters Parameter Values Comment Span 100 Hz Determines the frequency span over which the 200 Hz signal will be measured 500 Hz 1 kHz 2 kHz 5 kHz 10 kHz 20 kHz Lines 100 Determines the number of FFT lines to be measured 200 and displayed on the screen 400 800 1600 3200 6400 Centre Freq Span from Determines the frequency around which the selected 50 to 19 950 kHz frequency span is equally divided Record Length Determines the inverse of frequency resolution This field cannot be edited It is calculated internally and then displayed Post Weighting Z Determines the weighting to be applied to the FFT A spectrum In the case of sound measurements use A weighting to emphasise frequencies audible to the human ear Pre Weighting Determines the weighting to be applied to the input signal In the case of sound measurements use A weighting to emphasise frequencies audible to the human ear Note X frequency weighting A or B A requires that the Broadband excl Peak parameter is set to AC or AZ B requires that the Broadband excl Peak parameter is set to BC or BZ NOX
147. ulation Tone Assessment Option BZ 7231 Tone Assessment Parameters Tone at Cursor Parameters ccccescesseeeteeees Tone LOVE cecceeeceeeeeeeeeeeeeeeeeesaeeeseneeeeeeeeeteseeees Tone Level and Noise Level Tone Seek Criterion eccceeceeeceeeeeeeeeeeteeeteeeeaes TONE Standard ve scvaceteviwean uiai a Top Frequency ccccecceeseneeeeeeeeeeeeeeeeeeeeeeseeeeees TOP SOCKEUS aee a hr a gan nE a Total Averaging Time Total Harmonic Distortion ccccceeeeeeeeeeteeeeeeee Total Measurement Parameters Equivalent Continuous Sound Level for BZ 7230 i si FFT Parameters for BZ 7230 For FFT Analysis Software BZ 7230 116 General Parameters for BZ 7230 000 116 Maximum Time weighted Sound Levels for BZ 7 230 riene a r hand 116 Minimum Time weighted Sound Levels for BZ 7 230 rii n a a ine Parameters for BZ 7231 2 a Special Parameters for BZ 7230 Spectrum Parameters for BZ 7230 Total of FFT Spectrum ceeeeeceeseeeeeeeeeeneeeeeeneees Total of MAX Spectrum secese Total of Ref Spectrum sssrin Total Power Reading Transducer Database c cccccceeeeeeeeseneeeeeseeeeeeee Transducer US c cescceeeeeeneeeeeeeeeeeeeneeeseeneees Transient Trigger Input Trigger Internal External i Trigger Level ccccccsccssssesscensceessoresseesteesosensessesseeees Trigger Values ssssessssrsseasrnsrnsrrnsennennesnesnns
148. und the centre frequency Exponential Averaging With an averaging time of up to 999 spectra measured with Hanning window and 67 overlap Linear Averaging Up to 8388607 spectra measured with Hanning window and 67 overlap Triggered Start Transient Signal Type Linear averaging of up to 32767 triggered spectra measured with rectangular window and 0 overlap Continuous Signal Type Linear averaging of up to 32767 spectra measured with Hanning window and 67 overlap Up to 32767 spectra are averaged on each trigger Auto start A total of 10 timers allow set up of measurement start times up to a month in advance Each timer can be repeated Measurements are automatically stored when completed TRIGGERS Delay From 16383 samples before the trigger time to 300 seconds after a a Hold Off 0 to 300s Internal Trigger Uses the time signal from the measurement transducer The Internal Level is set in the relevant measurement units External Trigger Uses the Trigger Input The External FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Pull up Only for External Trigger For Type 2250 serial numbers between 2479653 and 2630265 the Trigger Input is pulled up to 5 V through a 7 5 kQ resistor when this parameter field is set to On For instruments with serial number 2630266 and above Level is set in the range 20 to 20 V Hysteresis Only for External Trigger 0 to 10 V Slope Only for Externa
149. up please refer to Table 7 1 Setups in violation of the standard are indicated as such on the display you may then accept to apply the default setup Tone assessment will be made if possible in spite of standard violations Tone Seek Criterion 0 1 to 4 0 dB in 0 1 dB steps TONE AT CURSOR A sinusoidal tone is available at the Headphone output to help confirm identified tones Frequency the frequency is selected by the Main cursor Gain 70 dB to 10 dB Options The generated tone may be mixed with the input signal please refer to the Preferences Headphone Settings described in section 7 7 3 TONE ASSESSMENT CURSOR All tones found are indicated in the display The Tone cursor is initially placed at the most prominent tone and may then be stepped through the tones found You can also use the Main cursor to step through the tones RESULTS Results are displayed in the Tone panel and in the Value panel They are not saved with the measurement All Tones Frequency Tone level Lp Masking noise level Lon Audibility ALtg Critical band CB Critical band fe Most Prominent Tone Tone Level Lp Adjustment Ky QUALITY INDICATORS In the display a quality indicator smiley will indicate that a hint is available for tone assessment quality Click on the indicator to see the hint listed in Table 7 2 so a FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Software Specifications
150. ursor FFT ANALYZER piect 007 The results from the Tone Assessment Calculation can only be displayed on the Hand held Analyzer s display when the Tone Cursor is selected see Fig 7 6 After finishing the Tone Assessment Calculation the tone cursor jumps to the most prominent tone If no tones are detected in the analyzed FFT spectrum a pop up message will inform you that no tones have been found When the Tone Cursor is selected the Tone Assessment calculation is performed on the FFT spectrum on the display The selected FFT spectrum may be either the FFT MAX or Ref spectrum Fig 7 6 Typical FFT spectrum display showing the various fields Tone at cursor Status indication generation of current Tone Assessment measurement Tone Parameter Panel Move main aa between the tones Indications of all tones found FC Off Lin in spectrum Critical Band its height represents Masking Noise level Value Panel where selected parameters are shown Most prominent tone h J J J indicated by dashed 0 0 40k 80k 12 0k 16 0k line Prom Tone 6 0 dB Lines 7 6 2 7 6 3 CHAPTER 7 Tone Assessment Option BZ 7231 81 The Tone Parameter Panel The Tone Parameter Panel shows the results for the Tone Assessment Calculation with respect to the position of the tone cursor The Tone Parameter Panel shows from left to right e Tone the frequency of the selected tone Prom Tone displayed
151. utoDetect e UA 1651 Tripod Extension for Hand held Analyzer UA 1654 5 Extra Styli UA 1673 Adaptor for Standard Tripod Mount QB 0061 Battery Pack ZG 0426 Mains Power Supply e AO 1476 USB Standard A to USB Mini B Interface Cable for hardware versions 1 3 1 8 m 6 ft e AO 1494 USB Standard A to USB Micro B Interface Cable for hardware version 4 1 8 m 6 ft HT 0015 Earphones BZ 5298 Environmental Software including BZ 5503 Measurement Partner Suite FB 0679 Hinged Cover for Hand held Analyzer 2270 H D03 2250 H D03 Hand held Analyzer Type 2270 with BZ 7222 Sound Level Meter Software BZ 7223 Frequency Analysis Software BZ 7226 Signal Recording Option and BZ 7230 FFT Analysis Software Hand held Analyzer Type 2250 with BZ 7222 Sound Level Meter Software BZ 7223 Frequency Analysis Software BZ 7226 Singal Recording Option and BZ 7230 FFT Analysis Software Included with 2270 H D03 and 2250 H D03 Type 4189 Prepolarized Free field 1 2 Microphone ZC 0032 Microphone Preamplifier BZ 7222 Sound Level Meter software BZ 7223 Frequency Analysis Software BZ 7226 Signal Recording Option BZ 7230 FFT Analysis Software KE 0440 Travel Bag KE 0441 Protective Cover for Type 2250 DH 0696 Wrist Strap UA 1650 90 mm dia Windscreen with AutoDetect UA 1651 Tripod Extension for Hand held Analyzer UA 1654 5 Extra Styli UA 1673 Adaptor for S
152. when Trigger type is set to External or Tacho is set to On Hysteresis OV to 10V Determines the hysteresis on the external trigger This parameter is enabled when Trigger Type is set to External or Tacho is set to On Slope Rising Determines the trigger slope on the external trigger Falling This parameter is enabled when Trigger Type is set to External or Tacho is set to On CCLD Pull Up On For instruments with serial number 2630266 and Off above this parameter is named CCLD Use this parameter to switch on or off a CCLD power supply depending on the requirements of the equipment you connect to the Trigger Input Note The Laser Tachometer Probe MM 0360 requires CCLD set to On For instruments with serial number below 2630266 the parameter is named Pull up Use this parameter to pull up the trigger input to 5 V via a 7 5 KQ resistor The CCLD Pull Up parameter is enabled when Trigger Type is set to External or Tacho is set to On A 6 Tolerance Window Parameters Table A 6 Tolerance window parameters Parameter Values Comment Tolerances For FFT Select FFT to display settings for one of the LAeq tolerance windows LAF Select LAeq to display tolerances for Lagg Average RPM Instantaneous RPM Select LAF to display tolerances for Lar Select Average RPM to display tolerances for average RPM Select Instantaneous RPM to display tolerances for instantaneous RPM Configure Window1
153. with the same units as the FFT spectrum When Units Y axis is set to Engineering the scaling of the bar graph can be Log or Lin and you can zoom in out or move the scale by tapping on the bar graph axis Instead of the Delta Sum parameter you can select the Total of the FFT Spectrum or LAF or LZF in the bar graph The FFT spectrum at time for the Max Delta Sum can be selected for display from the Delta Sum group in the graph selector see Fig 6 6 Fig 6 6 FFT ANALYZER ADVANCED Graph selector Delta Sum parameters 70 FFT Analysis Software BZ 7230 and Tone Assessment Option BZ 7231 User Manual Chapter 7 7 1 Tone Assessment Option BZ 7231 General Tone Assessment Option BZ 7231 works with sound spectra and allows you to e Assess tones in a measured FFT spectrum according to ISO 1996 2 2007 Acoustics Description assessment and measurement of environmental noise part 2 Determination of environmental noise levels Annex C informative Objective method for assessing the audibility of tones in noise Reference method e Assess tones in a measured FFT spectrum according to Denmark 1984 1991 Vejledning nr 6 1984 fra milj styrelsen M ling af ekstern st j fra virksomheder Orientering nr 13 1991 fra milj styrelsens referencelaboratorium for st jm linger M ling af h rbare toner i st j e Use the Generate tone at cursor feature to generate a pure tone on the headphone ou

FFT Analysis Software BZ-7230

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