Product Data

Brüel & Kjær B K

Real-time Frequency Analyzer — Type 2143Dual Channel Real-time Frequency Analyzers —Types 2144, 2148/7667

USES:

Sound intensity measurements to IEC 1043

Constant-percentage bandwidth frequency analysis of sound and vibration signals in real-time

Noise source location and source ranking of complicated structures (2144, 2148/7667)

Environmental noise measurements. Includes Taktmaximal

Building acoustics testing: sound transmission, absorption, reverberation time

Automotive acoustic and vibration testing

In situ sound power measurements (2144, 2148/7667)

FEATURES:

IEC 651/804 Type 1 accuracy (with suitable microphone)

Weight with batteries <10 kg (< 22lbs)

Battery life-time > 4 hrs continuous use

Inputs: microphone (preamplifier), sound intensity probe (2144, 2148/7667), accelerometer (charge) and direct

Real-time frequency analysis up to 22.4 kHz (single channel), 11.2 kHz (dual channel)

80 dB dynamic range, autocalibration

Fractional-octave digital filters

Storage rate: 1000 spectra/second (single channel), 500 spectra/second (dual channel)

Large internal non-volatile memory

PC/MS–DOS compatible 31/2″ disk-drive for back-up storage of spectra and set-ups

IEEE–488 and RS–232 interfaces

Zwicker Loudness and FFT application programs available

Real-time Frequency AnalyzersTypes 2143 and 2144, 2148/7667 areportable analyzers for acoustics, elec-troacoustics and vibration measure-ments in the field and in thelaboratory. Type 2143 offers dual-chan-nel autospectra while Types 2144 and2148/7667 also offer sound intensityand cross spectrum analysis. The ana-lyzers feature real-time digital filteringacross a wide frequency range. Real-time operation is important for theanalysis of non-stationary signals suchas decays and impulsive events.

The analyzers are operated bymeans of menus, and a system of on-screen help pages enables the full po-tential of the analyzers to be used inthe field.

The large internal non-volatile mem-ory and back-up disk storage facilitiesmake the analyzers useful data-gath-ering devices with further control anddata-processing possibilities via theirIEEE –488 and RS–232 interfaces.

Fig.1 Frequency ranges for real-time and multi-pass analysis (dual channel)

Fig.2 Back panel of Type 2144

Introduction

Real-time Frequency AnalyzersTypes 2143 and 2144 are robust an-alyzers, 18 × 36 × 29 cm in size andweighing less than 10 kg includingbatteries. The power supply providedis used for powering the analyzer inthe laboratory or for recharging thebatteries. Fully charged batteriesgive more than 4 hrs of continuousoperation in the field.

Type 7667 is a dual-channel soft-ware options for Dual Channel Port-able Signal Analyzer Type 2148 (seeseparate Product Data – BP 1285),which converts its operation to beidentical to that of 2144.

With the exception of the analogueinput modules (input amplifiers, fil-ters, attenuators and antialiasing fil-ters), the analyzers are digitalinstruments. This means that theircalibration is extremely stable, exhib-iting no drifting effects.

The internal spectrum memory canhold several hundred spectra. Thismemory is non-volatile so that saveddata is protected against power fail-ures. Back-up memory storage is pro-vided by a built-in PC/MS-DOScompatible disk-drive. Disks aretransferable to laboratory analyzerssuch as Brüel & Kjær Real-time Fre-quency Analyzers Types 2123 and2133 (BZ 5027 software required) orto a computer for further processingof spectra. Remote-control commandsand measurement data can be sentdirectly over the IEEE–488 parallelinterface or the RS–232 serial inter-face.

The analyzers operate in real-timewhen measuring in 1/1- or 1/3-octaves.For 1/12- and 1/24-octave analysisthere is a choice of real-time analysisover a limited frequency range ormulti-pass analysis over the full fre-quency range. Multi-pass analysis in-volves processing signals frombatches of filters in sequence, ratherthan from all filters simultaneously.This approach to analysis is valid forstationary or repeatable signals.Fig. 1 shows the frequency ranges forreal-time and multi-pass analysis insingle channel operation.

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Input/Output

Real-time Frequency AnalyzersTypes 2143, 2144 and 2148/7667have inputs on the back panel (seeFig. 2) for connecting accelerometers,microphone preamplifiers, a soundintensity probe and direct electricalsignals, and also have RS–232 andIEEE–488 input/output interfaces.

Each of the signal inputs has a dy-namic range of more than 80 dB. In-stantaneous overloads are indicatedby an LED on the front panel. Cu-mulative overload indications are giv-en on the screen as the percentage ofthe elapsed averaging time for whichoverload has occurred. Three differ-ent high-pass filters with – 0.1 dBcut-off frequencies of 0.7 Hz (0.3 Hzfor charge input), 20 Hz or 100 Hz canbe selected for all inputs. In addition,an analogue A-weighting filter can beselected for the microphone preampli-fier input and the direct input. Pre-A-weighting allows SLM-type meas-urements to be made, fulfillingIEC 651 type 1.

Microphone Preamplifier InputThe 7-pin Preamplifier Input socketsupplies power for the microphonepreamplifier, and a selectable polari-zation voltage of 0 V, 28 V or 200 V,

enabling connection of most types ofBrüel & Kjær measurement micro-phones.

Probe/Remote Control Handle Input (2144, 2148/7667)An 18-pin socket provides a conven-ient single-cable connection forSound Intensity Probe Type 3548,and includes microphone polarizationvoltage and power supply for thepreamplifiers.

Accelerometer InputThe analyzers have built-in chargesensitive preamplifiers with two mi-cro connectors. The input signalmeasuring range is adapted to thewide range of Brüel & Kjær acceler-ometers.

Direct InputVoltage signals are connected to thepreamplifier input via Lemo-to-BNCadaptors (included as accessories).Input coupling is AC.

Analogue to Digital ConversionThe analyzer has a 16- bit delta-sig-ma A/D-converter and a third orderanalogue anti-aliasing filter giving atleast 80 dB attenuation of aliasingfrequencies.

Fig.3 Front panel of Type 2144

Fig.4 Display modes available: single, dual, and difference

InterfaceFor integration of the analyzer into alarger measurement system undercomputer control, the IEEE–488 par-allel interface provides convenient ac-cess to all raw and processed data inthe analyzer. It also provides com-plete control of all the front panel and“soft” functions. The default state ofthe parallel interface is “on” when theanalyzer is first powered up.

The RS–232 serial interface pro-vides similar remote control possibil-ities and is particularly suited forfield data processing applications inconjunction with a battery-operatedlap-top computer.

Hard CopyA selection of print formats are in-cluded in the analyzers for directprinting of screen pictures on IBM,Hewlett Packard or Epson printers.Such a print-out can be obtained sim-ply by pressing ⟨Hard Copy⟩ on thefront panel (Fig. 3).

Display

The LCD can display all or any partof the 80 dB dynamic range of a spec-trum. Fig. 4 shows the display for-mats available. “Single” displays theinput spectrum at maximum resolu-tion. “Dual” simultaneously displaystwo input or recalled spectra or aninput spectrum and a recalled spec-trum. “Difference” displays (in theupper display) the dB difference be-tween an input spectrum and thespectrum in the lower display. Afourth option, the “slice” display, isavailable for viewing multispectra af-ter the completion of a measurement.Multispectra are discussed later.

Back LightingDisplay back lighting can be switchedon or off as required. As a power-saving feature, the back lighting canbe set to switch off automaticallywhen the analyzer’s pushkeys havenot been used for a user-specified pe-riod of time.

A/L-, I- and W-channelsThe A/L-, I- and W-channels areshown in the display immediately tothe right of the frequency spectrum(see for example Fig. 3). The A/L-channel shows the overall level of thespectrum measured with a broad-band linear (“L”) or A-weighting (“A”)filter.

The broadband level of a weightedspectrum is shown in the W-channel.The level is calculated on the basisof the band-pass filter outputs. Aweighting function (which may be lin-ear) can be applied independently tothe whole spectrum, the W-channel,or both. Impulse averaging can be ap-plied to broadband measurementsand uses fixed time constants of35 ms while the signal is rising andof 1.5 s when it is falling. Whenswitched on, the I-channel replacesW-channel measurements.

Operation

Set-up Mode/Measurement ModeOperation is divided into two modes:Set-up Mode and MeasurementMode.

Set-up Mode is used for configuringthe analyzer and can be steppedthrough systematically until the an-alyzer is fully configured with, for ex-ample, the Measurement Type, therequired frequency range, the axes ofthe display, filter bandwidth, and av-eraging mode. Fig. 5 shows the firstpage of the menus accessible usingthe “soft keys” ⟨F1⟩ to ⟨F8 ⟩ on theanalyzer’s front panel.

In order to make measurements,the analyzer must be put in Meas-urement Mode (hard key on frontpanel). In this mode, there is still ac-cess to some of the most importantset-up parameters, such as averagingand display range. Fig. 6 shows a typ-ical display in Measurement Mode(Types 2144 and 2148/7667).

Help PagesOnce a menu has been called to thescreen, it can be alternated with anassociated help page. The help pages,one for each menu page, provides suf-ficient information for field operationof the analyzer without reference toan instruction manual.

Overview of SettingsAll menu settings relevant for the se-lected Measurement Type (see below)are displayed in summarized form inthe Current Set-up menu (Fig. 7). Theanalyzer set-up consists of threeparts: Measurement Set-up, DisplaySet-up and Calibration Set-up. Acopy of the Current Set-up is savedalong with all measurement resultsso that results are fully documented.When the analyzer is switched off,the Current Set-up is preserved inthe non-volatile memory so thatwhen the analyzer is next switched

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Fig.5 First page of the Main menu

Fig.6 A typical 2144, 2148/7667 display in Measurement Mode

Fig.7 An overview of the Current Set-up (2144, 2148/7667)

Fig.8 2144, 2148/7667 display after completion of an autocalibration

on, the settings are exactly as theywere previously.

Pre-configured Set-upsFactory-programmed default settingsfor acoustics and vibration measure-ments are permanently available toenable quick measurements. Up tofour complete user-defined set-upscan be saved in the non-volatile mem-ory to enable rapid reconfiguration ofthe analyzer during field measure-ments. The user-defined set-up or anypart of it (Measurement, Display orCalibration Set-up) can be activated.The activated parts of the set-upoverwrite the Current Set-up. Aseach measurement file contains bothdata and set-up, set-ups can also bestored on and recalled from disk.

CalibrationWhen a system consisting of an ana-lyzer and transducer(s) is to be cali-brated, a reference source can beused to apply a known calibrationlevel to the transducer(s). An auto-calibration feature automatically ad-justs the sensitivity of the inputchannels so that the displayed resultscorrespond to the calibration level ofthe reference source.

If no reference source is availableand the sensitivities of the transduc-ers are known from their calibrationcharts, an approximate calibration ispossible by entering the sensitivitiesdirectly into the Calibration menu(Fig. 8).

Types 2144 and 2148/7667 offersimultaneous calibration of bothchannels. Furthermore, the sensitiv-ities to sound intensity and particlevelocity can be verified. For this, aspecial coupler, such as that includedin Brüel & Kjær Sound Intensity Cal-ibrator Type 3541, must be used.

dB reference values and units canbe keyed-in from the front panel ofthe analyzer for fast and easy cali-bration of, for example, hydrophones.

Pressure-Residual Intensity Index (2144, 2148/7667)Sound Intensity Calibrator Type3541 also allows the pressure-residu-al intensity index of the measure-ment system (microphones, preampli-fiers and analyzer inputs) to bemeasured. Fig. 9 shows an exampleof the pressure-residual intensity in-dex measured with Sound IntensityProbe Type 3548 (Type 4181 phase-matched microphones).

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Measurement TypesThe analyzers offer the followingMeasurement Types: 1 Ch. Autospectrum Analysis:

A-channel autospectrum is meas-ured).

2 Ch. Autospectrum Analysis:A- and B-channel autospectra aremeasured simultaneously.

Sound Intensity Analysis(2144, 2148/7667 only): Activeand reactive intensity, mean pres-sure, and particle velocity are

Fig.9 Typical Pressure–Residual Intensity Index of a Type 2144 analyzer and a SoundIntensity Probe Type 3548, measured according to IEC 1043 using Type 3541

Fig.10 Arrangement of a multispectrum. “Slice” display at 8 kHz

measured simultaneously. Thismeans that all information aboutthe sound field in one particulardirection is captured in a singlemeasurement. Furthermore, it al-lows calculation of A- and B-chan-nel autospectra, phase spectra,and coherence spectra.

Cross Spectrum Analysis (2144,2148/7667 only): A- and B-chan-nel autospectra with real and im-aginary part of the cross spectrumare measured simultaneously. Thismakes it possible to calculatephase and coherence spectra aswell as three frequency responsefunctions (H1, H2, and H3) in real-time.

AveragingExponential or linear averaging areavailable, with selectable averagingtimes. Averaging is controlled bymanual operation of the ⟨Start⟩,⟨Proceed⟩ and ⟨Stop⟩ keys. Averag-ing times available depend on the se-lected bandwidth and whether theanalyzer is in single or dual channelmode. For single channel 1/3-octaveanalysis, the ranges are 1 ms to24 hrs for linear averaging and 1/512 sto 512 s in a binary sequence for ex-ponential averaging. For dual chan-nel analysis, the minimum averagingtimes are doubled.

Maximum and Minimum HoldMaximum or minimum levels that oc-cur during real-time measurementssan be held on the display while ameasurement progresses and canthen be saved as the measurementresult. The Maximum Hold or Mini-mum Hold condition can be appliedto one or all frequency bands, or toany one of the A/L- or W-channels.Two different hold functions can bespecified and used at the same time.

Data ExcludeThe Data Exclude function is used toexclude unwanted noise events (forexample a door slamming) from ameasurement result. When a push-key is pressed during a measure-ment, the elapsed time counter isrounded down to the nearest multipleof 5 seconds and all data within the“ignore time” preceding the key-pressis deleted from the measurement.The total measurement time auto-matically extends to compensate forthe ignore time. Ignore time can beexpanded to up to 10, 15 or 20 sec-onds by pressing the soft key up tofour times in succession. The Data

Exclude function is applicable in sin-gle spectrum real-time analysis.

Multispectrum and SliceA multispectrum is a number of spec-tra stored in succession in the samefile. This file can be viewed from twoangles, either from the “front” wherethe spectra can be flicked throughone after another, or from the “side”where each frequency band is viewedindividually as a function of spec-trum number; this is called a “slice”(Fig. 10). The analyzers operate withthree types of multispectra:Normal Multispectrum: Spectracan be recorded as a function of time,for example for measurements of im-pulse noise, or they can represent ge-ometrical points when measuringsound power. The recording rate is upto 1000 spectra/second (single chan-nel operation).Gated Multispectrum: Allows mul-tispectra from successive trigger cy-cles to be averaged into a singlemultispectrum. The number of aver-aged multispectra equals the numberof triggers.

Gated measurements are normallyused for measuring noise from rotat-ing machines or other repetitivenoise.

Fig. 11 shows the gating principlein one trigger cycle. The “gate” opensafter a user-specified trigger delay

(positive only) has elapsed. One spec-trum is measured while the gate isopen. As the gate closes, the spec-trum is saved in an accumulator. Theopen-close-save sequence is then re-peated for all spectra in the triggercycle forming one multispectrum.Matrix Multispectrum (2144,2148/7667): Matrix Multispectrum isa part of the Trigger Multimodemenu of Types 2144 and 2148/7667(see Fig. 12). It allows the spectra ina multispectrum to be arranged in arow-column-direction system. Thisserves two purposes: one is to easethe overview of measurements, theother is to make sound intensity datacompatible with computer programsand Brüel & Kjær laboratory analyz-ers (for example Type 2133) so thatsound power determination and otherdata processing can be made.

Multispectrum TriggerThe following trigger conditions canbe applied to the start of averagingwhen collecting a multispectrum:Free Run: The measurement de-fined by the current set-up is contin-ually repeated after Averaging⟨Start⟩ is pressed.Manual: The ⟨Manual⟩ key triggersa measurement as defined by the cur-rent set-up. This is often used forsound intensity measurements withMatrix Multispectrum.

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Trigger

900204/2e

Trigger Delay(positive only)

GatingWidth

DataCollection

1

2

3

Fig.11 Gated measurement cycle

Fig.12 Arrangement of spectra in a matrix structure (2144, 2148/7667 only)

Fig.13 Menu for defining a normal multispectrum

Time: Measurement begins at a timespecified by the user. A fixed repeti-tion interval can be set where re-quired.Internal: Measurement begins whena specified trigger level is exceeded(positive-slope trigger) or fallen below(negative-slope trigger) in either aspecified frequency band or in one ofthe channels displaying the broad-band weighted or non-weighted spec-trum level. Types 2144 and 2148/7667 allow internal triggering on sev-eral Spectrum Types, for example in-tensity spectra or cross spectra.Internal triggering is used, for exam-ple, for pistol-shot reverberationmeasurements.External: Measurement begins onthe arrival of an external trigger sig-nal at the Trigger Input socket on theback panel of the analyzer. This isoften used for tacho-probe input withGated Multispectrum, or for run-up/coast-down measurements with Nor-mal Multispectrum.

Pre- and Post-trigger DelayThe user-defined post-trigger delay (0to 5000 s depending on set-up) can beused to delay the start of averagingfor a fixed period after the triggerconditions have been met. Alterna-tively, entering negative values forthe post-trigger delay results in apre-trigger delay. Pre-trigger delayenables spectra monitored prior tothe trigger conditions being met to beincluded as part of the measurementresult. The maximum pre-trigger de-lay is 34 spectra for 1/3-octave meas-urements.

When the selected triggering con-ditions are satisfied and the delayhas elapsed, the analyzer starts tocollect the multispectrum defined bythe Trigger Multimode menu. Fig. 13shows an example of the set-up for anormal multispectrum measurement.Pre-trigger delay is set to 5 secondscorresponding to 10 spectra.

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TaktmaximalTaktmaximal noise measurementscan be made according to TA lärm.Taktmaximal modes Averaging orSpectra can be selected. In Averagingmode all the spectra specified are av-eraged to one spectrum. Spectramode stores all spectra as a multi-spectrum. The Takt Duration can beset to 3, 5 or 30 seconds.

Boom and MultiplexerConnectors on the back panel allowremote control of Sound Source Type4224 and either Rotating MicrophoneBoom Type 3923 or Multiplexer Type2811 or 2822. A special Boom andMux menu is used for setting the an-alyzer up for building acoustics meas-urements: sound pressure level insource room and receiving room,background noise, impact level andreverberation time. Fig. 14 shows themenu page for setting up parametersfor a reverberation time data collec-tion.

AutosequenceA pushkey autosequence facility pro-vides full automation of measure-ments. The analyzer’s internalmemory can hold four different au-tosequences, each consisting of up to200 keypushes. An autosequence mayinclude any procedure that can beperformed manually by using the

hard and soft keys on the front panelof the analyzer.

A “countdown-to-start” can be setso that the execution of an autose-quence is delayed after the start sig-nal is given. One application of thisdelay is to allow an operator time toleave the measurement area beforethe start of measurements. Anotherapplication is to allow the analog cir-cuits to stabilize after “Wake-up” (seebelow).

Standby/Wake-up ModeFor applications where an autose-quence is required to be executedwithout the presence of an operator,the analyzer features a special Wake-up Mode. In this low-power mode, allfunctions except the internal real-time clock are switched off. Wake-upMode is indicated by a flashingStandby LED on the front-panel ofthe analyzer.

At a user-defined “Wake-up time”,all functions switch on again and theanalyzer executes a previously select-ed autosequence. If a measurementneeds to be repeated, a “Number ofWake-ups” and a “Wake-up Interval”can be specified.

Fig.14 Example of set-up for reverberation time data collection (2144, 2148/7667)

Fig.15 List of files in the spectrum memory (2144, 2148/7667)

Data Storage

Spectrum MemoryThe spectrum memory is the part ofthe memory allocated for storage ofmeasured data. The number of spec-tra that the spectrum memory canhold depends on the selected filterbandwidth, frequency range and, forTypes 2144 and 2148/7667, the Meas-urement Type. The following showsas an example the number of spectrathat the memory can hold, measuredwith the maximum real-time fre-quency range:

2143 (autospectra):Bandwidth Number of Spectra

1/1-octave 47361/3-octave 28411/12-octave 11361/24-octave 660

2144, 2148/7667 (sound intensity spectra):

Bandwidth Number of Spectra1/1-octave 11981/3-octave 5381/12-octave 1771/24-octave 98

Spectra are saved individually or asmultispectra in up to 111 files whichare transferable to disk memory.

Spectrum Recording RateThe analyzers can record spectra atintervals down to 1 ms with no lossof data (no “gaps” between measure-ments). This maximum rate is ob-tained with single channel, real-timeoperation. In general, the recordingrate depends on the chosen Measure-ment Type, filter bandwidth, frequen-cy range and, if linear averaging hasbeen selected, the linear averagingtime.

Disk-driveThe built-in 3 1/2″ high density disk-drive can be used for permanent stor-age of spectra. Results saved in thespectrum memory of the analyzer canbe transferred directly onto disk anda list of the files already on disk canbe viewed at any time. Formatteddisks are compatible with PC/MS–DOS and the analyzers are,therefore, powerful data-gatheringdevices. For processing on Real-timeFrequency Analyzers Types 2123 and2133, data must be stored on doubledensity disks.

Measurement TextEach file can be labelled with up to40 characters of text. When a file isselected, the corresponding file-textis shown at the bottom of the screendisplay. Files can be sorted in the filelist, by name (number), time, length,or type. “Type” classifies the spectrainto groups according to: filter band-width, Measurement Type, whetherthey were measured or calculated,and whether they are single spectraor multispectra. Fig. 15 shows an ex-ample of a file list. Text is added tothe selected file to aid identification.

Post-processing

The analyzers are mainly intended asdata gathering devices. However,they also have some data processingfacilities. Some of these facilitiesfunction in real-time and some canbe applied to recalled spectra.

Sound Power Calculation (2144, 2148/7667)Types 2144 and 2148/7667 allowsound power to be calculated on thebasis of SPL or intensity measure-ments. Data must be arranged in amultispectrum. The calculation ismade simply by entering the physicalsize of the enclosing area (seeFig. 16).

Spectrum ArithmeticThe Spectrum Calculator menu isused for arithmetic operations onspectra recalled from memory. Spec-tra that were measured using differ-ent filter bandwidths are madecompatible for calculations by auto-matic conversion to the user-selected“working bandwidth”.

The arithmetic basis for spectrumadditions and subtractions can be se-lected as either “dB” (for which 50 dBplus 50 dB equals 100 dB) or as “ab-solute power” for which dB units arefirst converted to absolute powerunits for the arithmetic operationand then converted back to dB for thefinal answer (50 dB plus 50 dB equals53 dB).

“dB” arithmetic is typically usedfor adding/subtracting single numberconstants or weighting corrections to/from spectra. “Absolute power” arith-metic is for adding and subtractingspectra or background noise spectra.

Integration and DifferentiationThe input spectrum can be integratedor differentiated once or twice. Thisis purely digital real-time processing.Integration is used for obtaining avibration velocity spectrum from anaccelerometer measurement.

Spectrum UnitThe spectrum unit is calculated inreal-time. There is a choice of five

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Fig.16 The Spectrum Calculator menu is used for sound power calculations (2144, 2148/7667 only) and spectrum arithmetic

different spectrum units for an inputspectrum:PWR: Power (Mean Square)RMS: Root Mean SquareENG: Energy (time integral of PWR)ESD: Energy Spectral Density (ENGdivided by bandwidth)PSD: Power Spectral Density (PWRdivided by bandwidth)Power (PWR) is the normal outputfrom the RMS-processor.

Digital Spectrum WeightingThe Spectrum Weighting menu isused for adding user-defined weight-ings or standard A-, B-, C-, and D-weightings to input spectra (real-time) or to spectra recalled from thememory. User-defined weightings areentered as a series of points, with theanalyzer interpolating between thepoints to produce the completeweighting function, or they can bebased on measured data. A total offour user-defined weightings can besaved in the non-volatile internalmemory. User-defined weightings canbe used, for example, to mask un-wanted frequency components.

Application Programs

The modular construction of Types2143 and 2144 ensures high versatil-ity and allows the analyzers to beused not only as digital-filter analyz-ers, but as “2-in-1” analyzers wherean application program is loadedfrom disk. In this way, the whole con-figuration of the analyzer can easilybe changed. The following applicationprograms are available.Type 7638 — Zwicker LoudnessOption: Allows real-time measure-ment of the loudness of impulsive(non-stationary) noise. The loudnesscalculation is based on ISO 532 B andalso simulates the post-maskingproperties of the ear. See ProductData sheet BP 1006.Type 7651 — Dual Channel FFTOption for Type 2144: Turns Type2144 into a dual channel FFT ana-lyzer equivalent to Type 2148. It hasup to 800 lines resolution and a dual

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channel real-time rate up to 25.6 kHz(1/3 overlap). Real-time zoom, crossand intensity spectra, frequency re-sponse functions. A separate ProductData sheet is available (BP 1285).This software can also be used withType 2143, but without cross-func-tions.

Computer Software

WT 9366 — Calculation of Rever-beration Time: For calculation of re-verberation times using measure-ments made on Type 2143 and 2144loaded with Type 7666 or 7667 soft-ware. A stand alone program or canbe installed as a module for UtilityProgram Type 5306.WT 9367 — Ln Calculation Soft-ware: The program is able to makecumulative distribution calculationson spectrum files from AnalyzersTypes 2143 and 2144 loaded withType 7666 or 7667 software. A standalone program or can be installed asa module for Utility Program Type5306.WT 9378 — Sound Intensity Pro-gram: For mapping intensity data.3D, contour, numeric, and sector-ranking plots. A separate System De-velopment sheet is available(BU 0131).Type 5304 — Sound Power Pro-gram: Standardized sound powersoftware for Type 2144 and 2148/7667. Controls a complete measure-

ment system and makes calculationsof sound power using the sound in-tensity method. The software runsunder Windows on a laptop computer.Type 5305 — Building AcousticsProgram: For calculation of airborneand impact sound insulation plus re-verberation time according to the in-ternational standards ISO 140 andISO 3382, and several nationalstandards. See Product Data sheetBP 1401.Type 5306 — Utility Program: Forthe entire 2140 family of portable an-alyzers. Displays spectra from the an-alyzer on a computer screen andenables hard copies of the data.WH 3075 can be added for generating3 D and contour plots.

Type 7679 — Sound Power Pro-gram: For determination of soundpower according to ISO 9614–2,ECMA 160 (engineering grade) andANSI S 12–12, using sound intensitymeasurements made with Type 2144.See Product Data sheet BP 1432.

Type 7680 — Sound Power Pro-gram: For determination of soundpower from sound pressure measure-ments according to ISO 3741, 3743,3744 and 3745. A seperate ProductData sheet is available (BP 1430).

Type 7681 — Noise Source Lo-cation Program: For location ofnoise components emitted from anoise source using pressure and in-tensity measurements made withType 2144. A seperate Product Datasheet is available (BP 1443).

Specifications 2143, 2144, 2148/7667

Input CharacteristicsAll inputs pseudo difference. Choice of analogueground floating or connected to chassis. Individ-ual set-up for each channelPREAMPLIFIER INPUT:Pseudo Difference Input: Two 7-pin Preampli-fier sockets or one 18-pin socket (for sound in-tensity probes)Input impedance (signal to signal ground):1 MΩ || 100 pFSignal ground to analogue ground imped-ance: 50 Ω || 10 nFInput ranges: Twelve 80 dB ranges with a FSDfrom 10 mV to 3.16 V (rms sine) selectable insteps of 5 dBFrequency Range: 0.7 Hz to 22.4 kHz, ±0.1 dBNoise: 1µV, measured in 1/3-octave bands ininput range 10 mV with input short-circuitedMicrophone polarization: 0 V, 28 V, 200 V from10 MΩ sourcePower supply: 28 VHeater Voltage: NoneHigh-pass filter cut-offs:−0.1 dB at 0.7 Hz (−3 dB at 59 mHz).Slope 6 dB/octave−0.1 dB at 20 Hz (−3 dB at 6.6 Hz).Slope 12 dB/octave−0.1 dB at 100 Hz (−3 dB at 33 Hz).Slope 12 dB/octaveA-filter: According to IEC publication 651 type 0DIRECT INPUT:Pseudo Difference Input: Two BNC sockets(via preamplifier-to-BNC adaptors)Input impedance (signal to signal ground):1 MΩ || 100 pFSignal ground to analogue ground imped-ance: 50 Ω || 10 nFInput ranges: Twelve 80 dB ranges with a FSDfrom 10 mV to 3.16 V (rms sine) selectable insteps of 5 dBFreque ncy Range: 0.7 Hz to 22.4 kHz, ±0.1 dBNoise: 1µV, measured in 1/3-octave bands ininput range 10 mV with input short-circuitedHigh-pass filter cut-offs:−0.1 dB at 0.7 Hz (−3 dB at 59 mHz).Slope 6 dB/octave−0.1 dB at 20 Hz (−3 dB at 6.6 Hz).Slope 12 dB/octave−0.1 dB at 100 Hz (−3 dB at 33 Hz).Slope 12 dB/octaveA-filter: According to IEC publication 651 type 0ACCELEROMETER INPUT:Pseudo Difference Input: Two micro connec-tors, 10–32 UNFInput impedance (signal to signal ground):39 Ω || 220 pFSignal ground to analogue ground imped-ance: 50 Ω || 10 nFInput ranges: Eighteen 80 dB ranges with aFSD from 1pC to 17.8 nC (rms sine) selectablein steps of 5 dBFrequency Range: 0.35 Hz to 22.4 kHz, ±0.1 dBNoise: Measured in 1/3-octave bands in inputrange 1pC with 1nF transducer capacitance:0.35 Hz to 35 Hz: < 3 fC35 Hz to 2.8 kHz: < 0.5 fC2.8 kHz to 8.9 kHz: < 1 fC8.9 kHz to 22.4 kHz: < 1.5 fCHigh-pass filters cut-off: −0.1 dB at 0.35 Hz (−3 dB at 50 mHz).Slope 6 dB/octave−0.1 dB at 20 Hz (−3 dB at 6.6 Hz).Slope 12 dB/octave−0.1 dB at 100 Hz (−3 dB at 33 Hz).Slope 12 dB/octaveCHANNEL–TO–CHANNEL MATCH:Max. Gain Difference: 0.1 dB from lowerfreque ncy limit to upper frequency limit (in pass-band)Max. phase differe nce for preamplifier anddirect input: 50 Hz to 315 Hz: <0.017°

315 Hz to 630 Hz: <0.021°630 Hz to 1.25 kHz: <0.042°1.25 kHz to 2.5 kHz: <0.083°2.5 kHz to 5 kHz: <0.166°5 kHz to 15 kHz: <0.333°MAXIMUM RATINGS:Input:

Preamplifier & Direct: 7.5 V peak, 50 V DC.Accelerometer: 33 nC peak

Signal Ground/Chassis Ground: For safe op-eration in accordance with IEC 1010, the voltagebetween signal ground and chassis ground (in“floating” mode) must not exceed 42V RMS. Toensure safe operation in accordance withIEC 1010 at higher voltages, the user must limitall input currents to 0.7mA peakSignal Ground/Analogue Ground: 5V peak. Ifthis limit is exceeded, the user must limit theground current to 50mA. If the voltage exceeds1V peak, the dynamic range is decreasedMAX. INDUCED COMMON MODE VOLTAGE:42V RMS, 100V peakCOMMON MODE REJECTION:Floating input, 50Ω source impedance:0.35Hz to 1kHz: > 75dB1kHz to 22.4kHz: > 50dBDIFFERENTIAL COMMON MODE REJECTION:50Ω source impedance: DC to 250 Hz > 35dBOVERLOAD DETECTION:Both analogue and A/D-converter overloads in-dicated.CROSSTALK:− 60dBATTENUATOR LINEARITY:±0.1dBANTIALIASING FILTER:Cut-off frequency: 30kHz (single channel),15kHz (dual channel). Provides at least 80dBattenuation of those input frequencies which cancause aliasing in the pass-bandSAMPLING RATE:1 × 65536 Hz or 2 × 32768 HzA/D-CONVERSION:Resolution: 16 bitQuantizing Error: Maximum 1/2 LSB

Digital Filters1/1-OCTAVE FILTERS:14-pole filters with centre frequencies given by103 n/10. Fulfil IEC 225-1966, DIN 45651 andANSI S1.11-1986, Order 7 Type 1-D, optionalrangeSingle Channel: −1 ≤ n ≤ 14. 16 filters with cen-tre frequencies from 0.5 Hz to 16 kHzDual Channel: −1 ≤ n ≤ 13. 15 filters with centrefrequencies from 0.5 Hz to 8 kHz1/3-OCTAVE FILTERS:6-pole filters with centre frequencies given by10n/10. Fulfil IEC 225-1966, DIN 45651 and ANSIS1.11-1986, Order 3 Type 1-DSingle Channel: −4 ≤ n ≤ 43. 48 filters with cen-tre frequencies from 0.4 Hz to 20 kHzDual Channel: −4 ≤ n ≤ 40. 45 filters with centrefrequencies from 0.4 Hz to 10 kHz1/12-OCTAVE FILTERS:6-pole filters with centre frequencies given by10(n + 0.5)/40

Single Channel: −18 ≤ n ≤ 173. All 192 filterswith centre frequencies from 0.365 Hz to21.752 kHz can be measured in a four-passmode, or 168 filters from 0.365 kHz to 5.464 kHzcan be shown in real-timeDual Channel: −18 ≤ n ≤ 161. All 180 filters withcentre frequencies from 0.365 Hz to 10.902 kHzcan be measured in a four-pass mode, or 156filters from 0.365 kHz to 2.738 kHz can be shownin real-time1/24-OCTAVE FILTERS:6-pole filters with centre frequencies given by10(n + 0.5)/80

Single Channel: − 36 ≤ n ≤ 347. All 384 filterswith centre frequencies from 0.360 Hz to22.067 kHz can be measured in an eight-passmode, or 312 filters from 0.360 Hz to 2.778 kHzcan be shown in real-timeDual Channel: − 36 ≤ n ≤ 323. All 342 filters withcentre frequencies from 0.360 Hz to 11.060 kHzcan be measured in an eight-pass mode, or 288filters from 0.360Hz to 1.392 kHz can be shownin real-timeBROADBAND FILTERS:Two broadband channels, labelled “L” and “W”,are associated each input channel (“A” or “B”).L-Channel: Represents broadband level of theinput signal (A-weighted or unweighted)W-Channel: Represents broadband level of themeasured spectrum, possibly post-weighted withA,B,C or D standard curves or user-defined (orSpacer-dependent weighting if in intensity mode)

System AccuracyDYNAMIC RANGE:All distortion (intermodulation and harmonic) andspurious noise at least 80 dB below max. inputvoltage for 1/3-octave autospectrumOVERALL FREQUENCY RESPONSE:±0.1dB at filter centres from lower frequencylimit to upper frequency limit(See Input Characteristics for frequency limits)NOISE:Voltage input: Measured in 1/3-octave bandsin input range 10 mV with input short-circuited:0.7 Hz to 22.4 kHz < 1µVCharge input: Measured in 1/3-octave bands ininput range 1 pC with 1 nF transducer capaci-tance:0.35 Hz to 35 Hz: < 3 fC35 Hz to 2.8 kHz: < 0.5 fC2.8 kHz to 8.9 kHz: < 1 fC8.9 kHz to 22.4 kHz: < 1.5 fCAMPLITUDE MEASUREMENT STABILITY:±0.1dBAMPLITUDE LINEARITY:±0.05 dB or ±0.005% of max. input voltage,whichever is greater, measured using sine waveinput at the filter centre frequency. With meas-urements more than 60 dB below max. input volt-age, the measuring sine wave is accompaniedby another sine wave of a lower frequency out-side the measured band, having an amplitudegreater than 20 dB below max. input voltageFREQUENCY ACCURACY AND STABILITY:0.01% without warm-up (no adjustment needed)

DetectorsDigital true RMS detection of filter bank and twobroadband channels. No crest factor limitationCONTROL:Start: Clears the average accumulator andstarts an averageStop: Stops the averaging processProceed: Continues an average without clearingthe average accumulatorAveraging Gate: External or internal trigger sig-nal for gating of the averaging processStart conditions: Free Run, Manual, External,Absolute Time, or Internal triggering at a spec-ified level with selectable slopeDelay: Pre- and post-trigger delay between startcondition and actual multispectrum start, set insecondsMultispectrum update rate: From 1ms (2msfor dual channel) to 24hours; 1ms resolution

AveragingLINEAR:Averaging without truncation.Single Channel: Averaging times from 1ms to24 hours selectable to a resolution of 1ms in therange 1ms to 1hr and to 1s in the range 1hr to24 hours

9

COMPLIANCE WITH STANDARDS:

CE-mark indicates compliance with: EMC Directive and Low Voltage Directive.

Safety EN 61010–1: Safety requirements for electrical equipment for measurement, control and laboratory use.

EMC Emission EN 50081–1: Generic emission standard. Residential, commercial and light industry.EN 50081–2: Generic emission standard. Industrial environment.CISPR 22: Radio disturbance characteristics of information technology equipment. Class B Limits.FCC Rules, Part 15: Complies with the limits for a Class B digital device.

EMC Immunity EN 50082–1: Generic immunity standard. Residential, commercial and light industry.EN 50082–2: Generic immunity standard. Industrial environment. Note: See “EMC”.

Temperature IEC 68–2–1 & IEC 68–2–2: Environmental Testing. Cold and Dry Heat.Operating Temperature (Analyzer): −10 to +55°C (+14 to +131°F)Operating Temperature (Disk drive): −5 to +50°C (+23 to +122°F)Storage Temperature: −25 to +70°C (−13 to +158°F)

Humidity IEC 68–2–3: Damp Heat: 90% RH (non-condensing at 40°C (104 °F))

Mechanical Non-operating:IEC 68–2–6: Vibration: 0.3 mm, 20 m/s2, 10–500 HzIEC 68–2–27: Shock: 1000 m/s2

IEC 68–2–29: Bump: 1000 bumps at 250 m/s2

Enclosure IEC 529: Protection provided by enclosures: IP 43

Dual Channel: Averaging times from 2ms to 24hours selectable to a resolution of 2ms in therange 2ms to 1hr and to 1s in the range 1hr to24hoursEXPONENTIAL:Single Channel: 19 averaging times from

to 512s in a binary sequenceDual Channel: 18 averaging times from 1/256sto 512s in a binary sequence. “Fast” and “Slow”(1/4 s and 2 s) sound level meter responses ac-cording to IEC 651 type 0

Spectrum MemoryNon-volatile internal memory for 111 singlespectrum or multispectrum files each labelledwith up to 40 characters of user-defined text.The text label is stored together with data andis shown in the file listControl: Manual save or multispectrum automat-ic saveMax. no. of spectra: 2457 for single channeloctave autospectra or 1474 for 1/3-octaveMax. (or Min.) hold, all bands: Compositespectrum of max. (or min.) RMS level occurringin each channelMax. (or Min.) hold, specified band: Retainsthe spectrum for which max. (or min.) RMS levelhas occurred in the specified band

Mass StorageBuilt-in disk-drive for storage of measured dataand optional programsData media: Removable 3 1/2″ double sided,high density micro floppy diskData format: Compatible with PC/MS-DOS fromversion 3.2. PC-DOS is a trademark of Interna-tional Business Machines Corporation. MS-DOSis a trademark of Microsoft CorporationFormatted capacity: 1440 kbytesFile list: Contains disk identification, user-defin-able volume label and file list sorting key. Eachfile is identified by user-definable file number,data type, size and measurement start time

Hard CopyGraphics printer: Any display on Type 2143,including graphics and all notation, can be print-ed on graphics printers with IBM, HP or Epsonprint formats or on Brüel & Kjær Graphics Re-corder Type 2313

AutosequenceAllows the user to specify an autosequence offront panel keypushes, the functions of whichcan be executed on command. Maximum 200key entries per autosequence. Up to 4 autose-quences can be saved in non-volatile memory

DisplayLiquid Crystal Display (dot matrix, super twistednematic) with back-light and resolution 480 × 200pointsDISPLAY FORMATS:Single: A single spectrum showing pressure,acceleration, intensity, particle velocity, phase,and coherence. Digital integration or differentia-tion of spectrum is possibleDual: Two spectra (two input spectra or inputspectrum and recalled spectrum) displayed inupper and lower parts of the display, respectivelyDifference: Two spectra. The upper is the dif-ference and the lower is the recalledSlice: A time slice through a multispectrumMenu: The text shown relates to the soft keycontrolY-AXIS:Annotation: Absolute units or relative units (dB).Selectable dB referenceCalibration: Pressure, acceleration. Verificationof particle velocity, active and reactive intensity.

1 512s⁄

10

Measurement of pressure-residual intensity in-dex. Direct entry of transducer sensitivity or au-tocalibration with an appropriate calibrator.Direct entry of dB referenceSpectrum type: RMS, power, power spectraldensity, energy spectral density or energyAmplitude scroll: Hard key controls to shift thedisplay up and down.X-AXIS:Spectrum display: Logarithmic axis with anno-tation in Hz at 1/1-octave centre frequenciesconforming with ISO R266. Range from 1 to 16octaves. 11 octaves at a time can be shown onthe displayFrequency scroll: Hard key controls to shift thedisplay left and rightSlice display: Linear axis annotated from withindex numbers from 1 up to a maximum of 999(representing time, points, etc.)CURSOR:Reads frequency in Hz on the x-axis (spectrumdisplay) or index number (slice display) and atthe same time reads amplitude level in dB orabsolute units and phase in degrees on the y-axis

OperationMenus: User-interactive menus are used to set-up the analyzer for measurements. 4 user-de-fined measurement set-ups can be saved andrecalled from non-volatile internal memoryMeasurement mode: Enables measurementsSpectrum view: For looking at spectra and slic-es in the internal non-volatile memoryHelp pages: Each user-interactive menu is pro-vided with a corresponding page of help text

IEC/IEEE InterfaceConforms to IEEE–488.1 and IEC 625-1 stand-ards. Any function shown on display (includingmeasured data, post-processed result, measure-ment set-up, display set-up or calibration set-up)can be transmitted to and from the analyzer

FUNCTIONS IMPLEMENTED:Source Handshake SH1Acceptor Handshake AH1Talker T5Listener L3Service Request SR1Remote/Local RL1Parallel Poll PP1Device Clear DC1Device Trigger DT1COMMAND SET:Simple and easy to remember standard engi-neering English. Resistant to operator errorCODE:ASCII (ISO 7-bit) code, or binaryINTERFACE TERMINATOR:Can be specified on the Interface MenuDEVICE ADDRESS:Can be specified on the Interface menu

RS–232 InterfaceConforms with the EIA Standard RS–232 (equiv-alent to CCITT V 24). Allows remote activationof the front panel key functions via a non-intel-ligent terminal, either directly or via a modem

Input/OutputTrigger Input: BNC connector for external trig-ger to start an average instantaneously or withuser-defined delayRemote Control: Two 8-pin DIN sockets for re-mote control of Rotating Microphone Boom Type3923 or Multiplexer Type 2811 or 2822. Two 8-pin DIN sockets for remote control of SoundSource Type 4224. 18-pin socket for connectionof Intensity Probe Type 3584

Power SupplyBattery: 6 rechargeable NiCd cells (QB 0008)operate the system for > 4 hrs continuous use at25°C. The operating time is reduced if disk-driveor interface bus is used and decreases with de-creasing temperature.

Mains: An external source or filtered DC powerin the range of 11–16 V DC will power the ana-lyzer continuously. The Brüel & Kjær Power Sup-ply ZG 0342 fits into the slot normally occupiedby the battery pack and is powered from 90 to264 V AC mains supplyPower Consumption: 900 mA during measure-ments at a typical battery drive-voltage of 7.5 V(back lighting off)

EMC

SUSCEPTIBILITY TO DISTURBANCES SPECIFIED IN EN 50082–2:Measured with floating input module.

LF Magnetic Field: (30 A/m at 50 Hz)

Radiated RF: (3 to 10 V/m, 80% AM, 1 kHz)

Conducted RF: (3 to 10 V, 80% AM, 1 kHz)

1 Input section with max. gain and input short-circuited2 Input section with max. gain and 1 nF termination

CabinetDIMENSIONS:Height: 175 mm (6.89″)Width: 356 mm (14.02″)Depth: 293.5 mm (11.56″)Weight: 9.3 kg (20.46 lb.)

Input/Output Level

Preamp., ProbeDirect via Preamp.1

< 10 µV

Charge2 < 1 fC

Input/Output Level

Preamp., ProbeDirect via Preamp.1

< 25 µV

Charge2 < 2 fC

Input/Output Level

Preamp., ProbeDirect via Preamp.1

< 1 µV

Charge2 < 16 fC

11

Brüel&Kjær reserves the right to change specifications and accessories without notice

Ordering InformationTypes 2143 and 2144: Real-time FrequencyAnalyzersInclude the following accessories:ZG0342 Power SupplyAQ 0035: 7-core DIN Cable (1.5m)ZG 0146: Battery Box6×QB 0008: 1.25V NiCd Batteries, type R 20

(“D” size)JP 0312: 3-pin PlugJP 0808: 8-pin DIN PlugDH 0541: Shoulder StrapAQ 0157: Charging Adaptor2×AO 0479: Lemo-to-BNC AdaptorBZ 5048: 2 program disks VP 7234

Optional Accessories

TRANSDUCERS:Type 3584: Sound Intensity Probe (2144,

2148/7667)Type 4190: General-purpose 1/2″ Measuring

MicrophoneType 2669: Microphone PreamplifierAO 0488: Lemo to B & K AdaptorType 4371: General-purpose Accelerometer

Brüel & Kjær supplies a wide range ofmicrophones and accelerometers. Please ask formore information regarding the different typesand their uses.

CALIBRATION:Type 3541: Sound Intensity CalibratorType 4204: Reference Sound SourceType 4226: Multifunction Acoustic CalibratorType 4228: PistonphoneType 4231: Sound Level CalibratorType 4294: Calibration Exciter

HARDWARE:Type 2822: Microphone Multiplexer,

12 channelType 3923: Rotating Microphone BoomType 4224: Sound Source

ENHANCEMENTS (2143):WH 2921: Memory Extension 1 MbWH 2924: Memory Extension 0.5 MbUA1350: Kit for Upgrading to Type 2144

APPLICATION PROGRAMS:Type 7638: Zwicker Loudness OptionType 7651: Dual Channel FFT Option for

Type 2144 (or Type 2143 withoutcross-functions)

COMPUTER SOFTWARE:WT 9366: Calculation of Reverberation TimeWT 9367: Ln Calculation SoftwareWT 9378: Mapping and Sound Power

ProgramType 5304: Sound Power ProgramType 5305: Building Acoustic ProgramType 5306: Utility Program for Types 2144,

2148Type 7679: Sound Power Program for Type

2144Type 7680: Sound Power ProgramType 7681: Noise Source Location Program

INTERFACE:AO 0195: Adaptor to convert IEEE–488

connector to IEC 625-1 (25-way)AO 0264: Interface Cable (2m), IEC 625-1

(25-way) to IEEE–488AO 0265: Interface Cable (2m), IEEE–488UA 0814: IEEE 24-way bus connector kit

MISCELLANEOUS:QB 0008: 1.25V NiCd Battery, type R 20

(“D” size)QR 1102: 10 Micro Floppy Disks (Double

Density)QR 1105: 10 Micro Floppy Disks (High

Density)

Brüel & Kjær B K

BP 1021 – 15 95/12

WORLD HEADQUARTERS: DK-2850 Nærum • Denmark • Telephone: +4542800500 •Telex: 37316 bruka dk • Fax: +4542801405 • e-mail: info@bk.dk