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CEL-393Precision ComputingSound Level Meter &Frequency AnalyserOperator's Handbook060023Issue: 6AApril 1994archive DocumentforDiscontinued In

LnValues Provided10, 50, 901, 50, 951, 10, 501, 5, 955, 50, 951, 10, 9010, 50, 901, 50, 951, 10, 501, 5, 955, 50, 951, 10, 9010, 50, 901,

CEL-393 Precision Computing Sound Level Meter(A, B, C, or D version),CEL-229 Microphone Preamplifier,CEL-186 Precision Measurement Microphone(or alter

CEL-284/2 Acoustic CalibratorAcoustic calibrator conforming to IEC-942 Class 1.Note: For C and D versions, and certain official verifications use RFT

CEL-433 InterfaceAllows B (and D) version to be connected to conventional RS-232Cinterfaces. Cables must be specified separately. See Section 5.3 of t

/10.393 Handbook

3. PREPARATION FOR USEThe CEL-393 is despatched from our works fully calibrated and tested,hence it is only necessary to fit the battery and connect t

WarningEnsure that the instrument is switched OFF when-ever connections or disconnections are made.The preamplifier may be fitted directly into its so

The instrument is not designed for permanent outdoor operation, how-ever the optional CEL-298/2 Preamplifier and its associated CEL-194/2Outdoor Enclo

/14.393 Handbook

4. DESCRIPTION OF THE INSTRUMENT4.1 Controls, Connectors and DisplayFigure 3 shows the location of the various controls, connectors, and thedisplay, w

Figure 3 Controls & connectors8900151234567890ACPMFRFPISCALF1:3F1:1OffALinConditioned ACOutputAuxiliarySocketFILTERSOFFPOWERDETECTORMain displayTi

When the switch is in the Off position, signals are treated as selected onthe weighting switch described above. In the other positions either octaveor

always default to SPL. In order to return to the SPL mode after any ofthe computed functions have been displayed, depress the F key.In general, the ke

from this displayed datum plus 63dB; ie on 30 range, answers in the span30.1 to 93 are valid. This procedure will not affect the main digital display.

Function 9F is described in Chapter 9, whilst 8F duplicates the singleoperation of the C key. The sequence 7F is only valid when the instru-ment is in

Main ClockTo change the default elapsed time mode to the current real time it is justnecessary to enter the required time in hours and minutes on a 24

Delayed Start TimeThis is entered as a four digit number representing the required start timeon a 24 hour clock, in the same 24 hour cumulative manner

The various memory modes are as described above in Chapter 1, andit is important to note that three of the modes are linked to the selectedperiod time

memory locations are indexed, the display will indicate 00.0. Subsequentoperation of a number key and M returns to the first Leqresult again.Memory ca

Operation of any numerical key followed by M will bring the start time ofthe first filter sweep in the memory to the display. Subsequent operationsof

Contents Page1. INTRODUCTION ...12 SCHEDULE OF PARTS ...53. PREPARATION FOR USE ...114. DESCRIPTION OF THE INSTRUME

4.2 DisplayFigure 4 gives an explanation of the various sections of the display alongwith the mnemonics used for the various quantities. This shows al

Main DisplayThis four digit indicator is the main answer display provided by theinstrument. It takes the format of hundreds, tens, units and decimalsw

The value given is qualified by the mnemonic indicator located on its righthand side. Results given are the actual values, so it is not necessary toma

0L MEMIf either or both of the above overloads are activated during a measure-ment period, the overload will latch-on to alert the operator to the fac

level. It is continually available throughout the current measurementperiod, and may be reset manually or under automatic control.Valid results may be

Figure 5 Basis of computation of energy average results89001782dB LAITm85dB LTm378dB LeqLTmis based upon averaging level over a set time period.Leqis

LTm3& LTm5The 'taktmaximal' results are required by certain West German meas-urement protocols. These values are calculated respectively

Half second samples are taken of the sound pressure level to calculatethese values. The results are written into a statistical probability distribu-ti

An analogue maximum arrangement is employed that is read by theprocessor on each 15ms duty cycle, and is operative on all four timeconstants. When Lma

Event mode may be re-entered only by switching the instrument OFFand ON again, having first interrogated any results in the memory.ResetsCurrent perio

Contents (Continued) Page6 SAMPLE OPERATIONS ...616.1 Profile Mode ...616.2 Environmental Mode ...636.3 Event Mode ...

The following outputs are provided in all versions of the instrument.ACWarningDo not insert two-pole plugs into this socket as theycould damage compon

This output accurately follows the fast and slow time constants, but Itshould be noted that when impulse is selected, both rise and fall timesof the o

When using the auxiliary input on the B version, attention is drawn to theoverall frequency response of the instrument, as described in Section5.2.2.4

factor will have to be used. Due consideration should also be given totheir temperature performance.There is no known alternative to the CEL-190 micro

5.2 Frequency AnalyserThe filter set comprises charge coupled digitally controlled filters whichmay be operated manually or automatically either by th

This controls the analyser in conjunction with number keys in the sameway as the other control keys. The key sequences needed to performthe various co

Having selected the required filter bandwidth (full or third octave) sub-sequent operation of the A key enables the band selected to be steppedup from

Having gained an appreciation of the function of the controls, operationof the filter is quite straightforward.IntroductionPrior to commencing an anal

reset any information that was stored prior to commencing a series offrequency analyses.On commencing an automatic frequency sweep the start time is c

1/3 OctavedB32.031.531.530.029.529.027.527.026.025.525.023.523.523.022.023.022.020.521.020.519.019.518.016.016.013.512.51/1 OctavedB36.034.031.529.026

1. INTRODUCTIONThank you for choosing the CEL-393 Precision Computing Sound LevelMeter.CEL experience in both Acoustics and Data Processing combine to

Answers must, however, be read out before the memory is reset to allowany of the other memory modes to be selected. To prevent eventsoccuring during f

recorder (F key), and then the required sweep selected on the CEL-393by the appropriate command number followed by the A key. The filterwill then move

ance, causing a roll off of around 2dB in the 16kHz octave, and 16 and20 kHz third octave bands, as shown in Figure 8.5.3 Digital Interface5.3.1 Intro

Programme InformationAs the CEL-393B can be programmed with a variety of Lnvalues, theprogram labels them A, B, and C, with A corresponding to the low

5. The floppy disk should now be entered into the disk drive andthe IBM computer switched on.6. The display on the IBM will show "CEL393 DATA CAP

Do not attempt to connect the CEL-393B to thecomputer after the program has been started in thecomputer.To end the program, press the RETURN key, the

2. The lead with the 15 pin D type connector should be pluggedinto the serial output socket on the CEL-393B, and the otherend to the 15 pin D type plu

If data must be displayed on the screen then press Y for yes,otherwise N for no, likewise for output to printer.If the data is to be stored on tape, t

7. Insert cassette with "CEL2" uppermost this time.Then:9. Type LOAD "CEL2" and then press RETURN.10. If stored data is to be outp

DisplayMnemonicPrint OutRequiredMaxLeqLTm3LTm5Ln1setLn2setLn3setSELTimeDurationAll Pass20kHz16kHz12.5kHz10kHz8kHz6.3kHz5kHz4kHz3.1kHzHexadeci-malCode8

on the main digital display. In addition, the computer is continuallysampling this level every 15ms, and the data is used to calculate thenoise rating

DisplayMnemonicPrint OutRequired2.5kHz2kHz1.6kHz1.2kHz1.0kHz800Hz630Hz500Hz400Hz315Hz250Hz200Hz160Hz125Hz100Hz80Hz63Hz50Hz40Hz31.5Hz25Hz20Hz16Hz12.5Hz

these and converting to the necessary conventional mnemonics that arerequired on the computer printout.The sound level meter's internal memory sh

Format Serial 1200 Baud, 8-Bits plus start and twostop bits.Control lines Listener ready.Data Five byte packages, first is mnemonic codefollowed by fo

Figure 9 Retrofit of filter890021Pin 1Filter boardROMSelf-adhesivefoam stripBatteryBattery coverInsulation filmPeel off backingand stick toback plateB

The kit comprises a circuit panel, two insulating pieces, and a newprogramme ROM. Fitting should be undertaken only by a competentelectronics technici

4. Fit the new programme ROM in place of the original A versionshown in Figure 9.Take care to ensure that the connectors are not damaged andthat it is

sources that could cause hearing loss to operators working in theimmediate area.Proceed as follows.1. Switch the instrument on, and check the battery

10. Mount the CEL-393 on a CEL-4627 Tripod to enable long termmeasurements to be made, and use the CEL-2962 Wind-shield if necessary.When the delayed

Measure traffic noise by a building near a main road using an L10(18hour) index. This is the arithmetical average of 18 one hourl L10indicesbetween 6.

4. Calibrate the sound level meter with a CEL-284/2 CalibratorType 1 to obtain a reading of 114.0dB as described in Section8.2.5. Fit the CEL-2962 Win

i) Profile ModeThis allows the operator to set a period time. The instrument will thencalculate and store the Leqresult for each individual period, th

15. After the delayed start has been reached, the first L10index(calculated for the period between 6.00 and 7.00 am) may beobtained by pressing 4M (se

1. Switch the instrument on, and check the battery level.For correct operation with alkaline manganese batteries, thevoltage should be greater than 8V

11. Press 1M to check that the memory has been cleared. If not,repeat step 10.12. Press F to return to instaneous display of SPL.When an event occurs

6.4 Frequency Analysis ModeThis mode is available only on the CEL-393B (and D). It is used when anumber of frequency scans have to be made in an area.

Do not move this switch during measurement.6. For the moment, leave the Off-F1:1-F1:3 switch set to off.7. Move the Lin-A-POWER OFF switch to Lin for

14. Press 0A to initiate a frequency scan, and note the position andtime when this occurs, so that they can be correctly cross-referenced.The CEL-393B

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the level in the band, the interval between the indicated frequencies willmake it obvious whether a third octave or octave scan is being displayed.The

/74.393 Handbook

At switch on, the CEL-393 will always default to a standard set ofoperating conditions pending receipt of operator instructions to thecontrary. These

920030CEL-393AX & BCEL-438CEL-493/3CEL-296/3CEL-278/3CEL-288CEL-4856/2CEL-296/3CEL-278/3CEL-288C4529/2C4530A/1.5C4530A/1.5IBM PCCEL-4853/2 CEL-485

21.21RECHNENDER PRÄZISIONSSCHALLPEGELMESSERCEL Instruments LtdTyp CEL-393nach DIN IEC 651 KL.1Iund DIN IEC 804 KL.1Obligatorishes ZubehörMikrofon Typ

Eigenstorung (Abschn. 6.6)Nach Erasatz der Mikrofonkapsel durch eine gleichwertige Kapazitat(C = 18pF) zeigt das Messgerät mit einzelnen Frequenzbewer

This will ensure that all of the requirements of the international standardsare still met. For some specialised applications specific approvals arereq

should indicate the level generated by the calibrator as indicated in itshandbook for this configuration.CautionDo not adjust the calibration using th

To ensure accurate calibration using the pistonphone, it is important thatthe following procedure be followed, otherwise significant errors may beintr

Freq. Time CommentsLevelFreq.Calibrator70(7R)70(7R)70AAALinFFFFRecommendedNeeds 13.2mm couplerNot recommendedNeeds 13.2mm coupler114dB113dB114dB124dB1

/82.393 Handbook

corrected by the amount shown on the barometer in order to compensatefor errors associated with atmospheric pressure and altitude.If the calibration p

estimated to be in the order of 4 hours total when used continuously infilter mode.Rechargeable NiCad cells may also be used, and these are available

not take any information into its data stores, nor does the bar graphoperate. Therefore battery checks should be kept as short as possibleto preserve

2 SCHEDULE OF PARTSThe CEL-393 is available without or with its frequency analysis and digitalinterface module, and identified as the A and B models r

FunctionsCurrent Period SPL, Leq,Ltm3, Ltm5,Lmax, and three Lnvalues(for example L10,L50and L90).Memory Profile ModeOne to four minutes Leqbased param

Time WeightingsFast, Slow, Impulse and Peak (100 microsecs).OverloadRangeSetting102030405060708090W'ghtingALinALinALinALinALinALinALinALinALinPul

Pre and post overload detectors with memory.CalibrationField calibration is achieved by means of the CEL-284/2Precision Acoustic Calibrator.Temperatur

3. The ranges of sound pressure level which may be measuredare as indicated under "Measurement Ranges" above.4. The reference point is 114.0

14) The recommended windscreen has negligible effect at frequen-cies <12.5kHz.15. The instrument should be calibrated with either a CEL-284/2electr

21. The warm-up time before valid readings can be made is1.5 minutes.22. Not applicable.23. The instrument complies with Tables II and III of IEC 651

serial number should be quoted in any correspondence concerning theinstrument.The manufacturers undertake to rectify any defect in the instrument that

880030Reason for Return/Nature of Fault DateReturn InformationCustomer ReferenceCustomer NameAddressPhone No.Contact NameInstrument TypeSerial NumberI

/94.393 Handbook

own manufacture, and they do not accept liability for any loss resultingfrom the operation or interpretation of the results from this equipment.A comp