SV 31 Acoustic Calibrator
Contents
1. SVANTEK INSTRUMENTATION FOR SOUND AND VIBRATION MEASUREMENTS SV 31 Acoustic calibrator SVANTEK Sp z 0 0 Pl Inwalid w 3 62 01 514 Warsaw Poland Phone fax 22 839 00 31 e mail office svantek com pl NIP 527 010 52 72 Users manual Warsaw August 2010 Production Department X Service ul Chodakowska 26 32 II p 03 816 Warszawa Phone fax 22 871 05 36 Phone fax 22 871 04 69 e mail prod svantek com pl SV 31 USER MANUAL Contents Tee IV EROCU CUO ANC 1 1 1 CAIBrAoO a A A AT Z EE 1 1 2 Accuracy of calibration eesaee aaa wena anna aaa a aaa aaa a zaaa aaa zaaa naka aaaazakanaaG wa 1 1 3 Classification of sound level meters and acoustic calibratorS 2 2 Acoustic calibrator SV 31 wxeusccunscuiiavoniuiutnunaiduounupassoanaesieuniulrndetndaedewenemnaeseawuweuwnseses 2 2 1 General description ee eee ee ee en ee ne eee ee 2 2 2 Usage Ol tne CANOE AO A Pda wda a dala 4 2 2 1 Automatic calibration cece cecececececceeeceeeeeeeeeeaeaeaeaeaeaeaeaeaeaeaeaeaeaeaentaees 4 222 DLIOIIUNCNONS irseseccsanagesasanagesasgcagusssanagasasanaqesasaoasasssaoasesssangqesasasgsesees 4 a ARE WCNC ANOS ee EE EEE EE EE EE E EEEE EEEREN 5 2 3 Replacing the battery nannnannnennnnnnnnnnennnannnnnnnnnnnnnnnrrnnrrsnrrnrrnnrrsnrrnnennnennnee 6 3 SV 31 Datasheet 2 0 cc cecececece ec ecececeeeeaeaeseseseseeaeaeaeceeeeeeeaeaeseeneaeaeaeaeenees 8 1 Introduction2. the requirement of calibrating the measurement channel before each measurement or measurement session and very often as well after the measurement for result verification purposes 2 Acoustic calibrator SV 31 2 1 General description The SV 31 acoustic calibrator is a small portable one range Type 1 device sound source see Picture 1 Powered by two LROS AAA batteries it contains a loudspeaker producing acoustic pressure reference microphone for monitoring generated level pressure and temperature sensors for measurements of atmospheric conditions and a microprocessor system controlling the operation of the calibrator Sinusoidal waveform of 1 kHz frequency is digitally generated and feeds the loudspeaker Sampled signal from the reference microphone indicates the level of currently generated signal in a feedback loop On the basis of information about the level of the signal actual values of pressure and temperature microprocessor adjusts amplification of the loudspeaker signal in order to produce appropriate sound pressure level in the calibrator s chamber Due to the feedback regulation loop the SV 31 calibrator does not require adjusting and operates in a wide range of temperatures and humidity see SV 31 Datasheet SV 31 USER MANUAL Picture 1 Acoustic calibrator SV 31 The SV 31 is designed for calibration of sound level meters with and 1 microphones Picture 2 shows the calibration procedure of Type 1 sound level met
3. 1 1 Calibration One of the fundamental questions that are most frequently asked while taking a measurement is whether its result is accurate Proceeding with a measurement without having a positive answer to this question may result in obtaining data of no practical use and wasting our time However we may easily obtain the answer by performing a calibration of the sound level meter together with the microphone and its preamplifier Calibration of the measurement device may be done in two ways by comparing the calibrated device with a reference device of known parameters or using a template of the measured quantity to perform a reference measurement Acoustic devices are usually calibrated in the latter fashion with so called acoustic calibrators Acoustic calibrator is a device which produces acoustic pressure of defined level and frequency In other words such calibrator is a template of acoustic pressure With help of such a template we can check the accuracy of the measurements performed with the sound level meter and or calibrate it if the error occurs 1 2 Accuracy of calibration Each measurement performed with any measurement device is burdened with an error Result obtained from such measurement is only an estimate of the real value of the measured quantity It is impossible to remove the error completely as the values given by the meter are discrete whereas the measured quantity is of continuous nature Hence the purpose of calibra
4. e called LOW BAT presents the batteries status The batteries voltages under 2 1 V cause LOW BAT blinking with approximately 2 Hz frequency lt is recommended to not use the SV 31 calibrator in this state as the generated level may differ from the declared values SV 31 USER MANUAL Picture 4 The top view of the SV 31 calibrator with one burning diode 2 3 Replacing the battery The battery should be replaced as follows F 1 a remove the rubber cover on the button and diodes side b holding the cover unscrew four fixing screws with your fingers c take off the cover and remove discharged batteries SV 31 USER MANUAL d put new batteries in place of the discharged ones with polarization as indicated on the printed board and calibrator s case diode holes e put on the cover so that the diodes fit the corresponding holes in it f holding the cover with one hand fasten the fixing Screws g put on the rubber cover SV 31 USER MANUAL 3 SV 31 Datasheet Output signal Sound Pressure Level SPL 114dB with respect to 20uPa in reference conditions Accuracy IEC 60942 2003 standard Type 1 SPL Accuracy 0 3 dB Frequency accuracy 0 02 Total Harmonic Distortions THD lt 0 75 Reference conditions Temperature 23 C Atmospheric pressure 101 3 kPa Humidity 30 80 RH Effective microphone load volume 250 mm microphone type 4134 SN 1591010 General da
5. er SVAN 945A with a 72 microphone Picture 2 Calibration of the SVAN 945A sound level meter with a 72 measurement microphone A Notice For calibration of a meter with a microphone the SA 30 reduction adapter must be applied Picture 3 presents the calibration procedure of Type 2 sound level meter SVAN 943B SV 31 USER MANUAL with a 14 microphone Picture 3 Calibration of the SVAN 943B sound level meter with a 14 measurement microphone 2 2 Usage of the calibrator 2 2 1 Automatic calibration The SV 31 calibrator is equipped with an optical system which detects the presence of a microphone in the calibrators chamber That allows the calibrator to be switched on automatically when it is placed on the microphone and to be switched off when it is dismounted For this reason usage of the SV 31 calibrator is as simple as putting it on the microphone performing the calibration and taking it off the microphone 2 2 2 Button functions The SV 31 calibrator is equipped with a multifunctional button for controlling operation of the device There are two functions of the button see Table 2 First of all the button is used to turn ON and OFF the device In this case the button pushing has immediate effect Either when the SV 31 is ON or OFF pressing the button over 10 seconds and releasing it will cause full reset of the system Normally this function is not necessary lt has been implemented in the case of inappropria
6. ta Effective load volume sensitivity 0 00027 dB mm Level stabilization time typical 7 sec max 10 sec Microphone dimensions v2 and 4 with reduction adapter SA 30 Storage temperature range 25 C do 70 C CE classification EMC EN 50081 1 EN 50082 1 Safety EN 61010 1 2001 Working conditions Temperature range from 10 C to 50 C Atmospheric pressure range from 65 kPa to 108 kPa Humidity range up to 90 RH Environmental conditions influence typical Temperature coefficient 5 10 dB C Pressure coefficient 1 10 dB hPa Humidity coefficient 1 25 10 dB Power supply Battery type two LRO3 IEC AAA ANSI alkaline batteries Continuous operation time 30 hours Standby mode approx 2 years Minimal working voltage 2 1V Dimensions and weight Weight 305 g with batteries Dimensions 65 x 65 x 70 mm
7. te operation of the calibrator caused by external EM radiation subnormal atmospheric conditions etc or internal inappropriate system reset as a result of battery replacement etc factors SV 31 USER MANUAL The operation time of the calibrator with a microphone put inside its chamber is limited to 3 5 minutes This functionality was added in order to save the battery e g when the calibrator is accidentally left with the microphone inside Notice Leaving the SA 30 reduction adapter in the chamber of the calibrator is equivalent with the state of the microphone being left inside Hence the calibrator will switch off automatically after 3 5 minutes from the moment the adapter is put inside the calibrator Table 2 Functional description of the calibrator s button Function description Short less than 10 sec Turn on off the device Full reset of the system 2 2 3 Indicators There are two LED to indicate the state of the SV 31 calibrator One of them is titled 114 dB and shows the state of the generated level After the calibrator is put on the microphone or switched on acoustic pressure inside the calibrators chamber is adjusted to the desired level During that process 114 dB diode blinks with a frequency of approx 2 Hz Device is ready when this diode burns with continuous light A Notice Calibration should not be performed until the 114 dB diode is burning with continuous light The diod
8. tion is to limit this inevitable error to a certain acceptable level Maximum absolute value of the error of measurement or of the generated signal in the case of the calibrator is called the tolerance and is strictly defined by the standards for the given type of device A sound level meter is calibrated correctly if and only if the measurement error is within the range of tolerance defined by the standards for the meter of a given class SV 31 USER MANUAL 1 3 Classification of sound level meters and acoustic calibrators The acoustic calibrators see IEC 60942 2003 and the sound level meters see IEC 61672 2002 are divided into classes and types respectively according to their accuracy Type 0 imposes the strictest requirements on the device Devices of this class are ranked as the most precise Each of the following types 1 2 and 3 allows for the wider range of tolerance see Table 1 Table 1 Tolerance values for the given types of acoustic devices excluding maximum expanded uncertainty of measurement f 1 kHz Class Type Sound level meter dB 07 10 Acoustic calibrator dB As indicated in Table 1 an acoustic calibrator has significantly lower tolerance than a sound level meter of the same class Intuitively we understand that the calibrator as a reference for acoustic pressure must be more precise than a measurement device Taking acoustic measurements according to norms and standards imposes
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