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Chapter 10

Reverberation time measurements

Norsonic Nor118

User Guide

reverberation time stated in the table a few pages back a

question mark will be shown to the right of the value.

Likewise, the question mark will appear if the back-

ground noise level is too high. All in all, the question mark

tells you that the measurement is not reliable. However, it

does not tell you why it is so.

Overload occurring during the impulse decay capture

is indicated by an

appearing above the result table. In

addition, no reverberation time will be calculated and the

table will reflect this.

Saving the measurement

While still displaying the result table the acquired data

may easily be stored.

To store the acquired data:

• Press  to save the measurement. e measure-

ment will be stored in a folder bearing today’s date as

its name and the file name will be the first free number.

Existing files will not be over written. If the folder did

not exist, it will be created when you store the data.

Recalling a stored measurement

A stored measurement is retrieved as any other measure-

ment stored. e values will be presented in a table identi-

cal to the result table. See the chapter

Memory handling

for

a discussion of storage and retrieval of measured data.

Making another measurement

If you want to make another measurement, you may do

this with or without storing the one you just did.

To make another measurement:

• While in the result table, press the t key. You will

now be prompted to either store the acquired data (by

pressing ) or start another measurement directly

(by pressing  again).

Leaving the table returning to

READY

mode

You may leave the table to go back to ready mode without

having to start another measurement first. is may be

the case if the trigger settings needs adjustment.

To leave the table:

• Press the  key to leave the table. You will now be

prompted to either store the acquired data (by pressing

) or exit directly (by pressing  again).

To store a reverbera-

tion time measurement,
press the

STORE

key

whilst still displaying
the reverberation time
results.

Содержание nor118

Страница 1: ...ower calculations third octave filters and statistics in every frequency band multispectrum and reverberation time measurements The instrument logs level vs time optional and when it is equipped with multiple time constants and the enhanced profile extension a multitude of functions is logged si multaneously The 120dB dynamic range eliminates the need for range setting A large memory and high spee...

Страница 2: ......

Страница 3: ...nor118 REAL TIME ANALYSER ...

Страница 4: ...trademarks of their respective companies Every effort has been made to supply complete and accurate information However Norsonic AS assumes no responsibility for the use of nor for the consequential dam ages of the use of this information and or the instrumenta tion described herein Furthermore Norsonic AS assumes no responsibility for any infringement of the intellectual property rights of third ...

Страница 5: ...with a few exceptions be installed as retrofit any time Our objective with this manual has been to address your goals and needs Please let us know how well we succeeded Thank you for choosing Norsonic The Nor has been designed to give you many years of safe reliable operation Your approach to the Nor118 documentation depends on what you want to do and how much you already know e Nor118 User Guide ...

Страница 6: ...xcellent for noise monitoring 8 The principle of optional extensions 8 Check which extensions are installed 9 Chapter 2 Taking a closer look Taking a closer look at the instrument 10 On the use of batteries 10 Battery Voltage vs Time 11 Setting the polarisation voltage 11 Setting the time and date 12 Chapter 3 Calibrating the instrument Calibrating the instrument 14 When to calibrate 14 No need to...

Страница 7: ... 21 Displaying the result tables 22 Statistics displaying the percentiles 23 Displaying the percentiles table 24 Storing the acquired data 24 Printing out the results 24 Chapter 5 Frequency analysis Frequency analysis 25 Setting up 25 Setting the duration 25 Statistics 26 Instruments with time profile installed 26 Consider setting the time constant 26 Setting C or Z as spectral weighting network 2...

Страница 8: ...me profile measurements 40 Selecting which functions to log 40 Copy the setting to Prnt Xfer 41 Setting the resolution 41 Measuring in enhanced mode 43 Displaying the functions measured 43 Presenting the L t as a table 43 Chapter 8 Adding markers to a measurement Adding markers to a measurement 44 e keys to use 45 Other markers inserted by the instrument 45 P and S markers have priority 45 Chapter...

Страница 9: ...urement 57 Leaving the table returning to ready mode 57 Chapter 11 About sound power measurements About sound power measurements 58 Rectangular parallelepiped 59 Hemispherical measurement surface 59 Hemispherical microphone positions 60 Additional microphone positions 60 Parallelepiped measurement surface 62 Microphone positions 62 Additional microphone positions 62 Reducing the number of position...

Страница 10: ...ry handling 72 Memory structure 72 Memory size 72 Storing a measurement setup 73 Storing a measurement 73 Retrieving stored setups and data 73 Clearing files and folders in the memory 74 Clearing a single file 74 Clearing folders or the entire memory 75 Chapter 15 Making hardcopies Making hardcopies 76 Setting up for printouts 76 Printing out measured data 77 Chapter 16 Noise monitoring Noise moni...

Страница 11: ...gs and measured functions 84 Level distribution 84 Indication range 84 Self noise levels 84 Field calibration 85 Measurement duration and resolution 85 Total range for measurement of A weighted levels 85 Total range for measurement of C weighted levels 85 Total range for measurement of Z weighted levels 85 Measurement range for C weighted peak levels 86 Power supply 86 Display 86 Keyboard 86 Adjus...

Страница 12: ... 90 Digital inputs 90 Digital outputs 90 Microphone heating 90 Data storage 90 Environmental conditions 91 Warm up time 91 Sensitivity for vibration 91 Sensitivity for magnetic fields 91 Size and weight 91 Information for conformance testing 92 Appendix 1 Index Index 93 ...

Страница 13: ...nor118 REAL TIME ANALYSER ...

Страница 14: ... To add further flexibility the Nor118 accepts prepo larised microphone cartridges as well as the conventional microphone cartridges designed for 200V polarisation voltage ere is more to this than just providing you with the option of using your existing stock of microphone cartridges by reducing the polarisation voltage to 70V optional extension the instrument will be able to measure levels up to...

Страница 15: ...ime of printing the weighting appears in the draft for likely to be approved as an international standard within short time As an optional extension the instrument functionality can be expanded to include the ability to measure with all three time constants applied simultaneously The main features an overview Level vs time e electronic level recorder concept is available in two versions basic and ...

Страница 16: ... However the methods described in weighted measurements involve a tedious calculation procedure before you end up with the single figure you need to be able characterise your measurement object So why not let the Nor118 take care of this for you Just specify the measurement surface type hemisphere or parallelepiped its dimensions and the location of your measurement object on the floor against a h...

Страница 17: ... high dynamic range 120 dB which eliminates the need for adjusting the gain there is very little to set up before a frequency analysis can be made successfully e measured functions are also available in tabulated form as numerical values By pressing the key before during or after a measurement you have instant access to the numerical version Another push on the key will restore the graphical displ...

Страница 18: ... of the Nor118 the memory can hold approximately 2500000 values the period dura tion will for all practical cases be determined by your need for time resolution Provide details maintain overview e level vs time feature is the tool you need for detailed analysis of the time profile However a measurement failing to provide an overview of the entire analysis cannot be accepted So we added a global an...

Страница 19: ...5 ms steps in 1 second steps above 1 second time resolution so beware unless you want to create a busy day for yourself there will easily be quite a lot of data generated so avoid more details than strictly needed Multispectral measurements e Nor118 functionality can be expanded to include multispectral measurements is extension takes the instrument s time profile capabilities to new heights by al...

Страница 20: ...and go feature which is standard is combined with the optional time profile each measurement will provide global data and a time profile with a resolution specified by you Of course the instrument will spend a little time stor ing the data housekeeping erefore if you start the session with hourly measurements exactly on the hour long store and go sessions will after a while experi ence a small but...

Страница 21: ...wever constant improvements will normally result in new extensions becoming available on a regular basis Check with your local Norsonic distributor or the factory for an update on this matter Opt 0 Tmax5 eqI and eq measurements accord ing to German Standards Opt 1 octave real time filters 8 16 000Hz Opt 3 1 3 octave filter bands Opt 4 Statistical calculations Opt 5 Parallel time constants Opt 6 Ba...

Страница 22: ...nce with low noise level measurement sessions On the use of batteries e Nor118 comes with four batteries 1 5V each Battery lifetime is typically 8 12 hours depends on measurement mode and brand of batteries If you switch to lithium batteries the life time will increase to 15 20 hours e use of alkaline or lithium batteries is strongly recommended to avoid leakage Rechargeable batteries may also be ...

Страница 23: ...ined without the use of electrical power flash memory If the instrument is connected to an external source the external source voltage vs time will be shown without voltage and use time information empty graph If powered from internal batteries and left unattended and unoperated the Nor118 will switch itself off after ten Time elapsed since battery replacement Combined battery voltage as an f t Ba...

Страница 24: ...ed when you use the and keys To leave the menu putting changes into effect press ere is no function available Clock The date and time setting menu Press SETUP 1 Instr 3 Clock to produce this menu Setting the time and date To set the time and date Press 1 3 Use the cursor keys to navigate in the menu and and to alter a setting or use the to key in a value Numerical inputs must be terminated by to e...

Страница 25: ...ng network Σ Global or Profile domain Time or frequency domain Absolute time on off Tabulation of results Battery status Graphical on screen A weighting Calibration men Generate printouts Power on off Display backlight on off Increment and decrement a parameter setting Start a measurement Pause and resume a measurement Stop a measurement Setup menus Instrument mode Leave a menu putting changes int...

Страница 26: ...ke place before a measurement session is commenced or when ever required by applicable standards If you know the microphone cartridge sensitivity you may key this in using the However doing so will never replace calibration with a sound calibrator as the sensitivity adjustment procedure will be unable to reveal possible microphone preamplifier or extension cable malfunctions No need to adjust the ...

Страница 27: ...el of the sound calibrator For a half inch cartridge this will typically amount to 0 2 dB lower for calibrators producing a 1000 Hz calibration signal e g the sound level meter should then be set to 113 8dB when using a 114dB 1000 Hz sound calibrator Other frequencies will require different correction values see the Field calibration side bar overleaf for more on this 4 Mount the calibrator onto t...

Страница 28: ...nominal sound pressure level of 114 0dB 1kHz In order to compensate for diffraction effects around the microphone we recommend adjusting the sound level meter to indicate 113 8dB diffuse correction off If other types of calibrators or electrostatic actua tors are to be used for the calibration we recom mend adjusting the sound level meter to indicate the following levels referred to the sound pres...

Страница 29: ...gging is affects the look of the measurement duration setup menu To read more about optional extensions see e principle of the optional extensions How the menu looks with and without the optional extension 6 installed is shown overleaf Navigating in the menus Observe the following general guidelines applicable to every Nor menu To navigate between editable parameter fields in the menu use the keys...

Страница 30: ...ntiles that fail to produce values in the table is is because you have not measured for a time long enough to provide the necessary number of samples Statistical sampling which should not be con fused with the sampling of the analogue to digital conversion takes place 10 times a second For comparison the sampling of the analogue to dig ital conversion runs at 48kHz Since the statistical sampling t...

Страница 31: ... and for all measurements e time constants apply to the the MAX and the MIN functions eq PEAK and E do not make use of time constants However units configured for German speaking markets will also measure the eqI e presence of multiple time constants eliminates the need for setup of the time constant Multiple time constants and statistics Observe that the statistics buffers optional extension will...

Страница 32: ... switch between absolute and relative time To switch between time elapsed since start of measure ment relative time and date time of day absolute time use the t key To display other functions measured Use the key For the German speaking markets these functions will include LeqI and TMax5 To adjust the display top scale If the bar graph fails to match the level measured use the and keys the vertica...

Страница 33: ...nds when you press the key the entire measurement will be erased upon resuming the measure ment If less than seconds have elapsed since the last time you resumed a paused measurement only the part of the measurement acquired since the last resume will be erased Data acquired earlier are assumed to be accepted by you e measurement time elapsed counter will be updated to reflect the back erase Note ...

Страница 34: ...t no longer is running no value is available Units not configured for the German speaking markets will have tables not containing the eq eqI and mx5 values Measure ment time Spectral weighting applied Measurement is running Units configured for the German speaking markets If also equipped with eqI and Max the sequence is as follows press key repeatedly SPL Leq Lmax Lmin LE Lpeak Accessible during ...

Страница 35: ...ing network indicator Units without statistics Units equipped with statistics e actual spectral weighting function used in the table depends on the setting active before the key was pressed At any rate press to toggle between primary and secondary weighting function Statistics displaying the percentiles Instruments equipped with the optional extension 4 statistics will measure the statistics every...

Страница 36: ...g to look through these files later as well aren t you Storing the acquired data Press the key e display will show the folder and file number All aspects of the memory handling are discussed in detail in Memory handling Printing out the results By connecting a printer to the interface the results can be output to a printer is is treated in detail in Making hardcopies Editing the user defined perce...

Страница 37: ...there is not much left to set up before the instru ment is ready to make a frequency analysis Actually the setup procedure boils down to specifying the measurement duration the time constant to be used and the use of or weighting ensuring that the fre quency mode has been activated and in case of extension present specifying the filter bandwidth Setting the duration Your instrument may or may not ...

Страница 38: ...e dura tion to avoid that the instrument starts logging the level as a function of time like the classic level recorders used to do Unless you want this to take place of course Cf Basic time profile measurements Enhanced time profile measurements and Multispectrum measurements for details on logging the level vs time with or without the spectrum as a function of time Consider setting the time cons...

Страница 39: ...display Activating the frequency mode In order to enable frequency analysis the frequency mode must be activated Activating frequency mode Press 4 to gain access to the frequency mode menu Navigate in the menu as usual Set the bandwidth as required As long as the frequency mode has been activated frequency analysis will be made during every measurement is means that the instrument will combine a t...

Страница 40: ...ill go on measuring until the total measurement time elapsed equals the preset duration When a terminated meas urement is resumed the back erase feature see below will not be activated To switch between absolute and relative time To switch between time elapsed since start of measure ment relative time and date time of day absolute time use the t key To display other functions measured Use the key ...

Страница 41: ... prolonging a measurement will not activate the back erase feature The back erase feature When you press the key during an ongo ing measurement the instrument will temporarily halt the measurement Pressing the key again will cause the instrument to resume the measurement while at the same time erasing the data acquired during the last ten seconds immediately preceding the pause If you ve measured ...

Страница 42: ...und level meter display mode or from frequency spectrum mode e tables are available during as well as after a meas urement Remember that values are shown during the measurement only e tables available are shown in the side bar Display ing the result tables Statistics displaying the percentiles Instruments equipped with the optional extension 4 statistics will measure the statistics every time is c...

Страница 43: ...h eqI and the sequence is as follows press key repeatedly SPL Leq Lmax Lmin LE Lpeak FUNC LeqI Accessible during measurement only not after e and are not accessible when the spectrum is displayed Units equipped with multiple time constants Units equipped with multiple time constants will measure and with all three time constants employed simultaneously In sound level meter display mode use the key...

Страница 44: ...istics is optional Units not configured for the German speaking markets will have tables without I Leq LeqI and Tmx5 values To switch between A and C or Z weighted values use the NETW key Use the FUNC key to select function Use the vertical cursor keys to scroll the centre frequency up and down Use the vertical cur sor keys to change the frequency band ...

Страница 45: ...editing process press the end right key e corresponding percentile value will now be displayed given that the measurement duration was long enough to provide a sufficent number of samples Using will not work here e user defined setting applies to every frequency band ey cannot have individual settings Missing percentiles ere may be percentiles that fail to produce values in the table is is because...

Страница 46: ...mum number of measurements per day is 9998 but this should be a limitation most people will be able to live with After all you are going to look through these files later as well aren t you Storing the acquired data Press the key e display will show the folder and file number as can be seen from the Fig below All aspects of the memory handling are discussed in detail in Memory handling Printing ou...

Страница 47: ...er parts One may therefore consider these two measurements as global measurements while the level vs time measurements represent the profile In the display the global measurements are denoted Σ pronounced sigma while the profile measurements are denoted pronounced delta To switch between the modes just press the Σ key e eq is measured for every period separately and stored in a buffer Likewise the...

Страница 48: ...ted as Marker Paused to indicate that these data will not be a part of the global level assessment The indicates profile global is indicated by a Σ Graph cursor Use keys to move the cursor along the graph This feature is not available during a measurement Display top scale Spectral weight ing function applied to the graph Measurement running Value at cursor s position Which resolution should you u...

Страница 49: ...peaking markets will have tables without I Leq LeqI and Tmx5 values To switch between A and C or Z weighted values use the NETW key To move the graph cursor use the keys but not during a meas urement only after Use keys to move to another frequency spectral weighting network To scroll through the table use the keys but only after a measurement Use FUNC to display another function ...

Страница 50: ...running If you press the global data acquisition will be halted but the profile will still acquire data ese data will be marked for pause to denote that they were acquired in pause mode and that they do not participate in the global level assessments When you later press again to resume the amount of periods marked as paused will be expanded backwards in time to include periods acquired in the tim...

Страница 51: ...file mode the instrument logs the weighted equivalenmt level the weighted maximum sound pressure level and the or weighted peak level At the same time the global mode measures the instantaneous the maximum and the minimum the equivalent level the sound exposure level and the maximum peak level All the global levels are measured as weighted and or weighted levels Combining multiple time constants w...

Страница 52: ...ugh it may be tempting to measure eve rything do not forget that you are going to review the acquired data afterwards How much time are you willing to devote to that Setting up the functions to log 1 To gain access to the profile function activation menu press 3 is menu looks as shown to the right 2 Navigate in the menu as usual and use the and keys to activate the functions required for your task...

Страница 53: ...ed in values you may set up instrument to just print a few of the functions measured However for convenience we offer the feature of setting up the same functions for printing as for meas urement If you then want to print fewer functions just go to the print functions setup menu and deactivate those you won t need To produce the print functions setup menu Press 1 8 Functions to be printed are deno...

Страница 54: ... to the profile Assume you have set up the measurement to also include profile and that the measurement is running If you press the global data acquisition will be halted but the profile will still acquire data ese data will be marked for pause to denote that they were acquired in pause mode and that they do not participate in the global level assessments When you later press again to resume the a...

Страница 55: ...Simple sound measurements and Frequency analysis apply even here Displaying the functions measured To see the different functions measured just use the key as usual Presenting the L t as a table Numerical presentation of the acquired data works even here Press while in profile mode to produce the table is can be done during as well as after a measurement An example of the table is shown to the lef...

Страница 56: ...tified by the digit 1 while trucks may be identified by 2 unexpected vehicles by 3 etc In the profile display the markers appear as dots or lines below the graph If you move the time cursor onto such a dot the marker type i e its number will appear in the display During a measurement adding any of the markers 1 2 and 3 will assign the corresponding marker number to the current period only Adding m...

Страница 57: ...minate an ongoing measurement prematurely by pressing the key and later resume the measurement by pressing an marker will be added to the period within which the key was pressed i e we mark out the first period after resump tion P and S markers have priority e marker 4 is a toggle marker i e once activated it will assign a marker to every period occurring until it is deac tivated again What happen...

Страница 58: ...de based on basic as well as enhanced time profile extensions installed Units equipped with basic profile extension Units equipped with basic time profile extension and filters of course have a very simple setup procedure To set up for multispectrum measurements basic time profile 1 Set up the instrument to make time profile measure ments as described in Basic time profile measurements 2 Press 4 a...

Страница 59: ...ter band func tions as well Are you going to use c or z weighting as spectral weighting function is is set up in the 2nd network menu press 1 Instr 5 2nd netw and navigate as usual If you fail to activate functions for the filter bands there will be no multispectrum data either Making multispectrum measurements Multispectrum measurements are made in the same way as ordinary time profile measuremen...

Страница 60: ...ter the frequency domain 2 Use the and the keys repeatedly if needed to reach the moment in time required Frequency Tim e 1 3 2 4 By following line 1 the time profile the level vs time of one specific fre quency band is obtained To display the time profile of another frequency band e g line 2 you must use the vertical cursor keys At any moment in time you may display the spectrum use the f t key i...

Страница 61: ...ltispectrum mode there are two tables available in profile mode Each function shown for all frequency bands use the key to go to another function e functions measured shown for a single frequency band or spectral weighting network ese are shown in the Fig to the right as well as over leaf together with the displays and tables available for the global part of the measurement To produce the result t...

Страница 62: ...50 Chapter 9 Multispectrum measurements Global mode Global frequency mode Multispectrum mode Profile mode Optional requires statistics ...

Страница 63: ...l functions available for a profile measurement apply even here If your instrument supports the use of mark ers they may be used in the usual way Pause and global back erasure also works as usual For a discussion of these features turn to Basic time profile measurements Enhanced time profile measurements and Adding markers to a measure ment ...

Страница 64: ...ach the microphone Once the steady state condition is reached the level wil increase no further If you now switch off the sound source the sound will take some time to decay e time it takes for the sound pressure to decay by 60dB is called the reverberation time Excitation signals Above we talked about having a steady sound source in a room when measuring the reverberation time However we may just...

Страница 65: ...on must be used hence noise source excitation is out of the question and the decay must be integrated backwards with respect to the time e Nor118 does this by default in fact you cannot switch the feature off is means that you will imme diately obtain the expected value in the statistical sense of the word of the decay Observe though that this will not free you from spatial averaging You must alwa...

Страница 66: ...etermine the level at a given standard devia tion Likewise the filters are not cleared instantly if the input signal is removed suddenly Instead they have a finite decay which may be considered as a virtual reverberation time e narrower the filter is the longer this virtual reverberation time will be e minimum reverberation times for the Nor118 are listed in the table to the right If reverberation...

Страница 67: ... set of trigger conditions to be versatile enough Such con ditions may include trigger by clock start measuring at a predefined time of day trigger when the level exceeds a certain predefined threshold trigger on an external trigger signal occurring e g a car passing a light barrier etc A sound level meter albeit as sophisticated as the Nor118 normally provides only one trigger condi tion the trig...

Страница 68: ...must terminate the ongoing measurement To terminate an ongoing measurement Press or In both cases the instrument will return to mode e instrument will measure for 10 seconds and count down to 0 to indicate how much is left of the measurement e acquired results are then presented as a table e table shows the calculated reverberation time for each frequency band and for the spectral weighting networ...

Страница 69: ...be created when you store the data Recalling a stored measurement A stored measurement is retrieved as any other measure ment stored e values will be presented in a table identi cal to the result table See the chapter Memory handling for a discussion of storage and retrieval of measured data Making another measurement If you want to make another measurement you may do this with or without storing ...

Страница 70: ... used for the measurement surface a a rectangular parallelepiped whose sides are parallel to those of the reference box in this case the measurement distance d is the distance between the measurement surface and the reference box b a hemispherical surface or partial hemispherical surface of radius r For sources usually mounted and or to be measured in rooms or spaces under unfavourable acoustical ...

Страница 71: ...mispherical measurement surface e hemisphere shall be centred in the middle of the box consisting of the reference box and its images in the adjoining reflecting planes point Q in the Figs overleaf e radius r of the hemispherical measurement surface shall be equal to or greater than twice the characteristic source dimension d0 and not less that 1 metre e radius of the hemisphere should be one of t...

Страница 72: ...positions each associated with equal areas on the surface of the hemisphere of radius r If a source is installed adjacent to more than one reflecting plane the Figs shown on the next page are used to define a suitable measurement surface and the microphone positions Additional microphone positions Sound pressure level measurements are required at additional microphone positions on the hemispherica...

Страница 73: ...numbered 14 15 16 and 20 4 5 15 14 6 16 20 10 6 0 Reference box Measurement surface Reference box z x 0 89r 0 45r 1r Measurement surface 16 4 5 14 15 6 10 20 Key microphone positions Additional microphone positions One reflecting plane Two reflecting planes Three reflecting planes 45 2 2 5 22 5 NB Dimen sions in metres 2 1 3 5 6 4 3 5 1 2 6 4 1 1 1 1 NB Dimen sions in metres ...

Страница 74: ... positions lie on the measurement surface a hypothetical surface of area S enveloping the source whose sides are parallel to the sides of the reference box and spaced out a distance d measurement distance from the box e microphone positions on the parallelepiped meas urement surface are shown on the following pages e area S of the measurement surface according to the micro phone position figures i...

Страница 75: ...ions in accordance with the procedures described above An example is when the radiation pattern is shown to be symmetrical e overhead position s may be omitted for safety reasons if so stated in the relevant noise test code Mic positions one reflecting plane Each plane of the measurement surface shall be considered on its own and so subdivided that the result is the smallest possible number of equ...

Страница 76: ...ample of microphone placement for a larger machine Details on the microphone posi tioning can be found in the ISO3746 l2 d d d d l3 l1 Reference box Microphone position Microphone placement with four microphones for floor standing ap pliances placed against a wall and three microphones for floor standing appliances placed in a corner ...

Страница 77: ... under test α Description of Room 0 05 Nearly empty room smooth hard walls made concrete brick plaster or tile 0 1 Partly empty room room with smooth walls 0 15 Room with furniture rectangular machinery or industrial room 0 2 Irregularly shaped room with furniture irregu larly shaped machinery or industrial room 0 25 Room with upholstered furniture machinery or industrial room with small amount of...

Страница 78: ...xceed 1m For indoor measurements wooden and tile floors are also permitted No reflecting parts that are not part of the source under test shall be located within the measurement surface The K2A factor e environmental correction factor K2A accounts for the influence of undesired sound reflections from room boundaries and or reflecting object near the source under test e magnitude of this factor dep...

Страница 79: ...K2A 10log 1 4S A dB K2A 10log 1 4 S T 0 163 V dB based on an actual reverberation time measurement Test room qualification requirements For the measurement surface in a test room to be satisfac tory for measurements in accordance with the require ments of the ratio of the sound absorption area A to the area S of the measurement surface shall be equal to or greater than 1 that is A S 1 e larger the...

Страница 80: ...by 4 e instrument will now enter the measurement control display 3 e Nor118 allows 1 40 microphone positions to be measured e initial measurement control display shows 8 positions but this may be extended to further pages covering the positions 9 40 by pressing the key next page 4 At the bottom of the screen the averaged sound pres sure level based on the measured microphone positions is displayed...

Страница 81: ...or in a corner Use next and previous to go between pages After a suc cessful set of measurements has been made the results are presented like this upon press ing the TBL key Although only 8 microphone positions are shown there are further pages so that a total of 40 microphone positions can be covered Use the key The measurement control display The results can also be printed out Turn to Making ha...

Страница 82: ...oor in m2 Hemisphere S 2πr2 Calculating the S When measuring in accordance with the ISO3746 the environmental correction factor K2 is obtained from this graph by enter ing the abscissa with the appropriate value of A S α Description of Room 0 05 Nearly empty room smooth hard walls made con crete brick plaster or tile 0 1 Partly empty room room with smooth walls 0 15 Room with furniture rectangular...

Страница 83: ...st object must be keyed in e calculated area S of the total measurement surface will then be displayed 3 Finally key in the acoustic environment correction 2 Sound power results Based on the averaged sound pressure level of all the microphone positions the measured background noise level and the selections and corrections made in the sound power setup menu the Nor118 will display the final W To se...

Страница 84: ...ory intended for storage of measured data is approximately 5 megabytes is is a number which says more or less noth ing to most people since it reveals nothing of the number of bytes required to store the measured values etc Let us therefore provide a few examples Example 1 e memory can hold more than 10000 global measurements with all available global functions and distribution when frequency anal...

Страница 85: ... examples of settings not read back However all settings of functions and parameters used in the measurements are read back Storing a measurement Once a measurement has been made it can be stored in the non volatile memory for future use To store the data Press the key after a measurement e data will now be stored in a folder with the name of today s date If this folder didn t exist it will be cre...

Страница 86: ...t shown as white text on a black background Press the key You will now be prompted to confirm your action However as default the cursor is positioned on the field to avoid erasing the wrong file 2 Use the keys to move the cursor to and press again e file is now deleted Once you ve pressed the RE CALL key the display wil show a list of folders and the con tents of one of them here this is the folde...

Страница 87: ...at you are displaying ere fore in order to clear this file press before you enter the menu All file names i e file num bers have a letter as suffix is letter indicates the measure ment mode F means frequency analysis but no profile L means that the file contains a simple global measurement but no frequency analysis and no profile M means a multispectrum measurement P means a measurement made in so...

Страница 88: ... on the paper e difference between the printers lies mostly in such things as character size and width which determines the number of characters that fit on a page erefore we recommend that you make a few experi ments with the setup and your printer to find the driver that produces the best looking printouts Setting up for printouts e setup for printouts is made in the IO Print menu To set up for ...

Страница 89: ...m You decide what to print by what you display by the time you press the key is means that to print the spectrum you must display the spectrum on the screen to print the profile you must display the profile and so on Norsonic AS Sound Power Measurement According to ISO 3746 EN 23746 Page 1 of 2 General Information and Overall Results Sound source Manufacturer Type Ser No Dimensions l w h Year of m...

Страница 90: ...ure for another period of the same duration and then store the acquired data start again and so on e snag however is that a little time will always be spent on storing the acquired data is means that if you for example set up the instrument to measure in periods of an hour and start the measurement exactly on the hour the measurement period start time will exhibit a lag after some hours of measuri...

Страница 91: ...ore e succeeding period will then each be very close to an hour long to enable restart again at etc Now what happens if you select a period duration whose multiples fail to match one hour If you set up the period duration to say minutes and start the measure ment the instrument will measure in periods of minutes and seconds to enable a restart exactly minutes after the previous period started Howe...

Страница 92: ...f applicable e functions to be measured requires extension and or e need for statistics if applicable e type of outdoor microphone unit for semi perma nent or permanent installations Adaptors needed if applicable Cabinet or casing required for the sound level meter Cables and cable lengths External power to the instrument batteries or mains connection Type of connection to remote modem modem direc...

Страница 93: ...d from remote For a complete list of remote control commands contact your local representative or the factory Mini D sub 1 8 9 15 Pin out of the cable Nor1441 the other end is standard fit ting directly into your Pin Signal Dir Remarks 1 DO 1 Out Digital output 2 DO 2 Out Digital output 3 DO 3 Out Digital output for calibration only high calibration ON 4 DTR Out RS232 5 TD Out RS232 6 PWR Out 3 3V...

Страница 94: ...ent may vary Please check with your local supplier for the latest information Type of instrument Sound level meter measuring exponential time weighted levels integrating averaging levels and sound exposure levels If octave band or 1 3 octave band filters are installed the instrument complies with and Analogue inputs Number of channels 1 Input connector 7 pin connector for Norsonic microphone syste...

Страница 95: ...sion e analogue input signal is converted to a digital signal by a multirange sigma delta converter with an effective sampling frequency of 48 kHz e anti aliasing filter is a combination of an analogue and a digital filter Frequency weightings Simultaneous measurement of and weighting or and weighting octave band or 1 3 octave band levels may be measured simultaneously if options providing these w...

Страница 96: ...ave or 1 3 octave filters if present and used in a measurement Class width 0 2 dB Number of classes 652 for levels between 10 dB above full scale 140 dB and 120 dB below full scale 10 dB e classes for the highest and lowest levels are extended to also include levels above and below respectively Sampling frequency for level 10 samples per second Display resolution 0 1 dB based on interpolation Indi...

Страница 97: ...ed Σ may be set from 1 second up to 100 hours less 1 second with 1 second resolution e global period may be subdivided in shorter periods designated time resolution from 1 second up to the global period As an option the time resolution may be set in an additional range from 100 millisecond and upwards to 1 second in steps of 25 millisecond Total range for measurement of A weighted levels e linear ...

Страница 98: ...ation within the stated specifications e maximum battery voltage for conformance testing is 4 1 6 V 6 4 V e instrument has a calendar clock with a typical lifetime of more than 10 years Contact your Norsonic service department for change of this component After replacement the instrument need factory calibration and to re install the options Display e display is a monochrome transreflective graphi...

Страница 99: ... below Activating windscreen correction Press 1 Instr 6 Correct to gain access to the Corrections menu Navigate in the menu as usual and activate the correction parameter Windscr by means of the and keys Do the same to deac tivate Windscreen correction activated is indicated by a W in the lower line of the display High levels As an option the instrument may measure levels 10dB higher than stated a...

Страница 100: ...lifier By lowering the polarisation voltage the level range can be extended without chang ing the microphone cartridge This feature shall be used in combination with the Nor1225 cartridge only Note that the needed correction will depend on the type of microphone and shall only be applied when using microphone cartridge type Nor1225 Activating the high level range Press 5 Lvl range to gain access t...

Страница 101: ...ally for the self noise of the microphone e noise levels for each of the spectral weightings must be specified e correc tion is applied by unlinear level subtraction e option allows levels close to the self noise to be displayed with reduced level linearity error When the level is equal to the self noise level the correction is 3 dB Diffraction around the instrument casing e instrument casing is d...

Страница 102: ...ce 100 ohm If not rede fined by remote commands DO 3 will go high when the calibration mode is enabled Microphone heating e microphone preamplifier Nor1206 contains a 225 ohm resistor suitable for heating the microphone preamplifier A floating voltage supply in the range 0 12V may be con nected between pin 10 and 11 As the lines will be in direct contact with the signal ground on the preamplifier ...

Страница 103: ...re 30 C to 60 C Humidity 5 to 90 RH dewpoint less than 40 C Atmospheric pressure 50 kPa to 108 kPa Warm up time The warm up time for the main instrument without preamplifier microphone is very short and the instrument obtains the final accuracy as soon as the self test is made Used with a preamplifier and microphone this time is prolonged due to the charging of the microphone with the polarisation...

Страница 104: ...nal symmetry for the microphone and preamplifier Battery voltage e instrument will automatically switch off if the battery or external voltage is too low for operation within the stated specifications e max bat tery voltage for conformance testing is 4 1 6V 6 4V Electromagnetic Compatibility When the instrument is tested for conformance to electromagnetic compatibility requirements the instrument ...

Страница 105: ...I S1 4 1997 type 1 random incidence correction 86 Attenuation compensating for preamplifier attenuation 16 88 Automated storage of measured data 78 B Back erase and statistics 4 and time profile mode 38 detailed presentation of the principles behind 21 Background noise reverberation time 53 sound power 68 Backwards integration 53 Basic time profile measurements 35 and multiple time constants 39 an...

Страница 106: ...ut impedance 90 DIN45657 84 Display of functions measured in the sequence they appear in global measurements 21 of the basic time profile 39 in enhanced profile 43 returning to live display after a measurement 21 technical specifications 86 Displaying functions measured in global measurements 20 in enhanced profile 43 Display topscale setting 20 DO 1 81 DO 2 81 DO 3 81 DSR 81 DTR 81 Duration of ba...

Страница 107: ...tiple time constants frequency analysis 31 the sequence they appear in frequency analysis 31 to log in enhanced time profile 40 G Gain accuracy AC out 90 analogue output 90 Global measurements absolute vs relative time 20 activating frequency mode 27 and statistics 18 and units configured for German speaking markets 22 frequency analysis 31 back erase feature in detail 21 displaying functions meas...

Страница 108: ... input section 83 High levels by reducing polarisation voltage 87 HP DeskJet 76 HP inkJet 76 I IEC61672 1 82 IEC 61672 19 Indication range 84 Inherent noise compensation 89 Instrument codes 9 ISO 3476 58 ITT Cannon MDSM 15PE 250 8550 021 89 K Keyboard lockout 79 Key microphone positions hemispherical surface sound power 61 L Least square fit 53 LEMO socket microphone input socket pinout 83 Level d...

Страница 109: ...ts in basic time profile 39 in enhanced profile 41 Multispectrum measurements 46 switching between global and profile 49 N Noise monitoring automated storage of measured data 78 things to consider 78 Nor1206 84 Nor1225 84 Nor1441 cable 81 Nor1489 cable for GSM modems 81 Nor1490 cable 81 Number of microphones sound power 68 O OL appearing in table reverberation time 57 Options available 9 checking ...

Страница 110: ...nd power 58 Reference Level Range 92 Reference Sound Pressure Level 92 Relative time 6 Relative vs absolute time in global measurements 20 Repeat storage mode 79 Reset the entire memory 75 Resolution of basic time profile measurements 38 of enhanced time profile measurements 41 better than 1 second 42 Resume an ended measurement frequency analysis 29 global measurements 21 a paused global measurem...

Страница 111: ...surface 62 rectangular parallelepiped 58 reference box 58 reference box requirements 58 results of a measurement 71 survey method 66 approximate method 66 test report requirements 58 Source coding See Markers Spatial averaging and backwards integration method 53 Spectral weightings technical specifications 83 Spectral weighting function selecting Z or C in global mode 19 Z or C 3 Spectrum A weight...

Страница 112: ...al mode 19 statistics and multiple time constants 19 Time constants technical specifications 84 Time profile measurements and pause 36 basic version 35 consider the resolution 36 display of the basic profile 36 enhanced profile 40 See also Enhanced profile logging the spectrum vs time 46 basic profile 46 enhanced profile 46 making 38 multispectrum measurements 46 pause marker 38 setting duration i...

Страница 113: ...manufactured in compliance with the provisions of the relevant internal Norsonic production standards All our products are tested individually before they leave the factory Calibrated equipment traceable to national and international standards has been used to carry out these tests is Declaration of Conformity does not affect our warranty obligations Dagfinn Jahr Quality Manager Tranby November 20...

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Страница 116: ...Your approach to the Nor118 documentation depends on what you want to do and how much you already know The User Documentation has been designed to help you get more benefits from all the analyser s features in less time than ever before Need to start by understanding the ideas behind the analyser s design Read the Introducing Nor118 section This section outlines in just a few pages all the funda m...

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