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Bedrock SM50 operating manual 

      

 

     © Embedded Acoustics BV,  2015   

 

 

 

    

SPL meter

The SM50 is also Sound Pressure Level meter (also known as SPL meter or SLM) that 
complies with IEC 61672 Class 2 and ANSI S1.4 Type 2. In fact, the SM50 electronics far 
exceed the requirements for a Class 2/Type 2 device.

The layout and buttons of the SPL meter module are similar to the STIPA modules, featur-
ing three screens: SPL measurements, settings and browse measurements.

SPL measurements screen, during measurement (left) and with settings keyboard showing 

(right)

The following sound pressure level measurement settings are supported:

• 

Time weighting: Fast (F) and Slow (S)

• 

Frequency weighting: Z (linear, unweighted), A-weighted, C-weighted

• 

Max hold (holds and displays the maximum level during the measurement 
interval; used with either Fast or Slow time weighting)

• 

Equivalent continuous (EQ): computes the time-integrated level over the 
measurement interval; the level shown corresponds to the level of a contin-
uous signal containing the same amount of energy as the measured signal.

• 

Peak values (PK): the highest instantaneous value within a measurement 
interval.

Note that MAX and PK are not the same; MAX represents the highest measurement over 
a short time averaging period (either FAST or SLOW), and PK represents the highest 
instantaneous  value in the signal (even if this is a peak of very short duration). The SM50 
allows PK measurements in combination with any frequency weighting, but only LCPK 
is commonly used.

Summary of Contents for SM50

Page 1: ...Bedrock SM50 Operating manual 2015 Embedded Acoustics BV Document version 1 4 IEC 60268 16 rev 4 IEC 61672 Class 2 ANSI S1 4 Type 2 ...

Page 2: ...com Phone 31 88 8770700 Fax 31 88 8770799 Email support bedrock audio com Updates of the system s firmware and documentation are released online www bedrock audio com NOTE Screenshots and product pictures shown in this manual correspond to the SM50 hardware platform 1 0 running firmware version 1 4 Once you update the firmware the screenshots may not fully correspond to what is being displayed on ...

Page 3: ...12 SPL meter 16 Real Time Analyzer RTA 19 Settings 21 Calibration 24 Status 26 Accessing saved measurements from a PC 26 5 Power and charging 28 Charging instructions 28 Power saving recommendations 29 Use of power banks and external battery packs 29 6 Cleaning maintenance and calibration 30 Battery disposal 30 7 Product warranty 31 8 Firmware updates 33 9 Buttons icons and symbols 34 10 Technical...

Page 4: ...ing the SM50 is quite easy thanks to its touch screen operation and intuitive menu structure Most users will get the hang of doing measurements with the SM50 without spending much time with this manual Nonetheless we strongly recommend that you do read through this manual before starting to use your SM50 in order to get acquainted with the various features of the device and the procedures for char...

Page 5: ... adapter suitable for your region Make sure that the device is switched off before transportation and storage During transportation and storage keep the device in a suitable casing or container preferably its original case The device needs to be protected from shocks and vibration due to transportation or falling excessive tem peratures liquids and moisture and any other external conditions that c...

Page 6: ...t these connections are protected against overvoltage and power surges The voltage supplied to the USB port should not exceed 5 5V As the USB power circuitry is connected to the battery pack excessive voltage applied to the USB port may cause the battery pack to catch fire or explode The XLR connector supplies 48V phantom power to the microphone This phantom voltage can be switched on and off thro...

Page 7: ... seconds in the power on state the device will be forced into the off condition This can be used to reset the device if it becomes unresponsive keep pressed to 10 seconds to switch off then press again to restart The SM50 will boot into the main menu You can launch its different modules from this menu STIPA pro app that gives you access to all STI measurement details Quick STIPA simple app to quic...

Page 8: ...ed a source of the STIPA test signal as well as an STI analyzer In your case the analyzer is your SM50 You can choose whatever type of STIPA signal source that suits your application best TalkBox media player or otherwise The Embedded Acoustics reference STIPA test signal is included with the SM50 on a USB flash drive and can also be downloaded from the Bedrock website free of charge This is a ful...

Page 9: ...ase consult tutorials and standards to make informed decisions about the STIPA signal playback level measuring positions number of repeated measurements etc The Quick STIPA module also shows some additional measurement information The A weighted sound pressure level The qualification band a letter between A and U that is used in some standards and defined in IEC 60268 16 rev 4 A label bad excellen...

Page 10: ...progress bar The save button is only operational when new unsaved measurement data is available from a finished measurement If this is not the case the save icon is colored gray The qualification band a letter between A and U is just a different way to represent the STI number it is fully redundant We currently recommend working only with the STI value itself unless the use of qualification bands ...

Page 11: ... Embedded Acoustics BV 2015 11 A crossed out STI value means that the measurement is not yet sufficiently reliable ...

Page 12: ...add to data Browse measurements review saved measurements Measurements are usually started from the STI and spectrum or the measurement de tails screen STI measurements are set up and started in the same way as when using the Quick STIPA module see above However in the STIPA pro module more details about the measurement are shown and the user has more elaborate options to configure the measurement...

Page 13: ... also shown mf TI the Transmission Index per octave band for each modulation frequency These measurement details will enable more experienced operators to determine not only the speech intelligibility of the tested channel but also the causes of intelligibility reduction induced by the channel Settings screen The settings screen gives the user three options Choose whether or not to display STI qua...

Page 14: ...d STI If you wish to add noise computationally the screen additive noise should be used to en ter the noise spectrum Note that the noise spectrum that you enter is only used if you also select the corresponding option in the settings menu entering the spectrum is not enough you also need to turn the additive noise feature on via the settings screen Additive noise screen A few remarks about adding ...

Page 15: ...surements saved in Quick STIPA can be browsed in STIPA pro and vice versa The measurement numbering range is shared between these modules This means that you can use STIPA pro to investigate measure ments done with Quick STIPA in more detail using the browsing screen in STIPA pro The settings you choose in STIPA pro additive noise level dependent masking affect the current measurement but also aff...

Page 16: ...y weighting Z linear unweighted A weighted C weighted Max hold holds and displays the maximum level during the measurement interval used with either Fast or Slow time weighting Equivalent continuous EQ computes the time integrated level over the measurement interval the level shown corresponds to the level of a contin uous signal containing the same amount of energy as the measured signal Peak val...

Page 17: ...tic level that the microphone can handle overload Both types of range warnings are shown as a warning label next to the corresponding measurement value Range warnings are shown in both level fields if the signal level is either too low or too high such as in this example The limiting factor for the overall dynamic range of the measuring system is usually the microphone If the standard microphone i...

Page 18: ...asuring continuously the battery is drained relatively quickly within 3 4 For longer measurements we rec ommend using the charger or an external power bank Internal data storage especially if you are recording all measure ment audio per the option in the Settings module When re cording audio the internal storage fills up in about 5 hours When you press save data from the current measurement is sto...

Page 19: ...s The corresponding broadband levels are also shown to the right of the spectrum While the spectrum graph already gives a first impression of the spectral content of the measured signal you may wish to read the exact value in each band This is done by placing the cursor dashed line over the band of interest The cursor can be moved left and right by pressing on the left or right side of the frequen...

Page 20: ...wever data recalled through the measurement browser are shown with the frequency weightings selected at the time the measurement is recalled even if these are different from the settings that were in effect during the measurement This allows you to inspect the effect of frequency weightings on all measurements saved previously Note that the spectrum and its corresponding broadband level are affect...

Page 21: ... internal real time clock that keeps running even when the device is powered off The clock needs to be adjusted if the battery has been depleted completely for instance when the device has not been used for a very long time The system date and time are used for time stamping the saved data If you download measurement data over USB the file creation date time are only accurate if the internal real ...

Page 22: ...rophone you can choose adjust the pre amp gain by choosing between 0 dB and 20 dB default Note that recalibra tion may be needed when changing With the standard microphone this setting should be 20 dB You can also set the backlight to automatically switch off if the touch screen has not been touched for a while This time out can be set between 30 seconds and 30 minutes or the backlight can be set ...

Page 23: ...his setting With firmware version 1 4 or higher a menu named audio recording is available Once audio recording is enabled the audio of each and every measurement is recorded onto the internal storage of the SM50 in wav format calibrated to 150 dB SPL at full scale Note that this uses up significant amounts of storage space Once enabled from the settings tab audio will be stored whenever saving a m...

Page 24: ...ndors These calibrators generate a test tone which is adaptively adjusted to a fixed accu rately know signal level usually 94 0 dB This makes calibration relatively easy insert the microphone tip into the port of the calibrator using an adapter with suitable dimensions for the microphone tip 1 4 7mm The device should now measure the nominal signal level produced by the calibrator The SM50 is easil...

Page 25: ...onnected a different signal source or microphone than the device is currently calibrated for The calibration factor is derived from the measured LAeq as well as the reference level of your calibration signal source You can now change the reference signal level press the corresponding button on the right of the screen and enter the correct value through the keypad that will appear on your screen Th...

Page 26: ...st as a mass storage device This allows you to access the internal file system of the SM50 You will see these directories folders Battery battery status information Calibr Calibration data SPL SPL measurement results STIPA STIPA measurement results RTA RTA measurement results System system files Updates place update packages here to update the firmware upon reboot IMPORTANT you can access the SM50...

Page 27: ...some versions of Excel and may require more attention in other versions of Excel If you are having problems import ing the output files into Excel import the files as text files rather than csv It may help to rename the files to another extension than csv e g txt Stored audio recordings are found in the same folders as the csv files with measurement data The following applies to stored audio recor...

Page 28: ... for a prolonged period you can safely keep the SM50 connected to a charger A few charging tips A LED next to the USB shows the charge status While blinking alter nating between green and orange the battery is still charging The LED burns constant green as soon as the battery is full If you find over time that the battery capacity is reduced significantly com pared to its original capacity we reco...

Page 29: ...can be carried out over the course of an 8 hour day without recharging Some ways to extend the battery life Switch off the device when you do not plan to use it for a while Choose conservative power settings in the hardware menu The LCD back light is a considerable factor in the overall drain on the battery Disable pre amp phantom power if you use a microphone that does not need it Use of power ba...

Page 30: ... screen provided that the following precautions are taken Do not spray cleaner directly onto the display Only use cleaning liquids specifically intended for LCD screens Battery disposal The device contains an 4 8v rechargeable NiMH battery pack At the end of the life cycle of this product care should be taken to dispose of this battery pack responsibly in compliance with rules and regulations for ...

Page 31: ...l our warranty programme covers all defects except for those resulting from acci dents misuse including improper electrical connections and improper maintenance The following is explicitly excluded from product warranty Any damage resulting from dropping falling or excess vibration Any damage done by liquids including damage resulting from excessive use of screen cleaning liquids Any damage result...

Page 32: ...urself as there are no user serviceable parts inside If you do see a legitimate need to open the device yourself please contact warranty bedrock audio first so we can discuss preserving your warranty rights Please be aware that the product is protected by tamper proof seals A worldwide pick up return service is included in the warranty This means that we will have the defective unit picked up at y...

Page 33: ... from www bedrock audio com Connect the SM50 to any PC or Mac through USB When prompted on the LCD screen choose connect through USB The SM50 s internal file system can now be accessed from your computer in the same way as any mass storage device Copy the firmware updated package to the folder named updates Now restart the SM50 using its power button The firmware update procedure will automaticall...

Page 34: ...een finished Measurument running Showing while recording is running Audio recording indicator Showing if audio recording is enabled NB tap save to store Remaining battery charge Battery charging Operating on external power 0001 Measurement number Serial number of current measurement Instrument busy Occurs when switching modules Menu navigation Tap arrows to flip through menus red block indicates p...

Page 35: ...udes the effect of additive noise according to the noise spectrum entered in the additve noise menu Adjust graph scale up down SPL meter module Overload indicator Underrange indicator Set time and frequency weightings Settings keyboard appears upon tapping this button RTA meter module Move cursor through frequency bands Tap left to move to lower frequencies right to move to higher frequencies NOTE...

Page 36: ...screen 320x240 pixels 65k colors Luminance typ 250 Cd m2 Durability 100k finger slides 1M taps Data storage 4 GB internal storage for data and firmware Accessible from PC through USB mass storage mode Environmental Temperature 5 35o C 41 95F Relative humidity 5 90 non condensing Power NiMH battery pack 4 8V nominal typ 2200 mAh Typical battery lifetime 4h Max charge current 1 8A Electromagnetic co...

Page 37: ...onged shelving Completely drain the battery and then fully recharge Repeat if necessary Device warms up during use Lack of ventilation Warming up of the device to temperatures of approx 35C 95F is normal If the de vice runs considerably hotter than that check ventilation and contact support if the problem persists Device not recognized by PC when connected through USB Driver problem Device in meas...

Page 38: ...which this declaration relates is in conformity with European Harmonised Standards as published in Official Journal of the EC Issue N A Issueof publication of the list of harmonised standards The compliance of the product has been based on the following standards EN 61326 2006 EMC Emissions EN 61326 2006 EMC Immunity EUT is suitable to be applied in residential and light industrial environments Ti...

Page 39: ... Embedded Acoustics BV 2015 39 ...

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