Nor-121 Environmental Noise Analyser

"Design the most advanced environmental noise analyser the world has seen!"
When we sat down to do just that, we had already been in dialogue for a long time with many of our customers to learn what it takes to accomplish this goal! And this is it - the Nor-121. A lightweight, rugged and hand-held analyser with 80 or 120dB dynamic range, built-in hard disk and PC-card slot. Displays and menus can be set in several languages. With the Nor-121 you can measure and record more than 1300 functions and parameters - there is a function for every need! Semi-permanent noise monitoring, permanent noise monitoring or just regular measurements there and then - with or without frequency analysis, annoyance recorder function, pure tone detection and determination, you name it. The Nor-121 fits in everywhere! We've even added features for indoor use! Your Nor-121 can also do building acoustics - sound reduction and reverberation time - in two channels! As for all our analysers, many of the features in the Nor-121 are optional and can be added upon order or as retrofit whenever required. In this way you don't pay for features never used. With this article we would like to introduce you to the Nor-121 and explain to you some of its unique features. The Nor-121 can be what you want it to be for you, with its multitude of possibilities combined with the ability to create user-defined setups. Made to measure - by you!
Summary of features
Specifically designed for environmental noise assessments Records the sound signal itself Stand-alone building acoustics mode - no PC needed Pure tone detection mode Parallel measurement reports with six levels of nesting each having individual time settings plus profile and event based data Real time frequency analysis (0.1-20 000 Hz) in octave and third octave bands with the results as instantaneous, Leq or percentile spectra Measures all time constants and the A, C and Linear weightings simultaneously High dynamic range - optional 120dB dynamic range Full size graphics display with backlight Internal hard disk and standard PC card for the storage of data Results can be exported via the PC slot, RS-232 serial or the Centronics parallel ports Advanced trigger functions Comprehensive marker functions with user selectable data labels Powered by long life rechargeable batteries or from external 11-18 V supply Internal oscillator to support automatic calibration of Norsonic weather protected microphone systems Accepts weather data from approved meteorological stations and integrates the results into the measurement files Allows the measurement in broadband and frequency domain of structural vibration levels.
A report is available for every environmental noise measurement application
The Nor-121 is report oriented. This means that it has been designed to provide you with reports on the environmental noise level rather than being just another sophisticated sound level meter. The Time Profile The (time) profile is the basis of any Nor-121 measurement. The Profile time resolution can be set from 10ms to a hundred hours, with a step size of 5ms for resolution settings below 1s. For resolution settings of 1s and above the step size is 1s. Profile lets you log a multitude of functions as they vary with time. Many of these functions can even be logged as octave or third octave spectra. The Global Report The Global report yields a single set of measurement values describing the entire measurement. Such values will typically be the LEQ, the SPLmax, the SPLmin etc. of the entire measurement as well as an octave or third octave spectrum. This is equivalent to the way a traditional sound level meter works. The Reports 1-5 The Reports 1-5 can be set up by you to provide more information than the Global, yet less than the Profile. Consider the following example: Assume that the analyser is set up for a 24 hours measurement with a Profile resolution set to 1 second. The Global will then provide the overall values for the measurement and the Profile will provide very detailed information. Further assume that we want to generate reports splitting the 24 hour period into day and night; business hours, evening and night; hourly reports, 30 minutes reports and finally even 15 minutes reports. For this we will use the Reports 1-5. If we set Report No. 1 to 12 hours which we then may refer to as either resolution or period length; Report No. 2 to 8 hours; Report No. 3 to 1 hour; Report No. 4 to 30 minutes and Report No. 5 to 15 minutes we have achieved this. Note that we have not packed the Profile data into hourly reports etc. The Report 1-5 live their own lives with their own functions defined separately. Total Flexibility The finest resolution available for Report 1~5 is determined by the Profile resolution you set up. This can be different from one measurement to another. The flexibility is total! The measurement duration need not be a multiple of the Profile resolution or a multiple of any of the Report resolutions! Likewise, a Report need not have a resolution that is a multiple of the Profile resolution! Each of the measurement report types can be set up to measure a multitude of functions simultaneously. The Global and the Profile can be set to measure the same or different functions - no restrictions apply. The Report 1-5 can be set to measure functions that are similar to or different from Global and/or Profile. Report 1-5 must, however, all measure the same functions, they cannot be set up individually. As a consequence of this, any of the Report 1-5 can be set to an arbitrary value (like 6 hours 23 minutes) regardless of what the other reports are set to, but the resolution cannot be better than that of the Profile and the functions measured will be the same for all the Report 1~5, but these may differ from the functions and resolutions used with Profile and Global! Extensive pause and continue functions are available. When paused the instrument will produce the time profile for the latest twenty seconds of the measurement. The time cursor can then be moved backwards in one-second steps before the measurement is resumed. Data acquired later than the adjusted time cursor position (i.e. data appearing to the right of the time cursor) will be erased from the measurement. Note that this applies to any statistics activated as well! You may also resume (and hence prolong) terminated measurements. The duration may be synchronised with the real time clock (the time of day) to maintain that measurements keep ending e.g. every hour on the hour, regardless of time elapsed between termination and resumption. To further enhance the concept, a timer function is available to control when the measurements are to be made and when the instrument is to remain inactive. This opens up for making automated measurements on e.g. weekdays only, leaving the instrument inactive during the weekends!
Functions follow design
What is a function? In the Environmental Noise Analyser Nor-121, the term function denotes the combination of RMS or peak detection employing certain time constants and certain spectral weighting functions involving the measurement duration whenever relevant. Sometimes, the time constant is not applicable and sometimes there is no spectral weighting involved. Typical examples of functions will be the A-weighted integrated equivalent sound pressure level the LAeq, the C-weighted SPL measured with F time constant, etc. The Nor-121 is able to measure and calculate more than 1200 different functions! However, they are all based on one of the following six data types: SPL The Instantaneous Sound Pressure Level LMAX The Maximum Sound Pressure Level LMIN The Minimum Sound Pressure Level Leq The Integrated Equivalent Sound Pressure Level LE The Sound Exposure Level LPEAK The Maximum Peak Level To form a function you combine a data type with a time constant: F, S, I; and a spectral weighting function: A, C, Flat, octave or third octave band frequency analysis. The forming of a function can be expressed graphically using a three-dimensional function space. Filling in the three dimensions with the data types, time constants and spectral weighting functions available, we arrive at the Function cube.
The Function cube expresses a three-dimensional space with the data type (e.g. SPL), the time constant (e.g. F) and the spectral weighting (e.g. A-weighting) as the dimensions. A function will then be a point in this space. Note that not all the points in this space are defined. For example, the (normal) LEQ has no time constant and for the Nor-121 the peak is not defined in octave and third octave bands.
So far we have yet to describe the statistics features. In the Nor-121 statistics are always based on SPL with a user-defined time constant. Hence, the statistics appear as a subgroup of the SPL, which is why it has not been included explicitly in the Function cube. Statistics can be presented in several ways - as statistical and cumulative distribution, but also as percentiles. There are 8 percentile settings available, selectable within the range L0.1 to L99. However, since the cumulative distribution forms the basis for the percentiles this graph can be used to find any percentile. To add flexibility, you may even set up the instrument to log a percentile as a function of time or frequency! Which percentile is, of course, entirely determined by you! To avoid getting totally lost when the degrees of freedom are so numerous, a set of predefined setups is available. Build your own setups from scratch or modify any number of the predefined ones and store these as your own personalised setups, thereby tailoring the instrument to match your very own needs!

The ability to display all the acquired data without sacrificing the overview

The Nor-121 is capable of measuring all the commonly encountered functions as defined by various IEC and ISO standards. Many of the functions may be measured using all the three time constants (F, S and I) simultaneously. Furthermore, most of the functions are also available with A and C type spectral weighting (in addition to no spectral weighting at all) - still in parallel! If you then add the ability to do parallel frequency analysis of a series of functions, you'll end up with more than 1300 functions available for measurement! To display all these functions the Nor-121 has five display formats: The function list Graphical level vs. time Graphical level vs. frequency (i.e. the spectrum) Cumulative statistical distribution Statistical distribution All displays are available as numerical tables (not shown) as well. Just press the Num key to switch to numerical and press again to return to graphical presentation. The function list provides a list of those six of the functions logged that you consider to be the most prominent functions. The functions available for display as level vs. time and level vs. frequency are taken from this list. Although it may look numerical, the function list is considered to be graphical, hence you may press the Num key to produce a numerical list of all the functions activated. The statistics functions (distribution and cumulative distribution) are based on the SPL with a specified time constant (F, S or I). In addition a total of 8 percentile settings can be defined. These will appear as functions available. To further add spice to this, there is, of course, one set of display formats per report type. All in all, this means that any given display format will be a function of the measured function and the report type (Profile, Global, Report 1-5).

Source coding, adding markers to the measurement

While measuring with the Nor-121 you may tag or code sources as they happen. A one-digit code (0-9) can be keyed in to later serve as an identification of the type of noise. This can also be referred to as adding a marker to the measurement. The source codes are therefore called markers in the Nor-121 menus. For e.g. traffic noise measurements a bus passing may be identified by the digit "0" while private cars may be identified by the digit "1", trucks "2", unexpected vehicles "3" and so on. In the level vs. time display the markers applied to the measurement are indicated by lines. For mnemonic reasons you may assign names to the markers. These names will appear in the instrument's display. You access the menu for setting this up by pressing Setup followed by the softkey Marker. This menu is separated from the Measurement control and the Trigger menus and all but one of the items must be set up before you make a measurement. The one is that you may change the names of any of the markers during a measurement. Note that if you do so, all the markers of that number will assume the new name assigned. Even those entered prior to the name change! This comes from the way the system works. The name is picked from the marker table each time the instrument needs to display a marker's name, hence the current setting will apply to the entire measurement. On the other hand this makes a redefinition very easy to do. Display showing level vs. time (C-weighted Leq). Applied markers are indicated as lines in the upper part of the L(t) graph). If you move the cursor onto any of them, the marker type will be shown using the mnemonic name you have assigned to it. This setup menu also provides the option to decide whether any of the markers also should be used as extra trigger controls for events and sound recordings. If you decide to use a marker as event and/or recording trigger control, it will appear in addition to (i.e. in parallel with) any other criteria established. In the Nor-121 markers come in two flavours, as single or toggle type markers. The single type markers add a marker (of the number you pressed) to the current profile period, while the toggling type remains on and therefore will be assigned to all the periods elapsing until the same marker key is pressed again. Type assignment is also made in the Setup/Marker menu. This must be set up prior to the measurement. You may introduce an automated time shift for the starting moment of a marker. The incident that you want to tag will in most cases have started already when you finally manage to press the marker key. A typical example could be a dog's barking. For long or detailed measurements containing a large number of periods you may want to use computerised automated postprocessing. This may include special handling of tagged intervals - such as excluding certain of them (maybe the barking dog?). It is then important to exclude the entire incident and not just the part of it that you managed to tag. This can be prepared for by specifying a Delta t in the Setup/Marker menu. The time shift range available is -5 to 0 seconds in one second steps.

Noise from the factory again... or was it a dog this time?

The Nor-121 is a powerful environmental noise monitoring device. The vast number of functions it can be set up to measure is one side of it, but just as important is the sophisticated event handling system and the built-in timer function. For the Nor-121 an event is a significant change in the sound level for more than a minimum period of time. The amount of level change required is predefined by you. Whenever an event occurs the instrument will log certain functions which either it does not log outside events or, these functions are logged with a different time resolution to provide more detailed information. The concept is to go for the details whenever important and correspondingly reduce the amount of information received the rest of the time. Traditional event handling deals with levels exceeding a predefined level threshold for a certain minimum of time. However, in the Nor-121 this has been expanded to include the inverted situation; i.e. that the level drops below a certain threshold (for a certain predefined minimum period of time). We have also taken this even further to include the situation where an event is defined as when the level stays between an upper and a lower boundary for more than a predefined minimum period of time. Events can be defined as taking place when the sound level exceeds a threshold, as soon as it drops below a threshold or, as shown here, as long as it stays between an upper and a lower boundary! In this way noise monitoring of an industrial plant can be made while a) the plant is running, but b) no trains are passing, for example. The Nor-121 event setup even includes the possibility of relative trigger, so that a single threshold may be used 24 hours a day. The relative trigger is specified as an offset from the measured level value of one of the measured functions. If the threshold is kept constant and the background level remains unchanged, no unintended triggering will take place (top). However, a significant change in the background level may ruin this (middle) unless the threshold is made dynamic by adapting to the current situation (bottom). This is called relative trigger. You may select which function to serve as the relative trigger condition! Furthermore, the criteria used to determine when an event is assumed to have terminated, may be set to something completely different from the start criteria and to make sure you get the whole picture you may set the trigger to be effective up to five seconds before the trigger condition is fulfilled! Recording the Sound Itself Setting up the analyser for recording of the sound itself is similar to event handling in the sense that you specify the criteria for sound recording to take place, in a menu almost identical to the event setup menu. In addition, you may set the recording to follow the event setup, i.e. whenever an event occurs sound recording is started. By connecting a pair of headphones to the rear panel Signal out terminal you may listen to the recorded sound. Since the instrument provides a large dynamic range, a gain setting has been added to enable convenient volume setting when listening to the recorded sound. Did we mention that you may even record what took place up to five seconds before the sound recording was supposed to start? Timer The Nor-121 has a built-in timer to enable delayed start and to enable that measurements shall take place in certain parts of the day/week etc. In this way the Nor-121 may restrict its monitoring activities to take place only during business hours etc.

Heard from you remote unit lately?

Imagine an environmental noise monitoring system sending you SMS messages to inform you about the measured noise level throughout the day! Or, reporting the status of its batteries! You know the system is working, because it just told you so. No longer will you have get in your car and drive, maybe for hours, just to check that everything is working as supposed to! All this takes is the Nor-121, a GSM modem and a weather-proof enclosure like our Nor-1506 system designed for semi-permanent use. For permanent monitoring applications, Norsonic offers a variety of solutions depending on the weather conditions in the area of use - from arctic to desert! When climatic conditions prohibits the use of the internal hard disk, just tell the analyser to use a PC card instead! Add one of our high-quality outdoor microphone units and you have a powerful system that will provide all the information you need, even sound samples whenever needed!

An annoyance recorder eliminating the need for a separate DAT recorder

Annoyance recorders have proven to be a very cost effective method of investigating domestic noise complaints, particularly those occurring outside normal office hours. To date systems have been based on Digital Audio Tape recorders connected to a conventional sound level meter and as such often have complicated set up and calibration procedures. Any error in these procedures could easily result in the failure to collect the evidence of the alleged offence. A novel approach to these systems is embodied in the Nor-121 through its digital recording of the actual sound at the same time as the measurement; hence there is no longer a need for a separate DAT recorder; everything is within your analyser! All calibration and range settings automatically relates to both the measurement and recording part of the system greatly simplifying the set up; there is even a default "annoyance recorder mode" that can be accessed directly on switch on. The instrument is housed within a tamper proof case and the only external components are the measurement microphone, mains connections and the plaintiffs hand switch. This hand switch has been specifically designed to make it suitable for use by subjects with limited manual dexterity and will activate the audio record for a predetermined period; the default setting is 60 seconds but may be set for any period between 1 second and 24 hours. The default set up also provides for a 5 second pre-trigger recording allowing the vital information occurring just before the switch was pressed to be recorded. Normal operational mode of the system provides for the logging of 5-minute period measurements being made each having the Leq,t and a range of Ln values supported by a 5 full third octave frequency analysis. In addition a 1 second Leq,t profile is logged and on this profile markers are provided to show when the plaintiff pressed the record switch to activate the record mode. This then opens a separate event file which contains the audio record along with a 125 millisecond Leq,t profile of each third octave band. All the necessary information is then available to allow the source to be both identified and quantified.

Using FFT to detect those pure tones

A multitude of environmental noise measurement results require compensation for the presence of pure tones. According to some national Standards, possible pure tones are found simply by inspecting the one-third octave band spectrum and look for single bands having more than 5dB higher level than the adjacent frequency bands. Other national Standards, however, such as the German TA-Lärm require that a detailed FFT analysis is carried out. The optional Pure Tone FFT mode will enable you to analyse the noise in accordance with the German requirements. As a spin-off, any measurement task requiring the autospectrum of a full frequency range FFT with a better than 2Hz line separation is supported. The measured noise spectrum is shown as a normal FFT spectrum during the acquisition process. The calculation of any pure tone presence is carried out while the measurement is running. The detected pure tones are marked by lines in the FFT spectrum graph. The detected pure tones are also available in a table which even provides the necessary compensation values!

Examples of Nor-121 displays when set to pure tone detection mode
Adding the indoor dimension - building acoustics with the Nor-121
With the Nor-121 you are not limited to environmental noise measurements only. Many of our customers make a lot of different types of measurement. No surprise they told us to continue our tradition of letting one instrument be able to do it all! Hence, a building acoustics extension is the logical next step. Sound insulation between rooms; façade insulation with noise or traffic as the source; impact noise insulation; reverberation time calculations based on noise or impulse excitation; even the final factor that says it all - the R'w or the L'n,w - they can all be found inside the handheld casing of the Nor-121! The Nor-121 is designed to be a two-channel analyser when working in building acoustics mode, but it works well as a single channel analyser too. If you already own a Nor-121 and want to upgrade it to include the building acoustics extension, the second channel may be installed during the upgrade process - or later, if that is more suitable. In environmental mode parts of the second channel is used by analysers equipped with the 120dB dynamic range extension. Two channels partly overlapping enable a higher dynamic range than a single channel does. In building acoustics you won't need the 120dB dynamic range so we spend the resources on full dual channel operation instead!
Built-in Noise Generator The building acoustics mode features a built-in noise generator with white and pink broadband noise. Sometimes, however, this is not enough. From time to time you will come across measurement sessions where you simply cannot get enough energy out to obtain a usable signal-to-noise ratio in the receiving room. Enter the serial analysis feature with bandpass filtered noise. Not a new thing to our customers, in fact this has been a feature available in every building acoustics measurement system designed by us since we started doing this back in the mid-seventies. The strong point lies in that the Nor-121 lets you combine parallel (real time) and serial analysis. If you start out doing a parallel analysis and find that some frequency bands do not provide results good enough, you may retake a measurement in those frequency bands only, one at a time! The frequency bands that proved good enough when you did the parallel measurement are retained, while those in need for more output power are measured again. The results of the serial measurements will then replace the bad results and you end with a succesful measurement without spending more time than strictly needed! Reverberation Time In the Nor-121 reverberation time measurements are made using either impulse or noise excitation - the choice is yours! Even here, you have the possibility to combine parallel and serial measurements by applying bandpass filtered noise. The decay curves captured are shown as level vs. time curves in the Nor-121 display. The level range from -5 to -25 or -35dB below the noise excitation level (or the maximum impulse level) is used for the calculation and the result is then normalised to a 60dB range. However, if you prefer to use the T15 (-5 to -20dB) or if you need to include the EDT (Early Decay Time) these are also available for you. Traditionally, we have sticked to the use of a triangular weighting function when calculating the reverberation time. This method gives a better repeatability than most, if not all, other methods. However, for a number of reasons (including the requirements set by some standards) you may want to use the least square fit method, so as an alternative we've included even that! A Self-contained Solution If you order, or later upgrade your Nor-121, to have two fully operating channels, all the building acoustics measurements are made dual channel. However, you may run the system as a single channel building acoustics system as well. In dual channel operation everything is dual. You can have the Nor-121 show the absolute level as measured by both channels simultaneously - in the same graph for easy comparison, or you can inspect the receiving room level and the level of an initial background noise measurement. There is a Last register for each channel (Last is the register where the most recent measurement resides) and an Average register where the measurements can be averaged together to provide room averaged values. For reverberation time measurements you have the choice of either averaging the calculated reverberation time values or to average the decays themselves (ensemble averaging) before calculating an averaged reverberation time value. If you are in need of the individual datasets used to create the average values, these are still accessible from a remote PC through the use of the Nor-SIC (Sound Insulation Calculations) software - available separately - as all the individual results are stored separately in the Nor-121. Although the Nor-121 often will play the role of a data acquisition unit, it is important to be able to verify the measurements while you're still on-site. Therefore the Nor-121 also calculates the R'w, L'n,w etc. for you. The results are shown in the display - you won't need a separate computer for this. Any retakes can then be made there and then. Time and money saved again!
Accessories available for your Nor-121
There is a wide range of accessories and postprocessing software available for the Nor-121:
Microphone cartridges Outdoor microphone units Sound calibrators Microphone preamplifers Extension cables	Cases for semipermanent monitoring Enclosures for permanent monitoring Software for transfer of the measured data	Environmental noise measurements software Building acoustics software Rotating boom Tapping machine Noise excitation equipment

Ordering information

Standard basic version: Environmental Analyser with parallel A-, C- and Flat-networks, parallel F, S and I time constants, internal Hard Disk Drive (>4.0GB). PCMCIA, RS-232 and Centronix interfaces. Includes Battery Nor-338, Charger Nor-337, Nor-1201 Preamplifier, Nor-1225 Microphone, Nor-1410 Preamplifier Cable (2m), Nor-1434 Windscreen, Nor-1267 Tripod Adaptor plate, Nor-1463 RS-232 cable, Nor-1477 AC-output cable, and Nor-1488 Parallel cable Opt.0: 0.1Hz - 20kHz, 1/3- and 1/1-octave real-time frequency analysis Opt.1: True audio recording of noise signal and voice notes Opt.2: High dynamic range (>120dB) for noise monitoring purposes. Opt.3: Noise generator output with white, pink, 1/3- and 1/1-octave noise for building acoustic applications. (Requires option 0.) Opt.4: Reverberation time calculations. (Require option 0.) Opt.5: 2-channel level and reverberation time measurements Opt.6: Sound Insulation Index calculations (Rw etc) based on level and reverberation time measurements (Requires opt. 3 and 4.) Opt.7: Pure-tone FFT mode Opt.8: Event-analysis with advanced trigger features (even for recording of the sound itself if option 1 is installed) Opt.9: Timer function for automatic sequencing of unattended measurements Opt.10: Statistical Ln calculations with cumulative and probability functions on spectral weighting networks (and on octave bands when option 0 is installed)

Technical Specifications

OVERALL PERFORMANCE The overall performance of the Nor-121 with a suitable microphone and preamplifier, corresponds to the Sound Level Meter Standards IEC 60651 Type 1, IEC 60804 Type 1, ANSI S 1.4 - 1983 Type 1 and ANSI S1.43 - 1997 Type 1. (Type 0 with suitable microphones) The filter characteristics meet Filter Standard IEC-61260 class 1 for analogue and digital filters as well as the ANSI S 1.11 - 1986 Type 1D Dimensions: (W×H×D) 36×5,5×20 [cm], 36×6,5×20 [cm] with feet Weight: 2,9 kg with battery

ANALOGUE INPUTS No. of channels: 1 (optionally 2) Microphone input: 7-pin LEMO connectors Preamplifier voltage: ±20V, 3mA Polarisation voltage: 0 or 200V selectable, ±1% Input impedance: >1Mohm/<200pF. INPUT AMPLIFIER Amplifier gain: 40dB in 5dB steps. <0.2dB gain error Additional gain: 0-5dB with an accuracy and resolution of ±0.1dB for calibration purposes Measurement range: 0.3µV-7V RMS (±11V peak). Corresponds to SPL values from –10dB to +137dB (140dB peak) with a mic. sensitivity of 50mV/Pa High pass filters: Selectable 1st order network with –3dB frequency at 0.03 Hz or 3rd order Butterworth filter at 16Hz (-3dB). SELF NOISE LEVELS Line input, spectral weighting networks; 90dB FSD. A: 10dB, C: 35dB, Flat (HP filter on): 37dB Mic. input, spectral weighting networks; 90dB FSD. A: 13dB, C: 16dB, Flat (HP filter on): 19dB Line & Mic. input, spectral weighting networks; 120dB FSD. A: 32dB, C: 35dB, Flat (HP filter on): 37dB High dynamic mode; A: 14dB, C: 17dB, Flat (HP filter on): 20dB Line corresponds to the self noise measured with short circuited microphone signal input connector while Mic. corresponds to the self noise measured with preamplifier Nor-1201 and an 18pF microphone equivalent Nor-1448-18pF. ANALOGUE OUTPUTS AC outputs (two): 2.5mm mono mini-jack sockets. The output is generated by the DSP. One channel is normally used for AC output, the other channel is normally used for playback of the recorded signal or for voice notes. Optionally it may also be used for generator output Output level: ±10V peak,1.0Vrms corresponds to full scale deflection on display. Outputs are short circuit proof to ground and output current is in excess of 10mA Output impedance: Max: 10ohm Frequency range (AC output): 1-20000Hz±0.5dB. ANALOGUE TO DIGITAL CONVERTER Converter type: Sigma delta with 64× oversampling Sampling rate: 48kHz Passband ripple: <0.1dB Stopband attenuation: >75dB above 1.3×cut-off frequency Digital filters: 6-pole IIR filters for octave and third-octave bands. The third-octave centre frequencies are set with the factor 10n/3 Frequency range: 0.125Hz-16kHz for octave bands (centre frequencies). 0.1Hz-20kHz for third-octavebands (centre frequencies) Filter response: The octave and third-octave filters meet the re-quirements of IEC61260 class 1, ANSIS1.11-1986 Type 1D order III and IEC 225 Spectral weighting networks: A, C and Flat. The Flat spectral weighting network response has a 1st order digital HP filter with fc (-1dB) selectable as 0.1, 1.0, 6.3 or 20Hz. LEVEL DETECTOR Detector type: Digital true RMS Resolution: 0.1dB Reference range: 50-130dB (20-130dB with the high dynamic optional extension) Primary indicator range: 55-130dB with crest factor <3 (20-130dB with the high dynamic optional extension). 55-120dB with crest factor <10 Linearity range: 85dB (115dB with the high dynamic optional extension) Pulse range: 88dB (115dB with the high dynamic optional extension) Reference frequency: 1000Hz Reference SPL: 114.0dB re.20µV Level detector accuracy (20Hz to 12.5kHz) measured at reference range relative to 94dB: +5dB above to 70dB below FSD: <0.2dB. 70dB to 80dB below FSD: <0.4dB. High dynamic optional extension: +5dB above, to 90dB below FSD: <0.2dB. 90dB to 110dB below FSD: <0.4dB Time constants: F, S, I Integration period: 5msec to 200 hours with 5msec resolution Crest factor capability: 10dB crest factor margin at FSD increasing to 90dB at 80dB below FSD (120dB with the high dynamic optional extension) Overload detector: Latched as well as instantaneous. DISPLAY Type: 133×101mm STN monochrome, transreflective display with switchable backlight (which has a timer set in a special menu) Picture resolution: 320×240 pixels [h×v] - ¼ VGA standard Displayed range: Selectable 20, 40, 60 80, 100dB Graphical resolution: 0.1-0.8dB depends on selected format Numeric resolution: 0.1dB Numerical range: -99.9dB to +199.99dB. MEASUREMENT STORAGE Memory card: PCMCIA type 1 or 2 flash card (4–400MB) Hard disk (optional): 6 Gbyte. I/O Digital interfaces: RS-232C (two), a general digital I/O socket (containing 8 configurable digital outputs, 4 configurable digital inputs and external trigger) and Centronics parallel interface. SIGNAL GENERATOR Signal types: Pseudo-random noise or sine wave Spectrum types: Pink, octave or third octave noise Repetition rate: Approx. 46 minutes corresponding to 0.00041Hz spectral line separation Filters: The octave and third octave filters meet the requirements of IEC 61260 class 1 and ANSI S1.11.1986 Type 1D Noise generator output level: 0 to -40dB re. 1Vrms in 0.1dB steps. GENERAL Power requirements: 11-15Vdc, 4–10W depending on measurement task. 40Wpeak when charging internal batteries Batteries: 4×D-cell type NiMh rechargeable batteries 7.5Ah Charger: Built-in microprocessor controlled battery monitor and charger. Charging time 2.5 hours with instrument switched off and 12–14 hours if charging takes place when instrument is switched on Operating time: Typically 12 h. Warm-up time: <30 sec. for 0.1dB accuracy Enclosure class: IP20. ENVIRONMENTAL Temperature range Storage: -30 to +60°C, gradient 15°C/hour. Operating: –10 to +50°C, gradient 15°C/hour. A certain warm-up time is required at low temeperatures before the hard disk can be accessed Temperature drift: <0.002dB/°C Relative humidity: 5-95%. No condensation Vibration with HDD running: 5m/s2, 5-500Hz sine wave Vibration with HDD not running: 50m/s2, 5-500Hz sine wave Shock with HDD running: 100G Shock with HDD not running: 200G EMC: In accordance with the EN50081-1 and EN 50082-1 Safety: In accordance with IEC61010. All specifications subject to change without notice.