The Norsonic range of noise monitoring solutions is very comprehensive. Based on our customer's inputs and demands we have designed instrumentation aimed at providing the solutions you need, regardless of whether you're in need of just a light-weight, portable, semi-permanent construction site monitoring system or complete systems for airport noise monitoring.Does your application require constant computer control? Or, would a daily or weekly download of the acquired data suffice?
How about getting an SMS (or an e-mail generated through the SMS system) from the noise monitoring terminals informing you about battery status and the sound level measured over, say, the past 24 hours?
How about calling the analyser and listen to the analyser telling you the current noise level? Through the use of recorded announcement technology the Nor121 analyser can be set up to this.
Maybe you prefer to have the reports generated in your computer after the data have been transferred. Or, would you prefer that the monitoring analyser does this for you?
How should the measured data be transferred to your computer system - via modem, cable, GSM or what?
Will you need a single microphone installation, a large scale industrial monitoring system, or maybe an advanced airport noise monitoring system?
We do even that! Together with our large-system software partner, Topsonic GmbH, we have installed several airport noise monitoring systems in Europe and the US using radar tracking to correlate flight paths with the measured noise levels.
The choices are numerous and so are our solutions as well - not to make things complicated, but to ensure that you get what you need, and not what we may think that you need!
With this article we would like to introduce you to our range of environmental noise monitoring solutions. As you will see, flexibility is a keyword here - by combining the various elements available there will be solutions for virtually every noise monitoring application!
An outdoor microphone system for every application
Measurement microphones are sensitive to environmental factors such as wind, rain and snow. These problems have been reduced in our special outdoor microphone systems. The design protects the diaphragm from the influence of the environment. For practical reasons we have divided our range of outdoor units into two groups; one for permanent and one for semi-permanent monitoring applications. The former group is the true outdoor microphone units, while the latter is referred to as environmental microphone units.
Outdoor Microphones
The outdoor microphone units have been designed for permanent installations in the field, such as airport noise monitoring or industrial noise monitoring systems.
A typical outdoor microphone system of this type includes anti-bird spikes, a windscreen and a rain cover, all of which are integral parts of the acoustic omnidirectional characteristics offered by the system. The rain cover contains an electrostatic actuator enabling a precise in situ calibration at 1000Hz from the internal sine wave generator.
Optionally, the complete frequency response may be calibrated using an external generator. A special adaptor allows acoustic calibration. The microphone diapraghm and housing are made of stainless steel to withstand pollution and corrosion.
The microphone cartridge is a ½" type with 200V polarisation voltage. The unit comes with a built-in A-curve spectral weighting network in addition to Flat response (no spectral weighting at all) and a 0 or ±20dB amplifier - all set by internal jumpers. An internal heating system is provided to avoid condensation. The output amplifier is a low noise type designed to drive long cables.
The microphone is delivered in two versions; Nor1210A, for airport noise monitoring (0° i.e. vertical incidence), and Nor1210C for community or traffic noise monitoring (90° i.e. horizontal incidence). Both versions are ptb (Physikalisch Technische Bundesanstalt, Germany) approved as part of an IEC 60651 type 1 system. Both versions also comply with ANSI S1.4.
The reason for having two versions is that the reference direction (IEC 60651) should be vertical for aircraft monitoring and horizontal for traffic noise monitoring. However, the need for microphone weather protection calls for a vertical mounting of the microphones.
Environmental Microphones
Our environmental microphone units constitute a low cost alternative. They are primarily intended for semi-permanent outdoor installations ranging from a few days to several weeks.
Although not designed for permanent outdoor use, the environmental microphones are rugged enough to withstand continuous rain and they operate over a wide temperature range.
The microphone housing is made of black anodised aluminium. The ½" microphone cartridge is heated from the preamplifier. The heater system together with a large desiccator unit in the bottom of the microphone housing prevents possible condensation problems. Acoustical calibration is done by means of a special calibrator adaptor.
Similar to the Nor1210 units the environmental microphone also comes in two flavours - a 0º-incidence version, Nor1211A and a 90º-incidence version Nor1211C.
Both versions fulfil the IEC 60651 requirements for a Type 1 sound level meter as a stand-alone unit. Specifications have been tightened relative to the requirements in IEC 60651 and ANSI S1.4, so that when the unit is connected to a sound measuring instrument with similar stringent requirements, the total measuring chain will fulfil the IEC 60651 requirements.
Interfacing Nor1210 to the Analyser
The Nor512 is the power-supply and actuator control unit interfacing the outdoor microphone Nor1210 to a sound measuring instrument. The Nor512 ensures that the self-noise in the microphone system is kept at a minimum.
Significant electrical interference may exist in the area where your Nor1210 is to be placed. This must not influence the measured values. Likewise, it is important to avoid that the microphone system itself disturbs any other electrical installations such as sensitive electronic installations on airports.
The Nor512 has been designed and verified to meet both these requirements shielding the Nor1210 measuring chain from incoming and radiating electrical noise.
Several versions are available to match different sound measuring instruments. Some versions are configured for remote calibration by means of an electrostatic actuator. In these cases a separate cable is connected to the digital I/O port on the sound measuring instrument or to the computer. Other versions are equipped with just a switch, or a switch in addition to the control cable. This switch enables manual operation of the actuator calibration. Most versions are powered from a separate mains adaptor. The Nor121, however, uses a version powered via a control cable directly from the analyser itself.
The Nor512 contains a power supply which is floating with respect to the signal ground and power supply input to avoid ground loops. The maximum permissible cable length between the Nor512 and the outdoor microphone is 500 metres. Lengths exceeding 25 metres call for the use of 0.5mm2 cables to minimise cable voltage drop.
Our range of environmental noise analysers provide the flexibility you need.
Our selection of sound analysers for environmental applications contains four types; a hand-held sound level meter - the Nor116; a hand-held sound level meter with real time fractional octave analysis and 120 dB dynamic range - the Nor118; a hand-held sound analyser - the Nor110 and finally the instrument that probably is the most advanced environmental noise analyser in the world - the Nor121.
Which instrument to choose will depend on the task. For simple A- and C-weighted analysis of the level vs. time in predefined periods, the Nor116 will be a good choice. High dynamic range and frequency analysis will call for Nor118 or Nor121. If event handling or frequency analysis is important you should consider the Nor110 or the Nor121. If recording parts of the sound itself is important the Nor121 becomes the natural choice.
Traditionally, our instrumentation tends to be all-in-one solutions, since many of our customers are involved in a variety of applications. Therefore, even though the Nor110 and the Nor121 have been designed with environmental noise monitoring applications in mind, they have also been fitted for building acoustics measurements.
On the other hand, the hand-held sound level meter Nor116 does simultaneous measurements of A- and C-weighted levels. It is therefore well-suited even for occupational safety measurements.
Hence, unless you're planning a permanent installation you should also take into consideration what else the instrumentation could be used for. For permanent installations, however, the type and amount of information will be the determining factor.
Common Features
All three instruments are able to measure for a predefined period, store the measured values and then restart. This eliminates the need for a controlling computer.
Likewise, all three instruments provide level vs. time information. This means that a measurement is divided into subperiods of equal duration. For example a one hour measurement may be set up with one-second subperiods. You will then get the Leq per hour, but also a short time Leq value for every second throughout the hour of measurement!
In addition to this, you may, of course, set up the instrument to log the maximum and/or the minimum SPL for each subperiod together with the instantaneous SPL values. Combined with percentiles this will make it easy to keep track of the noise level variations throughout the day.
All three instruments are battery-operated and, of course, equipped with digital interfaces so that data transfer to your PC is easy to handle.
Event Handling
If you use a time resolution too coarse, you are going to miss information. On the other hand, by setting up a very fine time resolution, you run into the risk of drowning yourself in information.
To avoid this the event handling feature of the Nor110 and the Nor121 can be used. By the term event we are thinking of a significant change in the sound level lasting for a minimum period of time. Such changes will normally be important for noise monitoring analysis. Consequently, if you devote more resources during an event than you do when "nothing happens" you may get the best of two worlds - a fine resolution giving details when you need that and the overview at a glance the rest of the time.
Both the Nor110 and the Nor121 can be set up to make a separate measurements during an event. Note that these measurements are made in parallel with what is measured when there is no event. They do not switch to event handling - the two tasks are carried out simultaneously!
However, when it comes to truly advanced event handling, nothing beats the Nor121! It allows you to define events not only as when the level exceeds or drops below a threshold, but also as when the level remains between an upper and a lower border. This opens up for applications where the event takes place when the factory is running, but no trains are passing, for example.
The Nor121 even addresses the common problem of setting adequate triggering levels that can be used around the clock. The feature is called relative trigger and it permits you to define an offset relative to any other measured function as event trigger criterion. For example, you may set the event trigger to 30dB higher than the hourly L50.
Two features only available with the Nor121 are the recording of the sound itself and the principle of pretrigger.
To ensure that the event you have measured comes from your measurement object and not from, e.g. the neighbour's dog, you may set up the Nor121 to record the sound itself, either based on its own set of trigger criteria or so that it records the sound itself every time there is an event. The recorded sound can later be played back and listened to via a pair of headphones or it can be used as input for pure tone analysis (using FFT)in the Nor121.
However, you may also set up the Nor121 to calculate the presence of any pure tones while the monitoring measurement process is running!
The pretrigger feature allows you to start the event handling up to 5 seconds before the trigger criterion is met. This is implemented by means of a ring-buffer. Even the recording of the sound itself may make use of this pretrigger principle. In this way you will be able to hear what took place immediately before the event occurred!
Cabinet and mast solutions to match your applications and your weather conditions!
Permanent (left) or semi-permanent (right) solutions - the choice is yours!
We supply a variety of cabinets to match your applications - single skinned or double skinned cabinets, and for semi-permanent applications, even a portable case - the Nor1506.
Cabinets for Permanent Systems
The Nor1501 is a double skinned aluminium cabinet designed for permanent outdoor installations. It can be mounted onto a wall or to the tiltable mast Nor-1329. The unique double wall construction with vented top protects the electronic equipment inside from overheating. The unit is also tamper proof. The door has a bar lock and swivelling handle with a cylinder lock.
An extensive delivery program ensures an optimal solution for almost any application. The normal version is waterjet- and dustproof in accordance with the IP55 / DIN 40050. Standard cabinet size is 600×600×300 [mm]. Other sizes on request. Standard colour is RAL7032, pebble grey, polyester powder varnish, structured. Other colours on request.
The Nor1511 is a single skin aluminium cabinet designed for indoor as well as outdoor use. Available in three protection classes, viz. IP54 , IP55 and IP65, it shares its extensive delivery program with the Nor1501 including colour and size.
The protection of the internal electronic equipment against heat and direct sunlight is, however, not in the same class as the Nor 1501. Hence, precautions against direct sunlight should be taken if the unit is placed outdoors.
Portable Cases
The weatherproof case Nor1506 has been designed to protect the sound measuring instruments from heavy weather conditions, such as rain and snow. It is available in several versions in order to be able to adapt to a multitude of applications.
When used with the environmental microphone Nor1211, this will form a system designed for semi-permanent outdoor monitoring. The system will maintain its performance even when left unattended under severe weather conditions for several weeks.
Internally, the case has two compartments. The upper compartment contains the measuring instrument, the sound calibrator and calibration adaptors. The lower compartment has space for two batteries, the environmental microphone Nor1211, a telescopic microphone stand, GSM modem, GPS and misc. cables, but can be arranged with special foam cut out to fit special applications and needs, such as more batteries. The battery lifetime is typically more than 64h for the Nor110, more than 14 days f or the Nor116, more than 8 days for the Nor118 and more than 72h for the Nor121. For the Nor-121 the actual battery life time will depend on the functions activated and the amount of audio recordings made. All values are per two batteries, as the Nor1506 is supplied with a dual battery configuration as standard. The charging time per battery is 7 hours and the typical weight without batteries, microphone, monopod and instrument is 6,3kg (13.9lbs).
Masts
The Nor1329 is a microphone mast for permanent installations. It may be tilted to provide easy service and calibration of the outdoor microphone unit and weather station (if applicable). Made of steel the mast is coated in a seven-step process in which zinc phosphate and powder are melted onto the hot-dip galvanised steel at a carefully controlled temperature. This process ensures a top quality finish and durability.
The mast is available in any length up to 7 metres. The mast should be mounted on a concrete foundation o or a steel foundation. The steel foundation is fast and easy to mount and is a well-proven technology used with lighting columns. A special anchor frame enables a fast and accurate mounting of the microphone mast onto the concrete foundation.
The microphone cable for the outdoor microphone and the cable for the weather station (optional) are mounted inside the mast to minimise wind induced noise and protect the cables from the sun and heavy weather conditions.
The Nor1323 is a light weighted portable telescopic microphone stand which can be up to 4 metres tall. The unit is made for use with the environmental microphone Nor1211 only.
The Nor 1330 is a portable lightweight telescopic microphone tripod which can be up to 7 metres tall. A guy rope kit supports the tripod to ensure maximum stability. This system is primarily designed for use with the environmental microphone system Nor1211. However, a special adaptor enabling it to be used with the permanent outdoor microphone Nor1210 is also available.
Weather Station Many noise monitoring applications need to take the weather into account. Our monitoring system solutions provide interface to the Reinhardt MWS 9 Weather Station in two ways - as a separate terminal communicating directly with the controlling computer or connected directly to a Nor121 analyser.
Direct computer connection will be the typical solution for systems using Nor110, Nor116 or Nor118 as the sound measuring instrument, or when most of the processing is assigned to the controlling computer.
Direct connection to the Nor121 will be an attractive alternative when most of the processing is to be carried out in the NMT itself. When the weather station is hooked up to the Nor121 the weather data are integrated into the reporting structure of the Nor121, so that weather data appear as a separate report! This means that you will have the temperature, the humidity, the barometric pressure, the wind direction, the wind speed and rain (precipitation) logged as functions of time available in the Nor121 in just the same way as the analyser measures sound.
The weather data are then available for read-out together with the noise level data
No monitoring system is complete without the controlling software
In general, there are two philosophies within environmental noise monitoring. One is to use a very simple sound level meter in the Noise Monitoring Terminal (the NMT). The other is to put more processing power into the NMT.
The simple sound level meter solution requires a tighter computer control and a more frequent transfer of data than the use of a more sophisticated sound measuring instrument.
The Norsonic monitoring solutions are normally of the second type - our instrumentation can do a lot of processing on their own. This has several advantages:
The amount of time spent on data transfer may be reduced significantly.
More NMTs can be controlled from a single computer - important when you are using GSM modems to communicate with the NMTs.
Data are still available in the sound measuring instrument in the case of communication failure.
The NorMonit Software Program
The NorMonit is now in its second generation - version 2. In a Norsonic environmental noise monitoring system you will use this program to set up NMTs, collect data from them and monitor a multitude of them simultaneously. The program has been designed with maximum capacity in mind - the limitations on the number of NMTs possible are not in the program, but lies in the PC configuration itself or the time spent on the communication process.
For example, it will typically take about half a minute just to establish a connection using a GSM modem. If you then add data transfer time you will see that this will impose restrictions on how many connections and data downloads you will be able to make per hour.
Having a multiple document interface, the Nor-Monit version 2 makes use of the familiar Windows® Explorer interface. Just drag an instrument icon to a graph window to start real time monitoring, or right-click on the instrument icon to open a new graph window and then start the real time monitoring there.
Up to six functions may be monitored in each graph-window simultaneously. The number of graph- windows is limited by your computer's resources and the size of you computer monitor's screen.
Note that the functions shown in a graph-window need not even come from the same instrument. For example, two may come from one instrument and the four others from four other instruments. Furthermore, the display need not even have to show identical functions (like Leq) - the only requirement is a common time resolution, which is set up in the individual instruments.
The NorExplorer is a module inside the NorMonit enabling you to explore the contents of a remote instrument in a manner similar to what you can do with your PC. To transfer data from the instrument to any folder in your PC for storage on your hard disk, just drag the file.
The NorMonit features extensive Object Linking and Embedding (OLE) capabilities. During the installation process, NorMonit scans your PC to look for Microsoft Excel®. When found, an Excel icon is inserted in the menu bar of the NorMonit. Clicking this icon will cause Excel to start running within the NorMonit V.2 program.
Alternatively, right-clicking a data file will allow you to start Excel using the selected file as data.
Setting up Instruments from the PC
For the Nor116, Nor118 and the Nor121, the NorMonit permits transfer of measurement setups from the PC to the instrument. This is a very handy feature for semi-permanent monitoring systems.
Imagine a system that is used to monitor the noise on a construction site and then moved to another once the project is terminated. Different applications may require different setups. With the measurement setup feature, the monitoring system can be moved and set up by unskilled personnel while a new measurement setup is transferred via GSM modem from a control room to the NMT.
In Need of Further Post-processing?
The NorMonit V.2 is a control and transfer program aimed at the administration and data acquisition of noise monitoring systems. You may want to do further post-processing on the acquired data to present them to decision-makers and maybe also the public.
Besides the OLE feature allowing you to run e.g. Excel from within the NorMonit V.2, you may also pick up the acquired data and use them in the post-processing program NorProfile.
This program lets you view and inspect level vs. time graphs complete with any markers (source codes) inserted throughout the measurement intact. Markers may be added, deleted and moved. When used with the Nor121 sound recordings are also imported. For a playback just double-click the sound recording marker and listen to the recorded sound (requires multimedia PCs).
Several measurements may be merged into one long level vs. time record or just shown in the same display. These measurements need not come from the same instrument, but may just as well have been measured by several. The only requirement is that they have measured the same function and share the same time resolution.
Rating analysis may be made on any parts or intervals of the L(t) graph. If frequency analysis was a partof the measurement, frequency analysis of any intervals is possible.
