FAQ - L642

What is the L642 most commonly used for?

The L642 is most commonly used I situations where acoustic data is collected over longer periods of time. Examples of this are:

  • Smart City solutions

  • Noise monitoring

  • Traffic monitoring

  • Vehicle classification

  • Animal (behavior) research

  • Crowd interaction at stadiums

  • Firework detection

  • Gunshot detection

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How is the L642 applicable in traffic monitoring?

The L642 can be used to monitor traffic acoustically. An L642 can be placed near a road or junction to map the passing traffic. The acoustic data can be collected to analyze and gain insight on the traffic of the junction. Also with the use of classifiers, passing cars can be classified and counted.

What is sound source localization?

Sound source localization is used to detect the location of sound sources. This is because the L642 has a microphone array. This microphone array uses the sound signals of 64 microphones to calculate where sound comes from. This data can then be used to construct the SoundSurface overlay which visualizes the sound sources with red colored ‘blobs’.

What is the difference between “Area mode” and “Camera mode” for beamforming modes?

Camera mode overlays the SoundSurface with the camera view. This way, the camera view can be used to localize sound sources. In Area mode, the SoundSurface is projected to an area, like a road. This shows a top down view of a google maps map of where the sound is coming from.

Why are high frequencies easier to find than low frequencies?

The L642 localizes sound with the phase difference between the microphones in the array. High frequent sound has a small wavelength and therefore a greater phase difference between the microphones. That is also why the peaks in the SoundSurface™ are smaller and more precise with higher frequencies.

What connection do I need for an L642?

The L642 can be connected to your (local) network with a POE network cable plugged in to the bottom of the device. Once the L642 is properly installed in the network, the data can be accessed via the web interface, WebSocket or API connection.

How is the L642 powered?

The device has to be powered with POE (Power Over Ethernet) over the network cable. This means that you need a POE injector, or a POE switch/router. For the L642(v), PoE 802.3af is sufficient. For the L642(v)+, PoE+ 802.3at is required.

What are the necessary network speeds for the L642?

A good network connection is required to access the full capability of the L642. An indication of the bare minimum necessary upload and download speed is 30 kbit/s, but preferably this is higher.

What is the web interface

The web interface is a user friendly space where you can easily read the data that the L642 records. In the user interface, the following data can be viewed:

  • SPL plots, a plot of the measured SPL over time
  • Sensor SPL, real time insight in the measured SPL of each individual microphone
  • SoundSurface, the acoustic camera image where the sound sources are visualized
  • Spectrum, the frequency spectrum of the recorded sound, displayed in a spectrogram
  • Events, set an SPL trigger and return the data when triggered

In the web interface it is also possible to set user defined measurement, SoundSurfaces™ and events, to be obtained via WebSocket.

How do I reach the web interface of the L642?

Your computer or laptop with which you want to reach the web interface must be connected to the same network as the L642. If this is the case type in your browser: http://<your-serial-number>.local.

This will bring you to the login page of the web interface. The default credentials can be found in the user manual.

Once logged in, you can start using the web interface and explore what the L642 is capable of. This web interface serves as an example of what can be done with the data from the API. A full documentation on the API can be seen at the documentation page in the web interface, or at this page: www.sorama.eu/dev

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Why do we advise non-camera units for smart city purposes?

The integrated camera has a field of view of ± 65°. This is enough for some applications, but for Smart-City purposes, this is not sufficient. That is why we advise to use the L642 in “area mode” and map the sound on a google maps image. This way, no camera is needed.