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01dB introduces the new version of the DUO Smart Noise Monitor. Totally modular, DUO provides its users with the most complete offering to upgrade from sound-level meter to monitoring station without changing equipment.

Visually, DUO remains the same: a metallic profile allowing fast and secure anchoring, a rubber grip for better handling, a screen that is perfectly legible in direct sunlight, high quality finish. Similarly, it maintains its incredible innovations: the world's only waterproof microphone, weather-resistant build, integrated GPS and Wi-Fi/3G wireless connectivity, which is essential to be able to control the DUO remotely. DUO has obtained CEI-61672 Class-1 certification (for the two reference directions 0° and 90°) from Laboratoires LNE (France), PTB (Germany) and METAS (Switzerland). This demonstrates the attention given by 01dB to ensure DUO's metrological quality.

01dB injected all of its know-how into acoustic monitoring to develop over 50 new remarkable functions for the DUO. It has now become a veritable monitoring station: event detection expert module, new acoustic indicators, SMS operating alerts, interface with weather station…Sound-level meter or monitoring station, one choice: DUO


DUO has innovative characteristics never before achieved by any producer in a single device:

Fully waterproof body
Metallic profile allowing quick and secure anchoring
Rubber grip for better handling
Colour screen perfectly legible in direct sunlight
3-key pad for simplified operation
Waterproof microphone supplied exclusively by G.R.A.S.
Integrated Wi-Fi/3G modem for remote operation and automatic data retrieval
Integrated GPS antenna for precise localisation and synchronisation
Batterywith operating time of 60 hours for simplified installation
Memory card of 2 to 128 GB for almost limitless storage.
Users now no longer need to choose between two systems. DUO is the right choice every time.


DUO has obtained the following CEI-61672 Class-1 certification:

France: type certification No. LNE-21674 Rev 0 of 21 July 2011 issued by LNE (Laboratoire National de métrologie et d’Essais
Germany: type certification No. PTB-1.63-4052726 of 6 February 2012 issued by the PTB (Physikalisch-Technische Bundesanstalt)
Switzerland: type certification No. CH-A3-120296-00 of 31 February 2012 issued by METAS (Bundesamt für Metrologie)
Portugal: type certification No. of 30 July 2012 issued by Instituto Português da Qualidade, I.P.
Spain: type certification No. 111839001 of 9 March 2015 issued by Centro Español de Metrologia (CEM).
These certifications were obtained for both reference directions 0° and 90°


To simplify the installation of DUO on the site, a function for the automatic detection of a calibration acoustic source allows the performance of a calibration and adjustments without the user needing to do anything more than switch the device on.

Furthermore, to ensure proper operation, an integrated measurement-chain verification system performs periodic checks. Electrical verification allows the testing of the entire measurement chain, including the microphone. It consists of injecting an alternating sinusoidal load on the microphone's terminals at the selected frequencies at one or two levels. The principle is to read reference values and check the deviation with respect to other measured values over time.


DUO natively integrates several modules for communications with external terminals:

Direct USB connection
Ethernet network (RJ45 cable)
Point-to-pointWi-Fi network
3G communication thanks to the Modem option (SIM card and subscription not included).
With a communication device (smartphone, tablet, PC…), the user can take control of the DUO using a simple Internet browser. DUO incorporates a web server called dBDUO, which provides access to all device functions (configurations, coding, acoustic calibration and electrical verification, real-time display of instantaneous values…).

Connection can be made wirelessly either in Wi-Fi mode or using the 3G modem.


DUO includes all the indicators expected by acoustic engineers: Leq, Lp, 1/1 or 1/3 octave spectrum, Fast Slow… These indicators may be measured and stored on the basis of an integration period (IP) of 20 ms (min.) to 3600 s (max.) in 5 ms steps.

In addition, 01dB also offers:

Perceived aircraft noise level: PNL and PNLT
Equivalent sliding noise level
Sliding statistical level
Noise exposure level.
The latter 3 indicators are mainly used for the monitoring of construction sites for the detection of noisy phases.


DUO incorporates two very advanced event detection modules.

Basic module:
The user can define an event, comprising a trigger that can be programmed over a maximum of 24 time periods. All settings (overall level, spectral level, rolling Leq, weather settings, etc.) instantaneously stored in the logging interval can be used to define the trigger. The event can be activated according to the days of the week and will trigger different actions: sending of a customized text message, recording of the audio signal, triggering of a parallel recording with a fine logging interval, TTL output, etc.

Expert module:
With this option, up to five events can be programmed, each comprising a combination of logic statements ("AND" or "OR") for several triggers (max. five).


DUO offers the possibility of interfacing with the VAISALA WXT520 (6 sensors) and WMT52 (2 sensors) stations. 01dB has selected these 2 stations for their specificity of not having any moving parts. This avoids any risk of mechanical operating failures due for example to ice or wear. The meteorological station and DUO share a common power supply, and the station's connection cable is 10 m in length, thus allowing great installation flexibility.

The meteorological data are stored on the DUO and transmitted in the same way as the acoustic data (USB cable, 3G modem…). The integration period for the meteorological data is a multiple of that applied to the acoustic data.

With the remote interface, the user may visualise the meteorological data and wind direction in real time.


The installation of a DUO sometimes requires the use of an external microphone line. To respond to this need, 01dB offers the new DMK01 unit. It comprises:

Stainless-steel body
Specific preamplifier allowing the re-use of the microphone and spike supplied with DUO
A specific anti-wind ball
A dummy microphone to protect DUO when the microphone is removed.
The unit connects to DUO's preamplifier input via a cable of 3 to 50 metres in length.

The periodic electrical verification function remains available.

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