All microphones from NTI Audio for the XL2 Analyzer include an electronic data sheet. The Automated Sensor Detection (ASD) of the XL2 automatically reads this data sheet, and recognizes the microphone model, sensitivity and calibration data. This ensures accurate measurement results.
But thanks to the System Self-test (Charge Injection Check – CIC) in the new M2340 microphone, the whole system used for measurements can be periodically verified and documented remotely. This is important in particular for stand-alone, remote-controlled measurement stations, which are usually employed for long-term level monitoring. Any damage to the monitoring microphone overtime can be detected using this self-test feature.
An internal precision generator in the MA230 – the microphone preamplifier in the M2340 – produces two square-wave signals with the fundamental frequencies 46.9Hz and 375Hz. Including the harmonics of these square-wave signals, the test signal covers the entire spectrum up to 20kHz. The generator is controlled via the ASD (Automatic Sensor Detection) data link to the microphone.
The test signal is capacitively coupled to the input of the MA230 preamplifier and attenuated by the capacitance of the microphone capsule. Before starting the measurement series, the reference spectral levels are recorded so that later measurements can be compared with this reference. If a capsule is damaged, its capacitance changes, which consequently leads to a change in the microphone signal level. This signal now passes through the preamplifier, the connecting cable and the input stage of the measurement instrument, where it is digitized and evaluated.
With the Remote Measurement interface, the XL2 makes all commands to control the M2340 and to query the measured values available to the user, while the monitoring system – such as NoiseScout – handles recording of the reference spectrum, regular verification and generating appropriate alarms in case of a significant level change or error.
Low-noise circuitry has a low impedance and therefore consumes more power. The new NTi M2340 measurement microphone achieves a good compromise between power consumption and low noise. According to NTi Audio, compared to the M2230, the current consumption has been reduced by 66% to 0.8mA in the M2340. The noise floor increases by only 1dB, while the maximum processable sound pressure level has been increased by 1dB. This makes the M2340 most suitable for power-saving applications such as long-term measurement stations.
The XL2 together with the M2240 measurement microphone is a powerful sound level meter, certified class 1 for noise measurement and noise monitoring applications. NoiseScout displays the noise levels measured by the XL2 Sound Level Meter live in a web browser. The measurement data recorded out in the field is presented online in charts and dash-boards with geographic visualization for all noise levels at a glance when using multiple noise level meters.
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