M2340

M2340 är en vidareutveckling av M2230 mikrofonen och är främst framtagen för att användas vid nivåmätning under lång tid.
Mikrofonen har ett inbyggt självtest (Charge Injection Check-CIC) och har en markant mindre strömförbrukning än M2230.

Här är mer information om CIC direkt från NTI Audio:

An internal precision generator in the MA230 – this is the microphone preamplifier in the M2340 – produces two square-wave signals with the fundamental frequencies 46.9 Hz and 375 Hz. Including the harmonics of these square-wave signals, the test signal covers the entire spectrum up to 20 kHz. 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 available all commands to control the M2340 and to query the measured values, while the monitoring system – e.g. NoiseScout – takes care of the recording of the reference spectrum, the regular verification and the alarming in case of a significant level change or error.