[Nagano, Michimura]

Microphone installagion

We have installed a microphone (B&K, 4188) beside a compressor around BS as shown in the following picture.

Its signal can be seen in K1:PEM-IY0_SENSOR10_OUT_DQ (sampling rate 2 kHz), which is calibrated to Pa (sound pressure).
(Sorry for its general name.)
The microphone's reliable frequency band is between 8 Hz and 12.5 kHz (off cource, upper limit is determined by DAQ sampling rate.)

Its time series data and spectrum are shown as follows.

Time series
 

Spectrum
 

As you can see in the time series data, the compressot make a relatively noisy sound every 16 minutes.
In the spectrum plot, the spectra in noisy and stable moments are shown.