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Entry  Wed Oct 24 14:15:34 2012, Ayaka, Update, Adaptive Filtering, microphone noise mic_open.pngmic_noise.png
    Reply  Wed Oct 24 15:29:52 2012, rana, Update, Adaptive Filtering, microphone noise 
       Reply  Wed Oct 24 17:02:01 2012, Jenne, Update, Adaptive Filtering, microphone noise 
       Reply  Wed Oct 24 22:20:24 2012, Den, Update, Adaptive Filtering, microphone noise mic_64k.pdf
          Reply  Thu Oct 25 09:53:23 2012, Ayaka, Update, Adaptive Filtering, microphone noise 
          Reply  Thu Oct 25 10:03:38 2012, rana, Update, Adaptive Filtering, microphone noise 
             Reply  Thu Oct 25 14:39:14 2012, Den, Update, Adaptive Filtering, microphone noise 
Message ID: 7607     Entry time: Wed Oct 24 14:15:34 2012     Reply to this: 7609
Author: Ayaka 
Type: Update 
Category: Adaptive Filtering 
Subject: microphone noise 

Previous results
I am measuring the noise level of the microphones. The circuit does not seems to limit their sensitivities but the circuit's noise seems to be different from other channels.

Measurement
I measured the circuit noise of all 6 channels. (input open)
(mic_open.png)
The noise level is about 10 times different from the others.

Comparing the acoustic signal, microphone+circuit noise, and ADC noise;
(mic_noise.png)
- blue; acoustic signal
- green; microphone+circuit noise
- red; circuit (the data was not took simultaneously.)
- sky blue; ADC noise

To do
I will remake the circuit though the circuit does not limit the sensitivity. I would like to make sure that the circuit does not affect badly and to make the circuit noise level the same.
At the same time, I will get the PMC control signal and see coherence between it and acoustic sound.

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