Calibration in AIC3254

murali kandasamy

Hi,

We are using AIC3254 with electret condenser microphones and are using the spectrum analyser component in the purepath studio to get audio spectrum. Different units give different spectrums for same input. Is there a way to perform calibration with the codec?

Thanks & Regards,

Murali

over 10 years ago

0 Justin Bohr over 10 years ago

TI__Mastermind 27990 points

Hi Murali,

I have asked my colleague to take a look at this for you. Could you explain a little more about your setup?

Justin

0 J- over 10 years ago

TI__Mastermind 46195 points

Hi Murali,

How much of error are you observing? 1dB, 2dB?

To determine the cause of the issue, perform the following:

Implement a bandpass filter with fl = 250Hz and fh =4kHz in the miniDSP before the Spectrum Analyzer component.
Input a 1kHz tone from an external signal generator (not microphone).
Observe variation from unit to unit.

Regards,

J-

0 murali kandasamy over 10 years ago in reply to J-

Intellectual 350 points

Hi,

Thanks for the reply. The difference I'm observing is ~10dB or more... All units exposed to the signal, they track the sound level changes but there is a constant offset among the units. I guess there could be differences in the microphone sensitivities. Is there a recommended way of overcoming this in software? Seeing that the dB values shall be in log units, how can a zero / span / scale be implemented?

Regards,

Murali

0 J- over 10 years ago in reply to murali kandasamy

TI__Mastermind 46195 points

Hi Murali,

Verify the microphone sensitivites in their datasheet, or simply use the same microphone with multiple devices to see if it casues this error.

I have created an example algorithm in the PPS wiki page to address this:

http://e2e.ti.com/support/data_converters/audio_converters/w/design_notes/2990.quick-system-calibration

Regards,

J-

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Calibration in AIC3254