Audio path gain, was: Re: Bluetooth module

[Hrabosh]

Al Johnson píše v Pá 04. 02. 2011 v 13:46 +0000:

> How did you pick 0.5mV as a suitable input amplitude? Measurement of peaks 
> when talking?
> 
> 

It was completely wrong! I did some internet search and found that
micropohone like that in FR usually produce signal with amplitude in
tens of mV. I was wondering if the singal was only 0.5mV it wouldn't
probalby get distorted so easily - so I went to check my generator and
saw that the attenuator was set incorrectly and so the signal was
probably way higher than 0.5mV. 

I was doing bass-fix to my Freerunner today so I did the the same
measurement with generator again. I run "Voice notes" and set the
generator so that the amplitude was simmilar to the amplitude of voice,
captured by the microphone. LAter on I was listening to the files
recorded when setting the generator and the 1kHz beep was clean and the
volume was OK.

I rewrite the text and put there all pictures from the scope I made.

http://hnet.endofinternet.net/elektro/Freerunner/ALSA/sound_setting.html

Seems that the sidetone may be set to 2 instead of 1, but mic should
stay 0.

Thanks for your question !

Zb.



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