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ADAU1761 - How would you maximize Signal-to-Noise ratio for small acoustical signals?

Question asked by vnadon_B_ING on Aug 14, 2015

Hi everyone,

 

I need to measure very low Sound Pressure Level signals (range -15 to max 30 dB(SPL)). I have designed a very good pre-amp with differential connection to the DSP ADCs, I setted the gain of my pre-amp to saturate my ADC input range for around 85dB(SPL).

 

At the moment I am using differential mode with input volume at 27 and 0dB Gain LDBOOST:

 

ADC_input_gain.png

 

With this config and some software gains in my algorithm schematic, I am able to measure levels around 0dB(SPL) to 30+dB(SPL) without much difficulty.

 

I'd like to improve the SNR to be able to measure around -10dB(SPL) to 30+dB(SPL) with more stability (accuracy). Is it better to boost the LDVOL or LDBOOST or lower them and Boost my software gains, or keep everything the way I setted it? Do you know other easy tricks with algorithms or whatever that can boost SNR for low level signals?

 

Thanks!

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