# Electronic – How to select ADC resolution, considering input signal SNR and digital signal processing

What I knew: The ADC resolution selection depends on the ADC inherent noise and input signal SNR.

Our application: Very high precision measurement of signals ranging 1kHz to 10kHz. We want to get as accurate result as possible, even 24-bit result.

The above statement, however, does not take digital signal processing after ADC sampling into consideration.

Since DSP techniques such as FIR, FFT and etc. may reduce the noises greatly, is it possible that increasing ADC resolution may also improve the measurement result when taking DSP techniques into consideration?

Post processing (via in DSP for example) has the potential to extract out salient features from above the noise but you have to be careful. You have to have sufficient bit depth so you don't introduce rounding/truncation errors. You have to ensure that you are conserving the nature of the noise (gaussian/poisson pdf) or else the noise floor may rise in an unpredictable way and may not be amenable to DSP techniques. These sorts of steps (matched filters etc.) typically at best can improve the SNR by factors of \$\sqrt{N} \$ and often the processing cost (# of operations) often follows \$N^2 \$ so these sorts of steps often become rapidly very expensive. But agains a proper analysis will show this.