Specific solution to signal-to-noise ratio(SNR) of AC signals

user3809432

I got a AC signal through ADC and do the FFT to the digital signal. I know the defination of signal-to-noise ratio(SNR) of AC signals, but I do not know how many dots(data from FFT) I should get to calculate the singal. The following chart is my FFT of the digital AC signal.

Thank you!!!

over 9 years ago

0 WM5295 over 9 years ago

TI__Guru 54715 points

You don't mention a battery monitor device in your post, I will see if it can be moved to a converter forum where someone may better consider your question.

0 Joseph Wu over 9 years ago

TI__Guru* 98045 points

Hi, is this question for a particular ADC?

Joseph Wu

0 user3809432 over 9 years ago in reply to Joseph Wu

Prodigy 40 points

Hi, not a particular ADC. Spectrum leakage makes the solution of SNR be difficult. I want to know that to get the real SNR, if I could add the power of leak spectrum to the signal power. If I could, how to do this(or how many leak spectrum could be added to the signal power )? Thank you !

0 Joseph Wu over 9 years ago in reply to user3809432

TI__Guru* 98045 points

For the analysis, you could can either use coherent sampling to get a complete sinusoid as part of the data record. This might require some adjustment to the input frequency, your sampling frequency. Alternately, you could use a windowing function to achieve the same effect.

I did find this article on the subject:

electronicdesign.com/.../choose-right-fft-window-function-when-evaluating-precision-adcs

Luis also wrote another blog in this material, it can be found with the link below:

e2e.ti.com/.../leverage-coherent-sampling-and-fft-windows-when-evaluating-sar-adcs-part-1

Joseph Wu

Data converters

Data converters forum

Specific solution to signal-to-noise ratio(SNR) of AC signals