how to calculate SNR?

HELLO,i had some question.i have do some some filtering FFT using a matlab program.but,i need to compared the original signal,noise signal,and filtering signal based on SNR.but i dont understand how to calculate the snr ratio.pls help me or give a suggestion method how to compare and analysis the signal.tq

Answer 1

[Anudeep Kumar]

Hey hafis,

You can use MATLAB's inbuilt 'snr' function.

snr(x,y) returns the signal-to-noise ratio (SNR) in decibels of a signal x by computing the ratio of its summed squared magnitude to that of the noise y:

Assuming we have :

• original_signal: the clean signal (without noise)
• noisy_signal: the signal with added noise
• filtered_signal: the result after applying your filter

snr_value = snr(original_signal, noisy_signal - original_signal);

In addition to this you can also manually calculate SNR using the formula

signal_power = mean(original_signal.^2);
noise_power = mean((noisy_signal - original_signal).^2);
snr_value = 10 * log10(signal_power / noise_power);

If we want to evaluate how well the filter worked:

noise_after_filter = filtered_signal - original_signal;
snr_filtered = 10 * log10(mean(original_signal.^2) / mean(noise_after_filter.^2));

I have attached the documentation of 'snr' for your reference.

https://www.mathworks.com/help/releases/R2024b/signal/ref/snr.html

Hope it helps!