Calculating SNR from dbfs (using spectrograms)

1. How do you find the SNR of a spectrogram?
2. How to calculate SNR in Matlab?
3. How do you calculate FFT from SNR?

How do you find the SNR of a spectrogram?

SNR = RMS_signal - RMS_noise (in dbfs)

How to calculate SNR in Matlab?

r = snr( xi , y ) returns the signal-to-noise ratio (SNR) in decibels of a signal, xi , by computing the ratio of its summed squared magnitude to that of the noise y : r = mag2db ( rssq ( xi (:))/ rssq ( y (:))) .

How do you calculate FFT from SNR?

So, the SNR calculation should be like this: SNR = 10*log10(A) where, A = M_sig/(M_1+M_2+M_3+... +M_N) and N is the fft length. As the fact that M_sig/M_n is a constant regardless of the fft length N. So, we get the SNR which depends on the fft length N, i.e., the longer fft length, the worse SNR.