2.2.1 | Sqtwolog
Sqtwolog thresholding selection rule was proposed by Donoho and Johnstone in 199414. The threshold \(\lambda_{i}\) is calculated as
\(\lambda_{i}=\sigma_{i}\sqrt{2logN_{i}}\) ,\(\sigma_{i}\ =\ \frac{\text{MAD}_{i}}{0.6745}\) =\(\frac{median(|\omega|)}{0.6745}\text{\ \ \ \ \ \ \ \ \ }\ (2)\)
where \(\sigma_{i}\) is the median absolute deviation (MAD), \(N_{i}\)is the length of noisy signal and \(\omega\) is the wavelet coefficients at \(i_{t}\) scale.