Fig. 2.

(a) The scale-frequency diagram of MODWPT. The first rectangle at level $j=0$ represents the entire spectrum of the original THz signal, $X$. At subsequent decomposition levels, the spectrum is divided into $2^j$ sub-bands of equal bandwidth by filtering the sub-bands of the previous stage with a pair of scaling and wavelet filters. The amplitude spectrum of the sub-bands are plotted for (b) MODWT and (c) MODWPT over $j=3$ levels of decomposition.