Hale wrote that the unclipped IQF of a seismogram amplified the Nyquist frequency by a factor 7x10 6 when we had the ratio t / Q = 10 and concluded that for typical seismograms with lengths longer than 1000 samples and Q value around 100, data is seldom pure enough to warrant the use of unclipped IQF . Wang introduced a cutoff frequency to set up a criterion for the stabilization by a mathematical formula.