- 1.
- Design the filters in the frequency domain. These may be trapezoidal tapered filters or some other suitable bandpass filter. We can consider these filters as making up a matrix whose horizontal coordinate is time (that is, the sample time of application of every filter) and whose vertical component is frequency as shown in the left-hand side of Figure 1.
- 2.
- Get the filter impulse responses in time domain. This essentially means taking an inverse Fourier transform of each column of the left panel in Figure 1.
- 3.
- Form the non-stationary impulse response matrix in time domain. The right panel in Figure 1 shows an example of this matrix for the case of three different filters to be applied in three windows of data. The wavelet is zero phase and the impulse responses are shifted so that the wavelet is centered along the diagonal.
- 4.
- Apply the non-stationary convolution. This is done by matrix multiplication between the matrix in the right panel of Figure 1 and the seismic trace to be filtered.

Figure 1

Figure 2

6/8/2002