- 1.
- Design the filters in the frequency domain, as before.
- 2.
- Take a Fourier transform in the horizontal direction (that is, a Fourier transform for each row of the matrix on the left panel of Figure 1) and form the corresponding frequency-domain convolutional matrix. Figure 2 shows the resultant matrix (amplitude spectrum only). This matrix is called the frequency connection matrix. On the left is a horizontally-shifted version of the matrix. The center ``trace'' corresponds to the stationary response and the ``traces'' away from it represent the departure from stationarity. Only a few ``traces'' are shown. On the right panel we have the complete dataset shifted so that the ``stationary trace'' is along the diagonal, which means that the off-diagonal energy represents again the departure from stationarity.
- 3.
- Take the Fourier transform of the input trace.
- 4.
- Multiply the frequency connection matrix (right panel of Figure 2) with the Fourier transform of the input trace to get the filtered trace in the frequency domain.
- 5.
- Take the inverse Fourier transform of the filtered trace to get it in the time domain.

6/8/2002