The example shows a signal recorded on 2 components ( the vertical component in green, the horizontal component in black). The Hilbert transform is used to change the phase of the part of the signal recorded on the vertical component and to put it in phase with the part of the signal recorded on the horizontal component. After changing the phase of the vertical component, the initial Lissajou curve becomes a line. A rotation is now applied to both components so that the wave is integrally projected onto the vertical axis. The Lissajou line is now parallel to the vertical axis.