This is a closer view of Figure 2.20 part B. There is a horizontal frequency axis marked with four equally spaced markers labelled ‘subcarrier frequencies’. Centred on each frequency is a wave shape with a high positive peak centred on the marked frequency, falling away sharply on either side in ripples of decreasing amplitude. Because the frequency markers are close together, there is a lot of overlap of the wave shapes, so that as the wave shape falls away on either side of the peak, at a value of about three-quarters of its peak value it intersects the wave shape centred on the adjacent subcarrier frequency. Each subcarrier peak coincides with zeros on all the other waveforms it overlaps with.