Figure 6a shows a synthetic shot gather for a 1D medium.
This gather is corrupted with internal multiples only. In Figure
6b, we display the internal multiple model obtained
using the CFP approach Berkhout and Verschuur (1999).
This internal multiple model is perfect and could be directly subtracted
from the data in Figure 6a. Note that the amplitude
of the internal multiples is significantly less than the amplitude
of the primaries, making the -norm unsuitable for estimating
the shaping filters. Figure 7 displays the
histograms of both the data and the internal multiples. The narrow
peak of the noise indicates that the -norm should be used.

inter
Figure 6 (a) A synthetic shot gather
infested with internal multiples. (b) The internal multiples model
obtained using the CFP technology. This model matches the
internal multiples in (a).

histodata
Figure 7 Histograms of the input
data (Figure 6a)
and of the noise (Figure 6b).
The density function of the noise is much narrower
than for the data. The -norm should be used to estimate the signal.