  We are investigating to what extent one can use a P(D) analysis to extract
number counts of unclustered sources from maps of the far infrared background.
Currently available such maps, and those expected to emerge in near future are
dominated by confusion noise due to poor resolution. We simulate background
maps with an underlying two slope model for N(S) and we find that in an
experiment of FIRBACK type we can extract the high flux slope with an error of
few percent while other parameters are not so well constrained. We find,
however, that in a SIRTF type experiment all parameters of this N(S) model can
be extracted with errors of only few percent.
