1. A method comprising: measuring a power spectral density on a subscriber loop; using a processor to correlate the power spectral density for said subscriber loop with a predetermined set of power spectral densities for a group of possible crosstalk disturbers; selecting a crosstalk disturber, from the group of possible crosstalk disturbers, having the most closely correlated power spectral density; and, refining the selection of the crosstalk disturber using a matching pursuit (MP) algorithm.