Impulse noise from nearby or intense electrical sources can disrupt communications over digital subscriber lines (DSL). The characterization of the nature, timing and length of impulse noise sources present on a DSL loop is a critical first step in mitigating the effect of impulse noise on DSL communications. DSL standards provide histograms for impulse length and inter-arrival time of impulses. These histograms can be used to derive the nature, maximum frequency and other statistics related to impulse noise on a DSL line.