A method for determining a contribution of burst noise to a bit error rate in a digital system for reception of an interleaved forward error correction-enabled digital symbol stream is described. The method is based on identifying errored symbols at a decoding stage, determining their positions in the interleaved stream, and performing a windowing operation such that the errored symbols located within the window in the interleaved stream are designated as burst errored symbols. A corresponding digital receiver and a digital transmission system are also disclosed.