A sequence (200) of symbols (201-1 - 201-3, 202-1 - 202-14) is received on a first channel. A noise contribution of a given synchronization symbol (201-2) is estimated; a reference noise contribution of at least one further symbol (201-1, 201-3, 202-1 - 202-14) is estimated. Based on the noise contribution and further based on the reference noise contribution the given synchronization symbol (201-2) is selectively considered when determining a coupling coefficient of crosstalk between the first channel and a second channel.