Abstract: A method and system to detect a change in a communications channel system. An ultra-wideband transmitted signal is transmitted and a received signal is received. At least one channel impulse response of a communications channel is determined. The determined channel impulse responses are adapted to a known channel impulse response of the communications channel to produce a respective adapted channel impulse response in such a manner that a correlation coefficient resulting from the determined channel impulse response and the known channel impulse response increases. The adapted channel impulse responses are filtered in a time direction via a filter unit to obtain a specific filter signal of the filtered, adapted channel impulse responses of the communications channel. The change in the communications channel system is detected at least on the basis of the specific filter signal of the at least one communications channel.