An amount of delay between a digital reference signal and a digital derived signal is measured, wherein the derived signal is derived from the reference signal. Measurement involves ascertaining a sign of a slope of the derived signal over a first time interval and producing a set of time-associated reference signs by ascertaining a sign of a slope of the reference signal over each of a plurality of different time intervals leading up to the first time interval. A first set of coincidence results is produced by detecting coincidence between the sign of the slope of the derived signal and each one of the time-associated reference signs in the set of time-associated reference signs. The first set of coincidence results is used alone or in combination with other coincidence results as an indicator of the amount of delay between the reference signal and the derived signal.