The absolute time of flight (AbsToF) is determined by a two-stage process, namely acquisition and tracking. The acquisition process is implemented when there is no previous memory of the absTOF value (for example during the first signal capture) or when the algorithm detects an anomaly in two consecutive measurements of AbsTOF. The acquisition process algorithm consumes more power, so it is not implemented during each measurement. Instead, the tracking algorithm is implemented during each measurement.