Abstract: A device for determining a complete track number of a track which forms part of a set of tracks on a disc-shaped record carrier, enabling direct control by means signals detected from servo sectors during each phase of positioning, and making a calculated estimate of a new track number on the basis of the displacement speed of the positioning member. The device reads a first track number in the group and estimates a second group number. It then estimates a complete track number on the basis of the displacement speed of positioning member body, determining the difference between the complete track number read and the estimated complete track number and comparing the magnitude of the difference obtained with a value determined by half a signal being produced if said magnitude is smaller than half, said signal validating the complete track number present in the first determination. A complete track number is determined by the sequential use of said estimates after each servo sector.