Abstract: Tachygraph recording discs carrying traces disposed in concentric strip-like tracks are analyzed in a device comprising a radial row of sensor cells under which the disc is rotated to provide point-by-point scanning of radial lines at a preselectable frequency given by clock pulses, the speed of rotation of the disc being controlled so that the scanning of each line corresponds to a given unit e.g. 1 minute of the disc time scale. Traces having different radial widths and locations, and which may possibly overlap, are detected as digital pulses which can be discriminated by a logic circuit and separately added and supplied to a recording and/or display device.