a digital apparatus recovers data recorded in fm or mfm on a magnetic media moving at a normal speed in which the reading of the media provides a sequence of timing / data pulses at variable intervals , which differ from a nominal interval due to speed error and magnetic &# 34 ; peak - shift &# 34 ;. the apparatus provides identification of a nominal interval between read out pulses and the reconstruction of a correct stream of pulses properly located within a window signal . it includes a digital measurement unit which at each read out pulse n received in input supplies at an output a code indicative of the actual duration of the interval n between the pulse n and a previous pulse n - 1 ; and a speed correction unit which corrects the measured duration of the interval n relative to speed error detected by the digital measurement unit during reading of a synchronization bit field . a peak shift correction unit included within the apparatus utilizing the corrected interval duration , and for mfm recording , the previous most recent history of received pulses establishes a nominal duration for the interval n . the nominal duration attributed to interval n is used by a regeneration unit to produce a suitable window signal and a regenerated pulse corresponding to the read out n pulse which is properly located within the window signal .