Apparatus and method for digitally synchronizing the timing of a

Abstract

A method and apparatus for implementing the same are provided for digitally synchronizing the timing of a sequence of electrical output pulses in accordance with a selectable, permissably non-linear function of the timing of a sequence of electrical input pulses. The method and apparatus are illustrated with reference to application thereof to overcoming the problem of degradation of synchronization caused by so-called 'peak shift' due to the adjacent data effect in the reading of binary data stored on magnetic disks or the like. Pulses of a timing reference signal having a uniform interval equal to a sub-multiple of the normal average interval of the desired output pulses are continuously counted to a number base equal to the denominator of said sub-multiple, and output pulses are produced whenever a pre-selected count value occurs. Output pulse timing correction values in accordance with the synchronizing function selected are stored in memory. A parameter of the input pulse sequence representing the occurrence of a new pulse therein is sensed and triggers substitution for the then existing count of the correction value accessed from memory at the address represented by the count existing prior to such substitution. Accurate synchronization of the timing of the output pulses with the actual, leading or lagging occurrence of input pulses is thereby accomplished on a continuing basis whenever a new input pulse produces the mentioned triggering, even with input pulse sequences from which only irregularly occurring, magnetic state transition boundaries may be sensed.