READ CIRCUIT FOR ELIMINATING FALSE PEAKS IN AN ALTERNATING CURRENT PLAYBACK SIGNAL

摘要

An improved read circuit for use with a magnetic read transducer in a magnetic recording system in which the read transducer generates an alternating current playback signal having alternating positive and negative peaks. The read circuit comprises an active differentiator responsive to the playback signal for producing a differentiated signal having positive and negative values with zero crossings in time coincidence with the positive and negative peaks of the playback signal, and a differential comparator for generating an intermediate playback signal having a first value when the differentiated signal is positive and having a second value when the differentiated signal is negative and for generating the complement of the intermediate signal. The read circuit comprises additional logic circuitry responsive to the intermediate playback signal and its complement for generating an output signal having first and second values corresponding to the positive and negative peaks, respectively, of the playback signal and capable of distinguishing false peaks or shoulders in the playback signal. The logic circuitry distinguishes false peaks by requiring that the intermediate playback signal remain in a state which is different from its immediately previous state for at least a predetermined time, such time being of duration sufficient to eliminate false peaks, which typically produce fairly rapid transitions in the level of the intermediate playback signal. The logic circuit design minimizes problems of peak shift.