Adaptive circuit for extracting timing information from a repetitive

Abstract

A circuit for discriminating among pulses in a series of recurring pulses based on the interval between adjacent pulses which circuit is particularly useful in extracting timing information from a series of pulses such as are induced in a servo head by movement relative thereto of a prerecorded servo track in a disc pack data storage system. The circuit includes a monostable multivibrator for producing a timing signal having a duration corresponding to the time interval between two successive pulses. The monostable multivibrator output is stored, for example in a data flip flop, so as to produce an output pulse from the flip flop if a succeeding pulse in the series occurs while the monostable multivibrator output is high. A feedback circuit connects the output pulse to the timing circuit of the monostable multivibrator to alter the duration of the timing signal produced by the monostable multivibrator in accordance with changes in frequency of the recurring pulses so as to maintain constant the width of the output pulse notwithstanding variation of the frequency of the pulse series. The feedback circuit includes an integrator which effects a reduction in band width of the feedback circuit so that noise pulses or the like that occur at random times have insignificant effect on the circuit and on the output pulses produced thereby.