Method and apparatus for detecting binary data by polarity comparison

Claim 1

A magnetic reproducing system comprising: a. sensing means for deriving an alternating electrical differentiated signal having a first and second frequency with alternating first and second polarity corresponding to the magnetization of a record medium having binary information stored within successive cells thereon, one half cycle of said first frequency corresponding to magnetization of one of said first and second polarities of opposite sense within a cell representing a first binary digit value and one full cycle of said second frequency corresponding to magnetization of an alternation from said first to said second polarity for first and second halves of a cell representing a second binary digit value wherein a polarity reversal occurs at a boundary between each of said successive cells; b. clock generating means connected to said sensing means for receiving said differentiated signal and being responsive to said differentiated signal to generate first, second, and third clock signals, said first clock signals occuring at times corresponding to a one-fourth position and a three-fourths position of each of said cells, and said second and third clock signals occurring at times corresponding to a position within a second quarter position and within a fourth quarter position of each of said cells, respectively; c. detection means connected to said clock generating means and said sensing means for receiving said first clock signals and said differentiated signal and being responsive to said first clock signals and said differentiated signal to generate a first sample signal for each cell of said succession of cells indicative of one of said first and second polarities corresponding to the magnetization of said record medium at a position within a first half of said cell anD a second sample signal for each cell of said succession of cells indicative of one of said first and second polarities corresponding to the magnetization of said record medium at a position within a second half of said cell; d. storage means connected to said detection means for receiving said first and second sample signals and being responsive to said first and second sample signals of a corresponding cell and a next first sample signal of an immediately succeeding cell for storing indications representing the sense of the polarities of said first and second sample signals of a corresponding cell and said next first sample signal of an immediately succeeding cell; and e. comparison means connected to said clock generating means and said storage means for receiving said second and third clock signals and said indications representing the sense of the polarities of said first and second sample signals and said next first sample signals and being responsive to said second clock signal and said indications representing the sense of the polarities of first and second sample signals of said corresponding cell indicative of like polarity sense to generate a first output signal indicative of a first binary digit value, being responsive to said second clock signal and stored indications representing the sense of the polarities of the first and second sample signals of said corresponding cell indicative of unlike sense of polarity to generate a second output signal indicative of a second binary digit value, and being responsive to said third clock signal and said stored indications representing the sense of polarities of said second sample signal and said next first sample signal indicative of like sense of polarity to generate an error signal.