Patent ID: 7817362

Claim:
In an apparatus for inspecting a magnetic recording medium, which inspects the magnetic recording medium characteristics in a procedure comprising recording test data onto the magnetic recording medium by a magnetic head, reproducing the recorded test data by the magnetic head, distributing the reproduced test data to N pieces of signals paths, where N is an integer greater than 1, converting the signals into discrete digital values by N pieces of A/D converters, and executing appropriate computation with the discrete digital values; an apparatus for inspecting a magnetic disk comprising a first reference signal generating source which generates reference signals of a controllable oscillating frequency f in , a signal switching means for selecting and outputting either a reference signal generated by the first reference signal generating source or test data reproduced by the magnetic head, a second reference signal generating source which supplies timing signals of frequency f ADC to the N pieces of A/D conversion means for triggering signal sampling and conversion, while controlling the frequency f ADC of a timing signal to be supplied to an individual A/D conversion means, and a data manipulation means in which errors occurring in parallel elements controlled to operate parallel of the N pieces of A/D conversion means are detected by appropriate computation and the detected values of errors are retained, and subsequent similar errors are compensated with the detected values during test data computation.