Method and apparatus for detection and identification of flaws in a magnetic medium by measuring the width of pulses stored on the medium

Abstract

A flaw identification circuit receives digitized read data and provides an error output representative of defects in a magnetic storage medium. A uniform data pattern is written on the magnetic storage medium. The flaw identification circuitry uses a precision delay circuit and a linear ramp circuit. The linear ramp circuit generates a linear ramp using the charging of a capacitor with a constant current source. This provides an accurate time base reference. The output of the linear ramp circuit is applied to a flash analog-to-digital converter. The flash analog-to-digital converter is directly triggered by the digitized read data signal. The output of the flash analog-to-digital converter is applied to a maximum comparator and a minimum comparator. If the output value of the analog-to-digital converter falls outside of the maximum and minimum value range, an error is signalled. The error is representative of shifts in the location of edges of data pulses in the digitized read data signal. This corresponds to a defect in the magnetic storage medium.

Dependencies are inferred from the claim text.