A method of determining defects on a media of an information storage device includes reading information representing data from a magnetized portion of the media, processing the read signal with discrete time signal processing, and detecting a phase shift in the read signal over a selected threshold. The method also includes sending an indication of a defect in the media in response to detecting the phase shift over the selected threshold, determining the location of the media of the defect, and storing the location of the defect in memory.