System and method for measuring erase band widths on magnetic media

Abstract

A method for measuring the width of an erase band located adjacent to a test track containing a periodic signal at a specified frequency is disclosed. For each position of a read head as it incrementally traverses the erase band and test track, an information signal is read, and a signal level data point is stored which represents the amplitude of the fundamental frequency obtained from a Fourier transform of the information signal. In addition, a media noise level data point is stored which represents an integration of a noise power spectrum obtained from the Fourier spectrum of the information signal over a predetermined frequency range. Once the signal and media noise level data points are obtained, the edge of the test track is approximated by determining from the signal level data points a point at which the amplitude of the stored signal level data points departs from an otherwise substantially constant background noise level. The edge of the erase band is also approximated by determining from the media noise level data points a point at which the amplitude of the stored media noise level data points departs from an otherwise substantially constant background noise level. The width of the erase band is derived by computing the absolute value of the difference between the positions of the edge of the test track and the edge of the erase band.