Browse Prior Art Database

Device to Screen Metal-Film Media for Media Noise

IP.com Disclosure Number: IPCOM000101052D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Lambert, S: AUTHOR [+3]

Abstract

A major component of media noise in metal film media is associated with the magnetic transitions written to encode information. Controlling this noise source is essential for any application of metal film media for data storage. Media noise is usually measured using a spectrum analyzer to determine the signal power as a function of frequency. The spectral peaks associated with the recorded waveform are removed by interpolation, and integration of the remaining noise spectrum yields a value for the noise power. This process can require about one minute to complete, an interval which may be too long to permit routine screening of disks on a production line. We propose here a simple alternative which yields the same information much more quickly.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 56% of the total text.

Device to Screen Metal-Film Media for Media Noise

       A major component of media noise in metal film media is
associated with the magnetic transitions written to encode
information.  Controlling this noise source is essential for any
application of metal film media for data storage.  Media noise is
usually measured using a spectrum analyzer to determine the signal
power as a function of frequency.  The spectral peaks associated with
the recorded waveform are removed by interpolation, and integration
of the remaining noise spectrum yields a value for the noise power.
This process can require about one minute to complete, an interval
which may be too long to permit routine screening of disks on a
production line.  We propose here a simple alternative which yields
the same information much more quickly.

      A large value of media noise is typically obtained when
recording in metal-film media at high transition density. It is
possible to measure the total power in the readback using a device
such as a power meter, but this will include both signal and noise
power.  Notch filters could be used to remove the frequencies
associated with the recorded data, but this eliminates any noise
contributions at those frequencies.  A high-noise state free of
recorded signals can be obtained by demagnetizing the film.  A
"reverse DC erase" is one way to do this.  A large DC erase current
is applied, followed by a DC erase of opposite polarity.  The noise
power will sho...