Autocorrelation analysis of particle magnetization in erased particulate media.

notes: This paper developed a complete analytical description of the origins and effects of noise in magnetic storage media. The research was part of an EPSRC project (GR/M46648/01, Noise in Advanced Magnetic Recording Tapes) with Hewlett Packard Peripherals (Bristol) to explore sources of media noise and their impact on the performance of HP's commercial (DDS-4) tape systems. The theory presented is generic, applicable to other media used in data storage, and provides guidelines for the reduction of noise and therefore errors in storage systems in general.© 2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.General analytical expressions for the magnetization power spectral densities of particulate media are derived by using the three-dimensional autocorrelation function. Expressions include the effects of AC demagnetized media and any DC components resulting from the presence of particle chains. The replay flux power spectral density is then obtained, assuming a linear replay transducer

Signal-to-noise ratios in recorded patterned media

publication-status: Publishedtypes: Proceedings PaperThe replay flux from isolated and sequences of recorded patterned elements was analysed and analytical expressions for the replay spectra were derived. The noise arising from bit size variations and bit position jitter has been modelled analytically allowing expressions for the signal-to-noise ratio for patterned media to be presented

Particle distributions and noise in metal particle tapes

©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.The magnetization spectrum from an erased (ac demagnetized or dc saturated) particulate medium was derived analytically using the autocorrelation function of a long line of separate and contiguous particles. The derived expressions indicated a strong dependence on the percentage of chains and their length inside the magnetic medium. Using the values of these quantities as fitting parameters, good agreement to measured noise spectra from a digital tape system was obtained

Correlations and noise in magnetic recording media

publication-status: Publishedtypes: Proceedings PaperA theory is presented which predicts the role of interparticle correlations in determining the magnetisation power spectral densities within magnetic recording media in the absence of recorded signal magnetisation. Magnetic correlations are represented in terms of the probabilities of the changes of magnetisation direction between neighbouring particles and this feeds through into determining the shapes of the power spectral densities and the correlation lengths

Switching times and transition widths in digital recording theory

©2001 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Calculations are carried out to show the effects of finite switching times of head fields and of recording media on recorded transition widths. In both cases the transition widths are increased and these effects are captured in simple analytical expressions

Exact harmonic coefficients for a magnetic ring head

©1999 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.The magnetic field of a ring head has been analyzed by Westmijze [1953], using a conformal mapping, and by Fan [1961], using Fourier techniques. Here these methods are reexamined and combined to give, for the first time, an explicit analytic expression for the harmonic coefficients in the Fan solution

Hysteresis loops and transition shapes during recording

©2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Hysteresis loop shapes corresponding to particular recorded transition shapes are calculated self-consistently. It is found that the closer a ramp function comes to the shape of the transition, the squarer the hysteresis loop that is needed

Accuracy of expressions for the magnetic field of a ring head

©2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.The Fourier method used by Fan has produced a representation of the field of a semi-infinite pole head consisting of a simple analytical approximation (Karlqvist field) plus an infinite series of correction terms. A method is developed in this paper by which other approximations to head fields have their infinite series of correction terms evaluated to make them exact. Expressions with only one correction term produced by Ruigrok and Szczech et al., are studied, and enhancement of them is shown to offer accurate approximations to the exact head fields

Medium magnetizations for longitudinal high-density digital recordings

©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.This paper reports on the influences of magnetic media remanent magnetizations on the output levels in digital magnetic tape and disk recording. While at low densities a high magnetization is required for a high output, a lower magnetization is required at high densities. However, for particular applications, an output near to the maximum can be obtained from a wide range of remanent magnetization values, which suggests possible uses for media with diverse properties

Recorded magnetization distributions in thin film disk media

©1998 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.The magnetization distributions in recorded transitions in thin film disk media are shown to consist of simple longitudinal magnetization transitions along with flux closure patterns. Together they give rise to the familiar sawtooth patterns but also indicate why arctangent and other approximations used in record theory have proved so successful even when sawteeth are known to be present