scholarly journals Iterative Signal Detection Scheme Using Multilayer Perceptron for a Bit-Patterned Media Recording System

2020 ◽  
Vol 10 (24) ◽  
pp. 8819
Author(s):  
Seongkwon Jeong ◽  
Jaejin Lee
Keyword(s):  
Signal Detection ◽  
Data Storage ◽  
Multilayer Perceptron ◽  
A Priori ◽  
Magnetic Data ◽  
Bit Patterned Media ◽  
Detection Scheme ◽  
Patterned Media ◽  
Storage Density ◽  
Priori Information

Because of the physical and engineering problems of conventional magnetic data storage systems, bit-patterned media recording (BPMR) is expected to be a promising technology for extending the storage density to beyond 1 Tb /in2. To increase the storage density in BPMR systems, the separation between islands in both down- and cross-track directions must be reduced; this reduction results in two-dimensional interference from neighboring symbols in those directions, which is a major performance degradation factor in BPMR. Herein, we propose an iterative signal detection scheme between a Viterbi detector and a multilayer perceptron to improve the performance of a BPMR system. In the proposed signal detection scheme, we use the modified output of a multilayer perceptron as a priori information to improve equalization and extrinsic information to decrease the effect of intertrack interference.

scholarly journals Soft-Output Detector Using Multi-Layer Perceptron for Bit-Patterned Media Recording

2022 ◽  
Vol 12 (2) ◽  
pp. 620
Author(s):  
Seongkwon Jeong ◽  
Jaejin Lee
Keyword(s):  
Data Storage ◽  
Probability Distributions ◽  
Storage System ◽  
Areal Density ◽  
Magnetic Data ◽  
Multi Layer Perceptron ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Ber Performance ◽  
Conventional Detection

As conventional data storage systems are faced with critical problems such as the superparamagnetic limit, bit-patterned media recording (BPMR) has received significant attention as a promising next-generation magnetic data storage system. However, the reduced spacing between islands at increased areal density causes severe intersymbol and intertrack interference, which degrade BPMR system performance. In this study, we introduce a soft-output detector using multi-layer perceptron to predict reliable information. A received signal is equalized and detected by the MLP detector. The MLP detector provides a well-estimated value by using the binary-cross entropy function as a loss function and the identity function as an activation function for the output layer of the MLP detector. This study investigates the received probability distributions out of the detectors and compares the performance of various versions against a conventional detector. Compared with the conventional detection, the proposed MLP detectors provide a small variance and better BER performance than the conventional detection. Simulations of MLP designs show an advantage over conventional detection. Moreover, the proposed MLP detectors with the demodulator exhibit better BER performance than the conventional detector with the demodulator.

Estimation of density, magnetization, and depth to source: A nonlinear and noniterative 3-D potential‐field method

Geophysics ◽  
1997 ◽  
Vol 62 (3) ◽  
pp. 814-830 ◽  
Author(s):  
Maurizio Fedi
Keyword(s):  
A Priori ◽  
Real Data ◽  
Field Method ◽  
Magnetic Data ◽  
System Of Equations ◽  
Source Depth ◽  
A Priori Information ◽  
Magnetization Direction ◽  
Priori Information ◽  
Magnetic Case

The depth to the top, or bottom, and the density of a 3-D homogeneous source can be estimated from its gravity or magnetic anomalies by using a priori information on the maximum and minimum source depths. For the magnetic case, the magnetization direction is assumed to be constant and known. The source is assumed to be within a layer of known depth to the top h and thickness t. A depth model, satisfying both the data and the a priori information is found, together with its associated density/magnetization contrast. The methodology first derives, from the measured data, a set of apparent densities [Formula: see text] (or magnetizations), which do not depend on the layer parameters h and t, but only on source thickness. A nonlinear system of equations based on [Formula: see text], with source thicknesses as unknowns, is constructed. To simplify the solution, a more practical system of equations is formed. Each equation depends on only one value of thickness. Solving for the thicknesses, taking into account the above a priori information, the source depth to the top (or to the bottom) is determined uniquely. Finally, the depth solutions allow a unit‐density gravity model to be computed, which is compared to the observed gravity to determine the density contrast. A similar procedure can be used for magnetic data. Tests on synthetic anomalies and on real data demonstrate the good performance of this method.

Air Bearing Simulation for Bit Patterned Media

2008 ◽  
Author(s):  
Hui Li ◽  
Hao Zheng ◽  
Yeoungchin Yoon ◽  
Frank E. Talke
Keyword(s):  
Thermal Stability ◽  
Steady State ◽  
Disk Surface ◽  
Hard Disks ◽  
Air Bearing ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Storage Density ◽  
Low Head ◽  
Disk Spacing

Patterned media is being considered as a means for achieving a storage density beyond 1Tb/in2 on hard disks by reducing cross talk and overcoming thermal stability problems. In this investigation, the flying characteristics of a femto-type slider over bit patterned media (BPM) is investigated. The discrete bits of the disk are modeled as cylindrical protrusions on the disk surface. The steady-state flying characteristics over BPM at ultra-low head disk spacing is simulated.

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