scholarly journals Modulation Code for Reducing Intertrack Interference on Staggered Bit-Patterned Media Recording

2020 ◽  
Vol 10 (15) ◽  
pp. 5295 ◽  
Author(s):  
Seongkwon Jeong ◽  
Jaejin Lee
Keyword(s):  
Storage System ◽  
Areal Density ◽  
Magnetic Storage ◽  
Two Dimensional ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Cross Track ◽  
Modulation Code ◽  
Intertrack Interference

A bit-patterned media recording (BPMR) system is a type of ultrahigh-capacity magnetic storage system that can extend to an areal density of 1 terabit per square inch or higher. However, because the space between islands in the down- and cross-track directions is reduced to extend the areal density, the effect of two-dimensional interference is increased. However, using a staggered array, which is one of the possible island distributions for BPMR, helps to decrease intertrack interference. A 7/10 modulation code for a staggered BPMR is proposed to avoid the effect of two-dimensional interference and provide distance among nonidentical codewords for improving the correcting capability.

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.

scholarly journals Target and Equalizer Design for High-Density Bit-Patterned Media Recording

1970 ◽  
Vol 6 (2) ◽  
pp. 128-135
Author(s):  
Santi Koonkarnkhai ◽  
Phongsak Keeratiwintakorn ◽  
Piya Kovintavewat
Keyword(s):  
Partial Response ◽  
Mean Squared Error ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Media Noise ◽  
Minimum Mean Squared Error ◽  
Squared Error ◽  
Cross Track ◽  
Partial Response Maximum Likelihood ◽  
Better Than

In bit-patterned media recording (BPMR) channels, the inter-track interference (ITI) is extremely severe at ultra high areal densities, which significantly degrades the system performance. The partial-response maximum-likelihood (PRML) technique that uses an one-dimensional (1D) partial response target might not be able to cope with this severe ITI, especially in the presence of media noise and track mis-registration (TMR). This paper describes the target and equalizer design for highdensity BPMR channels. Specifically, we proposes a two-dimensional (2D) cross-track asymmetric target, based on a minimum mean-squared error (MMSE) approach, to combat media noise and TMR. Results indicate that the proposed 2D target performs better than the previously proposed 2D targets, especially when media noise and TMR is severe.

A Magnetic Rotary Encoder for Patterned Media Lithography

2014 ◽  
Author(s):  
Shaomin Xiong ◽  
Yuan Wang ◽  
Xiang Zhang ◽  
David Bogy
Keyword(s):  
High Speed ◽  
New Technology ◽  
Hard Disk Drives ◽  
Magnetic Storage ◽  
Magnetic Islands ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Rotary Encoder ◽  
Digital Format ◽  
Field Programmable

Bit patterned media (BPM) is expected to enable the magnetic storage density in hard disk drives (HDDs) beyond 1 Tb/in2. BPM uses isolated magnetic islands to record the data information. However, the large volume fabrication of those patterned media disks at an affordable cost is a challenge for this new technology. A master template is the first step for patterned media fabrication. Using nano-imprint technology, the master template can be replicated to tens of thousands of pattern disks. A rotary electron beam lithography machine or plasmonic nanolithography machine is recommended to assist in the fabrication of the master template. In both systems, a high resolution encoder system for positioning in the rotary lithography machine is necessary. In this paper, a magnetic rotary encoder system is introduced. The encoder system can be operated at several thousand revolution per minute (RPM). The scale pitch is 90 nm which is one to two orders smaller than current optical encoders. The resolution is about 2.8 million counts per revolution (CPR). A flying magnetic head is used to retrieve the readback signal from the magnetic encoders. A field programmable gate array (FPGA) is implemented to finish the high speed signal processing and provide a digital format encoder signal to trigger the lithography machine at a rate of several Mega Hertz.

Investigation of Graph-Based Detection in Iterative Decoding for Bit-Patterned Media Recording

2014 ◽  
Vol 979 ◽  
pp. 58-61
Author(s):  
Piya Kovintavewat
Keyword(s):  
Iterative Decoding ◽  
Intersymbol Interference ◽  
High Density ◽  
Soft Information ◽  
Experimental Results ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Recording Density ◽  
Moderate Complexity ◽  
Intertrack Interference

High-density bit-patterned media recording (BPMR) can be obtained by reducing the spacing between data bitislands in both the along-and across-track directions, thus leading to severe intersymbol interference (ISI) and intertrack interference (ITI) because of small bit and track pitches, respectively. Here, we propose to use the graph-based detector, instead of the trellis-based detector, in iterative decoding to combat the ISI and the ITI for a multi-head multi-track BPMR system. Specifically, the readback signal is sent to the graph-based detector before iteratively exchanging the soft information with a decoder. Experimental results indicate that at low to moderate complexity, the proposed scheme outperforms the existing schemes, especially at high recording density.

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