Constrained equalizers and precoding for magnetic storage channels

The nonlinear write process of magnetic recording allows to write the symbols /spl plusmn/1 only. The magnetic channel is a differentiating channel. The locations of the transitions from +1 to -1 and vice versa in the input signal to the magnetic channel are important for the received waveform. This...

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Bibliographic Details
Main Author: Feyh, G.
Format: Conference Proceeding
Language:English
Subjects:
Additive white noise
Detectors
Equalizers
Gaussian noise
Magnetic memory
Magnetic noise
Magnetic recording
Magnetic separation
Maximum likelihood detection
Noise shaping
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Summary:The nonlinear write process of magnetic recording allows to write the symbols /spl plusmn/1 only. The magnetic channel is a differentiating channel. The locations of the transitions from +1 to -1 and vice versa in the input signal to the magnetic channel are important for the received waveform. This paper defines a noise enhancement constrained, finite dimensional equalizer. This equalizer trades some misequalization of the data signal for less noise enhancement after the equalizer. In a second step the misequalization is decreased by the precoding. Precoding shapes the communication signal before entering the communication channel. Since precoding works on the noise-free signal, there is no noise enhancement. Since precoding in magnetic channels is limited to shifting the positions of the transitions around, precoding does not allow for full equalization at the receiver. Therefore the equalizer in the receiver and the precoder are optimized. In order to find the optimal transition positions a linearized representation of the transition shift is produced. This representation leads to a constrained optimization problem.
ISSN:1520-6149
2379-190X
DOI:10.1109/ICASSP.1998.679615