| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 81 === Application of the class IV partial-response (PR_IV)
equalization to linear magnetic recording channels has been
shown successfully further increase the storage densities.
However, the linear and nonlinear intersymbol interference
(ISI) become severe and exceed the limits of the capabilities
of traditional linear equalizers. Consequently, equalizers
which are able to combat both the linear and nonlinear ISI nust
be considered. In this thesis, two kinds of PR-IV equalizers
are presented. The first type is a non-adaptive, analog minimax
PR-IV equalizer and the second one is the nonlinear digital
adaptive PR-IV equalizer including the RAM-DFE and CPWL-DFE.
The minimax PR-IV equalizer is a "next-best" alternative for
adaptive equalizer. It is optimally robust relative to a mean-
square performance measure which takes account of recording
channel parameters variations. The RAM-DFE which has a random
access memory replacing the transversal feedback section of the
DFE can shape the impulse response of the channel into the
desired PR signaling. Some improvements for increasing
convergence speed for the RAM-DFE are presented. The CPWL-DFE
uses a canonical-piecewise linear(CPWL) filter to replace the
RAM and hence has faster convergence speed. The drawback is
that it may converge to a local minimum during the training
mode. Another CPWL-DFE with different structure and suboptimum
solution is proposed. Comparisons between various kinds of
equalizers are simulated and interprted.
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