On Multi-Level Coded RLL Modulation for the Recording Channel
Date Issued
2008
Date
2008
Author(s)
Ku, Yu-Sian
Abstract
Nowadays the run-length-limited (RLL) codes are usually used to eliminate the restriction of synchronization and the intersymbol interference in the recording system. In order to increase the information recording density without changing optical or mechanical parameters, a Multi-level recording using run-length-limited (RLL) modulation is applied to the optical recording system. There are many architecture proposed which combine the partial response channel and Maximum Likelihood Detection (PRML). In this thesis, it is distinct from PRML architecture in the recording system model. We propose a serially concatenated coding system which combine with partial response channel , Multi-level RLL coded modulation and error-correct codes. We used the principle of soft-input and soft-output iterative decoding to resolve the information of data. The main idea is how to work out the soft value between binary bits and non-binary RLL coded symbols. In addition, in order to read the signal and that wasn’t interfered from the low frequency part of information, so you must reduce the direct current (DC) component. We also analysis the DC-balance issue for multi-level RLL modulation in this thesis.irst, we combine a 3-level 4/3 code rate run-length-limited encoder and a 1/2 code rate LDPC encoder over the partial response channel (1111) and (1221) mode separately and run the simulation under AWGN channel model. Moreover, the simulation results reveal the improvement of our proposed architecture. We can achieve a satisfied error performance and DC-free under the RLL constraint.
Subjects
multi-level run-length-limited codes
low density parity check codes
partial response channel
DC-free
soft-in-soft-out
Type
thesis
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