Maximum likelihood decoding applied to run length limited codes

To control the level of intersymbol interferences while providing synchronization for read-back data, run-length-limited codes are widely used in modern recording systems. The feasibility of utilizing the redundancies introduced by these codes and the intrinsic correlative aspects of magnetic recording channels is used to improve the output error probability. To accomplish this, a modified Viterbi algorithm is developed. Computer simulation models are used to evaluate the performance of the algorithm. The results prove superior performance of maximum-likelihood decoding over conventional bit-by-bit detection