Signal space detection for recording channels with jitter noise

A delay-constrained sequence detector is considered for recording channels whose major impediments include intersymbol interference and magnetic transition jitter noise. The jitter noise is data-dependent, and a given noise sample is correlated with neighboring noise samples. A sequence detector with a nite decision delay can be formulated in a nite dimensional vector space. For a correlated noise channel, the decision boundary is generally quadratic. In this paper, we present a technique for obtaining a minimal set of hyperplanes approximating a quadratic decision boundary with a negligible performance loss. In this process, a distance measure, which is consistent with the notion of the e ective SNR, is de ned and used as a design parameter to trade the complexity and performance. As an achievable performance bound, we derive the e ective SNR for the maximum likelihood sequence detector (MLSD) for these channels. The performance of the partial response maximum likelihood (PRML) detector commonly adopted for current data storage channels as well as the Viterbi algorithm (VA) based on the traditional Euclidean metric, which serves as the MLSD for additive white Gaussian noise, are also analyzed and compared with that of the proposed signal space detector. Index Terms sequence detection, signal space, digital magnetic recording, intersymbol interference This work was supported in part by the NSF under grant CCR-9805195. Y. Kim was with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA. He is now with Texas Instruments, Tustin, CA 92780, USA (e-mail: [email protected]). J. Moon is with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA (e-mail: [email protected]). To appear in IEEE Transactions on Information Theory 2