Soft signal space detection for magnetic recording

Summary form only given. Soft signal space detectors approximate the symbol-by-symbol maximum a posteriori probability detection algorithms whose optimization criterion is the symbol error probability. The soft signal space detectors (SSDs) yield probabilistic reliability information about the transmitted symbols in contrast to yielding hard decisions about these symbols, as the hard SSD detectors do. The soft information can be used as input to soft error correction codes (ECCs), such as turbo codes or low density parity check (LDPC) codes, resulting in large performance gains over hard channel decoders and hard ECCs.