Simple soft-output detection for magnetic recording channels

Recent success of turbo-like coding schemes on memoryless channels has sparked interest in using them on intersymbol interference (ISI) channels. Decoders for turbo and low density parity check (LDPC) codes perform much better with soft input information which has to be supplied by the channel detector as its soft output. We consider a class of ISI channels commonly used to model magnetic recording channels in a wide range of linear recording densities, and show that simple soft output detectors are possible, since the channel transfer functions belong to a family of special polynomials.