Dual FDTS/DF: A unified approach to dual-detection and modification for MTR codes

Dual-detector decision-feedback schemes have recently gained considerable i nterest in magnetic recording. Schemes such as dual decision feedback equal ization (DDFE), M2DFE, acid dual FDTS/DF are dual-detector versions of DFE, multilevel DFE (MDFE), and fixed delay tree search with decision feedback fixed-delay tree search with decision feedback (FDTS/DF) detectors, respect ively. At high recording densities, the dual-detector versions significantl y improve bit-error-rate (BER) performance and reduce error propagation. In this paper, we first give a unified approach to the bit-error-rate analysi s of dual-detector decision feedback schemes in an attempt to highlight the ir relationship, and then we show that the performance of dual FDTS/DF redu ces to that of DDFE for tau = 0 and reduces to that of M2DFE for tau = 1 wi th d = 1 code constraint, Further, we extend the dual FDTS/DF detection sch eme to maximum transition run-length (MTR) coded channels. On the basis of both BER and error event analysis, we propose a modified dual FDTS/DF detec tion scheme for MTR-coded channels that improves BER performance. The new s cheme modifies certain bits in the detection process for preventing the dom inant error event. Simulation results on 6/7 MTR-coded Lorentzian channel s how that the modified detector gives around 1 dB SNR improvement over the a dvanced (trellis-coded extended partial response) TC-(EPR)-P-2 detector.