A study on practical NLTS indicators for MDFE and M2DFE magnetic recording channels

A new method to determine the write precompensation value based on the sample data obtained from multilevel decision feedback equalization (MDFE) and its extension M2DFE channels is studied. Three parameters are proposed as NLTS indicators. These indicators are very sensitive to NLTS but not to other non-linear distortions including the amplitude asymmetry of MR head and the shift of sampling clock. Neither complex computation nor additional circuit is required. The adjustment can be conducted on drive level that uses MDFE channels. The method offers a more practical and cost-effective way to determine the write precompensation value especially in the mass production and fine adjustment