A CLASS OF SCHNEIDER WRITE EQUALIZERS FOR A (1,K) PEAK DETECTION CHANNEL

Schneider write equalization has been proposed in some digital recordi ng systems. In this paper, a class of Schneider write equalizers with zero degree phase shift and with added pulse width equal to T/M (M is an integer greater than 1, M greater than or equal to 2) for the (1, k ) peak detection recording channel will be investigated. The effects o f the equalizers on the linear peak shift and resolution for (1, 7) RL L sequences will be studied, and the capacity of the equalized recordi ng channel will be compared, under the assumption of an ideal Lorentzi an channel model. One of the equalizers with added pulse width T/2 tog ether with a 2/3 (1, 7) RLL code is applied to an R-DAT (rotary head-d igital audio tape recorder) and results show improvement in recording density and data transfer rate over an 8/10 (0, 3) dc-free code. This class of equalizer together with a (1, k) RLL sequence can be describe d as a new modulation sequence and the power spectrum will be computed based on the new modulation sequence. As added pulses of this class o f equalizers are very narrow, especially for large M, the linear chann el model might not be accurate because of nonlinear distortion due to inadequate write current risetime and/or to the demagnetization field from recorded transitions. Hardware implementations of the equalizers, including compensation for nonlinear effects introduced in the record ing process, will be considered.