Reduced-complexity sequence detection for E/sup 2/PR4 magnetic recording channel

Hardware complexity required for the implementation of E/sup 2/PR4 magnetic read channel results in slower operation and increased area and power consumption. The Viterbi (1967) sequence detector for E/sup 2/PR4 channel requires 16 states that could be realized as an array of 16 single step or two-step add-compare-select units. The method presented here reduces the complexity of the two-step implementation of the detector, by eliminating less probable branches from the trellis, using the sign of the input sample as a control value. Unlikely taken branches are dynamically eliminated from the detector, decreasing its complexity by roughly 50% with negligible penalty in signal to noise ratio. The resulting detector consists of four four-way, three three-way, three two-way ACS units and one adder that are dynamically assigned to 14 states of the detector.