MAXIMUM LIKELIHOOD SYMBOL DETECTION OF RLL CODED DATA

摘要

PROBLEM TO BE SOLVED: To achieve a parallel ML processing of an analog signal in an RLL encoding channel by integrating the analog signal weighted by a specified coefficient orthogonal over a symbol period. SOLUTION: An analog read back signal polluted by a noise from an optical recording medium 10 is converted to an equalization signal e(t) by an equalizer 12 and sent to a peak detection timing unit 13. The signal e(t) is weighted by a different specified Walsh's weight function of the signal e(t) by an analog Walsh conversion vector generator-sample unit 15. The unit 15 contains a vector generator 6, a sampling switch 17, a clock 18 which outputs a symbol clock pulse at each cycle of a PLL clock 14 to define a symbol clock period, a detector 19 to output an MLn bit decoding symbol to a line 20 corresponding to the signal e(t) and a tracking unit 21 to generate a phase correction signalΔϕ.