| 摘要 |
A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M > 2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder (204) converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=9(2,10) code provides high density recording to a multi-level storage medium. The M=9(2,10) encoder is implemented using an eighteen-state encoder and a modulo nine waveform encoder.
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