摘要 |
<p>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=4(2,10) code provides high density recording to a multi-level storage medium. The M=4(2,10) encoder is implemented using a three-state encoder and a modulo four waveform encoder.</p> |