Method and apparatus for constructing asymptotically optimal second order DC-free channel codes
US5450443A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 1, 1993 |
| Grant date | Sep 12, 1995 |
| Priority date | — |
| Expiry date | Sep 1, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M5/145
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An encoding apparatus for constructing an asymptotically optimal coding scheme for second order DC-constrained channels is disclosed. A first encoding function block breaks an input data stream into equal sized vectors of length m bits. A sign designation bit is then attached to each vector to make vectors of length m+1 bits. r redundancy bits are added to each vector, to produce balanced vectors of length m+1+r bits. A first moment is calculated for each vector. A determination is made whether the addition of this vector's first moment value to an accumulated running sum of all the vectors' first moments effectively drives the running sum in the direction of zero. If is does then that vector's first moment is added to the accumulated running sum of first moments and the vector is added to the output array. If not, then the value of that vector's first moment is inverted before being added to the accumulated running sum, and the individual bits of this vector get inverted, and the sign designation bit of that vector gets toggled so as to indicate upon decoding that the bits of this vector have been involved. This encoding process is repeated until all the first moments of all the i…
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