Apparatus for encoding unconstrained data onto a (1,7) format with rate 2/3
US4488142A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 31, 1981 |
| Grant date | Dec 11, 1984 |
| Priority date | — |
| Expiry date | Dec 31, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/005
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An algorithm and the hardware embodiment for producing a run length limited code useful in magnetic recording channels are described. The system described produces sequences which have a minimum of 1 zero and a maximum of 7 zeros between adjacent 1's. The code is generated by a sequential scheme that maps 2 bits of unconstrained into 3 bits of constrained data. The encoder is a finite state machine whose internal state description requires 3 bits. The encoder requires a lookahead of one future input vector (2 bits) and a look back at the last channel bit generated during the immediately preceding encoding operation. The error propagation due to a random error is, at most, 4 bits in bursts of 5. The hardware implementation is extremely simple and can operate at very high data speeds.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.