Digital coding technique which avoids loss of synchronization
US5461379A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 14, 1993 |
| Grant date | Oct 24, 1995 |
| Priority date | — |
| Expiry date | Dec 14, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/1492
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Loss of synchronization, due to a digital data signal having the same signal value for an extended number of bit or symbol periods, is overcome through the use of a coding scheme which assures transitions after each such period despite the absence of transitions in the signal to be encoded. Broadly, within the encoder, a digital input signal having m signal levels is transformed into a coded digital output signal having n possible signal values, where m<n. The transformation alters the current digital input signal value as a function of the previous coded digital output signal value and the current digital input signal value performed in a number system whose modulus is n. In a disclosed embodiment, a binary input signal is coded into an output signal having three signal levels. The transformation provided in the encoder of this disclosed embodiment provides a coded output signal whose value is equal to the previous coded output signal value +1, modulo 3, when the current value of the digital input signal is logical 1 and whose value is the previous coded output signal value -1, modulo 3, or, equivalently, the previous coded output signal value 2, modulo 3, when the current value o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.