Detection and verification of lapses or shifts of synch words in PCM data
US4843489A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1987 |
| Grant date | Jun 27, 1989 |
| Priority date | — |
| Expiry date | Nov 25, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/046
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A first counter operating at the PCM sampling frequency counts out the normal minimum period between successive synchronization words in the data stream. In a following "window" the detection of another synchronization word produces a check signal and in all other cases a provisional check signal. In such other case the data for the next period are marked as dubious. A second counter counts out twice the minimum normal interval between synchronization words and in a following "window", the appearance of a synchronization word produces a verification signal. The occurrence of a verification signal one normal interval after a provisional check signal removes the marking of intervening data as "dubious". If no verification signal is then produced, the intervening data are marked and treated as erroneous.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.