Circuit for processing an asynchronous signal containing a periodical synchronisation burst

摘要

The circuit includes a first asynchronous signal level comparator with a first threshold which is adjusted as a function of the first comparator output during a synchronisation pulse burst. Second and third signal level comparators are also included with respective second and third threshold levels which are correlated to the first threshold so the first threshold lies between the second and third thresholds. Pulse burst detection is performed when the output of the second comparator satisfies a predetermined movement criterion. The second threshold is shifted towards the first threshold and the pulse burst level moves to the level of the asynchronous signal preceeding the pulse burst.