Abstract: In the context of a DVD-RAM read-type architecture in which an optical storage medium (20) makes use of an eccentric wobble (164) to attain synchronisation information, a wobble PLL (179) is held in an acquired state whenever header regions (32, 33) embossed at regular intervals across the optical storage medium (20) are detected. More specifically, large dc variations associated with voltage spikes caused by header regions (32, 33) are scaled (260) relative to a dynamically varying amplitude envelope of the extracted wobble signal (164), such as to identify a start location (300) for each header region. The wobble PLL (179) is effectively allowed to free-run and hold state during periods of header, thereby mitigating the likelihood that the wobble PLL will loose lock during the header regions.

Abstract: In the context of a DVD-RAM read-type architecture in which an optical storage medium (20) makes use of an eccentric wobble (164) to attain synchronisation information, a wobble PLL (179) is held in an acquired state whenever header regions (32, 33) embossed at regular intervals across the optical storage medium (20) are detected. More specifically, large dc variations associated with voltage spikes caused by header regions (32, 33) are scaled (260) relative to a dynamically varying amplitude envelope of the extracted wobble signal (164), such as to identify a start location (300) for each header region. The wobble PLL (179) is effectively allowed to free-run and hold state during periods of header, thereby mitigating the likelihood that the wobble PLL will loose lock during the header regions.