Threshold crossing timing recovery for high capacity optical disc systems
AssigneeKoninklijke Philips Electronic, N.V.
InventorBin Yin
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Abstract
The invention relates to a method of providing timing error information in optical systems, especially for reading high capacity optical discs, i.e. optical discs with a capacity of about 27 GB or above. At these capacities current threshold crossing timing recovery does not perform well and even becomes unfeasible due to severe inter-symbol interference. The method suggests using an upper and/or lower secondary eye in the eye diagram of the data signal to acquire the timing error information. Hereby, threshold crossing timing recovery becomes feasible for high capacity optical systems, where the central eye is closed or nearly closed due to the inter-symbol interference.
Claims8
A method of providing threshold crossing timing recovery in an optical system, which optical system is adapted to read data signal samples (ys) from an optical disc, said method comprising the steps of:
- reading data signal samples (ys) at a sampling time (ts) from the optical disc by means of the optical system,
- feeding the read data signal samples (ys) to a timing recovery means (100) comprising a timing error detection means (20), determining timing error information (em) by means of the timing error detection means (20),
- adjusting the sampling time (ts) towards synchronous timing instants (tk) on the basis of the timing error information (ψk), characterized in that an eye pattern of the data signal samples (ys) is used in the step of determining timing error information (ψk), and that the timing error detection means (20) is adapted to extract timing error information (ψk) at the position of a secondary eye in the eye pattern.
Dependencies are inferred from the claim text.