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.