AN OPTICAL DISC READING APPARATUS AND METHOD THEREFORE

摘要

An optical disc reading apparatus, such as a Near Filed optical disc reading apparatus, comprises a disc reader (401) which generates a first signal by reading an optical disc (403). A bit detector (407) detects data values in response to the first signal and data reference signals which are indicative of expected signals for different data sequences. An air gap processor (415) generates a reading head position error signal indicative of a distance between the surface of the optical disc and a reading leans. A reference processor (409) modifies the data reference signals in response to the reading head position error signal. The invention allows improved bit detection and in particular allows fast adaptation of e.g. a Partial Response Maximum Likelihood (PRML) bit detector to variations in an air gap for a reading lens.