| 摘要 |
A disc drive apparatus ( 1 ), for writing/reading information to/from an optical storage disc ( 2 ), comprises: means ( 4 ) for rotating the disc ( 2 ) at a variable disc rotation speed; an optical system ( 30 ) for generating a scan beam ( 32 ); an actuator system ( 50 ) for positioning a focus point (F) of the scan beam ( 32 ); and a control circuit ( 90 ) for controlling the actuator system ( 50 ). The control circuit ( 90 ) comprises a learning feed forward block ( 110 ) comprising a memory bank ( 130 ) having N memory locations (M( 1 ) . . . (M(N)) and further comprises a digital reconstruction filter ( 150 ). The memory bank ( 130 ) is operated by a first clock signal (CLK 1 ) at a first clock frequency (phi 1 ), and the digital reconstruction filter ( 150 ) is operated by a second clock signal (CLK 2 ) at a second clock frequency (phi 2 ) having a fixed ratio to the first clock frequency (phi 1 ).
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