| 摘要 |
A data reproduction arrangement for recalling data that can be read out with an optical pickup from data storage tracks of a recorded medium, in which a beam of light is focused on the recorded medium. The beam is advanced along the data storage tracks by a tracking circuit, and a photodetector receives the beam of light reflected from the recorded medium. A direct-current coupled data signal is generated by the photodetector, and has an upper and lower envelope which are processed to obtain a criterion for controlling the focusing circuit and/or tracking circuit. The lower or upper envelope can be clamped to a predetermined level.
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