Adjusting amplitude detection threshold by feeding back timing-data phase errors

In apparatus for detecting recorded signals in an optical disk recorder/player sensed from an optical medium by a relatively movable pick-up means which supplies a readback electrical signal representative of sensed recorded signals, including, in combination:

• threshold means connected to the pick-up means for receiving the readback signal for deriving an amplitude detection threshold from the readback signal;
• a switching comparator connected to the pick-up means and to the threshold means for comparing the threshold with the amplitude of the readback signal and supplying first pulses each time the readback signal amplitude changes through the threshold;
• phase lock loop means connected to the switching comparator for receiving the first pulses for generating detection timing pulses timed to the readback signal amplitude crossing the threshold and generating phase error signals indicating any phase errors between the readback signal and the timing pulses;
• data decoding means connected to the phase lock loop means and to the switching comparator for respectively receiving said timing pulses and said first pluses for comparing the timing pulses with the first pulses to amplitude detect and indicate data carried by the readback signal;
• and
• threshold adaption means connected to the threshold means and to the phase lock loop means for receiving the phase error signals for generating a threshold adjustment signal indicating the direction of phase error and supplying the threshold adjustment signal to the threshold means for actuating the threshold means to adjust the amplitude detection threshold for reducing the phase error.

In a machine-effected method of controlling readback and detection of signals from a signal storage medium, including the steps of:

• sensing signals stored on the medium for generating a readback signal;
• timing a clock to the readback signal for generating a timing signal including comparing the phase of the readback signal and the timing signal for generating a phase errors signal indicating a phase difference between the readback signal and the timing signal;
• and
• deriving an amplitude detection threshold signal from the readback signal for detecting information carried in the readback signal, deriving a threshold adjusting signal from said phase error signal, adding the derived adjusting signal to the threshold signal for creating an adjusted amplitude detection threshold signal and detecting the information carried in the readback signal using the adjusted amplitude detection threshold.