Apparatus and method for correcting asymmetry of optical disk reproducing system
AssigneeSamsung Electronics Co., Ltd.
InventorsJe-Kook Kim, Young-Wook Jang, Suk-Jung Lee
Life of this patent
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Abstract
In an apparatus and a method for correcting asymmetry in an optical disk reproduction system, an analog RF signal is received from an optical diode and an asymmetry-corrected signal is output as a digital EFM signal. The apparatus includes envelope detectors for detecting upper and lower envelopes of the RF signal, a level controller for controlling the level of the sum of the upper envelope and the lower envelope and for outputting signal having the controlled level, and a comparator for comparing the level of the signal output from the level controller with the level of the RF signal and for outputting the comparison result as the digital EFM signal.
Claims15
An asymmetry correcting apparatus in an optical disk reproduction system, for correcting the asymmetry of an analog signal output from an optical diode and outputting the asymmetry corrected signal as a digital signal, comprising:
- a first envelope detector for detecting an upper envelope of the analog signal;
- a second envelope detector for detecting a lower envelope of the analog signal;
- a level controller for controlling the level of the sum of the upper envelope and the lower envelope and outputting a first reference signal having a level equal to the level-controlled sum;
- a first low pass filter for filtering out a high frequency component of the first reference signal and outputting the filtered result;
- a second low pass filter for filtering out a high frequency component of the digital signal and outputting the filtered result;
- an amplifier for amplifying a signal output from the second low pass filter by a predetermined amount and outputting the amplification result;
- a subtracter for subtracting the output of the first low pass filter from the amplifier and outputting the subtraction result;
- an adder for adding the output of the subtracter to the first reference signal and outputting the addition result;
- and
- a comparator for comparing the output of the adder received as a second reference signal, with the analog signal and outputting the comparison result as the digital signal.
An asymmetry correcting method in an optical disk reproduction system, for obtaining a digital signal by correcting the asymmetry of an analog signal output from an optical diode, comprising the steps of:
- detecting an upper envelope and a lower envelope of the analog signal;
- adding the upper envelope to the lower envelope;
- obtaining a reference signal by controlling the level of the addition result;
- extracting a direct current component of the reference signal;
- subtracting the direct current component of the reference signal from a direct current component of the previously asymmetry-corrected digital signal;
- obtaining a slice reference level by adding the subtraction result to the reference signal;
- determining whether the level of the analog signal is larger than the slice reference level;
- determining a first logic level to be the level of the currently asymmetry-corrected digital signal, when the level of the analog signal is larger than the slice reference level;
- and
- determining a second logic level supplementary to the first logic level to be the currently asymmetry-corrected level of the digital signal, when the level of the analog signal is less than the slice reference level.
Dependencies are inferred from the claim text.