Patent ID: 7391687

Claim:
A method of determining an optimum recording power for a recordable multi-speed optical disk having an inner power calibration area (PCA) inside a program region and an outer PCA outside the program region, the method to be performed in an optical disk system that records data on a recordable optical disk, the method comprising: (a) obtaining an optimum recording power for a minimum recording speed in the inner PCA and determining the obtained optimum recording power as a first optimum recording power, wherein step (a) comprises: (a1) performing a process of recording data on and reproducing the data from the inner PCA using a predetermined number of cycles, using various recording powers; (a2) obtaining an asymmetry of data reproduced from the inner PCA in each of the predetermined number of cycles, wherein obtaining the asymmetry of data reproduced from the inner or outer PCA in each of the predetermined number of cycles comprises: removing low frequency noise from the reproduced data by performing high pass filtering on the reproduced data; detecting a peak value and a bottom value of the noise-removed reproduced data; extracting a median value of a DC level by performing low pass filtering on the noise-removed reproduced data; and obtaining asymmetry of the noise-removed reproduced data using the following equation: β =  C - P - B P + B  where β represents asymmetry, C represents a low-pass-filtered median value, P represents the peak value, and B represents the bottom value; and (a3) determining a recording power obtained when the asymmetry obtained in step (a2) reaches its minimum as the first optimum recording power; (b) obtaining an optimum recording power for a maximum recording speed in the outer PCA and determining the obtained optimum recording power as a second optimum recording power; and (c) determining linear characteristics of recording speeds and their corresponding optimum recording powers using the first and second optimum recording powers.