Overwrite measurement method using pseudorandom sequence

A novel overwrite measurement method with pseudorandom bit sequence (PRBS), random pattern overwrite (ROW) to evaluate the recording performance under the more realistic condition is proposed. A pair of 31-b PRBS are utilized in this overwrite measurement. The ROW is defined as the averaged power over a period of normalized cross-correlation function between the waveforms before and after overwriting. The intrinsic correlation between an initially written pattern and an overwritten pattern, and the effect of the noise are eliminated in the ROW calculation. By using this method, we can effectively evaluate the overwrite characteristics in the condition similar to those in a hard disk drive.