Advanced DC-free track code pattern using diphase code for perpendicular recording

We describe an advanced dc-free track code pattern that uses diphase code for a perpendicular recording. Track code error rates are compared between diphase code, dummy-bit code, and conventional dibit code. The diphase code improves writing ability during servo track writing and maintains equivalent medium noise. Therefore, the diphase code exhibits a superior track code error rate within a wide range of radius on experimental hard disk drives.