First and second different write precompensation values are associated with different first and second non-return-to-zero, inverted (NRZI) data patterns. The first and second different write precompensation values cause a predetermined phase shift to be written into test data that comprises the first and second NRZI data patterns. The test data is mitten to a recording medium of a storage device using the first and second write precompensation value. The test data is used to determine a response of the storage device to the predetermined phase shift.

Disclosed herein are a system, non-transitory computer-readable medium, and method for encoding and decoding information on a data bearing medium. A message comprising a bit string is read. A plurality of substrings in the message may be associated with a phase invariant codeword.

Disclosed herein are a system, non-transitory computer-readable medium, and method for encoding and decoding information on a data bearing medium. A message comprising a bit string is read. A plurality of substrings in the message may be associated with a phase invariant codeword.

According to one embodiment, a magnetic disk device including a disk, a head configured to write write data to the disk, and a controller configured to write first data including a high-frequency pattern, detect, from a reproduced waveform obtained by reading the written first data, a difference between a first percentage by which high-frequency patterns of a first polarity are lost and a second percentage by which high-frequency patterns of a second polarity obtained by reversing the first polarity are lost, and adjust a high-frequency pattern of the first polarity of the write data or a high-frequency pattern of the second polarity of the write data on the basis of the difference.

A system includes a memory, a processor, an encoder, a head, and a decoder. The memory stores information. The processor processes information and controls operation of other components. The encoder encodes a first portion and a second portion of a servo track to form a first and second encoded values. The second code has a run length associated therewith. The first and second encoded values result in a Gray code. Each bit of the Gray code remains constant for at least a number of tracks corresponding to the run length. The head is configured to write the first and the second encoded values onto a media, and is configured to read the first and the second encoded values from the media. The decoder decodes the first encoded value and the second encoded value. The processor determines a servo track address from the decoded first value and the decoded second value.