Recording medium, a data storage apparatus and a method of preparing a recording medium

1. A method of preparing a recording medium comprising:

writing a first annular servo track on a first layer of the recording medium, wherein the first annular servo track has a magnetic polarization of a first direction; and

writing a second annular servo track on the first layer of the recording medium,

wherein

the second annular servo track has a magnetic polarization in a second direction opposite the first direction,

the second track is adjacent to the first track,

the first annular servo track has a first bit pattern, and

the second annular servo track has a second bit pattern.

2. The method according to claim 1 , wherein:

writing the first annular servo track comprises polarizing magnetic bits in a unidirectional positive polarization; and

writing the second annular servo track comprises directionally polarizing magnetic bits in a unidirectional negative polarization.

3. The method according to claim 1 , wherein writing the first annular servo track comprises passing an electrical current through a write element for magnetizing a magnetic bit.

4. The method according to claim 3 , wherein:

writing the first annular servo track comprises passing a positive direct current through the write element; and

writing the second annular servo track comprises passing a negative direct current through the write element.

5. A recording medium comprising:

a first annular servo track provided on a first layer of the recording medium; and

a second annular servo track provided on the first layer of the recording medium and adjacent to the first annular servo track,

wherein

the first annular servo track is provided with a first bit pattern,

the second annular servo track is provided with a second bit pattern, and

a bit randomization portion is provided in an annulus formed by an exterior perimeter of the first annular servo track and an interior perimeter of the second annular servo track.

6. A data storage apparatus comprising:

the recording medium of claim 5 , wherein the recording medium comprises

a data layer comprising a data track, wherein the data track corresponds to the first annular servo track and the second annular servo track,

a servo layer comprising the first servo track and the second servo track, wherein the first servo track and the second servo track are magnetically opposite in polarity;

a sensor head configured to carry out a read function or a write function on the data track;

a measurement circuit configured to measure a voltage in the sensor head while carrying out the read function or the write function; and

a position error determination circuit configured to determine a position error signal of the sensor head based on a change in the voltage.

7. The data storage apparatus according to claim 6 , wherein the change in voltage across the sensor head relates to a lateral deviation of the sensor head in carrying out the read function or the write function.

8. The data storage apparatus according to claim 6 , further comprising a direct current offset circuit configured to address an inherent sensor head resistance in the voltage.

9. The data storage apparatus according to claim 6 , further comprising a high pass filter configured to address an inherent sensor head resistance in the voltage.

10. The recording medium according to claim 5 , wherein:

the first bit pattern comprises magnetic bits directionally polarized to a first direction; and

the second bit pattern comprises magnetic bits directionally polarized to a second direction opposite to the first direction.

11. The recording medium according to claim 5 , wherein:

the first bit pattern comprises a unidirectional positive polarization; and

the second bit pattern comprises a unidirectional negative polarization.

12. The recording medium according to claim 5 , wherein:

the first bit pattern comprises magnetic bits directionally polarized according to a first frequency; and

the second bit pattern comprises magnetic bits directionally polarized according to a second frequency.

13. The recording medium according to claim 12 , wherein the first frequency is a same frequency as the second frequency.

14. The recording medium according to claim 13 , wherein the second bit pattern is phase-shifted by 180° from the first bit pattern.

15. The recording medium according to claim 5 , further comprising a plurality of bit randomization portions at regular intervals in any one of the first annular servo track and the second annular servo track, wherein the plurality of bit randomization portions comprise the bit randomization portion provided in the annulus formed by the exterior perimeter of the first annular servo track and the interior perimeter of the second annular servo track.

16. The recording medium according to claim 5 , wherein:

any one of the first and second bit pattern comprises magnetic bits directionally polarized according to a frequency; and

a random polarization of magnetic bits is provided in each cycle of the any one of the first bit pattern and the second bit pattern.

17. The recording medium according to claim 16 , wherein the random polarization is provided in a fixed phase portion of each cycle of the any one of the first bit pattern and the second bit pattern.

18. A recording medium comprising:

a first annular servo track provided on a first layer of the recording medium; and

a second annular servo track provided on the first layer of the recording medium and adjacent to the first annular servo track,

wherein

a bit randomization portion is provided in an annulus formed by an exterior perimeter of the first annular servo track and an interior perimeter of the second annular servo track,

the bit randomization portion is provided between the first annular servo track and the second annular servo track, and

the first servo track, the second servo track, and the bit randomization portion are implemented on a same layer of the recording medium.

19. A recording medium comprising:

a first annular servo track provided on a first layer of the recording medium; and

a second annular servo track provided on the first layer of the recording medium and adjacent to the first annular servo track,

wherein

a bit randomization portion is provided in an annulus formed by an exterior perimeter of the first annular servo track and an interior perimeter of the second annular servo track, and

the bit randomization portion is provided between (i) a first patterned servo portion in the first annular servo track and (ii) a second patterned servo portion in the second annular servo track.