Position determination using circular shift codes
AssigneeSeagate Technology LLC
InventorSteven Craig Smith
Life of this patent
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Abstract
A shift code that consists of N-symbol code words is provided as an L-symbol “master sequence” in which no sub-sequence of N symbols repeats, where L≦SN and S is the number of code symbols. A decoder determines a location in the code from N decoded symbols. The code locations may, for example, correspond to radial positions, or other position, times, and so forth. In one embodiment, the master sequence is continuously written to a data storage disk during a spiral write operation and a reader on a given circular track reads at least N symbols from the portion of the spiral that crosses the track and determines a code word. The radial position of the reader is then determined based on the location of the code word in the code.
Claims17
A method comprising utilizing a data writer to write a sequence that corresponds to a code with N-symbol code words, the sequence having L symbols with every N-symbol subsequence being non-repeating;
- and determining a location in the code by decoding an N-symbol code word.
A method comprising:
- writing to respective radial positions portions of a master sequence that corresponds to a code with N-symbol code words, the sequence having L symbols in which every N-symbol subsequence is non-repeating;
- reading at least N symbols of the master sequence from a radial position and determining a code word;
- determining the radial position based on the location of the code word in the code, and wherein the step of writing portions of the master sequence is a spiral write operation from one diameter of a data storage disk to another diameter of the disk, in which the master sequence is repeatedly written.
A disk including a plurality of tracks;
- and a spiral write pattern consisting of a repeated master sequence of a shift code with code words written in spiral crossings of the respective tracks.
Dependencies are inferred from the claim text.