Disk drive servo control using spirals

A method for servo control, comprising:

• detecting peak times of spiral signals generated by reading spirals prewritten on a magnetic medium;
• determining positions of said spirals based on said peak times;
• storing said positions of said spirals;
• seeking and tracking said spirals using said positions;
• writing servo on said magnetic medium based on said positions of said spirals;
• and
• seeking radially by changing an expected peak time for one of said spirals based on at least one of an offset and a spiral correction value and by translating a resultant peak time into a radial distance,
• wherein said offset is indicative of radial seek direction.

A servo control system, comprising:

• a peak detection module that detects peak times of spiral signals generated by reading spirals prewritten on a magnetic medium;
• and
• a control module that determines positions of said spirals based on said peak times, stores said positions of said spirals, seeks and tracks said spirals using said positions, and writes servo on said magnetic medium based on said positions of said spirals,
• wherein said peak detection module determines a peak time of a spiral by integrating spiral signal amplitudes and selecting a half-integral point based on a result of said integration.

A servo control system, comprising:

• a phase error detection module that generates a phase correcting signal;
• a phase lock loop module that synchronizes a self-servo write clock to a reference servos sector clock based on said phase correcting signal;
• and
• a control module that seeks and tracks spirals based on said self-servo write clock, and writes servo on said magnetic medium based on said based on said self-servo write clock,
• wherein said phase error detection module selects a first time stamp that differs from a second time stamp by a time that is substantially equal to a predetermined time and generates a phase error signal based on said selection.