Write clock rephase for magnetic recording device

A system comprising:

• a recording medium, the medium comprising magnetic bit cells arranged on tracks;
• clock circuitry configured to produce a write clock signal and a servo clock signal;
• a read head, operated with respect to the medium and the servo clock signal, to produce a waveform;
• a servo detector configured to produce, based on the waveform, a servo detect pulse that indicates a detection of servo data;
• a timestamp circuit configured to measure a timing difference that is based on the servo detect pulse and a write pulse of the write clock signal;
• a control loop calculator configured to control an adjustment of a phase of the write clock signal based on the timing difference to align the write clock signal with at least a portion of the bit cells;
• a write head, operated with respect to the medium and the write clock signal, to write data to the at least the portion of the bit cells;
• circuitry configured to operate a counter to count clock pulses of the write clock signal;
• and
• circuitry configured to produce a write clock sync pulse based on N increments of the counter, wherein N represents a number of bit cells in an area defined by a distance, on a track of the medium, from a first servo sync mark to a second servo sync mark,
• wherein the timestamp circuit is responsive to the write clock sync pulse.

A method comprising:

• producing signals that include a write clock signal and a servo clock signal;
• processing a waveform produced by a read head operated with respect to a recording medium and the servo clock signal, the medium comprising magnetic bit cells arranged on tracks;
• producing, based on the waveform, a servo detect pulse that indicates a detection of servo data;
• measuring a timing difference that is based on the servo detect pulse and a write pulse of the write clock signal;
• controlling an adjustment of a phase of the write clock signal based on the timing difference to align the write clock signal with at least a portion of the bit cells;
• operating a counter to count clock pulses of the write clock signal;
• and
• producing a write clock sync pulse based on N increments of the counter, wherein N represents a number of bit cells in an area defined by a distance, on a track of the medium, from a first servo sync mark to a second servo sync mark,
• wherein measuring the timing difference is responsive to the write clock sync pulse.