Head delay calibration and tracking in MSMR systems

A method comprising:

• performing a delay calibration operation for a first reader and a second reader configured to simultaneously read from a single track of a data storage medium, the first reader offset from the second reader such that the first reader and the second reader detect a same signal pattern offset in time, the delay calibration operation including:
• determining a relative offset between the first reader and the second reader, including:
• setting a fixed delay for a first signal from the first reader;
• setting a second delay for a second signal from the second reader;
• adjusting the second delay to align the second signal to the first signal using a timing loop, with the first signal used as a reference signal;
• and
• storing delay values for the first reader and the second reader based on the relative offset.

An apparatus comprising:

• a first receiver and a second receiver configured to simultaneously receive a data signal, the first receiver offset from the second receiver such that the first receiver and the second receiver detect the data signal offset in time relative to each other;
• a circuit configured to:
• determine a relative offset between the first receiver and the second receiver, including:
• adjust an adjustable delay of a second signal from the second receiver to align the second signal to a first signal from the first receiver using a timing loop, with the first signal used as a reference signal;
• the timing loop includes multiple selectable settings, including:
• a first mode having a first pull-in range and a first noise output level, the first pull-in range defining a phase difference between two signals within which the timing loop can converge by adjusting one signal to match the other, such that the timing loop will converge when the phase difference between the reference signal and the second signal is within the pull-in range based on the phase difference resulting from a selected value for the adjustable delay;
• and
• a second mode having a second pull-in range narrower than the first pull-in range, and a second noise output level less than the first noise output level;
• and
• execute read operations based on the relative offset.