Disk drive comprising a dual read element and delay circuitry to improve read signal
View Patent ↗A disk drive is disclosed comprising a disk having a plurality of data tracks, and a head actuated over the disk, the head comprising a first read element and a second read element. A data track is read to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element. The first read signal is delayed relative to the second read signal to generate a delayed read signal, and the second read signal is combined with the delayed read signal to generate a combined read signal. An estimated data sequence is detected from the combined read signal.
1. A disk drive comprising:
a disk comprising a plurality of data tracks;
a head actuated over the disk, the head comprising a first read element and a second read element; and
control circuitry operable to:
read a data track to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element;
delay the first read signal relative to the second read signal to generate a delayed read signal;
combine the second read signal and the delayed read signal to generate a combined read signal;
detect an estimated data sequence from the combined read signal;
generate a quality metric in response to the combined read signal; and
calibrate the delay in response to the quality metric.
2. The disk drive as recited in claim 1 , wherein:
the first read element is offset from the second read element along the length of a data track; and
the delay corresponds to the offset.
3. The disk drive as recited in claim 1 , wherein the control circuitry comprises an digital delay circuit for delaying the first read signal in discrete time.
4. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to calibrate the delay at a plurality of radial locations of the disk.
5. A method of operating a disk drive, the disk drive comprising a disk comprising a plurality of data tracks, and a head actuated over the disk, the head comprising a first read element and a second read element, the method comprising:
reading a data track to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element;
delaying the first read signal relative to the second read signal to generate a delayed read signal;
combining the second read signal and the delayed read signal to generate a combined read signal;
detecting an estimated data sequence from the combined read signal;
generating a quality metric in response to the combined read signal; and
calibrating the delay in response to the quality metric.
6. The method as recited in claim 5 , wherein:
the first read element is offset from the second read element along the length of a data track; and
the delay corresponds to the offset.
7. The method as recited in claim 5 , further comprising delaying the first read signal in discrete time.
8. The method as recited in claim 5 , further comprising calibrating the delay at a plurality of radial locations of the disk.