A magnetic recording disk drive uses a disk having pre-patterned servo
sectors extending generally radially across the data tracks. The servo
sectors include at least two position error signal (PES) bursts or
fields. The phases of the PES fields in the servo readback signal are
demodulated to generate a PES to control the disk drive actuator for
positioning the read/write heads. Each field contains generally radially
directed magnetized stripes, with each stripe comprising a plurality of
discrete radially-spaced generally parallelogram-shaped islands, each
island having its length oriented at an acute angle relative to a track
centerline. The stripes have alternating polarity of magnetizations in
the along-the-track direction. In one implementation there are four
fields: a first pair of fields A and B wherein the pattern of the radial
stripes in field A is the mirror image about a radial line of the pattern
of the radial stripes in field B, and a second like pair of fields C and
D, but wherein the radial stripes in fields C and D are shifted radially
from the radial stripes in fields A and B.