servo circuitry is disclosed that is configured to operate with a magnetic disk drive system . the servo circuitry is comprised of a first servo detector system , a second servo detector system , and a comparator . the first servo detector system and the second servo detector system each receive samples , taken from a read signal , that include servo data . the first servo detector system compares the samples to a plurality of servo codes to generate a first selected code . the second servo detector system compares a first shifted version of the samples to the plurality of servo codes to generate a second selected code . the comparator receives the selected codes and selects one of the selected codes . the selected code represents the servo data . the servo circuitry could also include a third servo detector system that operates on a second shifted version of the samples . alternatively , the first servo detector system , the second servo detector system , and the third servo detector system could each be programmed with different servo codes . the first servo detector system compares the samples to a plurality of first servo codes . the second servo detector system compares the samples to a plurality of second servo codes . the third servo detector system compares the samples to a plurality of third servo codes . the second servo codes and the third servo codes are shifted versions of the first servo codes . in either embodiment , the servo circuitry advantageously has improved phase shift tolerance .