A servo field preamble detector includes an upsampling module that generates a plurality of upsampled read samples by upsampling a read signal by an upsampling factor. An interpolation filter module generates a plurality of interpolated read samples from the plurality of upsampled read samples. A peak detection module identifies a plurality of peak samples from the plurality of interpolated read samples. A magnitude estimation module generates a magnitude estimation signal from the plurality of peak samples. A comparison module compares the magnitude estimation signal to a magnitude threshold and asserts a servo preamble detection signal when the magnitude estimation signal compares favorably to the magnitude threshold.