US Patent 7835094 Embedded track information for patterned media

A bit-patterned magnetic media (BPM) includes with respect to each data track regular bit-islands having a first size and large bit-islands having a second size. The placement of the regular bit-islands and large bit-islands within each data track results in a unique pattern. An amplitude-modulated readback signal is generated in response to a transducer head moving over the bit-patterned media. Based on the amplitude-modulated readback signal, channel response circuitry detects the pattern of regular bit-islands and large bit-islands associated with a particular data track. Based on the detected pattern, the channel response circuitry is able to uniquely identify the data track.