Robust sync marks for both random and bursty errors

Sync marks are used to correctly frame the read back signal from disk drives. Good sync marks should tolerate both random and bursty errors. This paper presents a sync mark design method that produces both large bit distance and large symbol distance for sync marks. Therefore, bit-by-bit detection can be used to tolerate random errors, while symbol-by-symbol detection can be used under bursty errors. To lower sync mark miss rate, we also propose a novel design that controls, rather than eliminates, error propagation across symbol boundaries. The controlled error propagation method results in shorter sync marks, therefore a higher format efficiency.