Optimal training symbol placement for frequency acquisition on magnetic recording channels

The modified Cramer-Rao bound (CRB) on frequency estimation error variance for magnetic recording channels is derived as a function of training symbol locations, and it is shown that placing the known symbols half at the beginning and half at the end of the sector minimizes the CRB. Simulation results show a 1.5 dB gain in loss-of-lock rate over having all known symbols at the start of the sector.