Frequency synchronization algorithm robust to pilot distortion in ATSC system

A frequency synchronization algorithm is proposed that is robust to pilot distortion in the ATSC system. Since conventional frequency synchronization algorithms only estimate the frequency offset from the received pilot, synchronization can not be achieved if the pilot is severely distorted. Accordingly, the proposed algorithm compensates most of the frequency offset using the symmetry property of the ATSC signal spectrum. However, because information about the phase offset is unobtainable from the symmetry property, the estimation may still have an offset due to asymmetric channel distortion. To overcome such problems, a second step compensates the remaining frequency and phase offsets using a conventional pilot-based algorithm. As a result, the proposed algorithm increases the estimation range of the frequency offset and can achieve perfect synchronization if the transmitted pilot level is greater than 25 percent of the original level.