Performance of unique word timing offset estimator

A quadrature amplitude modulation receiver must include a timing recovery circuit to identify the correct points in time to sample the output. Timing recovery is handled differently in synchronous systems than it is in burst mode systems. In synchronous systems the convergence (or dwell) time can be quite long without penalty. In burst mode systems timing must be recovered rapidly and is therefore aided by placing a unique word at the beginning of the preamble. The output of the matched filter is correlated with the unique word to find the timing offset required to align the time origin. This timing offset is used as the “delay” input to the fractional delay filter that synchronizes the signal in the receiver to the timebase [1][3][5]. This paper discusses the performance of the timing recovery circuit using a specific unique word: length-11 Barker sequence preceded by a cyclic prefix.