A signal interpolated timing recovery system with frequency offset detector

A method of frequency offset detection for signal interpolated timing recovery is proposed. The frequency offset is estimated by measuring the correlation between the preamble and the reference sinusoid. When the frequency offset exists, the phase error changes linearly. The offset can be estimated by the gradient of the phase errors. The simulation results show that the method significantly improves the stability of the timing recovery and increases the capture range. It also decreases the preamble length and results in higher format efficiency.