Optimization of symbol timing recovery for DTMB receivers

This paper proposes a symbol timing recovery (STR) scheme for DTMB (digital terrestrial/television multimedia broadcasting) receivers, which is implemented by an all digital DLL (delay locked loop) in time domain. Compared with the conventional early-late synchronizer, the improved timing error detector is self-normalized and bears sampling frequency offset up to plusmn 90 ppm, three times as much as the former method. Besides, automatic adjustment of loop bandwidth, controlled by a lock detector, is realized to provide better loop performance in both convergence speed and jitter. Simulation and hardware test results show that the new STR scheme can work reliably in both AWGN and multipath channels.