Abstract:

For carrier synchronization in the case of symbol rate sampling and low signal to noise ratios (SNRs), a novel hybrid carrier tracking loop is proposed, and an intuitive method of determining loop parameters is also investigated. The carrier synchronous loop improves the estimated accuracy of the carrier frequency offset and the phase offset in low SNR environments through modifying the original symbol hard decision method and adding sampling rate conversion blocks which enable the digital frequency-locked loop (FLL) and digital phase-locked loop (PLL) to operate under the condition of different rate sampling. The parameter determination method selects optimal parameters in the z domain directly according to the stability and unit step response characteristics of the closed-loop systems. Simulation results confirm the feasibility of this algorithm in terms of determining the parameters and indicate that the proposed carrier tracking loop achieves better synchronization performance at relatively low SNRs.