Single-cycle time-delay estimator suffers from the dependence on the selection of different cycle frequencies

which restricts its practical usage.To solve the problem

multi-cycle time-delay estimation method is discussed.And the estimation accuracy for multi-cycle estimator is also given.Simulation results based on BPSK and QPSK signals with stationary noise and slowly time-variant noise show that estimation theoretical accuracy is just the same as the simulation one with high SNR (＞-6dB)

and double-cycle estimator performs worse than tri-cycle estimator

but better than single-cycle estimator

which indicates the efficiency and robustness of the given method as well as the exactness of the accuracy analysis.