For the issue of low accuracy of phase difference estimation affected by the noise under the condition of frequency mismatch

an unbiased adaptive phase difference estimation method in the presence of frequency mismatch is proposed

which could improve the accuracy of phase difference estimation and enhance the ability of anti-noise. Therefore

firstly the expansion parameters of two sinusoidal signals are adaptive estimated

which is used to estimate the phase difference between two sinusoidal signals. Secondly

the deviation analysis of phase difference estimation is carried out by the expansion of Taylor series

the unbiased phase difference estimation with frequency mismatch is proved

and the performance of steady-state for phase difference estimation are also presented. Consequently

the phase difference estimation results of different methods are compared

the effect by different parameters are discussed

and the calculated results are provided to confirm the effectiveness and correctness of the proposed method.