In order to improve the precision of the autocorrelation method for frequency estimation under noninteger period sampling circumstance

a frequency estimation method of data extension based on autocorrelation is proposed. By analyzing on generation reason of frequency estimation error based on autocorrelation method

the method for restraining frequency estimation error is deduced. Firstly

frequency of sampled signal is pre-estimated.Then

if auto-correlation signal length is full period or not is judged

and data extension is carried out to make the length of autocorrelation signal equal or close to integer periods. At last

frequency of signal after extension is estimated. Simulation results indicate that the proposed method is not affected by non-integer period sampling and can improve the precision of frequency estimation effectively.