A fast and accurate estimation technique of frequency and initial phase of single-tone signal based on the phase of the DFT spectrum is proposed.To eliminate the ambiguity in DFT phase measurement

the sampled data are divided into two segments and the DFT is applied on them individually

then the frequency and initial phase of the signal are estimated with the phase difference of the two DFT spectra at their maximum amplitude position.Computer simulation results show that the variance of frequency estimation is close to the Cramer-Rao bound

and the

SNR

threshold is much lower than that of the ML estimators for moderate

N

(length of DFT).For

SNR

=6dB and

N

=1024

the RMS error of frequency estimation is about 1% of the frequency resolution of the DFT

and the RMS error o

f the initial phase estimation is about 2 degrees.Formulas for evaluating the RMS errors of frequency and phase estimation in white Gaussian noise for different

SNR

and

N

are also presented

which fit well with computer simulation results.This technique has been used in FMCW level radar and 1mm range measurement accuracy has been achieved.