非整周期采样信号频率估计的加窗相位差法

Windowed Phase Difference Method for Frequency Estimation of Non-integer Period Sampling Signals

针对相位差法频率估计精度受信号非整周期采样影响的问题,在相位差法基础上提出了非整周期采样信号频率估计的加窗相位差法。首先,利用FFT法获得信号频率粗估计值,根据频率粗估计值设计矩形窗,对采样信号重新分段,获得2段近似整周期采样的加窗信号;其次,利用第1段加窗信号求取频谱峰值所在位置;然后,利用DFT计算出2段加窗信号频谱峰值处的相位差,得到频谱峰值位置校正量;最后,根据频谱峰值位置及其校正量计算频率精估计值。模拟计算和实测实验表明,所提方法有效抑制了信号非整周期采样带来的影响,提高了相位差法的测频精度,改善了LFMCW雷达的测距精度。

Aiming at the problem that the estimation accuracy of phase difference method is affected by the non-integer period sampling,based on phase difference method,a windowed phase difference method is proposed to estimate the frequency of non-integer period sampling signals.Firstly,the coarse estimation frequency was obtained by FFT method,and two sections of approximate integer period sampling signals were obtained by adding a rectangular window which was designed according to the coarse estimation frequency.Secondly,the position of spectrum peak was obtained by using the first section signals.Thirdly,the phase difference between the two sections of signals was gained through the maximum amplitudes of the DFT spectrum,and then the correction frequency was calculated.Finally,the precision estimation frequency was obtained according to the coarse estimation value and the correction of the frequency.Calculation analysis and field experiments demonstrate that the proposed method can effectively suppress the impact of non-integer period sampling,thus improves the stability of the phase difference method and the precision of LFMCW radar ranging.