二维谐波频率的频域非线性预滤波估计方法

Two-dimensional frequency estimation based on nonlinear prefiltering in frequency domain

根据谐波信号在带噪信号的频谱中表现为异常脉冲这一特性,提出了一种新的有色噪声背景下二维频率估计方法。利用二维滑动中值滤波器能够滤除异常点的能力,提取噪声频谱,消除有色噪声对信号的影响。将有色噪声转化为白噪声,然后利用高分辨率的二维ESPRIT方法估计信号频率。在不需要知道有色噪声任何统计特性的情况下,该方法对有色噪声具有很强的普适性,仿真实验表明,在信噪比达到-18dB时,该算法仍然能够准确地估计频率。且由于算法中仅利用了二阶统计量,更便于实现。

A new method is presented to estimate frequencies of two-dimensional signal in colored noise. The main idea of this method is the observation that harmonics in colored noise show themselves as outliers in frequency domain. By using the capability of running median filters to remove outliers from data, we can get the power spectral of colored noise and get rid of the effect of the colored noise from observations.We use the two dimensional matrix pencil method or Esprit method to get the high resolution estimation of the frequencies. The outstanding advantage of this method is the strong adaptability to colored noise without knowing any of its statistical characteristics. The estimation result is of high resolution even when the SNR(Signal to Noise Ratio) is -18 dB. Because the presented method only uses second order statistics, it is easy to realize.