基于FFT系数的正弦信号频率估计算法

针对基于FFT系数实部的频率插值算法在峰值谱线相位接近于±π/2时频率估计误差较大的问题,提出了一种改进的正弦信号频率估计算法。该算法首先利用FFT系数的实部和虚部序列索引出峰值谱线位置,然后根据峰值谱线的相位,选取实部与虚部序列中幅度较大的序列进行频率插值。仿真结果表明：在信噪比为3 dB、采样点为128的情况下,整个频段上归一化频率估计误差均方根小于0.02,接近Cramer Rao下限,整体性能优于基于FFT系数实部的频率插值算法和Rife算法。改进的算法频率估计精度高,计算量小,易于硬件实现。

Frequency Estimation Algorithm of Sine Signal Based on FFT Coefficient

Larger frequency estimation error will appear when a peak spectrum line phase is closed to±p/2using frequency interpolation algorithm based on the real part of fast Fourier transform（FFT） coefficient. So an improved sine signal frequency estimation algorithm is proposed. The postion of peak spectrum line is firstly indexed by using the real part and imaginary part sequence of FFT coefficient. And then according to the phase of peak spectrum line, the se quences with larger amplitude in real and imaginary part sequences are selected to participate in frequency interpolation. Simulation results show that at the condition ofSNR=3 dB and sampling numberN=128, the root mean square of normalized frequency estimation error at the whole frequency band is less than 0.02 and closed to Cramer-Rao lower bound（CRB）. The total performance of the improved algorithm is better than the frequency interpolation and Rife al gorithm based on the real part of FFT coefficient. The improved algorithm has the characteristics of high frequency estimation precision and few computation amounts and it is easy to implement in hardware.