基于移位离散付立叶变换的线性频率估计方法

提出了一种基于移位离数付立叶变换的频率估计新方法。该方法利用离散付立变换的周期性，通过计算一组不同移位的ＤＦＴ值，从中可得到一个较高精度的频率估计结果，与传统的线性估计方法相比，具有较好的估计性能。新方法可以用ＦＦＴ算法来实现，因此，具有较大的工程实用价值。

On Improving Linear Frequency Estimation with Shifted Discrete Fourier Transform

UP, to now, in linear frequency estimation methods (based on discrete Fouriertransform), fixed deviation always exists, causing large estimation errors. In this paper, wepropose a new linear frequency estimation method (based on shifted discrete Fourier transform) that can significantly lower estimation errors.The difference between our SDFT (shifted discrete Fourier tranform) method and theusual DFT (discrete Fourier transform) method can be easily seen from eq. (1),in which theterm 1/m (0<1/m<1) is the shift introduced' with the introduction of this shift, the fixeddeviation, unavoidable in DFT method, can be eliminated. Computer simulation results arepresented in Figs. 1 through 3. Fig. 1 is for the case of no noise, Figs. 2 and 3 are respectively for signal noise ratio of 10 dB, and 0 dB. From these figures, it can be seen that fixed deviation is eliminated by SDFT method. Furthermore, it can also be seen from Figs. 2 through3 that output amplitude of noise is reduced to a certain degree.SDFT method is convenient for practicing engineers as it can be implemented throughthe familiar FFT (Fast Fourier Transform).