准同步DFT谐相角的线性修正算法

Linear correcting algorithm for quasi-synchronous DFT’s harmonic phase

针对准同步DFT谐波分析方法在信号频偏时的短范围泄漏问题,研究准同步DFT谐相角的线性特性,建立准同步DFT谐相角与信号频偏率、谐次、迭代次数之间的线性修正模型,给出了准同步DFT谐相角的线性修正方法。该方法首先根据相邻采样点之间的基波相角差只与信号频率和采样频率相关的原理来测量信号频偏率,再按照只与信号频偏率、谐次、迭代次数相关的谐相角线性修正公式对准同步DFT的谐波分析结果进行修正。实验表明准同步DFT谐相角线性修正算法能够有效抑制短范围频谱泄漏,在较宽信号频偏范围内获得高精确度的谐相角分析结果。

Aiming at the short-range leakage problem of quasi-synchronous DFT (QSDFT) harmonic analysis method when signal frequency deviated, the linear characteristics of QSDFT′s harmonic phase angle were studied, and linear correction model between QSDFT′s harmonic angles and signal frequency deviation rate, harmonic order and iteration number were established. Furthermore, the linear correction method of QSDFT′s harmonic phase was given. Firstly, the signal frequency deviation rate was measured by the principle that the fundamental phase angle difference between adjacent sampling points is only related to the signal frequency and the sampling frequency. And then, the harmonic analysis result of QSDFT was corrected through the phase linearity correction formula. Simulation and experiment results show that this proposed algorithm can increase the accuracy of harmonic phase efficiently in the wide frequency range by minimizing short-range spectral leakage.