离散时间傅里叶变换

回顾离散时间周期信号傅里叶级数 x [ n ] = ∑ k = < N > a k e j k 2 π N n a k = a k ± m N = 1 N ∑ n = < N > x [ n ] e − j k 2 π N n {\boxed{x[n] = \sum_{k=<N>} a_ke^{jk\frac{2\pi}{N}n} \qquad a_k = a_{k\pm mN} = \frac

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