设有连续时间周期信号，它的周期为T，角频率，且满足狄里赫利条件，则该周期信号可以展开成傅里叶级数，即可表示为一系列不同频率的正弦或复指数信号之和。-With continuous time periodic signal, its period is T, the angular frequency, and to meet the Diliheli conditions, the periodic signal can be expanded into a Fourier series, can be expressed as a range of different frequencies of sinusoidal or complex exponential signal and.