周期图法(periodogram)常出现在谱密度计算的内容中，在Fernando S. Schlindwein的论文中"Power Spectral Density estimation"解释了「周期图法」这词的源起。很明显地，这是由Arthur Schuster于1898年所创造。以下为Schlindwein摘自Schuster论文的文句中译：

In statistical signal processing, the goal of spectral density estimation (SDE) is to estimate the spectral density (also known as the power spectral density) of a random signal from a sequence of time samples of the signal. Intuitively speaking, the spectral density characterizes the frequency content of the signal. One purpose of estimating the spectral density is to detect any periodicities in the data, by observing peaks at the frequencies corresponding to these periodicities.