Fourier transform operator

例句：

1. 1. Inthe Fourier transform domain, the signalis represented as a complex number.
   在傅里叶变换域中，信号被表示为复数。
2. 2. The Fourier transform operatoris used to analyze the frequency contentof a signal.
   傅里叶变换算子用于分析信号的频率内容。
3. 3. The Fourier transform operator is a powerful tool foranalyzing signals in various fields.
   傅里叶变换算子是分析各种领域中信号的有力工具。