## Fourier series

#### Fourier series can represent any periodic time domain signal by a summation of harmonically related sinewaves. For example, the square wave (equivalent 1, 0, 1, 0, 1, 0, ...) data signal shown here can be constructed from sinewaves of descending amplitudes, spaced, in this example, at odd multiples of the fundamental frequency of the square wave. If we wished to represent the 1, 0, 1, 0, 1, 0, ... pattern perfectly, an infinite number of sinusoidal components would be required, implying that we need an infinite channel bandwidth! |