In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form. In these cases, the term 'waveform' refers to the shape of a graph of the varying quantity against time or distance. An instrument called an oscilloscope can be used to pictorially repesent the wave as a repeating image on a CRT screen.
By extension of the above, the term 'waveform' is now also used loosely to describe the shape of the graph of any periodically varying quantity against time.
Periodic sound waveforms also have distinctive timbres: see psychoacoustics.
Common waveforms include
Other waveforms are often called composite waveforms and can often be described as a combination of a number of sinusoidal waves added together.
Fourier transform describes the composition of distorted waveforms, such that any periodic waveform can be formed by the sum of a fundamental component and harmonic components.
Fourier analysis provides a method for decomposing a measured waveform into its harmonic components. This is readily achieved with a sampling instrument, which samples the waveform using an Analogue to Digital Converter and then applies a software discrete Fourier transform to find the mix of harmonic components which make up the waveform.
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