Waveform quite literally means the shape and form of a signal, such as a wave moving across the surface of water, or the vibration of a plucked string. A signal may refer to: an abstract element of information, or, more exactly, usually a flow of information (in either one or several dimensions). ... A wave crashing against the shore A wave is a disturbance that propagates. ...

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 represent the wave as a repeating image on a CRT or LCD screen. A Tektronix model 475A portable analogue oscilloscope, a very typical instrument of the late 1970s. ... The cathode ray tube or CRT, invented by Karl Ferdinand Braun, is the display device used in most computer displays, video monitors, televisions and oscilloscopes. ... Reflective twisted nematic liquid crystal display. ...

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.

Examples of waveforms

Periodic sound waveforms also have distinctive timbres: see psychoacoustics. In music, timbre is determined by its specturm, which is a specific mix of keynote,overtones, noise, tune behaviour, envelope ( ... ) as well as the temporal change of the spectrum and the amplitude. ... Psychoacoustics is the study of subjective human perception of sounds. ...

Common waveforms include

• Sine wave: sin(2 π t). The amplitude of the waveform follows a trigonometric sine function with respect to time.
• Sawtooth wave: 2(t − floor(t)) − 1. This looks like the teeth of a saw. Found often in time bases for display scanning. It is used as the starting point for subtractive synthesis, as a sawtooth wave of constant period contains odd and even harmonics that fall off at −6 dB/octave.
• Square wave: saw(x) − saw(x − duty). This waveform is commonly used to represent digital information. It is square wave of constant period contains odd harmonics that fall off at −6 dB/octave.
• Trapezoidal wave: This is a combination of a square wave and a sawtooth wave.
• Triangle wave: (t − 2 floor((t + 1)/2)) (−1)^{floor((t + 1)/2)}. This is the integral of the square wave. It contains odd harmonics that fall off at −12 dB/octave.
• Ocean wave: This is a characteristic form of a wave in a liquid medium

Other waveforms are often called composite waveforms and can often be described as a combination of a number of sinusoidal waves added together. In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C is the... The sawtooth wave is a kind of basic waveform. ... Subtractive synthesis is a method of sound synthesis characterised by the application of an audio filter to a source signal. ... Although it is widely used as a measure of the loudness of sound, the decibel is more generally a measure of the ratio between two quantities, and can be used to express a wide variety of measurements in acoustics and electronics. ... A square wave is a kind of basic waveform. ... A triangle wave is a waveform named for its triangular shape. ... Categories: Physics stubs | Physical oceanography | Waves ...

The 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. The Fourier transform, named after Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. ...

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 analog-to-digital converter and then applies a software discrete Fourier transform to find the mix of harmonic components which make up the waveform. AD on USB In electronics, an analog-to-digital converter (abbreviated ADC, A/D, or A to D) is a device that converts continuous signals to discrete digital numbers. ... In mathematics, the discrete Fourier transform (DFT), sometimes called the finite Fourier transform, is a Fourier transform widely employed in signal processing and related fields to analyze the frequencies contained in a sampled signal, solve partial differential equations, and to perform other operations such as convolutions. ...

See also

wav WAV (or WAVE), short for WAVEform audio format, is a Microsoft and IBM audio file format standard for storing audio on PCs. ...