# Waveform

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Waveform

Waveform means the shape and form of a signal such as a wave moving in a solid, liquid or gaseous medium.

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.

By extension of the above, the term 'waveform' is now also sometimes used to describe the shape of the graph of any varying quantity against time.

Examples of waveforms

Common periodic waveforms include ("t" is time):

*Sine wave: sin (2 π "t"). The amplitude of the waveform follows a trigonometric sine function with respect to time.
*Square wave: saw("t") − saw ("t" − 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.
*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.
*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.

Other waveforms are often called composite waveforms and can often be described as a combination of a number of sinusoidal waves or other basis functions added together.

The Fourier series describes the decomposition of periodic waveforms, such that any periodic waveform can be formed by the sum of a fundamental component and harmonic components. Finite-energy non-periodic waveforms can be analyzed into sinusoids by the Fourier transform.

ee also

* Sine wave
* Sawtooth wave
* Square wave
* Triangle wave
* Pulse wave
* WAV, an audio waveform file format
* Waveform monitor
* Waveform viewer
* Electronic tuners measure waveforms

References

External links

* [http://www.floom.com/images/waveform_gallery.htm Waveform gallery] of vocal sounds, including a stereo track

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### Look at other dictionaries:

• waveform — [wāv′fôrm΄] n. a graphic representation showing the shape of a wave that is often periodic and usually plotted with the amplitude of the wave on one axis and time on the other axis, as the sine wave of an electronic signal * * * wave·form… …   Universalium

• waveform — ► NOUN Physics ▪ a curve showing the shape of a wave at a given time …   English terms dictionary

• waveform — [wāv′fôrm΄] n. a graphic representation showing the shape of a wave that is often periodic and usually plotted with the amplitude of the wave on one axis and time on the other axis, as the sine wave of an electronic signal …   English World dictionary

• Waveform — Wellenform eines Stereo Musikstücks im freien Audioeditor Audacity Als Waveform, im Deutschen auch Wellenform, wird die grafische Darstellung eines Audio oder anderen elektrischen Signals bezeichnet. Eine Wellenform stellt den zeitlichen Verlauf… …   Deutsch Wikipedia

• waveform — bangos forma statusas T sritis automatika atitikmenys: angl. wave form; waveform vok. Wellenform, f rus. форма волны, f pranc. forme d onde, f …   Automatikos terminų žodynas

• waveform — signalo pavidalas statusas T sritis radioelektronika atitikmenys: angl. signal shape; waveform vok. Kurvenverlauf, m; Signalgestalt, f rus. форма сигнала, f pranc. forme d onde, f …   Radioelektronikos terminų žodynas

• waveform — bangos pavidalas statusas T sritis fizika atitikmenys: angl. wave form; wave shape; waveform vok. Wellenform, f rus. форма волны, f pranc. forme d’onde, f …   Fizikos terminų žodynas

• waveform — noun Date: 1845 a usually graphic representation of the shape of a wave that indicates its characteristics (as frequency and amplitude) called also waveshape …   New Collegiate Dictionary

• waveform — noun a) A graphical representation of a wave obtained by plotting some characteristic of the wave (such as amplitude), versus time b) The representation of an audio signal, store …   Wiktionary

• waveform — The form of a pulse; e.g., an arterial pressure or displacement wave; or of the pacemaker pulse as demonstrated on the oscilloscope under a specified load. pressure w. a graphic …   Medical dictionary

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