A sine, square, and sawtooth wave at 440 Hz
A composite waveform that is shaped like a teardrop.
A waveform is a variable that varies with time, usually representing a voltage or current.
Waveforms are conventionally graphed with time on the horizontal axis.
In electronics, an oscilloscope can be used to visualize a waveform on a screen. A waveform can be depicted by a graph that shows the changes in a recorded signal's amplitude over the duration of recording. The amplitude of the signal is measured on the -axis (vertical), and time on the -axis (horizontal).
Simple examples of periodic waveforms include the following, where is time, is wavelength, is amplitude and is phase:
- Sine wave. The amplitude of the waveform follows a trigonometric sine function with respect to time.
- Square wave. This waveform is commonly used to represent digital information. A square wave of constant period contains odd harmonics that decrease at -6 dB/octave.
- Triangle wave. It contains odd harmonics that decrease at -12 dB/octave.
- Sawtooth wave. 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 decrease at -6 dB/octave.
The Fourier series describes the decomposition of periodic waveforms, such that any periodic waveform can be formed by the sum of a (possibly infinite) set of fundamental and harmonic components. Finite-energy non-periodic waveforms can be analyzed into sinusoids by the Fourier transform.
Other periodic 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.
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