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词条 Waveform
释义

  1. Examples

  2. See also

  3. References

  4. Further reading

  5. External links

{{Other uses}}

A waveform is a variable that varies with time, usually representing a voltage or current.[1]

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.[2] The amplitude of the signal is measured on the -axis (vertical), and time on the -axis (horizontal).[2]

Examples

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.

See also

  • AC waveform
  • Arbitrary waveform generator
  • Crest factor
  • Frequency domain
  • Phase offset modulation
  • Spectrum analyzer
  • Waveform monitor
  • Waveform viewer
  • Wave packet

References

1. ^David Crecraft, David Gorham, Electronics, 2nd ed., {{isbn|0748770364}}, CRC Press, 2002, p. 62
2. ^1 {{Cite web|title = Waveform Definition|url = http://techterms.com/definition/waveform|website = techterms.com|accessdate = 2015-12-09}}

Further reading

  • Yuchuan Wei, Qishan Zhang. Common Waveform Analysis: A New And Practical Generalization of Fourier Analysis. Springer US, Aug 31, 2000
  • Hao He, Jian Li, and Petre Stoica. Waveform design for active sensing systems: a computational approach. Cambridge University Press, 2012.
  • Solomon W. Golomb, and Guang Gong. Signal design for good correlation: for wireless communication, cryptography, and radar. Cambridge University Press, 2005.
  • Jayant, Nuggehally S and Noll, Peter. Digital coding of waveforms: principles and applications to speech and video. Englewood Cliffs, NJ, 1984.
  • M. Soltanalian. Signal Design for Active Sensing and Communications. Uppsala Dissertations from the Faculty of Science and Technology (printed by Elanders Sverige AB), 2014.
  • Nadav Levanon, and Eli Mozeson. Radar signals. Wiley. com, 2004.
  • Jian Li, and Petre Stoica, eds. Robust adaptive beamforming. New Jersey: John Wiley, 2006.
  • Fulvio Gini, Antonio De Maio, and Lee Patton, eds. Waveform design and diversity for advanced radar systems. Institution of engineering and technology, 2012.
  • John J. Benedetto, Ioannis Konstantinidis, and Muralidhar Rangaswamy. "Phase-coded waveforms and their design." IEEE Signal Processing Magazine, 26.1 (2009): 22-31.

External links

{{commons category|Waveforms}}
  • Collection of single cycle waveforms sampled from various sources
{{Timbre}}{{Waveforms}}

1 : Waveforms
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