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Nyquist Theorem, Aliasing & Anti-Aliasing Filters

Nyquist Theorem Examples

Products such as cell phones, audio CDs, and iPods all adhere to Nyquists Theorem.

If the sample rate exceeds the Nyquist frequency we get...

Nyquist Theorem

  • Definition: The Nyquist Theorem is a theory that states that the maximum frequency that we can accurately sample must be equal to half of the sample rate.

References

This ensures that no data will be lost!

  • Where it came from:

Harry Nyquist

What is aliasing? (1996, October 20). Retrieved May 07, 2017, from http://www.earlevel.com/main/1996/10/20/what-is-aliasing/

Swedish-born American physicist and electrical and communications engineer.

Born: February 7, 1889

Died: April 4, 1986 (Age 87)

Aliasing of Signals - Identity theft in the frequency domain. (2015, June 12). Retrieved May 07, 2017, from https://allsignalprocessing.com/aliasing-of-signals-identity-theft-in-the-frequency-domain/

S. (2013, December 08). Audio Under Sampling (Aliasing Effect) Demonstration. Retrieved May 07, 2017, from

Overview

Chapter 2: The Digital Representation of Sound, Part Two: Playing by the Numbers. (n.d.). Retrieved May 08, 2017, from http://cmc.music.columbia.edu/musicandcomputers/chapter2/02_03.php

Aliasing Example

Aliasing Distortion

Harry Nyquist: A Founding Father of Digital Communications. (2005, October 19). Retrieved May 07, 2017, from http://www.electronicdesign.com/digital-ics/harry-nyquist-founding-father-digital-communications

  • Nyquist Theorem
  • Aliasing
  • Anti-Aliasing Filter
  • Examples
  • Happens when we try to record....

Harry Nyquist, American Physisist. (Unknown Publishing Date). Retrieved May 07, 2017 from https://www.britannica.com/topic/information-theory#ref710420

  • When a wave is moving too quickly...

https://allsignalprocessing.com/aliasing-of-signals-identity-theft-in-the-frequency-domain/

To help prevent Aliasing, we use...

"What Are Anti-Aliasing Filters and Why Are They Used?" What Are Anti-Aliasing Filters and Why Are They Used? - National Instruments. N.p., n.d. Web. 09 May 201

Anti-Aliasing Filter

  • Attenuating the higher frequencies and prevents the aliasing components from being sampled
  • A Low-Pass Filter

Anti-Aliasing Filter Example

  • Commercial Applications

Digital Anti-Alias Filtering:

Anti-Alias Multichannel Module (AAMM)

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