Comprehensive explanation of Aliasing?

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Discussion Overview

The discussion revolves around the concept of aliasing, particularly its definition, implications in signal processing, and its relationship with filters. Participants explore the theoretical aspects of aliasing, its causes, and potential solutions through filtering.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant requests a comprehensive explanation of aliasing and its relation to filters.
  • Another participant suggests starting with Wikipedia as a resource for understanding aliasing.
  • A different contribution defines aliasing as a distortion that occurs when a continuous signal is digitized, noting that smooth lines in a signal can become jagged.
  • It is mentioned that aliasing occurs when a signal is sampled at a frequency lower than the Nyquist rate, which is defined as double the highest frequency of the signal. This participant emphasizes the importance of sampling at or above this rate to avoid aliasing.
  • One participant proposes that aliasing effects can be mitigated by using a low pass filter before sampling, suggesting that the filter's bandwidth should be doubled to determine an appropriate sampling rate.
  • A participant expresses gratitude for the contributions and indicates plans to summarize the discussion for collective benefit.

Areas of Agreement / Disagreement

There is no explicit consensus reached among participants, as various aspects of aliasing and its mitigation are discussed without definitive conclusions.

Contextual Notes

Some assumptions regarding the definitions of aliasing and the Nyquist rate are present, but these are not universally agreed upon. The discussion does not resolve the complexities of the relationship between sampling rates and aliasing effects.

Meriem
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Hello,

I need a comrehensive explanation of Aliasing? and its relation to filters...

Thanks for the answers
 
Engineering news on Phys.org
start with wikipedia...
 
http://en.wikipedia.org/wiki/Aliasing

Aliasing is what happens when you take a continuous signal and digitize it. It can only be approximated and as a result, smooth lines in a signal (whether they are a synthesized sound wave or a picture or some other signal is irrelevant) become jagged.
 
Aliasing is a form of distortion that happens when you sample a signal with a frequency less than the nyquist rate, the sampling theory simply states that if we take a number of samples of a signal at double the rate of it's highest frequency, the original signal can be reconstructed using these samples, so what happens when you sample at a rate lower than nyquist is that there will be an aliasing effect.

The aliasing effect could be removed by passing the signal through a low pass filter before sampling, thus we could calculate the band of the filter and multiply it by two and then sample at this rate.
 
Thanks a lot guys, I have already used wiki...Thanks again!

I will post my summary in the coming days so we all benifit from it!
 

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