# Comprehensive explanation of Aliasing?

Hello,

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

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russ_watters
Mentor
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!