vjfaisal,
FIR (Finite Impulse Response) filters are cosntructed using weighted sums of current and past samples of input data.
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IIR (Infinite Impulse Response) filters are cosntructed using weighted sums of current and past samples of data plus weighted sums of previous samples of output data.
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The filter "taps" represent the delays between samples. For example the 1st tap would represent the current sample of data, the 2nd "tap" would represent the sample of data one sampling interval ago, the 3rd "tap" would represent the sample of data from 2 sampling intervals ago, etc.
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For more information, download the free book by Steven W Smith "The Scientist and Engineer's Guide to Digital Signal Processing". to get it, go to:
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h**p://www.dspguide.com/
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Also Search for "Digital Signal Processing". You'll get lots of hits.
Regards,
Kral