> It reinforces what I already understand about
> filtering electrical or electro-magnetic "waves".  I am looking for the
> definition as it applies to EE and sampled data.

Inside a computer a simple low pass filter working on successive samples is:

Filt <-- Filt + (New - Filt)*FFrac

Where FILT is the filter that is being updated, and NEW is the new sample
being accumulated into the filter.  FFRAC is the filter fraction, a value
from 0 to 1 for a normal low pass filter.  It governs how "heavy" the
filtering is.  A value of 0 is infinitely heavy, which means the filter
output never changes at all.  A value of 1 causes the input signal to be
passed thru without any filtering.  Do an example on paper to see how this
works.  I often cascade two of these things, called "poles", to make a "two
pole" digital filter.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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