John N. Power wrote:
>       If you are willing to implement an exponential filter (exactly
>       analogous to an RC hardware filter), you can do much better. From Z
>       transform theory, a one stage recursive filter can be modelled as
>       y(n) = x(n) + alpha * y(n-1)

This definitely does NOT model an RC filter.  For one thing, note that this
is an infinitely increasing series even with a constant input and an ALPHA
greater than 0.  It performs no useful "filtering" function that I can think
of.

As has been discussed many times here before, the right way to model an RC
filter is:

  FILT <-- FILT + ALPHA * (NEW - FILT)

See the archives for many detailed discussions.


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