orien1202 wrote:
> Hi,
> I have a question about anti-aliasing filters which I thought would fit in
> this discussion thread.
> I have an RC circuit and my ultimate goal is to estimate the value of the
> capacitor using least square estimation. In order to carry out this
> estimation I need to discretize the system transfer function and find the
> ARMA model, however to do that I need to use an anti-aliasing filter first
> to make the transfer function bandlimited.
> I tried using a Butterworth filter, which does very well is preserving the
> magnitude response of the system however the phase is really not preserved
> and since I'm trying to estimate the value of the capacitor in the system I
> thought preserving the phase is important for my estimation purposes.
> However I am now not certain any more.
> So my question is how do I know if preserving phase is important in an
> application or not? and if it is what is the best anti-aliasing filter that
> would preserve phase?

I'm thoroughly confused. Are you trying to guess the size of the
capacitor in an R-C rolloff you can't examine? Do you want to design a
filter and need to determine the appropriate capacitor value? Are you
hunting mosquitoes with a shotgun? :-)

Jerry
--
Engineering is the art of making what you want from things you can get.
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