[SI-LIST] Re: DC data

>A symmetric FIR (Finite Impulse Response digital filter) low pass filter
>with an odd number of taps (so that there is a tap at exactly the center of
>the symmetric impulse response shape) has flat group delay, that is,
>exactly the same time delay at all frequencies, which can be compensated
>for easily. That can be implemented in software.

AND in software you CAN implement non-causal filters, if that is
desireable.  For example, ANY filter if applied to the data twice,
once in the forward time direction and once in the backward time
direction, will have the minimal phase impact given the other
filter characteristics.

In software you merely filter the data, reverse it, filter again,
reverse again.  You can't do that in real-time, but if the "chunk"
size processed is small, it can appear as if it were real-time.

THere is LOTS to learn about filtering.  Best thing for you is
to decide what criteria are critical, rate them in decreasing 
importance, then find already worked out methods that achieve
those.  DON'T re-invent the wheel.
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