On 8/14/2010 5:35 PM, Olin Lathrop wrote:

> I was trying to point out that sometimes you can make a "better" filter
by using more lighter filters in series than one heavy one.

This debate between Dave and Olin highlights the difficulty in defining
and describing system requirements. While I realize it's way beyond the
scope of the original poster's question, others may recognize that this
discussion is broaching along the area of maximum likelihood estimators.
Dan Simon's book 'Optimal State Estimation' covers this area well.
Relative adjectives like "better" can be turned into objective statistical
statements once the system requirements and the signal and noise
properties have been defined.

Richard Hamming's 'Digital Filters' book is an informative and very easy
to read book which I highly recommend. His approach to finding the
frequency response of a digital filter is very intuitive and I still
prefer to use it in many cases instead of Z-transforms. While some
sections are advanced, I think the original poster would gain a lot by
reading it. In addition, Hamming's 'Numerical Methods for Scientists and
Engineers' has a few chapters on digital filters too. In particular,
there's a section describing the frequency response of integration
formulas like Simpsons Rule that I found very interesting (and useful!).

Scott

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