Hello, Sebastiaan, Thank you for your advice. Actually I am aware of basic characteristics of half band filter. It is very well explained in Rick Ryon's "Understanding Digital Signal Processing (2nd Ed.)" ( http://www.amazon.com/Understanding-Digital-Signal-Processing-2nd/dp/0131089897/ref=sr_1_1?ie=UTF8&s=books&qid=1257900094&sr=8-1 )
The thing I do not have any clue is the 'inner' and 'outer' coefficient things in FIR filter. I guess this is something related to the practical implementation issue rather than the fundamental concept. I did a simple googling yesterday and found a paper. ( http://ce.et.tudelft.nl/publicationfiles/1090_509_shahbahrami_prorisc2005.pdf) I hope I can find a way to get started. :-) I will also try with 'Goodman' and 'Carey' as keywords for further searching. I appreciate your comment and advice. Best regards, ILKYOUNG. 2009/11/10 Sebastiaan Heunis <[email protected]> > Hi > > I think Brian is just referring to the fact that you can see that the > HBFs are implemented as symmetric FIR filters (the coefficients). A > HBF is just a special filter that is designed so that the cutoff > frequency will always be at fs/2, so if you filter with it and > decimate by 2 afterwards (which is why you would use an HBF), you > don't get aliasing. Also, the decimation in the CIC filters can be > set to a wide range of values, so the HBF will always have to cut at > fs/2 regardless of the decimation in the CIC. From what I've read, > Goodman and Carey came up with them so you can probably look for some > papers if you're interested. > > Sebastiaan > > -- > Sebastiaan Heunis > Radar Remote Sensing Group, University of Cape Town, South Africa > Tel: +27 72 950 9370 >
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