Re: [Discuss-gnuradio] USRP2 Halfband filter coefficients help

[ILKYOUNG KWOUN]

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 <address@hidden>

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