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Re: [Discuss-gnuradio] complex bandpass vs real low-pass


From: Nick Foster
Subject: Re: [Discuss-gnuradio] complex bandpass vs real low-pass
Date: Wed, 2 May 2012 14:59:25 -0700

On Wed, May 2, 2012 at 2:55 PM, Marcus D. Leech <address@hidden> wrote:
I have been in the habit of using complex-bandpass filters even when I'm just looking for a symmetric response.  I did some measurements
 today and found a 40-45% performance advantage to using a low-pass real filter when a symmetric response is desired.  What's the "crux"
 of the performance difference?

Needless to say, I ran around and changed all my recent "stuff" to use low-pass filters :-)

Complex * complex multiplies are more computationally expensive than complex * real. For edification and titillation you can read the volk_32fc_x2_multiply_32fc source. There's an Orc version too which is easier to read. The moral of the story is you should probably avoid complex coefficients unless you know you need them.

--n
 


--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org



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