At 02:04 AM 4/13/2007, Bob McGwier wrote:
In the DttSP software, the sdr core for PowerSDR (Flex Radio) and others, we have a block LMS approach to automatic noise reduction. It does a really good job of doing noise reduction and automatic notch (your choice) and it definitely does not introduce nasty sounding distortion. It is much more stable than standard LMS based automatic notch filtering. When I developed the algorithm, I was surprised that others had not done it. I then learned of some subtleties which do need mitigation but were pretty straightforward. You adjust the filter once per block rather than once per sample, so you must be careful not to introduce discontinues (distortion) at the block boundaries. Once handled, this is the only way this should be done.
That code is available for svn download (visit the Flex Radio web site or the dttsp-linux yahoo group).
Hmm, interesting. Need the radio to run this on though, to evaluate how well it performs. :)
73 de VK3JED http://vkradio.com