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SigmaStudio Adaptive Mixer?

Question asked by GTG737 on Apr 22, 2010
Latest reply on Oct 31, 2012 by GatsbyDSP


I have been using the ADAU1761 Eval board and the latest SigmaStudio for a couple of months now to try and implement an adaptive noise cancellation with 2 digital microphones as audio inputs. This noise canceling is part of me and my 5-Person Senior Design team at Georgia Tech's school of Electrical Engineering. We have 2 weeks before we must present the final demonstration. So, a quick resolution to this question is greatly appreciated.


About a month ago, I thought I had found a breakthrough when I discovered this SigmaStudio Help pdf from 2006 which describes 2 different "Adaptive Mixer" blocks within the SigmaStudio library. Those blocks however, appear to be gone from the latest SigmaStudio version. The relevant part of that PDF can be found attached.


Now, To work around that we have just recently implemented an adaptive filter from the raw building blocks, (using MatLab to model the filter and translating over the blocks from the MatLab/Simulink DSP filter building tools to SigmaStudio) but it is very inconsistent. When using sine wave tones as controlled inputs, it seems to work perfectly sometimes (quite at random) and not work at all most of the time. It relies on the "Signal Subtract" basic DSP block to remove the calculated noise. From what we are hearing, when the filter isn't working, my team thinks the "signal subtract" might be actually adding the noise to the output signal instead of taking it away.


Can someone please provide guidance to where I can find/acquire the Adaptive Mixer blocks mentioned in the 2006 PDF? If not, can someone please provide insight as to why the "signal subtract" might be adding signals instead? I will try to get a copy of the SigmaStudio file and post it here tomorrow to provide further reference to our current algorithm.


Thank you,