V G wrote:
> Hey all,
>
> Does a product currently exist on the market that:
>
> Takes two or more microphone inputs and applies noise canceling to
> them, then provides a noise-suppressed output? (Ex: by phase shifting
> and adding the waves)
>  =20
Doing it effectively requires a little more that phase shifting afaict,=20
instead you have a system that dynamically adjusts a filter to try and=20
match the magnitude and phase as closely as possible. The difference of=20
the two signals (the "error signal" from the adaptive filter) then=20
contains the stuff that was only picked up by one microphone (you.This=20
is known as two input adaptive filtering.

One of my lecturers at uni "Patrick Gaydecki" developed a general=20
purpose DSP box that can do this. His device has a website at=20
http://www.signalwizardsystems.com/ and it can be purchased from=20
http://www.saelig.com/category/DA.htm . It seems a little on the=20
expensive side for what it is though (I guess as with most such things=20
the real value is in the firmware). He has also written a rather good=20
book on DSP.=20
http://www.amazon.co.uk/Foundations-Digital-Signal-Processing-Algorithms/dp=
/0852964315/ref=3Dsr_1_1?ie=3DUTF8&s=3Dbooks&qid=3D1281405047&sr=3D8-1
> If not, how difficult would it be to make one? Perhaps with a dsPIC or PI=
C32.
>  =20
The hardware isn't that complex really, afaict the real effort is in=20
developing the firmware but if you are just developing for one situation=20
you can likely make it simpler than the stuff for a general purpose box.
--=20
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