Please give me a complete example.
2nd order, 
3dB <=180hz.

 
Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F69CD29.98C97F52@abvolt.com>...
> There is no problem with achieving an infinite attenuation at DC or any
> particular frequency. Just create zero in the transfer function at that
> frequency. 
> 
> Blocking DC is very simple: the numerator should look like z - z[-1] for
> the first order filter or z - 2*z[-1] + z[-2] for the second order. That
> condition is satisfied for any Butterworth, Bessel or Chebyshev-1
> filter.  
> 
> Vladimir Vassilevsky
> 
> DSP and Mixed Signal Design Consultant
> 
> http://www.abvolt.com
> 
> 
> 
> 
> Andrew Xiang wrote:
> > 
> > Hmmm, infinite attenuation? how to realize that? Is it possible?
> > 
> > Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F693329.F22BEB71@abvolt.com>...
> > > LMS requires an infinite attenuation at DC. Even the smallest DC shift
> > > at the input will eventually cause an error buildup which I believe you
> > > are observing.
> > >
> > >
> > > Vladimir Vassilevsky
> > >
> > > DSP and Mixed Signal Design Consultant
> > >
> > > http://www.abvolt.com
> > >
> > > Andrew Xiang wrote:
> > > >
> > > > DC is high cut off, however, there is some low freq stuff. The HPF is
> > > > a second order IIR filter with slow roll off but about -80dB at DC.
> > > >
> > > > Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F679238.95F1E113@abvolt.com>...
> > > > > Andrew Xiang wrote:
> > > > > >
> > > > > > Anyone encountered this problem when using NLMS? The h shifts up after
> > > > > > running for sometime, I noticed this for both white noise and color
> > > > > > voice signals. What caused the shift and how to avoid it?
> > > > >
> > > > > Place a good HPF in front of NLMS.
> > > > >
> > > > > Vladimir Vassilevsky
> > > > >
> > > > > DSP and Mixed Signal Design Consultant
> > > > >
> > > > > http://www.abvolt.com

There is no problem with achieving an infinite attenuation at DC or any
particular frequency. Just create zero in the transfer function at that
frequency. 

Blocking DC is very simple: the numerator should look like z - z[-1] for
the first order filter or z - 2*z[-1] + z[-2] for the second order. That
condition is satisfied for any Butterworth, Bessel or Chebyshev-1
filter.  

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com




Andrew Xiang wrote:
> 
> Hmmm, infinite attenuation? how to realize that? Is it possible?
> 
> Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F693329.F22BEB71@abvolt.com>...
> > LMS requires an infinite attenuation at DC. Even the smallest DC shift
> > at the input will eventually cause an error buildup which I believe you
> > are observing.
> >
> >
> > Vladimir Vassilevsky
> >
> > DSP and Mixed Signal Design Consultant
> >
> > http://www.abvolt.com
> >
> > Andrew Xiang wrote:
> > >
> > > DC is high cut off, however, there is some low freq stuff. The HPF is
> > > a second order IIR filter with slow roll off but about -80dB at DC.
> > >
> > > Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F679238.95F1E113@abvolt.com>...
> > > > Andrew Xiang wrote:
> > > > >
> > > > > Anyone encountered this problem when using NLMS? The h shifts up after
> > > > > running for sometime, I noticed this for both white noise and color
> > > > > voice signals. What caused the shift and how to avoid it?
> > > >
> > > > Place a good HPF in front of NLMS.
> > > >
> > > > Vladimir Vassilevsky
> > > >
> > > > DSP and Mixed Signal Design Consultant
> > > >
> > > > http://www.abvolt.com

Hmmm, infinite attenuation? how to realize that? Is it possible?


Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F693329.F22BEB71@abvolt.com>...
> LMS requires an infinite attenuation at DC. Even the smallest DC shift
> at the input will eventually cause an error buildup which I believe you
> are observing.
>   
> 
> Vladimir Vassilevsky
> 
> DSP and Mixed Signal Design Consultant
> 
> http://www.abvolt.com
> 
> Andrew Xiang wrote:
> > 
> > DC is high cut off, however, there is some low freq stuff. The HPF is
> > a second order IIR filter with slow roll off but about -80dB at DC.
> > 
> > Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F679238.95F1E113@abvolt.com>...
> > > Andrew Xiang wrote:
> > > >
> > > > Anyone encountered this problem when using NLMS? The h shifts up after
> > > > running for sometime, I noticed this for both white noise and color
> > > > voice signals. What caused the shift and how to avoid it?
> > >
> > > Place a good HPF in front of NLMS.
> > >
> > > Vladimir Vassilevsky
> > >
> > > DSP and Mixed Signal Design Consultant
> > >
> > > http://www.abvolt.com

LMS requires an infinite attenuation at DC. Even the smallest DC shift
at the input will eventually cause an error buildup which I believe you
are observing.
  

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

Andrew Xiang wrote:
> 
> DC is high cut off, however, there is some low freq stuff. The HPF is
> a second order IIR filter with slow roll off but about -80dB at DC.
> 
> Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F679238.95F1E113@abvolt.com>...
> > Andrew Xiang wrote:
> > >
> > > Anyone encountered this problem when using NLMS? The h shifts up after
> > > running for sometime, I noticed this for both white noise and color
> > > voice signals. What caused the shift and how to avoid it?
> >
> > Place a good HPF in front of NLMS.
> >
> > Vladimir Vassilevsky
> >
> > DSP and Mixed Signal Design Consultant
> >
> > http://www.abvolt.com

DC is high cut off, however, there is some low freq stuff. The HPF is
a second order IIR filter with slow roll off but about -80dB at DC.





Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F679238.95F1E113@abvolt.com>...
> Andrew Xiang wrote:
> > 
> > Anyone encountered this problem when using NLMS? The h shifts up after
> > running for sometime, I noticed this for both white noise and color
> > voice signals. What caused the shift and how to avoid it?
> 
> Place a good HPF in front of NLMS.
> 
> Vladimir Vassilevsky
> 
> DSP and Mixed Signal Design Consultant
> 
> http://www.abvolt.com


Andrew Xiang wrote:
> 
> Anyone encountered this problem when using NLMS? The h shifts up after
> running for sometime, I noticed this for both white noise and color
> voice signals. What caused the shift and how to avoid it?

Place a good HPF in front of NLMS.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com