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Its fun trying to implement LMS on Matlab, but if you are pressed for time, there should be couple of examples on the web , for instance http://www.utdallas.edu/~golden/MATHANN/ANNSOFTWARE.html or can try http://wwwpub.utdallas.edu/~emd/adaptshort.html Thanks -Mukul --- Jeff Brower <> wrote: > Premkiran Mannava- > > Thanks for your inquiry. I don't think I can help > with this. Please reply to the > group. > > Jeff Brower > DSP sw/hw engineer > Signalogic > > -------- Original Message -------- > Subject: Re: [matlab] Re: problem in normalization > factor in low pass filter > implementation > Date: Wed, 17 Jul 2002 12:13:53 +0100 (BST) > From: premkiran mannava > <> > To: Jeff Brower < > > Hello sir, > > Could you help me out with a matlab program which is > written for widro hoff lms > algorithm for adaptive filtering? It is needed as a > part for my work and it is > urgent. if possible write the code itself > > kiran > > Jeff Brower <> wrote: > > Henry- > > You're not reading carefully. I said all of the > "x[n]" components, like > this: > > y(n) = 2*y(n-1) - y(n-2) + x(n)/8 - x(n-3)/4 + > x(n-6)/8 > > Jeff Brower > DSP sw/hw engineer > Signalogic > i_am_henry wrote: > > > > Hi Jeff, > > > > Thank you for you help first. > > > > Yes, I have applied the gain/normalization > factor (1/8) to all the > > input components according to the equation. > > > > However, for > > y(n) = 2*y(n-1) - y(n-2) + x(n) - 2*x(n-3) + > x(n-6) > > the filter response tranfer function is > > Yn 1 - 2*z^-3 + z^-6 > > ---- = -------------------- .............. > (1) > > Xn 1 - 2*z^-1 + z^-2 > > > > > > For > > y(n) = 1/8 * (2*y(n-1) - y(n-2) + x(n) - > 2*x(n-3) + x(n-6)) > > the filter response tranfer function is > > Yn 1 - 2*z^-3 + z^-6 > > ---- = -------------------- .............. > (2) > > Xn 8 - 2*z^-1 + z^-2 > > > > The filter frequency respose of Equ. (2) is > different from (1). > > > > Regards > > Henry Chang > > Assistant Computer Officer > > Chinese Univerisity of HK > > > > --- In matlab@y..., Jeff Brower wrote: > > > Henry- > > > > > > Are you sure the gain factor (1/8) is not > supposed to be applied to > > the x[n] > > > components only? What happens if you try > that? > > > > > > Typically the gain/normalization factor is > intended to insure unity > > gain (or desired > > > gain) in the passband, but the frequency > response of the filter > > (shape) should remain > > > unchanged. > > > > > > Jeff Brower > > > DSP sw/hw engineer > > > Signalogic > > > > > > > > > i_am_henry wrote: > > > > > > > > Dear all, > > > > > > > > Currently, I am working on implementing > recursive low pass > > filter > > > > with design equation extracted from > manual > > > > y(n) = 2*y(n-1) - y(n-2) + x(n) - > 2*x(n-3) + x(n-6) > > > > > > > > The frequency response of the filter is > good. > > > > > > > > However, the manual also mention, in > actual implementation, > > there > > > > is a normalization factor of 1/8 based > upon the gain of the > > filter. > > > > That is, the equation become: > > > > y(n) = 1/8 * (2*y(n-1) - y(n-2) + x(n) - > 2*x(n-3) + x(n-6)) > > > > > > > > But the frequency response of this filter > is bad. > > > > > > > > Is it some common practice to design a > filter with desired good > > > > frequency response but later add some > normalization factor to > > > > normalize the signal? What is the > advantage to do so? > > > > > > > > Thank you for your help. > > > > > > > > Henry __________________________________________________ |
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Re: [Fwd: Re: Re: problem in normalization factor in low pass filter implementation]
Started by ●July 17, 2002
