On Apr 10, 12:53 pm, Jerry Avins <j...@ieee.org> wrote:> dbd wrote: > > On Apr 9, 7:28 am, "bharat pathak" <bha...@arithos.com> wrote: > > >> ... > > >> In window based design you will always have same ripple in > >> passband and stopband. hence the designed filter meets > >> the half band criteria of perfect symmetry around fc = Fs/4. > > >> ... > >> regards > >> bharat pathak > > > In a window based design you will always have the same -error- in > > passband and stopband. Ripple can be avoided by the use of > > sidelobeless windows. > > What window is completely free of sidelobes? > > Jerry > -- > Engineering is the art of making what you want from things you can get. > �����������������������������������������������������������������������Examples of sidelobeless windows: triangle to a power (2 or greater) Hanning-Poisson (for large alpha) See the fred harris 1978 Proceedings paper For examples with applications: Kay, S. Smith, D. An optimal sidelobeless window Signal Processing, IEEE Transactions on Vol. 47 No. 9 Sept. p2542 1999 P. Depalle and T. H�elie. Extraction of spectral peak parameters using a short-time Fourier transform modeling and no sidelobe windows. In Proceedings of IEEE Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, USA, 1997. Dale B. Dalrymple
Question on Digital Signal Processing (3rd Editions)- Proakis & Manolakis
Started by ●April 9, 2008
Reply by ●April 10, 20082008-04-10
Reply by ●April 10, 20082008-04-10
On Thu, 10 Apr 2008 15:53:55 -0400, Jerry Avins <jya@ieee.org> wrote:>dbd wrote: >> On Apr 9, 7:28 am, "bharat pathak" <bha...@arithos.com> wrote: >> >>> ... >>> >>> In window based design you will always have same ripple in >>> passband and stopband. hence the designed filter meets >>> the half band criteria of perfect symmetry around fc = Fs/4. >>> >>> ... >>> regards >>> bharat pathak >> >> In a window based design you will always have the same -error- in >> passband and stopband. Ripple can be avoided by the use of >> sidelobeless windows. > >What window is completely free of sidelobes? > >JerryDouble hung? Casement? Sorry... ;) Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org
Reply by ●April 10, 20082008-04-10
On Apr 10, 4:35 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:> On Thu, 10 Apr 2008 15:53:55 -0400, Jerry Avins <j...@ieee.org> wrote: > >dbd wrote: > >> On Apr 9, 7:28 am, "bharat pathak" <bha...@arithos.com> wrote: > > >>> ... > > >>> In window based design you will always have same ripple in > >>> passband and stopband. hence the designed filter meets > >>> the half band criteria of perfect symmetry around fc = Fs/4. > > >>> ... > >>> regards > >>> bharat pathak > > >> In a window based design you will always have the same -error- in > >> passband and stopband. Ripple can be avoided by the use of > >> sidelobeless windows. >> >What window is completely free of sidelobes? > > >Jerry > > Double hung? > > Casement? > > Sorry... ;) > > Eric Jacobsen > Minister of Algorithms > Abineau Communicationshttp://www.ericjacobsen.orgDoesn't that require that we determine an acceptable definition of 'sidelobeless' on the architectural domain? No more, or less sorry... :) Dale B. Dalrymple
Reply by ●April 11, 20082008-04-11
dbd wrote: ...> Examples of sidelobeless windows: > > triangle to a power (2 or greater) > > Hanning-Poisson (for large alpha) See the fred harris 1978 Proceedings > paper... Thanks much. I have more to play with. Insights are grand! Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●April 13, 20082008-04-13
>Hi,after reading through the replies, i am still unable to solve the mentioned question.How to proved the polyphase interpolation? Thanks, Boon Hi,> > This actually means that we are doing a poly-phase > decomposition of the same filter. > > Let us take an example of I = 2 and following filter > > h(n) = [h0 h1 h2 h3 h2 h1 h0]; > > this when delayed by one clock will result in > > h(n-1) = [0 h0 h1 h2 h3 h2 h1 h0]; > > now we need to perform decimation by 2 to get our phases > > p0(n) = h(n/2) = [h0 h2 h2 h0]; > p1(n) = h((n-1)/2) = [0 h1 h3 h1]; > > you may want to perform all calculations using non-causal > approach as equation talks about n = 0, +/- I ........ > >Regards >Bharat Pathak > >Arithos Designs >www.Arithos.com > >DSP design consultancy and training company. > > > >>Hi, >> >>The question is as follows: >> >>10.19 Prove the following expressions for an interpolator of order I. >>(a) The impulse response h(n) can be expressed as >> >> >>h(n)=∑_(k=0)^(l-1)▒P_(k(n-k)) >> >>where >> >> P_k (n)=P_k (n/I),for n=0,±I,±2I….and 0 otherwise >> >
Reply by ●April 13, 20082008-04-13
On Apr 13, 1:54 am, "marathonBoon" <sealb...@yahoo.com.sg> wrote:> >Hi, > > after reading through the replies, i am still unable to solve the > mentioned question.How to proved the polyphase interpolation? > > Thanks, > Boon > > Hi, > > > > > This actually means that we are doing a poly-phase > > decomposition of the same filter. > > > Let us take an example of I = 2 and following filter > > > h(n) = [h0 h1 h2 h3 h2 h1 h0]; > > > this when delayed by one clock will result in > > > h(n-1) = [0 h0 h1 h2 h3 h2 h1 h0]; > > > now we need to perform decimation by 2 to get our phases > > > p0(n) = h(n/2) = [h0 h2 h2 h0]; > > p1(n) = h((n-1)/2) = [0 h1 h3 h1]; > > > you may want to perform all calculations using non-causal > > approach as equation talks about n = 0, +/- I ........ > > >Regards > >Bharat Pathak > > >Arithos Designs > >www.Arithos.com > > >DSP design consultancy and training company. > > >>Hi, > > >>The question is as follows: > > >>10.19 Prove the following expressions for an interpolator of order I. > >>(a) The impulse response h(n) can be expressed as > > >>h(n)=��_(k=0)^(l-1)��P_(k(n-k)) > > >>where > > >> P_k (n)=P_k (n/I),for n=0,��I,��2I��.and 0 otherwiseBoon No one around seems to have the book and edition your problem comes from. If you want have people respond to the question you are going to at least be able to state it in a manner that can be understood without reference to definitions in your book. Towards that end, without the book, I don't know what "interpolator of order l" is defined as. Also, in the expression: h(n)=��_(k=0)^(l-1)��P_(k(n-k)) the character: �� as rendered by my newsreader's character set has no meaning I understand. Perhaps no one else can interpret it either. Of course, on comp.dsp you can't count on discussion disappearing because of a lack of definitions, but lack of definitions usually sets the discussion free to wander. And we have. Dale B. Dalrymple
