Design of multirate filters

On Feb 26, 10:32&#4294967295;pm, Jerry Avins <j...@ieee.org> wrote:
> aitezaz....@gmail.com wrote:
> > On Feb 26, 9:00 pm, Jerry Avins <j...@ieee.org> wrote:
> >> aitezaz....@gmail.com wrote:
> >>> jerry would you please comment on my previous post ? it is here for
> >>> your reference
> >>> --------------------------------------------------------------------------
> >>> Jerry i read article about Gibbs Phenomenon. What i got from this is
> >>> that this problem arises when we truncate the filter response in time.
> >> Nit exactly. Truncating the coefficients decreases the *frequency* of
> >> the ringing, extending it further from the transition. It has no effect
> >> in the *amplitude*.
>
> >>> That means if i increase the filter length with the same sharp
> >>> filters, i should get the better performance. But, when i increased
> >>> the filter length of the sharp filter, the performance improved from
> >>> what it was with fewer number of taps but it was still worse than the
> >>> performance of filter with larger transition bandwidth. Now where can
> >>> be the problem?
> >> The sharper transition.
>
> >>> Im using the following code to generate the filter.
> >>> Fs_3 = 1e6; &#4294967295;% Sampling Frequency
> >>> Fpass = 250e3; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295;% Passband Frequency
> >>> Fstop = 500e3; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; % Stopband Frequency
> >>> Dpass = 0.0028782312868; &#4294967295;% Passband Ripple
> >>> Dstop = 0.001; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295;% Stopband Attenuation
> >>> dens &#4294967295;= 80; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295; &#4294967295;% Density Factor
> >> That's not code, it's specification. Some program uses it to run code.
> >> Bad things happen when a sorcerer's apprentice lets himself believe he's
> >> a sorcerer.
>
> > of course i wrote below the MATLAB command firpm that uses Parks-
> > McClellan algo for filter design. does that imply i should know this
> > algorithm before designing filters?
>
> No. I meant to distinguish between the specification for a filter and
> the code that calculates coefficients to meed that specification.
> Driving a car doesn't involve knowing how to design one. Believing that
> driving is akin to mechanical engineering does nobody any good.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
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All right thanks for your help anyways. it meant a lot to me... i will
try to compensate in the regions you highlighted jerry.

Best Regards,
Aitezaz