Re: Design of FIR filter with Sharp Transition and High Stop Band Attenuation

Ok.. This was my first posting in DSP guru so I am sorry for being a little
sloppy. Here are the specs. The filtered signal is sampled at 19.0699MHz.
It needs to be filtered by a half band filter. The filter must have cutoff
at 9.53495 MHz. Its a digital filter and yes I do know that with FIR`s I
should not expect much steep a transition. But I want to get as steep as I
can get since the signal is actually a sampled Luminance singnal from a
camera CCD. Hence any attenuation all attenuation below the nyquist rate
will cause contrast problems. Well so here are the design specs

I need 60Db attenuation at the nyquist rate i.e at 9.53495Mhz. Hence I
will need to move my cutoff to below 9.534...Mhz but closer to it the
better i.e narrower the transition widthe the better.

Ofcourse I want ripple free pass band too. So having so ideal requirements
can you suggest I can get ?

As Jerry said " Engineering is the art of making what you want from things
you can get." ......my question is what is the best that is available.

thanks
Gaurav
>gaurav811 wrote:
>> Hi
>>
>> I have to design a FIR filter with very steep transition at cutoff and
>> high stop ban attenuation. FIR bcoz I need linear phase. I have matlab
>> available. Fdatool is useless since its FIR dont have a good
transition.
>>
>> In literature search I came by papers talking about Sharp transition
FIR`s
>> using Frequency response masking and multirate filters. I wanted to
know if
>> someone has any experience with these filters ? I am going to try to
>> implement these and wanted to know what issues/problems I can face and
are
>> these papers claims any good.
>>
>> If you also know of some technique for implementing sharp transition
FIR`s
>> with low number of coeff`s let me know. Also if you know some
material/book
>> that might help me with this point it to me.
>>
>> thanks in advance. Any information relavent or irrelavant is welcome.
>
>How sharp is sharp? What attenuation do you call high? The "better" the
>filter, the more coefficients it will have. There are some phenomena you

>can use to advantage, such as the alternating zeros in half-band
>filters, that can reduce the number in special circumstances. Without
>better specs, no specific suggestion is possible.
>
>Jerry
>--
>Engineering is the art of making what you want from things you can get.
>¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
>


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