Dear Young
Wp = Pass-band edge frequencies i.e it refers to those frequencies that are
passed
Ws=Stop band edge frequency i.e it refers to those frequencies that are
blocked
Rp=Maximum pass band attenuation in dB
Rs= Minimum stop band attenuation in dB
Wn= Cutoff Frequency: i.e it is the frequency at which the output differs by
3db from the pass band frequency i.e Wp;
In ideal filter , transition between passband to stop band is very sharp but
it is very difficult to make an ideal filter.
Therefore, in real scenario the amplitude gradually changes from passband to
stop band and i.e the reason why Wp and Wn are different
Best Regards
Prajit S Nair
On 8/2/07, young.sonny wrote:
>
> Why is there a difference between the value of Wp you enter in buttord
> and the value of Wn for Butterworth filter with Rp = 3? What is the
> purpose of Wn? If it is the ..."corresponding cutoff frequency...",
> what is Wp, the passband corner frequency and how does it
> differ/compare with Wn?
>
>
>