Forums

digital filters

Started by Sergio Dominguez August 27, 2004
Hi all,

I have written a digital filter (quite simple and generic) as

a*s^2+b*s+c
___________
d*s^2+e*s+f

The filter discretized using Tusting. The code is verified and seems to be
fine. Now, if have the filter

K*S
_____________
s^2+(a+b)*s+ab

Hence a=0; b=K; c=0; d=1; e=a+b ; f=a*b

and filter one time series, and have the filters

K*s 1
_____*_____
s+a s+b

Hence one filter with a+0; b= k; c=0; d=0; e=1; f=a
and another filter with a+0; b= 0; c=1; d=0; e=1; f=b

and I filter the same signal through this two filters... the answer varies.
Can somebody give me a hint on why this would be happening??

Sergio

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