Bandpass IIR Filter design

On 17.05.2007 19:21, Rune Allnor wrote:
> I heard that, too, and that rumour -- for all I know it's true --
> kept
> me for years from having a go at filter design. Once you get down
> to the nitty-gritty details, all you need is the BLT for at most order
> 2.
> All higher order filters are expressed in terms of biquads, so
> apply the BLT on each of them in turn, and you are good.
> 
> The hard part was not to implement the details, but to find them.
> Antoniou's book came out months after I had finished my little
> project, just at the right time for me to appreciate its value.
> 

The description can be founded here:

http://www.mathworks.com/access/helpdesk/help/toolbox/signal/index.html?/access/helpdesk/help/toolbox/signal/bilinear.html

I think the matlab implementation itself is only about 1 A4 sheet.

Rene

On 17 May, 21:18, Rene Gerber <renegerb...@trashmail.net> wrote:
> On 17.05.2007 19:21, Rune Allnor wrote:
>
> > I heard that, too, and that rumour -- for all I know it's true --
> > kept
> > me for years from having a go at filter design. Once you get down
> > to the nitty-gritty details, all you need is the BLT for at most order
> > 2.
> > All higher order filters are expressed in terms of biquads, so
> > apply the BLT on each of them in turn, and you are good.
>
> > The hard part was not to implement the details, but to find them.
> > Antoniou's book came out months after I had finished my little
> > project, just at the right time for me to appreciate its value.
>
> The description can be founded here:
>
> http://www.mathworks.com/access/helpdesk/help/toolbox/signal/index.ht...
>
> I think the matlab implementation itself is only about 1 A4 sheet.

It's up to you: Implement this on algebraic form, from scratch,
based on available texts and easily implemented formulas, or
emulate matlab where the algorithm requires a top-notch
numerical library at the base.

If you use matlab, the choise doesn't make much of a difference.
If you use anything else, 90% of the job with doing things "the
matlab way" is to get that matrix inversion up and running. And
after you managed that, you still have as much work to do as
on algebraic form, to get the actual filter design to work.

Rune