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Would Q prewarping bring any improvements if taken into cookbook implementations ?
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Having looked this up, indeed the impulse invariant method doesn't warp, but is a precise aliased version of the analogue filter.hugoderwolf wrote:I was thinking about that the other day as well, but haven't checked it out entirely. But I think that if you prewarp both cutoff and Q, that's equivalent to an impulse-invariant transform. At least with respect to the poles. In this case, you'd lose the nice properties of BLT.
Yep, in the end it's all about how positions of poles and zeros are mapped. There's BLT and II where both get mapped in the same way. Most other methods out there (matched-z and friends) are in the end some kind of hybrid.Ninja_Edit wrote: Having looked this up, indeed the impulse invariant method doesn't warp, but is a precise aliased version of the analogue filter.
https://ccrma.stanford.edu/~jos/pasp/Im ... ethod.html
Nonono, lettuce & tomato go first! Otherwise the bacon gets cold, and that's a pity.Ninja_Edit wrote:I'd prewarp the bacon first.
Thanks for this info.hugoderwolf wrote:I was thinking about that the other day as well, but haven't checked it out entirely. But I think that if you prewarp both cutoff and Q, that's equivalent to an impulse-invariant transform. At least with respect to the poles. In this case, you'd lose the nice properties of BLT.
Been trying to find open source implementation based on this code with no success.keithwood wrote:You might want to look at this paper: http://www.ece.rutgers.edu/~orfanidi/ece348/peq.pdf
Thanks!matt42 wrote:That paper has a matlab code implantation at the end. Probably wouldn't be too tricky for you to figure out a translation to C++ or whatever.
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