Impulse response

Reply to Impulse response on Tue, 24 Jan 2012 01:17:31 GMT

moog1 — Tue, 24 Jan 2012 01:17:31 GMT

Anybody who enjoys graphs might like to fiddle with this one..
It demonstrates that a unit-impulse signal input to a filter, outputs the impulse-response..

..a brick-wall filter giving us the sinc function.
Only needs vanilla

http://www.pdpatchrepo.info/hurleur/impulse-response.pd

Reply to Impulse response on Thu, 26 Jan 2012 10:59:53 GMT

katjav — Thu, 26 Jan 2012 10:59:53 GMT

That's a nice illustrative patch, moog1. Such demo's can be equally useful as mathematical formula's, when it comes to understanding dsp.

Your patch shows two responses: one around index zero and one around index N/2. If you take out the window and overlap, only the response around index zero remains. Then center the unit impulse at index N/2, and the response is centered as well. See attached.

Katja

http://www.pdpatchrepo.info/hurleur/impulse-response2.pd

Reply to Impulse response on Thu, 26 Jan 2012 12:44:01 GMT

moog1 — Thu, 26 Jan 2012 12:44:01 GMT

@katjav said:

If you take out the window and overlap, only the response around index zero remains. Then center the unit impulse at index N/2, and the response is centered as well..

Katja

Thankyou .. now it's close to the true theoretical impulse response of the filter

Reply to Impulse response on Sun, 29 Jan 2012 21:33:33 GMT

moog1 — Sun, 29 Jan 2012 21:33:33 GMT

I've been playing around with the patch, as I was trying to get an accurate 'filter kernal' from it..
It certainly gives insight into how it all functions. I've increased the fft block size to 4096, and added a routine to copy to a centered kernel of 128 samples.
Added in a 'bp object' routine for interest as well .. bit more lipstick too
..still vanilla

http://www.pdpatchrepo.info/hurleur/impulse-response3.pd

Reply to Impulse response on Wed, 11 Jul 2012 10:55:10 GMT

giuliomoro — Wed, 11 Jul 2012 10:55:10 GMT

is there any particular reason why you don't use a bandlimited impulse?