Hi community.

Looking to implement a particular high-pass filter. See attachment for graphs.

6khz cut off, 1.5db slope. Low frequencies experience an almost 180 degrees phase-shift. The amount of phase shift decreases as the frequency is increased.

Any ideas?

http://www.pdpatchrepo.info/hurleur/Screen_shot_2013-08-13_at_12.20.07.png

Do you happen to have access to that openpipe.m file?

I did have a quick look for it but couldn't find anything. I'd hoped it was a stock matlab object, but I know nothing of matlab so I take it it isn't!

What I can give you though is the bit of text from the thesis i'm citing.

"The characteristics of the reflection filter depend on the geometrical dimensions of the bore. Irish whistle bore radius is equal to 7,5 mm. Scavone in [6] provides a function which takes the pipe radius and calculates coefficients of an arbitrary order digital filter using the invfreqz function. Figure 3.7 presents the transmittance of the second-order digital filter corresponding to the Levine-Schwinger solution for an unflanged cylindrical pipe of radius 7,5 mm."

Hopefully this is of help!

maybe its the openpipe.m from here ftp://ccrma-ftp.stanford.edu/pub/Publications/Theses/GaryScavoneThesis/thesis.pdf
pg 202?

I believe that is the one. Any ideas on how to implement something like that or the one outlined in the first post?

I'm modelling a pipe of radius 9.4. I already have a filter implemented already, which Maelstorm you may recall, but I wanted to know more about the phase change.

Any thoughts?