Examples of IIR Filter Design

[@mikehagerty9666]

Thanks again for the videos! A tiny flaw at [01:00], the sum over inputs, x[n-k] should begin at k=0.

[@allsignalprocessing]

In MATLAB 'freqz' will generate mag and phase response. The commands for a Butterworth filter are buttord and butter. With the help file and the chevy1/ellip examples you should be able to get the syntax correct.

[@shankarpandit2167]

Sir I how I make band pass filter which is based on RDFT & inverse RDFT in matlab when I have already block diagram but I am unable to simulate it please help me

[@jiwann4213]

Dear Barry, I am trying to use actual bilinear transformation method without using MATLAB inbuilt functions to design a digital filter from given digital specs. I approximated a low pass filter from a digital specs given by Bilinear transformation (found N and and other coefficients). I ended up with order 7 . For which I have to have three 2nd order and 1 first order digital filters. I want to make it a high pass filter. for now I cascaded them by using "H_7 = dfilt.cascade(H0,H1, H2, H3) ". I can see the magnitude response of a low pass filter (looks pretty ideal). How can I convert this lowpass into a high pass digital filter. Also I am not able to use this cascaded LP filter to test/filter a wave signal/image. could you please help?

[@allsignalprocessing]

You need to apply a lowpass to highpass frequency transformation to the lowpass filter. There are several ways to do this. You can apply the frequency transformation in the s-domain before applying the bilinear transform (which I prefer), or you can apply it in the z domain to the digital lowpass filter.

[@jiwann4213]

Barry Van Veen Thank you Barry. You video helped.

[@temenow]

Dear Barry, thank you for those wonderful videos. I got myself a bit confused, which one is preferred, the one with built in function in matlab (as in fdatool) or trying to write the codes? What is the difference between the different tools like fdatool, filterdesigner, dsptool, and the like? Is there a note or reference you would advice for step wise design of a low pass filter IIR type? It has to be with similar behavior as the FIR type designed earlier. Thank you in advance.

[@allsignalprocessing]

Here is a section of code for plotting one of the figures [Hb,W]= freqz(Bb,Ab,2048); h = plot(W/pi,20*log10(abs(Hb))); set(h,'LineWidth',linwidth); title(['Butterworth Filter, Order = ',num2str(Nb)]) axis([0 1 -80, 5])

[@mariosmustache]

Great video! I just wanted to know what command you used for the plot. I've been trying different things and I can't get what you have. Thank you!

[@leolouie9549]

@Boston Houston Yup, have been watching on flixzone for since november myself :D

[@marwanal-yoonus280]

Thank you so much for your helpful illustrations. IRAQ

[@jiwann4213]

P.S. I designed a Butterworth Filter.

[@fidamuhammadshinwari7813]

good