## Forums Search for: Butterworth

## DSP.SE and comp.dsp cross-over

inHi Guys, Just thought I'd post this...

Hi Guys, Just thought I'd post this link: http://dsp.stackexchange.com/questions/85/are-there-any-standard-implementation-forms-for-tunabl e-butterworth-filters to show that there's already some cross-over between comp.dsp discussions and DSP.SE content. Good to see! Ciao, Peter K.

## Low pass filters in the time domain?

inHi, I have an IQ signal that I mix with a complex oscillator to bring signals down to 0 hz. I now need to do a lowpass filter on the signal to...

Hi, I have an IQ signal that I mix with a complex oscillator to bring signals down to 0 hz. I now need to do a lowpass filter on the signal to remove all other signals before demodulating the signal. Currently, I have this working by using a 5 pole butterworth filter with a cut off frequency of 3000Hz. This works nice, and I can get the coefficients from online resources. However, what I reall...

## designing an arbitrary 10 tap IIR filter

inHi, i would like to design a 10 tap IIR butterworth filter with a given cutoff. What tools are available to help me realise this in C. for...

Hi, i would like to design a 10 tap IIR butterworth filter with a given cutoff. What tools are available to help me realise this in C. for example for RBJ's biquad filters there are equations on how to update your coefficients when your cutoff or sr changes. i'm looking to do something similar but on a higher order filter. thanks for any suggestions or pointers ... regards, sam ...

## Following peer review - the derivation of the representation of sampling by Diracian Delta functions

inRevised after peer review, approached with a little less haste So... Sampling with a period of T is given by (after asciification) as...

Revised after peer review, approached with a little less haste So... Sampling with a period of T is given by (after asciification) as .. (1/T)sum (n : 0, inf)(d(t-nT) * f(nT) ) ... with * representing multiplication and not convolution as we are still in the time domain. However, (and this is where my protest came in having previously fully revised Fourier, Laplace, Butterworth...

## Re: Bessel Filter (Digital)

in> could we be more clear as to why Bessel seems okay for analog and not > with digital? > > i have never implemented a Bessel filter in either...

> could we be more clear as to why Bessel seems okay for analog and not > with digital? > > i have never implemented a Bessel filter in either domain, i don't > remember even doing it in school. i do remember seeing it and the > design equations and such in sections besides that of other filters > (Butterworth, Tchebyshev 1 and 2, Elliptical, Gaussian). i remember > seeing plots of their group d

## Newbie in matlab..need help urgently!

inI am trying to implement a bandpass filter on a signal data, xx. It is of 200,000 samples and the sampling frequency is 40 kHz. I am using a...

I am trying to implement a bandpass filter on a signal data, xx. It is of 200,000 samples and the sampling frequency is 40 kHz. I am using a butter filter function and my program is as followed: HalfFs = Fs/2 Wp = [1000 1550]/HalfFs; Ws = [950 1600]/HalfFs; Rp = 3; Rs = 40; %Calculate the minimum order of Butterworth filter [n,Wn] = buttord(Wp,Ws,Rp,Rs) [b,a] = butter(n,Wn); yy ...

## Newbie in matlab..need help urgently!

inI am trying to implement a bandpass filter on a signal data, xx. It is of 200,000 samples and the sampling frequency is 40 kHz. I am using a...

I am trying to implement a bandpass filter on a signal data, xx. It is of 200,000 samples and the sampling frequency is 40 kHz. I am using a butter filter function and my program is as followed: HalfFs = Fs/2 Wp = [1000 1550]/HalfFs; Ws = [950 1600]/HalfFs; Rp = 3; Rs = 40; %Calculate the minimum order of Butterworth filter [n,Wn] = buttord(Wp,Ws,Rp,Rs) [b,a] = butter(n,Wn); yy ...

## Standard filters for interpolation/decimation?

inI'd really like not to reinvent the wheel for my current hobby project, so I beg of all DSP people out there - what are the standard filters...

I'd really like not to reinvent the wheel for my current hobby project, so I beg of all DSP people out there - what are the standard filters used for 16X interpolation/decimation? Are they windowed-sinc, Chebyshev, Butterworth, or something else? And what are the coefficients, can I find tables of them somewhere? My goal is to create a simple VST guitar distortion plugin which uses non-lin...

## matlab filter shape versus sample frequency

inHi. I was using some matlab functions to show the shapes of some basic butterworth filters when I noticed that my shapes were changing depending...

Hi. I was using some matlab functions to show the shapes of some basic butterworth filters when I noticed that my shapes were changing depending on my sampling frequency. Of course, I wouldn't expect this. Can anyone explain why this is happening? Thanks, Blair I have pasted code here which best demonstrates what I mean... % Written by: Blair Fonville % Last Modified: Jan 12...

## Filter design pls help

inI was given a project to design, simulate and synthesize a digital low pass filter with cutoff frequency 150 Hz and stop band attenuation of 80...

I was given a project to design, simulate and synthesize a digital low pass filter with cutoff frequency 150 Hz and stop band attenuation of 80 db/decade The filter i have chosen is iir Butterworth filter with order 4 I have relialized the filter using fdatool in matlab Can any one pls help me with the vhdl code thx in advance

## FIR filters

inHi all Im currently trying to design a FIR filter in Matlab (fdatool) v7.04 and im experiencing a few problems. A list of these have been...

Hi all Im currently trying to design a FIR filter in Matlab (fdatool) v7.04 and im experiencing a few problems. A list of these have been included below: 1) Im currently trying to design a filter with a flat passband and therefore i have choosen to use a butterworth - filter slope 12dB/ Oct. However when trying to select this option, Matlab blocks you. Is the reason for this FIR filt...

## Small/easy Challenge

inWorking on some other problem the below coefficient expressions popped out as a byproduct. I'm curious to know if the expressions are (well)...

Working on some other problem the below coefficient expressions popped out as a byproduct. I'm curious to know if the expressions are (well) known. Hopefully you don't find it too lame that I post it as a challenge to derive the expressions. I have no idea how easy it is. A 3rd order Butterworth lowpass filter, H(z), can be realized as a parallel connection of two allpass filters, one of order ...

## Filter Design Question WRT samplerate

inhi, i'm designing a lowpass IIR Butterworth filter (direct form II transposed) in Matlab using fdatool, and there are several different ways...

hi, i'm designing a lowpass IIR Butterworth filter (direct form II transposed) in Matlab using fdatool, and there are several different ways of specifying the frequency 1. normalized [0,1] 2. Hz 3. kHz 4. MHz for 2-4, it makes sense because for those selections, i can enter in a Fs (samplerate) and a Fc (cutoff) but for the normalized [0,1] i can only enter in a wc (cutoff) ... ...

## low frequency IIR BPF - help !!

inHi All, I have never worked on DSP before so please forgive my lack of education! I have a signal sampled every 1mS by a 14bit ADC. From...

Hi All, I have never worked on DSP before so please forgive my lack of education! I have a signal sampled every 1mS by a 14bit ADC. From this signal I wish to extract a signal between 0.4Hz and 2.5Hz (while discarding some components less than 0.4Hz), so I designed a 2nd order butterworth BPF using Matlab, and it works fine. Next I implemented the filter on Visual studio using C#, and it wor...

## Which noise?

inDear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially...

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially the white one. I tried to filter with normal filter (butterworth band pass), but I did not obtained a lot of success. So, I thought was better delete the White gaussian noise with an adaptive filter. I used the demo of Simuling of LMS but I have probl...

## equations for Butterworth IIR filters, where are they hiding?

inI came across this webpage: http://mymbs.mobeard.org/~pfisher/fov2-0010016c/fov2-0010016e/FOV2-001001A3/chapters/25katsianos /index.html It...

I came across this webpage: http://mymbs.mobeard.org/~pfisher/fov2-0010016c/fov2-0010016e/FOV2-001001A3/chapters/25katsianos /index.html It lists the equations for the filter coefficients up to 5th order in a form that seems relatively easy to implement. I have come across other derivations that seem more laborious. Now unfortunately, the author has made the equations as GIFs with very small

## IIR design methods

inHi all. I have come across this arcane problem where I need to filter some data, and where tests in matlab indicate that it is curcial to...

Hi all. I have come across this arcane problem where I need to filter some data, and where tests in matlab indicate that it is curcial to use a filter with no ripple in the pass band. I know of two types of digital filters that can be constructed with no ripple in the pass band, the Butterworth and Chebychev II. Now, using analog templates for designing discrete time low pass filter...

## IIR design / FDATool?

inI'm new to Matlab, and to IIR design, so sorry in advance if these questions are dumb. I've been playing with filterbuilder and FDATool just...

I'm new to Matlab, and to IIR design, so sorry in advance if these questions are dumb. I've been playing with filterbuilder and FDATool just to get familiar with the options / design flow. There seems to be a lot of overlap. Why would somebody want to use filterbuilder rather the FDATool? Say I design a 6th order, DFII Butterworth LPF, with Fs = 48000 and Fc = 10800. I do a fixed ...

## noise..how to regulate it?

inDear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially...

Dear chaps, I have a problem. I have a signal recorded from a ultrasonic transducer of a chemical reaction. It is rich of noise, expecially the white one. I tried to filter with normal filter (butterworth band pass), but I did not obtained a lot of success. So, I thought was better delete the White gaussian noise with an adaptive filter. I used the demo of Simuling of LMS but I have probl...

## Cascade All Pass Filters

inHello All, Im designing and audio equalizer in Simulink. I have 15 FDATool blocks for filters with dbGain blocks after them for the gains. My...

Hello All, Im designing and audio equalizer in Simulink. I have 15 FDATool blocks for filters with dbGain blocks after them for the gains. My filters are IIR filters designed using the butterworth design method. The problem is that in the passband of my filters the phase is not perfectly linear. Could someone help instruct me on how to use matlab to design an all pass filter to linearize...