## Forums Search for: Butterworth

## calculating the coefficients of a butterworth iir filter

inHallo everyone! I wanted to ask your advice on the following problem: i have to generate a butterworth iir bandpass filter with...

Hallo everyone! I wanted to ask your advice on the following problem: i have to generate a butterworth iir bandpass filter with cutoff frequencies of 0.008 and 0.05 Hertz. This will be used in filtering a time signal sampled at 1 Hz (so the sampling frequency is high enough to work with the time signal) My initial problem is to calculate the coefficients. Ive thought of a few ways to cal...

## Speech Recognition using Butterworth filters

inI am aiming to build a very basic speech recognition system around an 8-bit microcontroller(PIC / AVR), which is capable of 'recognizing' four...

I am aiming to build a very basic speech recognition system around an 8-bit microcontroller(PIC / AVR), which is capable of 'recognizing' four to eight words..(i.e, give a specific string output when it receives the corresponding input data through a mic.) Someone told me that designing Butterworth filters for processing the input data and then sampling it at different points is a pretty go...

## Discrete high-pass Butterworth filter design rules

inSome time ago I've programmed a 2'nd order Butterworth High-Pass filter using the tool:...

Some time ago I've programmed a 2'nd order Butterworth High-Pass filter using the tool: http://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html. I noticed it always generated filters which transfer function in the discrete time domain would be: (1) y0 = (b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2) / a0 (2) b0 + b1 + b2 = 0 (3) b0 = b2 (4) a0 + a1 + a2 = 0, where: y0 - output at curr...

## 6dB/oct butterworth crossover doesn't have flat response

inHi folks, sorry if I'll be asking a dumb question :). I'd like to build a 6dB/oct crossover (with variable number of bands and crossover...

Hi folks, sorry if I'll be asking a dumb question :). I'd like to build a 6dB/oct crossover (with variable number of bands and crossover points). First order butterworth LP and HP filters seem to be working fine and provide nearly flat magnitude response IF the crossover point isn't high enough, hence close to the nyquist, then it starts forming something that looks like a high-shelf of +6dB. ...

## Bandpass IIR Filter design

inDear list Im designing a bandpass iir filter (prototyp) for a small realtime system. I already implemented the lowpass butterworth filter for...

Dear list Im designing a bandpass iir filter (prototyp) for a small realtime system. I already implemented the lowpass butterworth filter for a variable order by calculating the normalized butterworth polynomials in 2nd order systems and then applying the bilinear transformation. This results as well in 2nd order systems in the z domain which can be used as a biquad cascade for the ii...

## Deriving the analog Butterworth filter from the maximal flatness condition

inI've been wondering whether the often-stated maximal flatness conditions on analog Butterworth filters are enough to uniquely determine the...

I've been wondering whether the often-stated maximal flatness conditions on analog Butterworth filters are enough to uniquely determine the coefficients of the transfer function? Let's review these conditions for a filter of order n: * The DC must be passed through the filter unmodified, |H(0)| = 1. * The cut-off frequency must be at w = 1. (Cut-off normalization.) * The 2n-1 first derivat...

## Digital ButterWorth Filter Design

inHi All, I am working in Digital ButterWorth filter design. I am using Fourth-order, zero-lag filter design. The Coeffecients...

Hi All, I am working in Digital ButterWorth filter design. I am using Fourth-order, zero-lag filter design. The Coeffecients calculation by using formula dCutoff2 = dCutoffFrequency * 1.247 Wc = Tan((Application.Pi() * dCutoff2) / dSampleFrequency) K1 = Sqr(2) * Wc K2 = Wc ^ 2 A0 = K2 / (1 + K1 + K2) A1 = 2 * A0 A2 = A0 K3 = (2 * A0) / K2 ...

## butterworth high pass fourth order design

inhi, can anybody help me to design and implement an fourth order butterworth high pass filter in s domain.here are the specs input = 1kHz...

hi, can anybody help me to design and implement an fourth order butterworth high pass filter in s domain.here are the specs input = 1kHz sine order = 4 fs = 20kHz As = 80dB thanks in advance sid

## Recommend a faster responding Low Pass Filter than a 2nd Order Butterworth?

inI have a signal that generally lasts about 6 seconds and has a lot of Low-Frequency, < 10 Hz, noise in it. I would like to use a filter...

I have a signal that generally lasts about 6 seconds and has a lot of Low-Frequency, < 10 Hz, noise in it. I would like to use a filter to obtain a reliable answer for the mean value of the signal, as soon as possible following the start of the data stream. I use a 2nd order discrete-time Low Pass Butterworth Filter with a 10 Hz sample rate, and I can change the cutoff frequency on the fly, vi

## A question about bilinear xform and Butterworth LPF

inI recently implemented a generalized digital IIR Butterworth low-pass filter class. It calculates the coefficients as if the filter was...

I recently implemented a generalized digital IIR Butterworth low-pass filter class. It calculates the coefficients as if the filter was implemented as a cascade of second-order canonic sections if the order is even, or a cascade preceded by a single real pole if the order is odd. The critical digital frequency is translated by the usual formula and then s--> (z-1)/(z+1). All of this i

## adding up coefficients

inHello, Recently I designed my first IIR filter from a 1st orde Butterworth. After implementation it works as it should. My second filter a...

Hello, Recently I designed my first IIR filter from a 1st orde Butterworth. After implementation it works as it should. My second filter a 2nd order Butterworth is ready on paper. What occured to me is when I add up the coefficients from the 1st order filter the sum = 1. Surprisingly adding up the coefficients of the second order IIR filter the sum is also = 1. Spare me the Math but is ...

## bilinear transfermation

inHai! every one. This question is basic for DSP experts.I try to design digital butter worth filter(lowpass) in C.First I converted given digital...

Hai! every one. This question is basic for DSP experts.I try to design digital butter worth filter(lowpass) in C.First I converted given digital specs to analog specs.after that i caluculated prewarped analog specs.I found order, cutoff frequency of analog butterworth filter.After that I used butterworth filter tables to find normalized denominator coefficients of analog filter.Now i tried to con...

## ButterWOrth filter using matlab

inhi everybody, I am working on MAtlab for verification of Butterworth Filter for low pass filter, I have written the following program for...

hi everybody, I am working on MAtlab for verification of Butterworth Filter for low pass filter, I have written the following program for it, N=20;%Order of Filter fc=200;%Cut-off frequency of filter fs=5000;%Sampling Frequency fin=1000;%Input frequency of pure sine wave n1=fs/fin; %No. of samples in sine value n2=fs/fc; i=1; %Input Coeff...

## Scaling cutoff freq of Butterworth filter

inDear group, I am currently using a butterworth lowpass filter for filtering sets of parameter files. For this purpose, I found an "optimal"...

Dear group, I am currently using a butterworth lowpass filter for filtering sets of parameter files. For this purpose, I found an "optimal" cutoff frequency to generate the filter. I have, however, the necessity of changing the "sampling rate" of the parameter set, but at the same time get the "same" results in time. So, is there any method of scaling the cutoff parameter of the filter ...

## Run time estimate of a butterworth filter

inI am completely new to the field of DSP -- so this question may be elementry I was wondering about the worst case performance of a...

I am completely new to the field of DSP -- so this question may be elementry I was wondering about the worst case performance of a butterworth bandpass filter. I know that the FFT algorithm has a worst case performance of O(N log N). Does a second order bandpass filter have a similar computational cost? How does this cost vary as a function of the order of the filter? Any insight would ...

## Minimal lag, non-causal smoothing filter

inI want to smooth time-series data with ideally zero-lag. The filter can be non-causal. I am currently using a butterworth filter and then...

I want to smooth time-series data with ideally zero-lag. The filter can be non-causal. I am currently using a butterworth filter and then advancing the output in time. However, since the butterworth filter's lag is not constant, the output series does not line up as desired with the input. My goal here is to highlight the prominent turning points in the time series -- points where signal chang...

## Matlba butterworth IIR filter implementation - sample by sample filtering basis

inHi all, I want to implement an butterworth low pass filter to filter the DC component of a signal inside a PLL - phase locked loop. I am...

Hi all, I want to implement an butterworth low pass filter to filter the DC component of a signal inside a PLL - phase locked loop. I am processing sample-by-sample. Therefore I have to filter the signal sample by sample (Not the whole signal or block by block). I have implemented a filter to filter the whole signal. But Im struggling to modify it make it work sample by sample bas

## Reg:Design of Butterworth approximated filter using FIR filter design technique

inI need to design a butterworth approximated low pass, high pass, band pass, band stop filter characteristics.This i did using DFT...

I need to design a butterworth approximated low pass, high pass, band pass, band stop filter characteristics.This i did using DFT technique which is a very heavy algorithm.So My question is how to design the FIR for my requirement.So can anybody help in how to proceed... Thank you :-) With Regards, SRS

## Allpass decomp

inDoes anyone know or is anyone able to explain why a 4th order digital butterworth bandpass/bandstop filter can't be represented/decomposed into...

Does anyone know or is anyone able to explain why a 4th order digital butterworth bandpass/bandstop filter can't be represented/decomposed into a parallel connection of two real allpass filters? A 2nd order and a 6th order butterworth bandpass filter can be decomposed into a parallel connection of two real allpass filters by why not a 4th order filter? Sorry, if this question is lame/stupid....

## Re: delay added by matlab butterworth filter

Yes. I assumed that Rune was being hyper-pedantic to protest the ambiguous way that the question was put. If I erred, I apologise to him. Jerry

Yes. I assumed that Rune was being hyper-pedantic to protest the ambiguous way that the question was put. If I erred, I apologise to him. Jerry