## Forums Search for: Butterworth

## Obtaining 1/3 octave levels from a PSD

inhello i am looking for the easiest way to calculate 1/3 octave levels from an acquired signal sampled at a high rate (usually 350kHz). as i...

hello i am looking for the easiest way to calculate 1/3 octave levels from an acquired signal sampled at a high rate (usually 350kHz). as i understand it, the usual method is to create a bunch of butterworth filters and calculate the RMS level in each band, decimating occasionally to increase resolution at lower frequencies. my question is: can the 1/3 octave levels be accurately cal...

## butterworth filter

inHello I am an engineering student, relatively new with filters and matlab, I need to design a bandpass butterwoth filter with 2 bands in matlab...

Hello I am an engineering student, relatively new with filters and matlab, I need to design a bandpass butterwoth filter with 2 bands in matlab using the buttord function. I know how to do it for just one band and iwas trying to apply the same approach using 2 bands but i did not work. My questions are: Do i have to design 2 separated bandpass filters and combine them or is there a way do it toget...

## What am I missing about IIR Filter Design?

inEvery article I see regarding IIR filter design seems to make the subject far more complicated than it needs to be. For example, in this...

Every article I see regarding IIR filter design seems to make the subject far more complicated than it needs to be. For example, in this DSPRelated post "IIR Coefficient Calculation - ger_lough" the discussion goes on in great length about specific formulas for different protoypes (Butterworth, Chebyshev, etc) sampling rates, Q, pole locations, etc. I wrote an IIR Filter design program wher...

## Is 'Bessel' digital lowpass filter standard?

inHi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important...

Hi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important aspect is that the ringing (overshoot) shouldn't be higher than about 3%. When using a 3rd order Butterworth, I get about 9% overshoot, which is too much. Someone hinted my that a Bessel filter would be better suited. This program is a good start http:...

## Design of a Filter

Hi, I am modelling the physical layer of an 802.11 transmitter (to implement it into an FPGA). At this moment I want to design the...

Hi, I am modelling the physical layer of an 802.11 transmitter (to implement it into an FPGA). At this moment I want to design the digital filter responsible of pulse shaping (before the DAC). My doubts are: 1. FIR or IIR filter?, why?. 2. For each option (FIR or IIR) there are different types of filters (FIR: Raised_cos_Barlett, Raised_cos_Blackmann, etc, ... or IIR: Butterworth, Cheby...

## Simulating analog filter with FIR

inAny techniques for obtaining a 'best fit' digital filter (1st choice FIR, 2nd choice IIR) for an analog filter. The analog filter specifications...

Any techniques for obtaining a 'best fit' digital filter (1st choice FIR, 2nd choice IIR) for an analog filter. The analog filter specifications be from an equation (e.g. butterworth etc) or a set of measured frequency response values. This will allow me to simulate digitally an analog process.

## Adjustable Gauss Polynomial

inFor those interested in filter design, I want to introduce you to the Adjustable Gauss Polynomial. I am not selling anything here, and I...

For those interested in filter design, I want to introduce you to the Adjustable Gauss Polynomial. I am not selling anything here, and I would imagine you could implement this in MatLab if you wanted to. A couple of years ago I was experimenting with polynomial filters such as the Butterworth. My goal was to find a polynomial that was more compatible with digital filter design. One thing I t...

## Mysterious gain when designing a butterworth filter in MATLAB

inFor a high order filter, if I make Wn too small, I get an inexplicable gain term on the resulting filter. I am trying to use zpk form and then...

For a high order filter, if I make Wn too small, I get an inexplicable gain term on the resulting filter. I am trying to use zpk form and then go to second orders sections. It works, but only sometimes. Here's an example: % This gives me a filter of gain 100 dB and I have no idea why? [z,p,k] = butter(n,.1); [sos,g] = zp2sos(z,p,k); Hd1 = dfilt.df2sos(sos,g); fvtool(Hd1) % But this gi...

## What is wrong in this IIR filter code?

inHi, Given are following coefficients to a second order butterworth highpass filter with a 3 dB cutoff freq of 4.48 Hz: double a0 =...

Hi, Given are following coefficients to a second order butterworth highpass filter with a 3 dB cutoff freq of 4.48 Hz: double a0 = 1.0; double a1 = -1.999722319818149; double a2 = 0.999722358365939; double b0 = 0.999861169546022; double b1 = -1.999722339092044; double b2 = 0.999861169546022; that is used in the following direct form IIR filter implementation: double Yn, Yn1, Yn2, ...

## IIR Filter for Baseband comms

inHi, My simulations show that having IIR low pass filter to simulate baseband model of a communication systems will introduce inter symbol...

Hi, My simulations show that having IIR low pass filter to simulate baseband model of a communication systems will introduce inter symbol interference (ISI). regardless the filter type (Butterworth, Cheby, Elliptic,...) all gives a significant ISI. The simulation shows it gives a significant BER degradation, it can be around 3 to 5 dB. Is that a realistic value compared to the real ...

## Correcting for DAC and analog filters

inHi, I want to identify a DT equivalent system of a transmitter. It should include the Zero-Order-Hold DAC, interpolation filter (and...

Hi, I want to identify a DT equivalent system of a transmitter. It should include the Zero-Order-Hold DAC, interpolation filter (and possibly mixer + any image rejection filters etc). I created a simple SIMULINK model which implements a 4x interpolation-DAC with the following specs: fs=200 MHz (i.e., fs_DACOUT=800Mhz), Butterworth reconstruction filter (fcut=100Mhz). Then I send BLWGN...

## Re: Questions regarding Octave

inEric, Sending you the working code back again, %------------------------------ modified code start % 5/1/96 Eric Jacobsen % % Design a...

Eric, Sending you the working code back again, %------------------------------ modified code start % 5/1/96 Eric Jacobsen % % Design a butterworth filter and determine the equivalent FIR taps. % order=4; % Order of filter. cutoff=0.25; % Cutoff relative to 1.0 = 1/2 sample rate. [B,A]=butter(order,cutoff); %---------------- removed "end;" line (not required) -- Regards B...

## Importance of phase in Audio

inHello all, i am designing a low pass filter and high pass filter to pass my audio samples. in matlab i checked out both butterworth...

Hello all, i am designing a low pass filter and high pass filter to pass my audio samples. in matlab i checked out both butterworth and chebyshev(cheby2) 3rd order filter. I have observed there is a lot of differance in the phase plot of both the filters. Now my query went to what actuall effect of phase in audio? please anybody help me in solving this. Looking for the repl...

## Announcing ScopeIIR 5.0

inHi All, This is to announce the release of ScopeIIR 5.0, which is a comprehensive Windows tool for designing and analyzing Infinite Impulse...

Hi All, This is to announce the release of ScopeIIR 5.0, which is a comprehensive Windows tool for designing and analyzing Infinite Impulse Response (IIR) filters. The Trial Edition is free for 30 days. ScopeIIR designs high-order IIR filters based on Butterworth, Chebyshev, and Elliptic prototypes. It designs lowpass, highpass, bandpass, and bandstop filters. ScopeIIR provides a...

## Performs IIR filtering using BF537 EZ-KIT

Hello!! I am trying to implement an bandpass butterworth IIR filter with fixed point coefficients. I have a wave file that should be filtered...

Hello!! I am trying to implement an bandpass butterworth IIR filter with fixed point coefficients. I have a wave file that should be filtered with this filter. I do not know how to set the filter characteristics in fdatool(matlab), so that all coefficients be in fixed point arithmetics, because I need them to programming Blackfin 537 EZ-kit Lite. Thanks in advance

## IIR BandPass nominator

inHello everybody, I have problem with nominator of H(z) of bandpass filter. I develop musical open-source software (non-commercional) and I...

Hello everybody, I have problem with nominator of H(z) of bandpass filter. I develop musical open-source software (non-commercional) and I wrote my filter-design algorithms based on polynomials (without complex aritmetic). I have all working well (Bessel, Butterworth, Chebyshev, inverse Chebyshev and Cauer's elliptic filters Low, High Band pass and band Reject). Now I decided do rewrite my al...

## Beginers question on nos of taps

inHi, How do the number of taps of an IIR or FIR filter corelate to the order of the filter?? Lets say I have a 2nd order Low pass Butterworth...

Hi, How do the number of taps of an IIR or FIR filter corelate to the order of the filter?? Lets say I have a 2nd order Low pass Butterworth filter, does that mean the nos of taps will be 2?? Also will the number of taps vary with the corner frequency. Thanks -Glidden This message was sent using the Comp.DSP web interface on www.DSPRelated.com

## High-pass filter without phase shift

inHi, I'm trying to design a high-pass filter to filter out DC component (bias) from a noisy accelerometer measurement. I've tried to go with a...

Hi, I'm trying to design a high-pass filter to filter out DC component (bias) from a noisy accelerometer measurement. I've tried to go with a second order Butterworth filter with coefficients from http://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html. The filtering works just fine, but the filter has a non-linear phase shift, so I don't know if that's the right choice. I'd also like to go w...

## Problem measuring frequency response of filters

inHi everyone, I'm fairly new to DSP and am having trouble measuring the frequency response of various (mainly Butterworth) filters that I wish...

Hi everyone, I'm fairly new to DSP and am having trouble measuring the frequency response of various (mainly Butterworth) filters that I wish to use in a program. To test the response I'm running the filters on white noise using a 1024 point buffer (which is what the program will use) then taking the DFT of the output. I'm doing this 1000 times and averaging the result. The result...

## IIR filter reference designs

inHi all. I'm struggling to implement my own codes for IIR filter design by analog prototypes. The Butterworth filter works, the Chebyshev type...

Hi all. I'm struggling to implement my own codes for IIR filter design by analog prototypes. The Butterworth filter works, the Chebyshev type 1 doesn't. The books I have available are Proakis & Manolakis' 3rd edition, Oppenheim & Schafer 1975+1999, Leland B Jackson 1989. Most show, relatively crudely, the main steps in filter design. Only P&M show any examples of Cheb 1 filters in suff...