Please check my filter!

Started by NightHawk in comp.dsp15 years ago 9 replies

Im trying to implement an 8th order Butterworth low pass filter in Matlab. I know you can design filters in matlab, but because of the...

Im trying to implement an 8th order Butterworth low pass filter in Matlab. I know you can design filters in matlab, but because of the specific implementation of my project, im doing with no matlab functions in an m file. So, the problem im having is that the input before filtering is EXACTLY the same as the output... what am I doing wrong? The sampling frecuency is 44100 hz. The filter cutoff...


Re: LPF butterworth filter question

Started by Rune Allnor in comp.dsp8 years ago 78 replies

On 21 Mai, 08:59, zs wrote: > On m=E1j. 19, 19:37, Rune Allnor wrote: > > Again, you seem not to have the slightest clue what you > ...

On 21 Mai, 08:59, zs wrote: > On m=E1j. 19, 19:37, Rune Allnor wrote: > > Again, you seem not to have the slightest clue what you > > are talking about. > What I'm talking about is filter design and visualization: when > designing a filter, I think it's useful to see its actual response > first, without taking 'secondary' effects into a


50Hz bandstop filter don't work ....

Started by gpezzella in comp.dsp8 years ago 12 replies

Hello Thanks to website: http://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html I have create a bandstop filter with this...

Hello Thanks to website: http://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html I have create a bandstop filter with this parameter: Parameter: ************************************************************************ filtertype = Butterworth passtype = Bandstop ripple = order = 3 samplerate = 500 corner1 = 48 corner2 = 52 *********************************************...


"Correcting" output of a filter

Started by Ross in comp.dsp10 years ago 31 replies

"Correcting" is not going to be the right word, but here's my problem. I would like to have a brick wall filter with no phase delay...

"Correcting" is not going to be the right word, but here's my problem. I would like to have a brick wall filter with no phase delay and moderate computational complexity. (Yes, I know, who wouldn't). I'm actually using Butterworth lowpass filters of order 4 as designed by Tony Fisher's web page. Imagine I create a 4 pole LPF, with a corner frequency of 31Hz with a sampling rate of 44.1...


Help me with bessel filter concepts

Started by gangadhar.m in comp.dsp13 years ago 6 replies

I am implementing a Crossover in c sharp platform. I have already implemented 24th order Butterworth and Linkwitz Riley filters. Now I need to...

I am implementing a Crossover in c sharp platform. I have already implemented 24th order Butterworth and Linkwitz Riley filters. Now I need to implement 24th order Bessel filter with cascaded biquad sections. Can any of you help me with the procedure? Regards Gangadhar


Matlab filter coefficients

Started by kerasus in comp.dsp12 years ago 5 replies

Hi, I have a problem in designing a filter. I have a 4th order IIR Butterworth bandpass filter whose Second order systems are represented by...

Hi, I have a problem in designing a filter. I have a 4th order IIR Butterworth bandpass filter whose Second order systems are represented by : sos = [1 0 -1 1 -1.9837350041630541 0.98388232243107987; 1 0 -1 1 -1.7068352267865177 0.74814388078659311]; and the gain is: gain = 0.10073985362198344 ^ 2; I'm getting the filter coefficient values with sos2tf() function su...


Mysterious gain when designing a butterworth filter in MATLAB

Started by Sam in comp.dsp10 years ago 11 replies

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...

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...


Low pass filters in the time domain?

Started by tomb18 in comp.dsp5 years ago 23 replies

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...

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...


IIR Filter for Baseband comms

Started by Mas Bas in comp.dsp14 years ago 4 replies

Hi, 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 ...


Standard filters for interpolation/decimation?

Started by BrokenForm in comp.dsp16 years ago 2 replies

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...

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...


Controllable cut-off freq for DF2 SOS

Started by ombz in comp.dsp9 years ago 11 replies

Hi everybody I'd like to have a 2nd order low-pass filter with real-time controllable cut-off frequency (fc). I am working on a 16-bit...

Hi everybody I'd like to have a 2nd order low-pass filter with real-time controllable cut-off frequency (fc). I am working on a 16-bit fixed-point processor and therefore I've chosen a DF2 SOS structure to implement a Butterworth LPF. In order to simplify things, I've made up a table containing g, a1 and a2 of the filter for different cut-off frequencies = fn*(0.006250, 0.006250, 0.012500, 0.02...


What am I missing about IIR Filter Design?

Started by FilterDan in comp.dsp5 years ago 11 replies

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...

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...


IIR design / FDATool?

Started by Pete Fraser in comp.dsp9 years ago 13 replies

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...

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 ...


Newbie in matlab..need help urgently!

Started by Anonymous in comp.dsp14 years ago 1 reply

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...

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!

Started by Anonymous in comp.dsp14 years ago 5 replies

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...

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 ...


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

Started by gareth in comp.dsp5 years ago 3 replies

Revised 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...


Performs IIR filtering using BF537 EZ-KIT

Started by anonim in comp.dsp10 years ago

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


Correcting for DAC and analog filters

Started by Peter Mairhofer in comp.dsp4 years ago 1 reply

Hi, 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...


Simulating analog filter with FIR

Started by Peterpan in comp.dsp13 years ago 7 replies

Any 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.


Filter Design Question WRT samplerate

Started by sammyd in comp.dsp16 years ago 5 replies

hi, 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) ... ...