Another Goertzel question

Started by Rick Lyons in comp.dsp14 years ago 39 replies

Hi Guys, our DSP pal Jon Harris and I have exchanged a few E-mails regarding the Goertzel algorithm. If you recall, the Geortzel...

Hi Guys, our DSP pal Jon Harris and I have exchanged a few E-mails regarding the Goertzel algorithm. If you recall, the Geortzel algorithm is implemented with an IIR filter structure with a 2cos(2*pi*k/N) feedback coefficient and an -exp(-j2*pi*k/N) feedforward coefficient. The value k, which defines the frequency at which the filter resonates, is typically specified to be a...


IIR Filter Difference Equation Implementation

Started by Benjamin M. Stocks in comp.dsp14 years ago 3 replies

Hi All, I have a beginner-esqe question: all of my DSP literature shows the IIR Difference Equation as: y(n) = b(0)x(n) + b(1)x(n-1) +...

Hi All, I have a beginner-esqe question: all of my DSP literature shows the IIR Difference Equation as: y(n) = b(0)x(n) + b(1)x(n-1) + b(2)x(n-2) + ... + a(1)y(n-1) + a(2)y(n-2) + ... But then the C code implementations I see are something along the lines: FeedForwardVariable = (b[0] * x[n]) + (b[1] * x[n-1]) + (b[2] * x[n-2]); FeedBackwardVariable = (a[1] * y[n-1]) + (a[2] * y[n-2]) + ...


Fixed Point issues

Started by Xefteris Stefanos in comp.dsp14 years ago 4 replies

Hello, I am trying to implement an FIR and an IIR filter in fixed point arithmetic. The actual filter is of no importance(so I have implemented...

Hello, I am trying to implement an FIR and an IIR filter in fixed point arithmetic. The actual filter is of no importance(so I have implemented the simplest filter possible),as long as it is in fixed point,and moreover as I can give as input the desirable precision. I wrote the following piece of code,but the results are totaly bogus.. Can anybody suggest some help?I dont know if I have to ...


IIR filter - DC offset after swapping coefficients

Started by Anonymous in comp.dsp14 years ago 10 replies

Hello, I have an application that has a standard IIR high pass filter with a long time constant. During certain conditions, a shorter...

Hello, I have an application that has a standard IIR high pass filter with a long time constant. During certain conditions, a shorter time constant is required, so new coefficients .. with a shorter time contant ... are swapped in. After a designated period, the original coefficients are returned. The problem I'm encountering is during this last step. After the original coefficients a...


Hilbert IIR filter implementation

Started by praveen in comp.dsp14 years ago 10 replies

Hello, I wanted to know how to implement Hilbert transform using IIR filter. Any reference or article or suggestion will be great. I wanted to...

Hello, I wanted to know how to implement Hilbert transform using IIR filter. Any reference or article or suggestion will be great. I wanted to implement it on a DSP processor. Hardware structure, filter coefficient????? waiting for reply With regards praveen


linear phase iir filters

Started by shamganth in comp.dsp14 years ago 52 replies

sir, iam doing my postgraduation in communication in south india at Anna University. Iam doing my project in Linear phase IIR filters. I...

sir, iam doing my postgraduation in communication in south india at Anna University. Iam doing my project in Linear phase IIR filters. I have the base materials for Linear phase iir filters. I wish to implement the Linear phase IIR filter system in Matlab. so yet i haven't get an idea how to implement the system. If anyone came across those websites and have the materials relates to the codi...


"Time revresion technique"

Started by shamganth in comp.dsp14 years ago 2 replies

sir, iam trying to implement Linear phase IIR filter. To acheieve Linear phase in IIR filter we have the main technique of Time reversion...

sir, iam trying to implement Linear phase IIR filter. To acheieve Linear phase in IIR filter we have the main technique of Time reversion of the section. If anyone is doing in the same please reply. thanks in advance.


IIR filter design

Started by Erik de Castro Lopo in comp.dsp14 years ago 13 replies

Hi all, As we all know, designing IIR filters is easy enough for low filter order but is far more difficult when higher order filters are...

Hi all, As we all know, designing IIR filters is easy enough for low filter order but is far more difficult when higher order filters are required to meet design contraints like low passband ripple, narrow transition bands and high levels of attenuation in the stopband. I'm currently working on a program for designing IIR filters and this software has recently produced a LP filte...


Fixed point implementation of 4'th order IIR filters

Started by Heureka in comp.dsp14 years ago 7 replies

Hi Does anyone have some guidelines on how to implement a 4'th order low-pass Butterworth IIR filter in fixed point. My cut-off frequency is...

Hi Does anyone have some guidelines on how to implement a 4'th order low-pass Butterworth IIR filter in fixed point. My cut-off frequency is relatively close to the DC frequency so high precision is needed for the coefficients. What about realization structure and so on! I have implemented the bit-flipping algorithm in http://www.cmsa.wmin.ac.uk/~artur/pdf/Paper16.pdf for quantization of...


rounding errors : fixed point precision

Started by Robin48gx in comp.dsp14 years ago 3 replies

I know that bits precision required for an IIR filter is proportional to the number of IRR stages. I learnt this aftermaking a 9 stage IIR using...

I know that bits precision required for an IIR filter is proportional to the number of IRR stages. I learnt this aftermaking a 9 stage IIR using doubles years ago, only the 2nd and third order ones worked correctly. Anything more went to the rails (generally), due to overflows. I also used binary scaling conventions when I worked in simulation in assembler many years ago. I am very i...


OT: Xmas wishes to you guys

Started by Rick Lyons in comp.dsp14 years ago 38 replies

Hi, before I forget: Here's wishin' you guys a Merry Christmas and a Happy New Year! Of course, these good wishes are also directed at...

Hi, before I forget: Here's wishin' you guys a Merry Christmas and a Happy New Year! Of course, these good wishes are also directed at any of you who do not celebrate Christmas such as: Muslims, Hindi, God-less Atheists, Buddhists, motorcycle mechanics, Sikhs, Jews, IIR filter designers, Shinto, Democrats, Neo-Pagans, Government Employees, Scientologists, people from Ohio, and ...


Fast response filter?

Started by Luiz Carlos in comp.dsp13 years ago 56 replies

Is there a way to define the response time of a filter? What can I do to obtain a filter where it's impulse response is limited to a certain...

Is there a way to define the response time of a filter? What can I do to obtain a filter where it's impulse response is limited to a certain period of time? Ok, an IIR filter has an infinite impulse response, but it becomes very small after some time! Luiz Carlos


IIR filter design

Started by in comp.dsp13 years ago 4 replies

Hi all ! Thank you for reading this post. I have a small problem. I would like to design an IIR filter for a FPGA and simulate it with...

Hi all ! Thank you for reading this post. I have a small problem. I would like to design an IIR filter for a FPGA and simulate it with octave/matlab to see if it works as it should. So I don't use the included 'filter' function, but I designed it myself. As one can see it in the code provided here, the design works for 2nd order filters, but not for orders 3 and more. Who could help me ?? ...


Bus width between registers in IIR

Started by in comp.dsp13 years ago 13 replies

Hi all ! Thank you for reading this message ! I would like to know how width are the busses between the registers of an IIR filter (ie...

Hi all ! Thank you for reading this message ! I would like to know how width are the busses between the registers of an IIR filter (ie implemented in a FPGA), because these filters have coeffs > 1. I have seen that the result of b0*x(n-1) can be as large as 5e5 with a simple sin as input signal ! Could anybody help me ?? thanks in advance ! Sam


Conversion distortion

Started by Richard Hendeberg in comp.dsp13 years ago 5 replies

Hi, I'm implementing a IIR-filter on a Motorola DSP56367 processor. When I convert the sampled audio to float and back again it gets...

Hi, I'm implementing a IIR-filter on a Motorola DSP56367 processor. When I convert the sampled audio to float and back again it gets distorted. First I assumed that it was my filter that was written incorrectly but just converting the data corrupts it. I use the cast function in g563c. int rx_data, tx_data; float temp; temp = (float) rx_data; tx_data = (int)temp; I loaded rx_data...


pole-zero plot with zeros |a|

Started by Philip Newman in comp.dsp13 years ago 11 replies

A simplified two-path fading radio channel can be modelled as a first-order FIR filter, with delay T, and the strength of the direct signal being...

A simplified two-path fading radio channel can be modelled as a first-order FIR filter, with delay T, and the strength of the direct signal being b0 and the strength of the indirect signal is b1. The channel can be equalised by the use of an IIR filter, which has the opposite frequency response. The frequency response is given by: G/(1+az^-1) where G = 1/b0 and a = b1/b0 However, d...


Classical IIR filter problem

Started by kalki in comp.dsp13 years ago 5 replies

Hi, I had designed a digital IIR filter from the existing analog prototype. The filter coefficients were obtained using MATLAB. The DSP which...

Hi, I had designed a digital IIR filter from the existing analog prototype. The filter coefficients were obtained using MATLAB. The DSP which is used here is the TMS320F2812 processor. The problem is scaling of filter coefficients.The input data length to the filter is 12 bits. I had scaled the filter coeffiecients to 9 bits. But then with these available datalengths,its difficult to predi...


Complex version of an impulse

Started by Impulse in comp.dsp13 years ago 7 replies

Hi all, I've got an analyic signal for which I'm designing an IIR filter with purely real valued coefficients. I'd like to look at the...

Hi all, I've got an analyic signal for which I'm designing an IIR filter with purely real valued coefficients. I'd like to look at the impulse response of this filter, but since the normal impulse is purely real and the coefficients are all real, the impulse response is also purely real. In order to get a complex impulse response, I need a complex impulse. Is this: .... 0 0 0...


DSP sample rate question

Started by Jon Dohnson in comp.dsp13 years ago 6 replies

Hello, I have a quick question. Say I am working on a DSP low pass filter that will be utilizing a 10Hz cutoff frequency. This is a two pole...

Hello, I have a quick question. Say I am working on a DSP low pass filter that will be utilizing a 10Hz cutoff frequency. This is a two pole butterworth based recursive (IIR) filter. I -think- our highest frequency component will most likely be (rate of change in digital input to the IIR) around 8kHz. My manager who is primarily experienced in analog filter thinks that we'll only need to w...


designing an arbitrary 10 tap IIR filter

Started by sammyd in comp.dsp12 years ago 14 replies

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...

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 ...