## group delay DC filter

Started by in comp.dsp15 years ago 7 replies

Dear all, My task is to implement a very narrow high pass filter to remove a DC offset of a signal. So the cut off frequency of the filter is...

Dear all, My task is to implement a very narrow high pass filter to remove a DC offset of a signal. So the cut off frequency of the filter is very low. The filter must be linear phase. A first implementation was made using a double cascaded moving average filter. The filter seems to do its job very well. Unfortunately the group delay of the filter is too large. I have read some articles o...

## Block Processing Issue

Started by in comp.dsp18 years ago 3 replies

Hello, I have a question about filter implementation. If I have a sequence x[n] and divide it into blocks of M samples per block and do...

Hello, I have a question about filter implementation. If I have a sequence x[n] and divide it into blocks of M samples per block and do the following: 1) Update filter-coefficients 2) Filter the kth block 3) k=k+1 4) Go to 1 How should the filter be implemented ? In matlab I have 2 options: Either I implement the filter like this: [output,final_conditions]=filter(numerato...

Started by in comp.dsp19 years ago 1 reply

Hi there, I?m going to start my thesis work on Inertial navigation system for mobile Robot(Gyro-inclinometer),so i need to use filter...

Hi there, I?m going to start my thesis work on Inertial navigation system for mobile Robot(Gyro-inclinometer),so i need to use filter algorithm.I?ve some idea about kalman filter,but i would like to know which filter is most suitable to my project.What are the alternative adaptive filter techniques for Kalman filter?Could anyone please suggest me the filter techinque(or where can i find r...

## POTSBAND Design filter

Started by in comp.dsp8 years ago 1 reply

Hi, Can anyone give introduction about POTSBAND Design filter? and what the purpose of this filter??? I found matlab code for this...

Hi, Can anyone give introduction about POTSBAND Design filter? and what the purpose of this filter??? I found matlab code for this filter, function [b,a]=bandfilter(fs, f1, f2) %POTSBAND Design filter for 300-3400 telephone bandwidth [B,A]=(FS) %Input: FS=sample frequency in Hz %Output: B/A is a discrete time bandpass filter with a passband gain of 1 %The filter meets the specifications o...

## multirate filter design

Started by in comp.dsp16 years ago 5 replies

Hi, When one designs a fractional rate change filter, when specifying the filter parameters do you design the filter at the interpolated rate...

Hi, When one designs a fractional rate change filter, when specifying the filter parameters do you design the filter at the interpolated rate or the decimated rate? For example if you have an input rate of Fs then interp by 64 decimate by 125 filter and the filter will be implemented in a P/Q polyphase fashion do you design the filter at the 64*Fs rate? Assuming that the signal is alr...

## Box car filter

Started by in comp.dsp17 years ago 4 replies

Hello, I've got after the FM demodulation (by derivative : (IdQ-QdI) / (I=B2+Q=B2)) a low pass filter. This filter is a IIR Butterwoth 4th...

Hello, I've got after the FM demodulation (by derivative : (IdQ-QdI) / (I=B2+Q=B2)) a low pass filter. This filter is a IIR Butterwoth 4th order. But I know that I can use a box car filter. But what is a box car filter ? Is it a FIR filter with rectangular window ? Or FIR filter with all the coefficients to value one ? I think that I just need to make an integration of my FM demo...

## FIR filter coefficients - are they ever zero??

Started by in comp.dsp18 years ago 5 replies

Hi, I am implementing a FIR filter. A typical application for the filter would be a wireless communications system. Assuming the filter...

Hi, I am implementing a FIR filter. A typical application for the filter would be a wireless communications system. Assuming the filter is programmable, is it possible for any of the filter coefficients to be zero? I ask this as the multiplier unit in my filter's tap can be simplified if the coefficients are never zero. Reference to a credible source will be much appreciated. Many th...

## non integer interpolation

Started by in comp.dsp15 years ago 8 replies

Hi All, I am trying to understand how a non-integer interpolating filter works. For ex: In a 1.5 case, you would upsample by 3 and...

Hi All, I am trying to understand how a non-integer interpolating filter works. For ex: In a 1.5 case, you would upsample by 3 and then down sample by 2. How is the convolution between input samples and filter coefficients choosen given that there are 3 sub filter? for an interolation by 3 filter the 1st sub filter(for a 15 tap) would be Y1(n)=x(n)*h(0)+x(n-3)*h(3)+x...

## How to design and apply a frequency filter on top of a previous filter to get a given filter?

Started by in comp.dsp14 years ago 1 reply

Hello everybody, I have a microphone with a given internal frequency filter IF(x) that I found experimentally in lab. I have around 10 points...

Hello everybody, I have a microphone with a given internal frequency filter IF(x) that I found experimentally in lab. I have around 10 points defining this filter from 100 hz to 16 Khz. (I can improve the granularity if required) I want to apply a A weighting filter AF(x) on the source ofthe microphone. but the output will be wrong if I apply directly the A filter from the output of t...

## what are coefficients of a filter??

Started by in comp.dsp19 years ago 4 replies

Dear folks I am studying about dsp and i need to calculate coefficients of a filter. I know that a filter is described by its transfer...

Dear folks I am studying about dsp and i need to calculate coefficients of a filter. I know that a filter is described by its transfer function H(w)=sum h(n)exp{-jwt). But I don't know what are coefficents of that filter. More specifically I need to present the coefficients of a filter g by the coefficients of a filter h, provided G(w)=exp(-wj)H(w+pi) Can I find the coefficients of...

## Parks-McClellan FIR Filter

Started by in comp.dsp15 years ago 6 replies

Hi, I have a question regarding filter coefficients for a Parks-McClellan filter. I'm trying to write a simple software loop for the filter...

Hi, I have a question regarding filter coefficients for a Parks-McClellan filter. I'm trying to write a simple software loop for the filter using its difference equation, but I've noticed a difference between the number of taps. For, say, a ten tap FIR filter designed using a Hamming window, there will be eleven filter coefficients C0, C1,...C10 which mulitply by the filter inputs x(n)...

## Polyphase decimating filter - not working in lab- why?

Started by in comp.dsp17 years ago 2 replies

Hello... I created a polyphase filter filter based on F.Harris's book shared register design. This is a Decimation by 2, 100 tap, Fs...

Hello... I created a polyphase filter filter based on F.Harris's book shared register design. This is a Decimation by 2, 100 tap, Fs =100MHz, Low pass 20MHz - stop band 24MHz filter. Each MAC is 28-bit length, 14-bit ADC input, and the filter output is truncated. I also created a Xilinx distributed arith filter to compare using the same filter coefficients. ( For some reason I could no...

## Is this a famous filter, and how to compute the orthogonal filter?

Started by in comp.dsp19 years ago 5 replies

Hi all: A paper gives a filter: [ -2 3 -6 3 -2 3 4 2 4 3 -6 2 48 2 -6 3 4 ...

Hi all: A paper gives a filter: [ -2 3 -6 3 -2 3 4 2 4 3 -6 2 48 2 -6 3 4 2 4 3 -2 3 -6 3 -2 ]/64 and uses its orthogonal filter to solve a problem, but the author did not give out what is its orthogonal filter exactly. I wonder is this filter a famous one and the orthogonal filter is notorious...

## what kind of digital filter is this

Started by in comp.dsp19 years ago 3 replies

Hello all, I found the following digital filter algortihm Function filter(input: extended):exteded; begin x:= (input+...

Hello all, I found the following digital filter algortihm Function filter(input: extended):exteded; begin x:= (input+ a*x[-1]+b*x[-2]); filter:= (c*x+d*x[-1]+e*x[-2]); x[-2]:= x[-1]; x[-1]:= x; end; Can anybody tell my what type it is? Is it a IIR or a FIR filter, or something special? Thanks in advance em

Started by in comp.dsp10 years ago 5 replies

Hello, Some basic questions about behavior of a FIR LMS adaptive filter. In Matlab I'm using their supplied adaptfilt.lms function. ...

Hello, Some basic questions about behavior of a FIR LMS adaptive filter. In Matlab I'm using their supplied adaptfilt.lms function. let: mu = adaptation constant = .08 for all experiments x(n) = filter input d(n) = desired filter output y(n) = filter output e(n) = error signal = d(n) - y(n) h(n) = impulse response of system to be modeled afilt(n) = value of filter taps at end of data...

## FILTER code (FORTRAN)

Started by in comp.dsp15 years ago 12 replies

Hi, I've to apply some special shaped filter to long signals, the filter coefficients I know already but the existing filter routine is...

Hi, I've to apply some special shaped filter to long signals, the filter coefficients I know already but the existing filter routine is probably to slow. I want to update the filter routine without becoming a signal processing expert ;-) What is the right way to apply a filter a) in time domain or b) in frequency domain It is possible to use some existing...

## filter of amplitude versus filter of (I,Q)?

Started by in comp.dsp15 years ago 7 replies

I have a client who filters complex data. They first calculate the magnitude, then filter that. I suggested they should filter the complex...

I have a client who filters complex data. They first calculate the magnitude, then filter that. I suggested they should filter the complex data, then calculate the magnitude. The same filter is used in each case, and the filter coefficients are purely real. The results are different, which is not a surprise, but I cannot find a simple way to explain why this is. Any suggestions woul...

## Haar Filter for QMF

Started by in comp.dsp15 years ago 1 reply

Hi, Its known that Haar filter is the only FIR filter achieves the perfect reconstruction when used in QMF filter. Then why is it not used? Why...

Hi, Its known that Haar filter is the only FIR filter achieves the perfect reconstruction when used in QMF filter. Then why is it not used? Why do people go for longer length filters and pseudo QMF? What are the disadvantages of Haar filter that it cannot be used in QMF filter? Thanks in advance.

## moving average filter

Started by in comp.dsp11 years ago 4 replies

Sirs, I have just started going through filter basics and the first filter topic is moving average filter. My understanding of a filter has...

Sirs, I have just started going through filter basics and the first filter topic is moving average filter. My understanding of a filter has always been that a part of the information (can be noise or unwanted *information* in a certain context) gets removed. By the same logic, the power of the signal gets reduced after filtering process. When I look at the moving average filter, it appear...

## Matched Filter Question comes back

Started by in comp.dsp17 years ago 6 replies

I was following the previous posts on Matched Filters. Very interesting. Some questions keep haunting me. These may be stupid. I dont...

I was following the previous posts on Matched Filters. Very interesting. Some questions keep haunting me. These may be stupid. I dont know. 1. If the Transmitter Filter (i.e., Pulse Shaping Filter) G_T(t) is symmetric, then the matched filter G_R(t) is same as the pulse shaping filter. Hence for Raised Cosine (RC) pulse shaping filter, the matched filter is also RC. For RRC pulse shaping, ...