# Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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### Where can I find a table of $z$-domain coefficients for Butterworth filters?

The primary source lists Butterworth polynomials in s-domain and provides a link to bilinear transform for digital implementation. But, who needs analog specification in our digital world? Why should ...
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### How to choose one among different types of LPF?

My signal graph is as follows I have < 10 reputation, thus cannot post the photo... The graph are simply roughly the series of -5, 0, +5, 0, -5, 0, +5, 0.... but with sawtooth-like small peaks ...
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### Low pass fir filter with non-unity gain

In my filter specs, the passband gain is given as 6.02db. How do I achieve this? Usually all texts give the passband gain as 0db (as well as passband ripples if any).
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### Interpolation by factor of 2

I want to up-sample my input signal by a factor of $2$. I saw zero padding followed by low pass filter method being used in few cases. But still I need some help in this. Say I have $10$ input ...
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### Oversampling then filtering and downsampling

Currently I'm working on a project to record ELF (Extremely Low Frequency) signals from a receiver. The highest frequency of interest is about 30 Hz and the system should have a flat frequency ...
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### Filter order vs number of taps vs number of coefficients

I'm learning DSP slowly and trying to wrap my head around some terminology: Question 1: Suppose I have the following filter difference equation: $$y[n] = 2 x[n] + 4 x[n-2] + 6 x[n-3] + 8 x[n-4]$$ ...
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### How to filter pulse like jumps in a signal?

I have a noisy signal with jumps to high value and back to normal for limited time bins (40 for example) which I want to filter to have a smooth signal with no jumps. Here is the graph, the blue one. ...
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### How to get translation and roation data using 6DOF MPU6150

I am trying to get the position data from an IMU 6 Degrees of Freedom (MPU-6150) board using an Arduino Uno. I am trying Jeff Rowberg’s example MPU6050_DMP6.ino that may be found here. This is the ...
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### Types of rounding in coefficients quantization

Suppose we have create an IIR filter with matlab function "ellip", and then we want to quantize the coefficients using: \begin{align*} bq=Quantize('round',b,2^8); \cr aq=Quantize('round',a,2^8); \...
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### Fill matlab “ellip” function through transfer function magnitude response

The matlab "ellip" function can be used to design the unquantised coefficient set. From matlab website: $[b,a]=ellip(n,Rp,Rs,Wp) ,$ n: order of filter Wp: normalized passband edge ...
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### Determine the type of filter from the transfer function

i got that system $x_n \to x_n-x_{n-1}$, so $h_n=[.....,0,1,-1,0,...]$, with $h_0=1$ and $h_1=-1$, so the transfer function given by: \sum_{i=-\infty}^{\infty} h_ne^{-jwn} = h_0e^{-jw(0)}+h_1e^{-jw(...
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### Dynamically changing cut-off and sampling frequency of a digital filter

I have designed a low pass filter that smooths the output coming from an accelerometer attached to a vibrating machine. I designed this assuming cut-off frequency $f_{c1}$, and sampling frequency $f_s$...
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### Relative performance of RLS and LMS filters

It's known that the RLS filter converges faster than the LMS filter in general, but that if you're tracking time varying parameters the LMS algorithm can perform better. My question is under what ...
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### Choice of cost function in adaptive noise cancellation

Why is the least squares cost function used in adaptive noise cancellation with the recursive least squares (RLS) algorithm, but the mean squared error used in signal estimation? For an ergodic ...
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### Realtime filtering on a microcontroller, with dynamic cut off frequencies

Is it possible to dynamically filter a signal in realtime on a microcontroller? What I mean by dynamically is to change the cut off frequency of the filter on the fly. I have some DSP knowledge ...
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Does anyone have any good references for deriving parameters of an IIR Low pass/High Pass filter directly in the digital domain using the magnitude squared at the corner frequency? I have been able ...
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### IIR filter parallelization

Is there any current ideas about IIR filter algorithm parallelization with thread count greater than filter order? Ideally, parallelization method should load GPU efficiently.
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### Bessel filter second-order sections Q and Fc multiplier derivation

A practical guide for digital IIR audio filters has cookbook-style values for creating higher-order Bessel filters out of biquads, but the values listed aren't very precise: ...
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### how to extract telephone audio only from an mp3

I have mp3s of radio talk shows in which the host interviews people on the phone. The host uses a microphone, and the interviewee uses either a landline phone or a cell phone. I want to save just the ...
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### Chebfun versus Parks-McClellan

There is a Matlab-based package called Chebfun that (among other things) computes polynomial approximations of functions. See here: http://www2.maths.ox.ac.uk/chebfun/. I don't know anything about ...
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I have to design 2 IIR bandpass filter with the following specifications: Sampling frequency 1000 Hz Pass-band 50 Hz to 200 Hz Order 6 using bilinear transform and impulse invariance with Butterworth ...
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### Implementing IIR filter using FSM

How do I implement an Infinite Impulse Response (IIR) filter using Finite State Machine(FSM)? The problem is FSM has finite memory, but an IIR filter has infinite outputs. The closest match is this ...
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### Online filter for EEG

My goal is to build a real-time filter for EEG data. The data are being recorded in 512Hz and I wish to filter it (in a real-time, from 0.5Hz to 30Hz in the most optimal way). Unfortunately I'm not ...
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### A filter for for a realtime system?

Apologies if this is too basic. I need to implement a band-pass filter, for a realtime system. Not sure what to use. FIR? IIR? Something else ? Any tips would be highly appreciated.
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### What is the ideal FIR length, given a specific pulse length?

I am trying to ascertain what the 'ideal' FIR filter length should be, given the pulse length $T_p$ of a windowed sinusoid in noise that I seek to filter. As parameters into an FIR filter that I ...
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### A Simple Lowpass Filter Behaving so Strangely

I don't know much about filter design. After reading a few articles on wikipedia I am playing with filter design and I see something weird and would like some help in understanding what exactly is ...
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### Vestigial Filter problem?

I have been stuck on this question for a while now. It has to do with vestigial sideband. I wasn't sure if I should be dividing $H(\omega)$ graph values by 2 because only the positive side of the ...
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### Reverse Engineering Bessel LPF (sample frequency needed)

I have the following sourcecode. For all I know, it should be a Bessel LPF at 10Hz. Is there a way to get the sampling frequence out of this? ...
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### Choice of Gaussian kernel parameters when lowpass filtering before image resampling?

I need to decimate a signal by a factor of q. More specifically my signal is a 3D "image": $\ I(x_i,y_j,z_k)$, which I need to downsample by a factor of two in the z direction. I want to do lowpass ...
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### Applying a filter kernel defined by a continuous equation in the frequency domain

I have a filter kernel $K(\omega)$ completely defined in the frequency domain as a continuous function of angular frequency $\omega$. I know $K(\omega)$ defined as a continuous mathematical equation. ...
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### Pre-emphasis / De-emphasis filter design

I've designed a simple FM communication system and found that high-frequency noise is a real problem. It appears that this is a well known issue, which has been solved through pre-emphasis of high ...
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### FIR filter gain

I'm writing a C function to generate bandpass FIR filter coefficients using a simple window method (more details here FIR filters by windowing) The important code snippet is the following (f1 and f2 ...
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### Characterizing real-time sampled signal

I have a signal which is sampled in real-time. At every time interval I receive a value. I need to characterize this signal as active or inactive (to take priority in the control actions). By active ...
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### Oversampling and decimation: What filter to use?

I have a sensor producing (more or less) bandlimited data with a cut-off of about 45Hz, with a roll-off and AWGN. I have an ADC that samples said signal at 800Hz, with a single-pole anti-aliasing ...
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### Matlab filter design,through group delay

I have the measurements of a filter’s Group delay and S-parameters. The S-parameters are of the following form, presented in a touchstone file. !Agilent Technologies,N5242A,MY49421489,A.09.33.09 !...