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Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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How to handle non-causality when decomposing a 4th order IIR filter into a parallel bank of second order filters?

What I am trying to do I am trying to code a Gaussian smoothing filter using the 4th order IIR filter described in Van Vliet's paper "Recursive Gaussian derivative filters". My code works ...
Omar Emara's user avatar
2 votes
5 answers
448 views

Why does the frequency sampling method for FIR filter design operate in this manner?

I'm studying FIR filter design and it's time for the frequency sampling method, my teacher said that to use this method you need to follow the following steps: Sample the periodic frequency response ...
minghierid's user avatar
0 votes
1 answer
42 views

How can I calculate how much of my signal at the beginning and end will be affected by the filtering process?

I'm using a Butterworth bandpass filter to process my signal (low-pass + high-pass, I am also applying a notch filter). I would like to calculate how much of my signal at the edges will be affected by ...
moray_'s user avatar
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3 answers
181 views

Recover high pass filtered square wave

I'm designing UHF RFID receiver. My receiver has high pass filter and I would like to recover original square wave and then use matched filter. My high pass filter is in hardware and it is difficult ...
rf-engineer's user avatar
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0 answers
41 views

Butterworth Bandpass Filter Design

Determine the transfer function for the Butterworth bandpass filter? (At the Transfer Function Factoring and Sp Substitution stage) The Parameter $$a_{pass} = - 1dB$$ $$a_{stop} = - 20dB$$ $$f_{pass1} ...
SKevinAR18's user avatar
0 votes
2 answers
57 views

Linear Phase in equiripple filters

How come equiripple filters are symmetric/anti-symmetric in time, but do not posses linear phase, but only piecewise-linearity? Do not all FIR+symmetric/anti-symmetric have Generalized linear phase?
Processor48's user avatar
1 vote
2 answers
119 views

Filter secondary bounces of a pulse signal

I have a single "pulse" signal (looks like a gaussian but it is not exactly), followed by several bounces, with a constant period, that probably come from the electronics used (I don't have ...
g6kxjv1ozn's user avatar
1 vote
1 answer
80 views

Filtering of sampling effects

I again need your help. You were already nicely able to help with predicting the signal I'm dealing with. Thanks a lot. (Forecasting of a periodic movement based on sensor data) Now I need to remove ...
Alexander Jasper's user avatar
1 vote
1 answer
82 views

How does Pre-emphasis mitigate finite precision effects?

"The digitised speech signal $s(n)$ is put through a low order digital system (usually first order FIR filter) to spectrally flatten the signal and make it less susceptible to finite precision ...
Anantha Krishnan's user avatar
2 votes
1 answer
227 views

Phase response of non-symmetric FIR filters

FIR filters are said to have linear phase when the filter coefficients are symmetric or antisymmetric with respect to time instant n=0. I am trying to design a ...
Deepa's user avatar
  • 315
2 votes
1 answer
69 views

Multiscale Mathematical Morphology Filtering on Python

For context, I'm basing my code on the information provided in the paper "QRS Detection Based on Multiscale Mathematical Morphology for Wearable ECG Devices in Body Area Networks" by Fei ...
karimnh's user avatar
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0 answers
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How can I smoothen this Chebyshev type I bandpass filtered signal?

I'm unable to figure out the cause behind my noisy bandpass filtered signal, despite my adaptation of the paper's parameters, in which they specified it to be a 4th order Chebyshev type I bandpass ...
karimnh's user avatar
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0 answers
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Filtering a Square Wave [duplicate]

I'm looking for information about how to filter a square wave. I don't want to filter it out, but extract it from the rest of the signal. Most filtering I've encountered usually only care about a ...
A. Que's user avatar
  • 101
0 votes
1 answer
36 views

How can I make use of Saramäki and MATLAB implementation of the Remez multiple exchange algorithm for FIR filter design

Seeking assistance with an optimized and well-documented implementation of the Parks-McClellan algorithm, I explored beyond the original FORTRAN code provided in A Computer Program for Designing ...
Fadi EID's user avatar
1 vote
1 answer
49 views

Initial conditions for 2 IIR causal filters applied to the same time-series consecutively

I have a buffer of shape (n_samples, n_channels) in which new samples are coming in at regular intervals and old samples are discarded. In this example, the buffer array is called ...
Mathieu's user avatar
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1 answer
70 views

Computing FIR filter coefficients

I'm trying to understand the math behind FIR filter design. I'm focusing on the simple case of an ideal LPF with the following frequency domain behavior: When the IDFT is applied, I end up with: I ...
Kienan's user avatar
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1 vote
0 answers
92 views

Is there a method to detect sum of sinusoidal signal?

Consider we have $N$ samples. In that $N$ samples we may have $M$ samples from sum of sinusoidal signal plus noise. Obviously $M<N$. In case $N=M$ we have only $N$ noise samples. Let us assume $M$...
Creator's user avatar
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2 answers
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How do I isolate a part of this signal in time-domain in Matlab?

I want to isolate a reflection part of a signal which I've transformed from Frequency to Time-Domain (see Picture). So far, I've tried to create a Hamming-Window with the specific window-width for the ...
Anne-Mary's user avatar
0 votes
1 answer
54 views

Unstable high-pass filter on mouse-generated signal

I am making a Desktop application using PyQT as the app is a Digital Filter You can add zeros and poles to a unit circle and apply the filter to the data the data can be of two types 1- saved data on ...
Mohamed Hazem's user avatar
1 vote
2 answers
89 views

Turning non-symmetric filter into a symmetric filter

I would like to ask if there is a systematic way to turn a non-symmetric filter into a symmetric equivalent with the same frequency response. For example, let's say I have a finite length filter with ...
AAM's user avatar
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1 vote
2 answers
90 views

A filter that decays proportionately to the wavelength of each freq? So for each wavelength at each freq, that freq's amplitude is attenuated by (*c)?

I am trying to design a filter that decays amplitude of signal passed through it proportional to the number of wavelengths that pass at that frequency in a given time. In other words, where for every ...
mike's user avatar
  • 533
2 votes
1 answer
144 views

Group delay equalization for second order IIR notch filter

A couple of second order notch filters seem to be appear regularly in the literature (see e.g., Tseng, Chien-Cheng, and Soo-Chang Pei. "Stable IIR notch filter design with optimal pole placement.&...
rhz's user avatar
  • 447
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0 answers
24 views

Cutoff Frequency Calculation for Basic Multimode / State-Variable Filter

I am working with a basic multimode / state-variable filter topology which combines highpass, lowpass, and bandpass outputs. I am wondering if there is a formula I can use to calculate cutoff ...
Emmett Palaima's user avatar
3 votes
2 answers
740 views

Confusion on when a filter is considered band-pass

As part of an assignment, I was given a filter with a specific set of poles and zeros, namely poles at $0.51 \pm 0.68i$ and zeroes at $1.5$ and $−0.7$. This part of the assignment is titled as "...
Nyquist-er's user avatar
2 votes
2 answers
194 views

What is the meaning of the filter coefficients in case of an analog filter?

I'm trying to improve my poor understanding of analogue filters. Similarly to this question, I've always wondered why libraries like scipy offer an option to design an analogue filter, and when I ...
bluenote10's user avatar
1 vote
1 answer
44 views

Identify the smoothing filter from boundary pattern

I have a collection of discrete timeseries, which has already been smoothed temporally. However, the smoothing operation does not consider the boudary properly, and results in obvious distortion. I ...
Vapor's user avatar
  • 11
3 votes
0 answers
53 views

Half-band IIR filter design with cascaded allpass structure

I am trying to design a simple half-band complementary filter bank following this paper. I don't have a Matlab license at the moment, so I am trying to implement it in Python, but I'm running into ...
Florent's user avatar
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0 votes
1 answer
65 views

I/Q scatter plot of raised cosine filter in QPSK

I am using a raised cosine filter in my QPSK receiver and I see this IQ diagram of the signal, but it seems off to me. Can someone explain why this happens? This is the MATLAB code I used to generate ...
Jacob's user avatar
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1 vote
0 answers
50 views

IIR filter design for "data-aided" least-squares filtering

Consider a discrete-time signal consisting of a desired signal component and noise, as follows. $$y_k=d_k + n_k, \qquad k\in\{0,1,\dots,K-1\}$$ This signal is applied to a linear time-invariant (LTI) ...
rhz's user avatar
  • 447
1 vote
1 answer
171 views

FIR filter design for resampling

I am working on an audio resampler that is realized as a polyphase FIR filter. While testing, I found that it does not suppress aliasing as well as I would have expected. For testing, a sine sweep is ...
wolframw's user avatar
4 votes
1 answer
85 views

Connection between LTI filters and damped + driven harmonic oscillator?

In physics, a damped harmonic oscillator that is driven by a sinusoidal force has a steady state solution: $$ x(t) = \frac{F_0}{m Z_m \omega} \sin(\omega t + \varphi) $$ where $$ Z_m = \sqrt{\left(2\...
bluenote10's user avatar
2 votes
4 answers
324 views

3-point highpass filter

I came across an interesting question from Strang & Nguyen$^\color{magenta}{\dagger}$ where it asks to design a $3$-point (or 4-point) high-pass filter with better performance than the $2$-point ...
Sami Al-Dalahmah's user avatar
0 votes
1 answer
42 views

Why do extremals need to be located at the left-hand and right-hand band edges of each band?

I am reading the Remez algorithm for designing FIR filters. In the first paragraph of section 15.3.1 of Andreas Antoniou's digital signal processing book, I have two questions. extremals are to be ...
yixin_gui's user avatar
2 votes
2 answers
152 views

Design of digital filters with negative group delay

I am currently working on digital filters that can predict my input signal(assume that input signal is bandlimited). In other words, I want my filter to have a flat magnitude response in bandwidth of ...
wanghr's user avatar
  • 21
1 vote
2 answers
105 views

Resolution after Oversampling, Filtering-Decimation

The ADC I am working on has a resolution of 24 bits and a Signal-to-Noise and Distortion (SINAD) of 108.4 dB. Assuming only quantization noise is present, the Signal-to-Noise Ratio (SNR) of the ADC ...
MrT's user avatar
  • 21
0 votes
0 answers
40 views

Separating 'heart sound' from 'lung sound'

I have audio files recorded from electronic stethoscope and in those files I want to filter out heart sounds and retain just the breathing sounds. How can I do this using just the signal processing ...
hamza nawaz's user avatar
2 votes
1 answer
91 views

low shelving filter frequency response diagnosis

I am building a second order modified biquad filter based on an implementation by Will Pirkle in "designing audio effect plugins in c++". However when I look at my implementation's ...
Brian Barry's user avatar
2 votes
1 answer
172 views

group delay of Bessel filters

Wikipedia states that Bessel filters have a group delay within passband of $1/\omega_0$. While the inverse relationship to knee frequency makes sense, it ignores the effect the filter order has on the ...
Yair M's user avatar
  • 305
1 vote
0 answers
22 views

Why lag compensator is preferred over PI for sinusoidal reference?

In this post, LJSilver mentioned that a PI compensator is not appropriate for a constantly changing reference, such as a sinusoidal waveform. In this scenario, a lag compensator is considered the ...
internet's user avatar
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0 votes
0 answers
27 views

Filter response weighted formula representation

I am trying to represent a filter response numerically using the formula shown in the end. I know its electromagnetic response. Could you please help me understand how to make in Matlab such filter ...
rocko445's user avatar
  • 171
2 votes
1 answer
78 views

Problem by designing and filtering a Bessel-Thomson filter in Python

I have an issue when I want to filter a signal with a 4th order Bessel-Thomson filter with a cutoff frequency at 18 GHz. 1. Generate data at 50 Gbps (T-spaced) ...
user70072's user avatar
1 vote
1 answer
94 views

Allpass Filter with Sign Switch

I want to design a digital allpass IIR filter with the following transfer function. $$ H(\omega) = 1 \textrm{ for } \omega < \omega_1 \textrm{ or } \omega > \omega_2 $$ and $$ H(\omega) = -1 \...
Jiro's user avatar
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1 vote
0 answers
88 views

Calculating the settling time of lowpass and bandpass SOS filters constructured using SciPy

I have constructed a high pass filter using scipy: ...
BeginnersMindTruly's user avatar
2 votes
0 answers
49 views

Trying to understand scipy.signal.kaiserord

I am trying to understand scipy.signal.kaiserord example. The example says We will use the Kaiser window method to design a lowpass FIR filter for a signal that is sampled at 1000 Hz. We want at ...
Thoth's user avatar
  • 131
1 vote
0 answers
117 views

Understanding the parameters of a notch filter

Adobe Audition has a very interesting notch filter that have been very useful to me. It has the following parameters According to their documentation, the chosen frequency is the center frequency and ...
TheGMX's user avatar
  • 11
1 vote
0 answers
48 views

Filter coefficients conversion from Matlab for FPGA, follow up

My question is a follow up of original question, specifically the answer provided by @Dan Boschen Dans answer. The question is about converting floating point coefficients to fixed point signed ...
Mikef's user avatar
  • 111
2 votes
1 answer
193 views

Intuitive explanation of magnitude-phase-relationship for minimum phase filters

I know that, given the magnitude response $|H(e^{j \omega})|$ of a filter $H(z)$, it's minimum-phase response is given by $$ \phi(\omega) = -\mathscr{H}\Big\{ \log(|H(e^{j \omega})|) \Big\} \ . $$ I ...
herrzinter's user avatar
5 votes
1 answer
449 views

FIR filter design with nonlinear phase from measured amplitude and phase responses

I am having trouble when design FIR filter fitting to the complex data (i.e., amplitude and phase responses from measurements). I did try to use Matt. L's lslevin method here since this method is to ...
user190055's user avatar
0 votes
1 answer
108 views

Raised cosine filter and root raised cosine filter IQ for modulated signal QAM/QPSK

If I am passing a QAM signal through Root raised cosine Tx filter and measure the constellation at output, it seems very bad. If this bad output again pass with other another root raised cosine Rx ...
kecbackbencher's user avatar
0 votes
1 answer
88 views

Theory behind transfer function transforms of the type $H(s) \rightarrow H(f(s))$

My brother wanted me to derive a high-pass version of a Butterworth low-pass filter. I found that the transform $H \left( s \right) \rightarrow H \left( j - j s \right)$ does the thing, but I can't ...
Emanuel Landeholm's user avatar

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