Questions tagged [butterworth]
The butterworth tag has no usage guidance.
98
questions
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1answer
34 views
Ripple in a SciPy Butterworth SOS Filter
I have a script using SciPy for checking the RMS of various Butterworth Bandpass Filters of varying orders.
I would expect the RMS values to increase and decrease linearly and consistently as you get ...
0
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1answer
73 views
Butterworth filter of the acceleration and drifting displacement problem
I am only mechanic engineering and I need to filter my acceleration from MEMS mobile phone which has a noise and drifts. Here is my data. Acceleration vs time from an app mobile phone ...
0
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2answers
68 views
Pre-Warping is not working on bilinear transform
New here and I just wanna ask the question of what happens when your pre warping doesnt work on your bilinear transform?
I am assuming my isnt working as part of my research I have read that the ...
1
vote
1answer
65 views
number of multiplications per second required by the system
Consider a system implementing a rational sampling rate change by 5/7: for this, we cascade upsampler by 5, a lowpass filter with cutoff frequency π/7 and a downsampler by 7. The lowpass filter is a ...
1
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0answers
36 views
Number of multiplication operations needed in rational sampling rate change with IIR Butterworth filters
I am trying to get a general sense of how many multiplication operations are needed for a 4th-order Butterworth filter (IIR filter) with a rational sampling rate change. I am excluding any ...
0
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0answers
36 views
Butterworth filter
Can someone please explain how would the image of a biosignal say PPG be affected when a higher-order Butterworth filter is used. Please don't tell about bode curve, I need practical aspects of it.
...
0
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1answer
45 views
How to figure out number of multiplications in rational sampling
I am trying to understand the following:
Consider a system implementing a rational sampling rate change by $\frac{5}{7}$: for this, we cascade upsampler by 5, a lowpass filter with cutoff frequency $\...
3
votes
2answers
267 views
Are IIR filters (and specifically Butterworth filter) causal?
I am new to signal processing. I am learning now about filtering and I am trying to implement high pass filter (HPF),and later band-pass filter (BPF). I implement the filters in ...
0
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1answer
34 views
Roll off rate vs filter order?
The concept of "increasing roll off rate with increasing filter order" applies only to butter worth or also chebyshev and other filter types?
1
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1answer
34 views
Filtering artefacts and filtering short signals
I have a signal from EEG sensors and I try to denoise it from AC frequencies. For that reason, I estimated PSD of my signal and found that 50 Hz and 100 Hz are likely to represent noise. I constructed ...
2
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1answer
41 views
How to derive 2nd order Butterworth condition for the damping coefficient mathematically?
The magnitude of 2nd order low pass filter is given as
$$|H(\omega)|^2= \frac{1}{(1-(\frac{\omega}{\omega_o})^2)^2+(\frac{2\zeta\omega}{\omega_o})^2}$$
Now in order to achieve maximally flat within ...
0
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1answer
62 views
Pole locations of Butterworth filter
I am reading Proakis book "DSP using Matlab", 3rd edition.
I am reading chapter 8, section 8.3, p. 402, and I am confused regarding the equation of poles (roots of denominator of system ...
0
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2answers
31 views
Design and a notch filter using two Butterworth filters in parallel (MATLAB)
I am doing a project to filter out a 1kHz noise inserted to a 30sec .wav audio file.
To filter out the 1kHz noise, I am required to design using two Butterworth filters connected in parallel where ...
0
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2answers
48 views
Relationship between order of filter and amplitude/phase response
I am learning about digital filters, for example a lowpass butterworth filter.
In many languages, the implmentation requires specification of the order of the filter, which I believe is the number ...
0
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1answer
33 views
What is absolute ripple specification and how does it arrive in low pass prototype for Butterworth?
Digital Signal Processing by John G. Proakis, Dimitris G. Manolakis(4th Edition) gives the prototype function for Butterworth low pass filter in an analog system which is fine till the point where the ...
0
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0answers
51 views
Lowpass Butterworth filter equation
I am using a 5th order lowpass Butterworth filter with a varying cutoff frequency, $f_c$, to smoothen some data coming from a spectrometer. An example of a spectrum, plotted with the filtered data, ...
0
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0answers
38 views
Difference in results between iirj and mkfilter with Butterworth filter in BandPass
When I generate a filter on www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html
and another iirj (github.com/berndporr/iirj) these are not the same results.
Configuration (mkfilter):
Type : ...
0
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0answers
42 views
removing noise using Scipy.signal.butter:
I am going to remove the noise from a brain recorded signal. It was a continuous recording and with sample rate=30kHz, it was digitized. So now it is a digital signal.
I have written the code here ...
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3answers
726 views
Butterworth filter transfer function in time domain
Preliminaries
I need to know the response of Butterworth filter in time domain of the following input (at least numerically):
$$
x(t) = \theta(t)(1-\exp\{-at\})\exp\{-bt\}, \quad a,b>0,\quad a\gg b
...
0
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1answer
196 views
How is the formula of the cutoff frequency of a 2nd order Butterworth low-pass filter derived?
According to articles and notes, the cutoff frequency of a 2nd order Butterworth lowpass filter:
is expressed by the formula:
$\omega _c = {1\over\sqrt{R_1R_2C_1C_2}}$
and since $\omega _c = 2 \pi ...
0
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1answer
37 views
Converting a simple analog Butterworth filter into a digital filter
I was just studying an old circuit analysis textbook that was describing how to design a Butterworth filter, and that seemed easy enough.. then, I started to wonder if I can take this analog filter ...
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0answers
72 views
Apply a butterworth filter to columns of a large dataframe
I have a large dataframe (7200, 132) and each column is a signal. I want to apply a butterworth filter to each signal, however, I'm not sure how to do this in Python.
When I do it in matlab I can ...
2
votes
2answers
104 views
Why is my signal attenuated after applying a HighPass-filter?
I am new to DSP, but I've been attempting apply a butterworth high-pass filter on a 1D array (Values peeking at 300~) to eliminate any noise, yet when applying a high pass filter, I'm ending up with ...
0
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1answer
47 views
Cut-off frequency in Fourier-Spectrum of a noise message
I have a problem involving cut-off frequency.
I have a voice message in an audio file .mat which have an eletromagnetic noise. I am trying to recover the original message by applying digital ...
2
votes
1answer
200 views
Large spike at beginning of signal after applying Bandpass filter
Foreword: I am a PhD student and fairly unexperienced with many signal processing and engineering concepts, please be gentle.
I am attempting to filter out a frequency range of 1Hz to 2Hz from a 2....
1
vote
1answer
170 views
Applying a 2D band pass filter (Butterworth ?) to an array with NaNs
I am trying to filter out the low frequencies of an array looking like this :
For now, I am taking transects of this array and applying a 1D - butterworth band pass filter :
...
1
vote
1answer
84 views
Plotting curved peaks on PSD graph
I am a PhD student with little engineering experience, currently attempting to recreate the signal processing techniques used in this paper: Monitoring Vital Signs and Postures During Sleep Using WiFi ...
0
votes
1answer
64 views
Frequency response plot and actual behavior of a digital Butterworth LPF
I have been struggling with a not-too-high (2nd) order digital Butterworth low-pass filter both in SciPy and MatLab (latest of both).
The intention is to apply this filter on signals with different ...
0
votes
1answer
137 views
Using a Butterworth high-pass filter together with Fast Fourier transform
I have a signal and I'm interested in identifying the dominant frequencies greater than 1/3600 Hz. To do this, I use Fast Fourier Transforms and examine the locations of the peaks in the frequency ...
1
vote
2answers
212 views
How Butterworth low-pass filter can be applied on a digital signal (i.e. discrete representation of a signal)?
I would like to know how to apply a low pass filter (Butterworth) to a digital signal. So, I have some values of the signal, let's say $S(t)$. Those values are equally spaced in time. I have read the ...
0
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1answer
98 views
what is the theory behind Butter function?
I want to understand why this code used tan and cos ?
...
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0answers
19 views
What is the meaning of these Fixed Point Properties e.g.CustomSectionInputDataType?
I was trying tom implement a Butterworth filter and i came across a example on Mathworks site which emphasizes to customize various terms related to the filter.
Following are some of the terms i could ...
0
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1answer
885 views
How to choose order and cut-off frequency for low-pass Butterworth filter?
When using IMU data (accelerations and angular velocities), many papers use a 4th order low-pass butterworth filter with a cutoff frequency of 5 Hz. However, none of them really justify why those ...
0
votes
1answer
117 views
Why does sampling frequency affect the filter results?
I have a big issue, basically my goal is to create a low-pass butterworth filter around 0-35Hz with a sampling frequency of 5000Hz.
My Matlab code is
...
0
votes
1answer
98 views
Bandpass filter with very high sampling rate
Consider a bandpass filter with Low Cut 17Hz, High Cut 22 Hz, Fs = 45000 Hz and Order = 6. When I pass a mixture of multiple sinusoidal waves through this filter (with a sine wave of frequency 20 Hz), ...
0
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1answer
79 views
Analytical design of a bandstop Butterworth filter
I am trying to analytically design a bandstop Butterworth filter. I am trying to use:
$$|H(s)|^2 = \frac{1}{1+\big(\frac{s}{j\omega_1}\big)^{2N}}+\frac{1}{1+\big(\frac{s}{j\omega_2}\big)^{-2N}}$$
to ...
2
votes
1answer
195 views
Odd-order Butterworth filter gain at cutoff frequency
Wikipedia gives the gain of an n-order Butterworth filter as
$$G^2(\omega)=\left |H(j\omega)\right|^2 = \frac {{G_0}^2}{1+\left(\frac{j\omega}{\omega_c}\right)^{2n}}$$
here. If you look at the gain ...
0
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0answers
92 views
how to detrend a carrier phase with butterworth filter?
I am new with detrending techniques, I have a carrier phase measurements and I want to detrend it by 6th order butterworth digital filter. After creating the digital filter I get its numerator (...
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2answers
2k views
FIR butterworth also possible or just IIR?
can we use butterworth and other such filters like chebyshev,elliptic etc with FIR
or they can be only used with IIR?
0
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1answer
74 views
difference between conventional analog butterworth filter and that implemented through IIR
I am confused what is difference between conventional analog butterworth filter and that implemented through digital technique using IIR
-1
votes
1answer
132 views
“Side Lobes” When Using a Butterworth filter
So I am attempting to filter a signal containing frequencies at 7Hz, 11Hz, and 74Hz. The signal lasts for 30s and looks like this between -1s and 1s:
Using a butterworth filter of order 2 with lowcut=...
1
vote
1answer
91 views
iir biquad filter not working
I am trying to implement a butterworth bandpass filter
My filter requirement is Fs= 500Hz, Fc1=0.4Hz, Fc2=4Hz, Oreder=2.
Below is the code which is implemented on 16bit-mcu and is called for every ...
1
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0answers
90 views
Digital or analogue filtering?
I'm trying to self learn the art of signal processing whilst moving through my third year pure maths degree.
Sorry if my terminology is incorrect however I hope I am understandable!
I am looking at ...
0
votes
1answer
127 views
Time-domain LPF not showing expected behavior
I am trying to implement a simple first-order Butterworth Low-Pass filter in Python. I have some code that makes use of scipy.signal.butter and scipy.signal.filtfilt. It works fine, but I wanted to ...
2
votes
2answers
409 views
How to compare many bandpass filters (for their signal propogation delay)?
Let's say we have an audio signal sampled at 96 kHz, and we want to compare several bandpass filters to find the one with the lowest rectangular-envelope-propagation-delay (see graph below).
The band ...
2
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2answers
320 views
Initialize Hi Pass Filter
I want to remove the DC from a ADC, so I designed a two-pole, 1 Hz high-pass Butterworth filter for a signal sampled at 10kHz. The filter coefficients are:
...
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0answers
251 views
How can I manually find the coefficients, poles and zeros of Butterworth low pass filter in MATLAB instead of using the built-in functions?
Actually I need to filter a raw ECG signal using low pass Butterworth filter at 70 hertz. And j need to implement the Butterworth filter first for that. Please any help since I'm very new to this ...
0
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1answer
403 views
Question of Digital filter; stability and order
Below 1~6 are my question.
Shortcomings of IIR filter.
Mean of unstable. (Things that will happen when system is unstable.)
How to select the best order(n).
What happens when I raise order too much.
...
0
votes
2answers
2k views
Bandpass butterworth filter in python is not working
I've implemented this bandpass filter in matlab for the audio signals and it's working as expected. Now, I tried to implement the same thing in Python but it doesn't produced expected results, it just ...
0
votes
1answer
618 views
How to decompose raw acceleration signals into gravity and dynamic acceleration?
I have a data from $3$-axis $50$ Hz accelerometer, acceleration over each of $3$-axis: $acc_X,\ acc_y,\ acc_z$.
I want to decompose acceleration into gravity and movement components.
First ...
