Questions tagged [butterworth]

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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 ...
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0answers
2k views

Simple (Arduino) digital butterworth filter : why do I see oscillations?

I want to filter deviations from an ADC over time (low pass), not very critical. So I first tried exponential averaging, something like y= (7*y+x)/8. That gave useful results, but there is an obvious ...
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0answers
201 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 ...
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0answers
93 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 ...
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0answers
254 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 ...
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0answers
3k views

Implement a Butterworth Filter in C#

I'm very new to signal processing, but was asked to implement a filter function for Butterworth low pass filter for given order, cutoff frequency and sample rate. After reading some articles I think ...
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0answers
4k views

Design of a Butterworth lowpass filter in MATLAB

I'm using the Signal Processing Toolbox in MATLAB to design a Butterworth low-pass filter. I'm told that my filter has been giving some unexpected results. In particular, when the values from this ...
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0answers
66 views

Filter 3D volumetric image with a Butterworth filter in Python

I have been looking for a way to filter a 3D volumetric image in python with a Butterworth filter, but I haven't found any good solution. I have tried this: ...
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0answers
178 views

Pre-Processing Wi-Fi Channel State Information (CSI) Data

I was successfully able to collect some CSI data using the existing tool(s) on GitHub (https://github.com/StevenMHernandez/ESP32-CSI-Tool). The CSI data is a pair of imaginary and real number which ...
0
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1answer
129 views

Creating a 4th order Butterworth filter R

I have sampled my data at 2000 Hz and want to generate a fourth order low-pass zero-lag filter with a cut-off frequency of 150 Hz. I have put the code below that I have created but I have the ...
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1answer
31 views

I am looking for an analytic description of a continuous-time Butteworth High-pass filter in the time domain (=impulse response)

having derived the Butterworth Lowpass Time domain response, I am now struggling to find a similar function for a Butterworth Highpass filter. I understand you need to replace s by 1/s. But this leads ...
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1answer
58 views

Why use both a high pass and a low pass filter in a Butterworth implementation for noise reduction?

I am a new to audio processing . I want to develop an application that reduces audio noise using a Butterworth filter. I found some existing code doing this, but I still do not understand the use of ...
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0answers
44 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. ...
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1answer
135 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 $\...
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68 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, ...
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0answers
149 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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0answers
20 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 ...
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0answers
121 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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0answers
72 views

Difference between MATLAB's $\tt butter$ and my calculated coefficient

So I figured recently that MATLAB's butter function was giving slightly different coefficients than those I calculate for a simple first order low pass filter, and ...
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1answer
342 views

Parameters of Butterworth filter that approximates the amplitude response of a Gaussian filter?

For a given narrowband Gaussian filter with a specific central frequency and filter width, I need corners of a bandpass Butterworth filter whose amplitude response is close enough to the Gaussian ...
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1answer
175 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=...