Questions tagged [filtering]

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STFT overlap add method - What am i doing wrong?

i am trying to implement a short time fourier transform of an audio signal to do some filtering (subtract another stft signal using spectral subtraction). I am using a hamming window function with 50% ...
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0answers
48 views

How does the “additive operator splitting” exactly work?

I am reading about the non-linear (or non-homogenous) diffusion method (aka anistropic diffusion method). There are several ways of implementing this method. In all cases, we first need to discretise ...
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0answers
108 views

Use of an impulse-response system to model sediment transport along a river reach

I am new to signal processing and have come into the subject from the study of rivers and basic geophysics. I am trying to test an idea previously put forward that the sediment transport response of ...
2
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0answers
40 views

Filtering for Wright-Fisher HMM

I am trying to understand what filter may be suitable for the following HMM: The signal is a Wright-Fisher one-dimensional diffusion characterised by the SDE $$dX_{t}=\frac{1}{2}\left(\alpha(1-x)-\...
2
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0answers
86 views

maching convolution filters to results

I am practicing for an exam and I need help in the following question (it is just for me- no grade...) we get an input image, 6 convolution filters and 6 results. we need to find the matches between ...
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0answers
154 views

Open source GPS+IMU sensor fusion?

Are there any Open source implementations of GPS+IMU sensor fusion (loosely coupled; i.e. using GPS module output and 9 degree of freedom IMU sensors)? -- kalman filtering based or otherwise I see a ...
2
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0answers
130 views

Fractional equalizer with non-integer oversampled signal as input

I would like to know how the output sequence from a fractionally spaced equalizer, with a non-integer oversampled input signal, is generated. For example, for $T=T_{sym}/2$, my actual code is ...
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0answers
49 views

Respiration (breathing) signal movement artifact removal

Situation: I have breathing data of participants who have done different things during the study which caused their breathing change; watching mindless video to which resulted in unconscious regular ...
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0answers
109 views

Avoiding transients during filtering: Padding or Gustafsson's method?

I'm pretty uneducated when it comes to filtering, more of a stats guy, but I have to bandpass some signals and after a bunch of reading today I understand that the ...
1
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0answers
63 views

Noise Reduction: How can I filter out saw or other tool noises?

I recently came across old recording from the 1930's. Unfortunately not only is the quality low, it's a bunch of carpenters talking as they saw things and make all sorts of other noises. I've tried: ...
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1answer
257 views

How to calculate the Fourier transform of a mean filter in Matlab?

In Matlab, how can I calculate the discrete-space Fourier transform of a mean which takes the average of 4 adjacent points, with this kernel $$\begin{pmatrix} 0 &1& 0\\ 1 &0&...
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0answers
74 views

Using a Passive 1st Order RC filter to Extract DC Component

I am trying to extract the DC component out of a PWM signal produced by the MCU using a LPF. I understand that 1st order RC filter is looked upon as being amateurish because the gain in the passband ...
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2answers
3k views

What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...
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0answers
88 views

Processing digital sound in Audiokit to sound like the 1960's

I am looking to imitate 70's analog equipments sound. I was wondering is there a way to create tape saturation / distortion inside Audiokit? I want to add that and randomized tape crackles and ...
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0answers
156 views

Electromyography: is this interference from the heart/how to remove it?

I'm using electromyography to evaluate the activity of lumbar erector spinae at various levels of effort. For this I also intend to sample the activity at complete rest (in prone lying). In my first ...
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0answers
38 views

Multitapering in time domain to obtain smoother filtered signals?

Suppose we want to approximate the instantaneous power $z(n) = |y(n)|^2$ of the discrete-time signal $y(n)$, where $y(n)$ is the result of filtering $x(n)$ with a given window $h(n)$, $y(n) = x(n) \...
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0answers
94 views

Fastest way to subtract known music tracks from live videogame audio stream

I want to isolate video game "action" sounds from the video game soundtrack. Given all ~20 songs, I'd like to filter them out from any live audio stream during gameplay. What is a fast and robust way ...
1
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1answer
481 views

Bandpass filtering an audio signal with MATLAB's $\tt kaiserord$: unknown new frequency component

I am trying to filter an audio signal with kaiserord in MATLAB, but I'm having a problem. Here is my code: ...
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0answers
35 views

How do I smooth-over transition from a time-series generated by one system to a time-series generated by another system?

So I have generated a time-series with length on 2N samples, where the first N are generated by one auto-regressive system and the N+1 to 2N are generated by another, similar, auto-regressive system. ...
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0answers
47 views

Proximal operator of image Laplacian

Let $\alpha, \beta > 0$ and $\Delta := \nabla^T \nabla$ be the discrete laplacian operator, $$\nabla: \mathbb{R}^{n_x \times n_y \times n_z} \rightarrow \mathbb{R}^{3 \times n_x \times n_y \times ...
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0answers
2k views

Implementing a 2d butterworth filter for image processing?

I am at the moment trying to implement a bandpass butter worth filter which i then can use to apply on my original image. Problem is though My implementation of it using OpenCV doesn't seem to be ...
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0answers
163 views

amplitude compensation after filtering and mixing audio

I am working on a mixer which lets me mix dry and wet signal in a user defined ratio. Wet signal is basically just the all pass filtered signal. The mixing takes place in frequency domain and so does ...
1
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0answers
948 views

Instantaneous power estimation by discrete hilbert transform - how far does it smooth?

In my research area, instantaneous power in a specific frequency band is commonly estimated by the following procedure: Apply a bandpass filter on the raw signal (e.g. 80-90Hz bandpass). Estimate ...
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0answers
33 views

Multi-channel filter for correlated noise suppression

Short question We need to cancel the correlated noise from recorded datasets, as shown in the figure below, coming from arrays of charge sensitive sensors. I would like to ask to this community to ...
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0answers
28 views

2nd derivative using gaussian filter (gnu scientific library) - offset?

I am working on an application where I use gaussian filtering (convolution) to smooth a signal and at the same time get the 1st and 2nd derivative in real time. The signal is an equidistant sampling ...
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0answers
27 views

Classifying motor imagery from EEG data: Feature selection

I am an undergraduate student who is trying to classify motor imagery from EEG data! I have no experience working with EEG or any neuroscience background, I only have a very basic knowledge of how ...
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0answers
33 views

How to build intuition for tuning a Kalman Filter?

I'm working on designing a Kalman Filter for more accurately predicting the position of a ultrawideband RFID tag in an indoor space. Before testing with live data, I've been playing with randomly ...
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0answers
44 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 ...
0
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1answer
39 views

Recoverable continuous function after average sampling

I have a personal interest in this question, but I don't know if it is unfounded. Suppose I have a continuous function x (t), which is sampled using an average sliding window, which performs a ...
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0answers
18 views

Supression of sinusoidal interference

I have a bit of project that I'm doing for SIN interference removal. Just not sure Am I doing everything correct: Fs = 1000; Ts = 1/Fs; order = 12; t = 0:Ts:1-Ts; x = sin(2*pi*4*t); noise = ...
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0answers
37 views

How to downsample my data readings from 0.5hz to 0.001667hz. Do I filter and downsample?

I have a device that, in the lab, takes voltage readings every 2 seconds. However in real-life application the device would only wake every 10 minutes and then take a 100 readings whilst awake. How do ...
0
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1answer
57 views

Zone Plate Reconstruction

I am trying to reconstruct the Zone Plate image and am struggling to remove the last remaining aliasing. ShaderToy: https://www.shadertoy.com/view/wdGGWK In the shader above you can see that I am ...
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0answers
20 views

Image Processing Perspective Transform

This youtube video shows the current world record for smb1 speedrun, but it is recorded from a phone on a CRT TV. https://www.youtube.com/watch?v=IuVLtaB8uQk Is it possible through perspective ...
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0answers
143 views

Polyphase resampling delay

I want to implement polyphase resampling. For this, I wrote a script in matlab. The script performs the following sequence of actions: ...
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0answers
17 views

Why are guard bands employed in FBMC even though the prototype filter has near perfect leakage performance?

FBMC employs prototype filter which has a good performance in reducing the spectrum leakage to almost zero but there are a few implementations online where they have still used guard bands on either ...
0
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1answer
116 views

Adaptive Band pass filter for extracting respiratory waveform from accelerometer data

I am recording data from an accelerometer attached to the chest (1000Hz). I need to extract the respiratory waveform. I tried an adaptive bandpass filter based on a dominant frequency in my signal ...
0
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1answer
54 views

How to sketch this multirate system spectrum?

In the following system: The signal x(n) is upsampled by 2 and then filtered. The signal and the filter have the following spectrum: After upsampling the spectrum of X would look the same except ...
0
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1answer
61 views

Continuous time double exponential filtering in state space form?

I'm trying to determine the continuous time formulation of the double exponential filter so that I can adapt it more flexibly for my particular problem. Typically, this model is expressed as a pair ...
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1answer
51 views

Comparisons of FIR Causal filters of type HRIR in Discrete Time and Frequency Domains

I have just implemented a Discrete Time Convolution between HRIR filter at a range of angles. I also implemented an Overlalp-and-Add method and FFT and IFFT to compute the same convolution in ...
0
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1answer
116 views

How the zero - phase filter without filtered signal truncation at the end can be implemented?

I mean what for the window FIR filter the filtered signal is truncated at the end because impulse response of the filter is symmetric. For example the code from here (in python) (lowpass FIR filter) ...
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0answers
34 views

Applying a filter on an input sequence in matlab

Given a input sequence $x = {x_1, ... x_n}$ and a filter with l elements $h = [h_1, ..., h_l]$ with l < n. We want to filter the input sequence with the specified filter. My first thought was to ...
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1answer
188 views

Manual filter or digital filter first for EEG?

I am getting conflicting advise regarding how to clean my EEG data: 1) Manually remove artefacts first and then apply digital filters OR 2) Apply digital filters first and then manually remove ...
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0answers
93 views

How to filter a sequence of frames?

I'm have a sequence of 2-dimensional MxN frames. I have concatenated these frames to form a 3-dimensional MxNxT matrix. Now i want to filter this 3D volume by 2 types of filters (a 2D log-Gabor in xy-...
0
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1answer
122 views

Remove high resolution spurious peaks from sinusoidal signal

I have the current from a LEM transducer measured. The measurement is taken on the output of a transformer. The signal is a 50 Hz signal, measured at 100kHz. When the demand of the system is increased ...
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0answers
259 views

How to include phase noise in sinusoidal kalman filter model?

I am modelling simple sinusoidal motion using a Kalman filter from the following equation of motion: $ \ddot{x} = -\omega^2x $ So my matrix equation of motion is: $$ \begin{bmatrix} \dot{x} \\ \...
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0answers
293 views

Prediction-error filter for images

I am interested in studying local pixel value dependencies in images and I am wondering if it exists a general form of prediction-error convolutional filter that is able to suppress the image's ...
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0answers
479 views

What is Single pole filter?

Can anybody tell me why do we use single pole filter? And may be an example of Single pole filter in matlab. Good literature recommendations are also welcomed.Moreover, that would be good if anyone ...
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0answers
27 views

If a signal is added to another in the freq. domain, how to filter it out?

I have two signals, $x$ and $y$. I know that $F(x)=F(s)+F(n)$ and $F(y)=F(n)$, where $s$ is the 'clean' signal, $n$ is the added noise and $F$ donate Fourier Transform. To obtain the clean signal, I ...
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0answers
610 views

What is pulse train filter?

I have recently seen some code written in modelling tool like Simulink, ASCET which uses PT1 filter? Why do we use a pulse train filter? What is the difference between FIR, IIR, Chebyschev, ...
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0answers
173 views

MATLAB, recover a signal that has a cosinusoidal interference and that has been AM modulated

I have a signal which has been AM modulated but the channel also added a cosinusoidal interference A cos(2 * Pi * f0 * n * Tc + Phase), at the same ...