Questions tagged [filtering]

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1answer
47 views

Constructing frequency domain filter from a 2d spatial kernel

Given a 2d spatial kernel $h$, I want to construct the corresponding frequency filter $H$. In theory, $H$ is simply obtained by calculating the DFT of $h$ using a FFT algorithm. But in practice, there ...
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1answer
22 views

ANSI S1.11.2004 Octave-Band Filter implementation

I am trying to implement some code to firstly generate an Octave-Band and Fractional-Octave Band filter. I have used MATLAB's octaveFilter method to generate compliant Class-1 and Class-0, 1/1 and 1/...
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1answer
53 views

RF-Chain Signal Delay for Sensor Switching

Lets have a RF-chain as above with system bandwith from HP corner to the green line say 1 MHz. The signal accumulates delay as it passes through this analog chain, and due to it being non-liner filter ...
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1answer
24 views

Pulse shaping with root-raised cosine filter for a non-Gaussian channel

I am here to check whether my line of thinking is correct. Root-raised cosine (RRC) filtering is one way to minimize intersymbol interference (ISI). Hence, we apply matched RRC filters on both sides ...
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1answer
39 views

Help identifying filter

Apologies in advance for asking something so basic, this is not my field at all so I'm a bit lost where else to find this info. I'm trying to understand this piece of code that detects sudden drops in ...
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4answers
225 views

Deconvolution to Remove Gaussian Blur in 1D Signal (Wiener Filtering?)

I've got a set of biology data that I'm trying to denoise (effectively, a population statistic can only be measured convolved with a gaussian of known width) My problem is this: I can measure (f*g), ...
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1answer
36 views

Minimum phase conversion with Cepstrum method, how to scale the result?

I am trying to convert a zero phase spectrum (magnidue response curve with zero phases) to a minimum phase spectrum, because I need a totally causal impulse response for FFT spectral filtering, and ...
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1answer
27 views

Why does applying RRC to the signal increase bandwidth?

Please see this question: Why samples per symbols $\geq 2$ in the GNURadio Constellation Modulator block?. The first answer here says "filtering the signal, you have bandwidth expansion". ...
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1answer
75 views

Memory efficient filtering with scipy.signal in Python

I have several EEG channels that need filtering, and one channel may reach a recording length of 12 hours or potentially even more. This results in billions of data points stored which, when loaded, ...
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1answer
66 views

Implementation of Overlap Save Filtering with Decimation

I am trying to implement Matlab code which performs FIR filtering with complex bandpass filter using Overlap Save method and perform decimation as well by using different length forward and inverse ...
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0answers
46 views

Laplacian filter in matlab

I want to compute the output image by first dividing the image into 8*8 blocks and applying laplace filter separately and combine them but I am not getting the correct output Here is the code: ...
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1answer
55 views

Expected value of a quantized noisy signal

I am given a noisy signal $y(t) = x(t) + w(t)$, where $x(t)$ is my desired signal and $w(t)$ is the noise. In my scenario, the noise is very strong, much stronger than the desired signal $x(t)$. ...
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0answers
33 views

Deep Learning for Online EEG Denoising

I'm currently working on the development of deep learning methods for online artifact removal from EEG signals. I'm interested in removing common biological artifacts such as EOG and EMG individually ...
1
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1answer
43 views

The result if order of two filter are reversed

Apply the Composite Laplacian Filter first, then apply the gaussian filter. Apply the gaussian filter first, then apply the composite laplacian filter. My work as below: Here we assume the original ...
2
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1answer
114 views

Bandwidth of PSK modulated signal

What does it mean that the bandwidth of PSK modulated signal without applying any filtering or shaping of the pulse, is equal to the sampling rate with "1st lobe" equal to two times of ...
1
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1answer
52 views

Offset after Butterworth bandpass filtering

guess I'm stuck with this filtering problem and I'm thinking it has something to do with my raw data but I'm not so sure. So the problem is the following, please refer to the figures below, basically, ...
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0answers
15 views

Accelerometer drift: What hardware-level signal conditioning operations are being performed under the hood of a MEMS accelerometer chip?

I'm in a debate with a peer who says that filtering accelerometer signals at the chip-level has nothing to do with mitigating the problem of drift Often, additional software-level filtering is ...
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2answers
59 views

DSP signal filtering and number formats

I'm working on a dsPIC33, using Audio Codec Board - Proto to read audio samples and for reproduction. In order to implement a relatively simple signal processing algorithm, I'm reading audio samples ...
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0answers
18 views

Training of adaptive filters

I am trying to understand adaptive filters as I want to implement a denoising algorithm based on them. Do we need to train all thee adaptive filters before they start their actual process? For the ...
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1answer
72 views

Alternatives to offline Kalman filtering

Recently I got into vehicle models and filtering in general and immediately faced with the following question. I have the recorded GPS data from car driving on a highway. However, there is a ...
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2answers
228 views

Using oversampling to increase resolution of a DC-signal as input

Currently I'm working on a project which uses oversampling to increase the resolution of a 12 bit ADC to a maximum of 16 bits. My goal is to fully understand the theory behind oversampling and why it ...
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1answer
28 views

Difference between the average operation and the application of the equivalent LPF

I would be glad if someone could answer my question. I have a bit stream of data and I want to extract the low frequency component. When post processing the data I can calculate the average value over ...
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0answers
126 views

Linkwitz-Riley Allpass filters of Nth order from cascaded SVF second order sections

I am in the process of implementing a Linkwitz-Riley filter of 16th order. (LR-16, 96dB/oct) I am using 2nd order SVF sections with three modal outputs on each section. (LP, BP, HP) I am looking to ...
3
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1answer
180 views

Derivation of the lowpass to bandpass transformation

I have a basic question. The "well known" lowpass to bandpass transformation is $$ s \longmapsto \frac{\bar{s}^2 + \omega_1\omega_2}{\bar{s}(\omega_1 - \omega_2)}, $$ which gives a bandpass ...
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2answers
121 views

Scipy Butterworth highpass filter results in distortion and bloated output

Trying to use Scipy Butterworth filter to filter frequencies below 54 Hz from audio files. Audio files are stored as WAVs. Sample rate is 44100. When I try using this filter the result is distorted (...
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3answers
104 views

Noise added to a Random Process

if we have a discrete random process \begin{equation} x\left(n\right)\:=\:0.2x\left(n-1\right)+w\left(n\right)+w\left(n-1\right) \end{equation} where $ w\left(n\right)$ is a noise with a mean $ m_w=0....
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1answer
37 views

Help or suggestions with Line detection in microscopy images

I'm doing a personal project in which I want to select some very specific lines in a microscopy image. The first picture is the raw image, the second picture is the image for the lines (in yellow) I ...
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0answers
17 views

Can I use BRISQUE to compare different filtering techniques for the same acquired image?

BRISQUE compares your image with a pre-learned model with opinion scores. I am not sure about this but would image resolution affect the result of BRISQUE? Moreover, if I have 2 filters and I would ...
1
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3answers
273 views

How to practically correct for group delay imposed by a digital filter (Python)

I'm using Python to filter a signal using a Butterworth filter (scipy.signal.butter) and subsequently passing this through a forward-backward filter with cascaded second order sections (scipy.signal....
1
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3answers
64 views

Seeking advice on how to denoise a video from poor CCTV lighting

I have grainy CCTV footage that will need some amount of clean up. I request for ideas on the best way to clean out the noise. I am attaching a frame extracted from the video here for hints on the ...
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0answers
27 views

Removal of parallel-line like streaks

Just wondering what image processing techniques can remove some artifacts of parallel-line like streaks, which are shown in the red box in the above picture. I was thinking about removing it from ...
2
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1answer
87 views

Deriving a Kalman Filter Equation for a Linear Gaussian Filtering Model with Non Zero Mean Noise

I am trying to answer an exercise question from the book Simo Sarkka - Bayesian Filtering and Smoothing. The question is: Does anyone know if there is a resource that has the solutions for this book?
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1answer
174 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 ...
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1answer
80 views

Classical spectrum analyzer model

I am trying to reproduce a numerical model of classical spectrum analyzer, described in "Fundamentals of Spectrum Analysis" by Christoph Rauscher. Classical model consists of a few local ...
3
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1answer
123 views

Use of the harris-Moerder Nyquist Pulse Shaping Filter

I became aware today through fred harris' excellent presentation at the DSP Online Conference (https://www.dsponlineconference.com/) of the harris-Moerder pulse shaping filter which was published 15 ...
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0answers
28 views

Is convolving a signal by a wavelet (in time domain) equivalent to wavelet filtering?

I am a noob in signal processing. Please help me understand if the following relation is true or not: ...
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5answers
250 views

An intuitive explanation as to why a matched filter is time reversed?

It easy enough to study correlation, and matched filters. But the challenge I see unmet anywhere to date and which I struggle to meet myself is a simpler presentation, to with more difficult task I ...
0
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1answer
155 views

Applying zero-phase filtering in the frequency domain - also works in real-time?

In my application a filtering in the frequency space is desired. I designed two high-pass filters: $h_1$ Butterworth IIR filter, and $h_2$ FIR. I designed them using Python's ...
1
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1answer
228 views

Apply “non-causal” filter buffer-wise, a.k.a “soft real-time filtering”

I am dealing with digital filtering of signals, both offline and in real-time. Typical filtering purposes are highpass filter or bandpass filter. So far I worked on prerecorded signals (e.g. ...
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0answers
22 views

Low pass filter output

What will be the output when a square wave of time period 1sec is applied to the input of LPF of cutoff frequency 1Hz. Please help me, I am not getting the exact expression. What if cutoff of LPF is ...
1
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2answers
107 views

Question about ideal filters

Following shows the discrete time Fourier transform of an ideal low pass filter with cutoff frequency $\omega_c$: $$H\left(e^{j\omega}\right) = \begin{cases} 1, & \text{if $|\omega| \le \omega_c$...
1
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1answer
40 views

Which one can be accompanied by linear filters?

I have a matrix : \begin{bmatrix} 1 & 2 & 3\\ 1 & 4 & 5\\ 2 & 6 & 7 \end{bmatrix} After doing operation 1 , I get \begin{bmatrix} 0 & 0 & 0\\ 1 & 2 & 3\\ 1 &...
6
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1answer
207 views

A Simple Algorithm to Filter / Smooth / Denoise a Noisy Staircase Graph

Is there a way to remove the noise and smooth the graph into a staircase graph.
1
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1answer
80 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 ...
0
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1answer
29 views

How does filter works in noise reduction?

On page 22 of the slide, the 1D array is [1, 1, 1, 1, 1], but the dots are uneven. Then why their values are the same? What's the value of the point that the arrow is pointing at? Though it gives ...
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1answer
28 views

How does Correlation for 1D Signals work?

On page 2 of the slide, I don't understand the example. Like $j$ and $s$ are both on the x-axis, what does j+s mean? The filter is $(f(−1), f(0), f(1)) = (−0.5, 0, 0.5)$. How can we use it? Could ...
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0answers
56 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 ...
3
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3answers
173 views

Deconvolving a 1d Signal Using a Lookup Table of Kernels

assuming I measure a signal that has different PSFs per position in time. for example: ...
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2answers
97 views

Distortion of OFDM signal when using RRC filter

I am trying to transmit OFDM signal in pass-band based on RRC filter, but what I noticed that the signal before the RRC filter is completely different compared with signal after the RRC filter (It ...
0
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1answer
41 views

Next steps for analyzing this PWM algorithm and choosing a low pass filtering technique?

The Broadcom BCM2711 GPIO controller used by the Raspberry Pi has a hardware PWM implementation option using an algorithm that provides an average value defined by a rational fraction $N/M$ defined as ...

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