Questions tagged [filtering]
The filtering tag has no usage guidance.
299
questions
2
votes
1answer
39 views
How to find point of inflexion of a digital signal?
Let's say I would like to find a point of inflexion of a digital signal which has been gathered via sampling of a continuous time domain signal with sampling period $100\,\mu s$. The digital signal ...
0
votes
1answer
21 views
localization with TDOA under Doppler shift
In a localization system, I use the TDOA (Time Difference of arrival) method. The transmitter is moving at a speed v and its communication signal is received on 3 receivers at different times. For a ...
0
votes
1answer
32 views
Fourier Transform High Pass Circular Filter Intuition
The situation
I need to apply a high pass filter to an image. The approach I'm following uses Fourier transform to apply a circular filter which would eliminate low frequencies.
Say I have a frequency ...
0
votes
1answer
23 views
Gaussian Blur For Entire Image
I am trying to simulate the blurring process (defocus) of a sinusoidal. For this I have build my own Gaussian filter and performed the convolution in Fourier domain.
The result of the blurred signal ...
0
votes
0answers
31 views
How to effectively stationarise non-periodic wave signals?
I am pre-processing a non-periodic signal for further implementation of autoregressive modelling on the signal. The signal is shown in the following figure. However, when I applied the Augmented ...
2
votes
1answer
45 views
A filter removing forbidden information in the stop-band
Is it possible, and how could it be done, to make an extension of filters that converts the signal in the filter's stop-band into noise with no information content or at least with zero correlation to ...
0
votes
0answers
111 views
Design an FIR linear phase lowpass filter using windows to meet the following specifications. What is given in the question? How to start solving it?
What is given in this question? I have not seen a single solution of these types of filter design problems in the internet. So I am confused, how do I proceed solving these problems. Can you guide me ...
0
votes
1answer
43 views
What's the correct way to align two signals downsampled at 10 Hz?
I'm trying to build a dataset where one of the features is a signal which has originally been sampled at 500 Hz, while another feature is a signal which was sampled at 100 Hz. I want to downsample ...
2
votes
1answer
171 views
Does it make sense for my filter to depend on the discrete sample variable n?
I feel a little nervous asking this question as I am not sure if know what exactly I am trying to ask. But please see if you can help.
Ok, I have a filter whose output grows as long as the input is ...
1
vote
1answer
66 views
Aritifacts of time-varying IIR filters
I'm doing something like spatial audio algorithm using IIR modelled HRTFs. At each frame I get a direction information with azimuth and elevation, and then I have to find or interpolate the ...
5
votes
1answer
426 views
Deblurring 1D Data Using Direct Inverse Filtering
In my assignment I have been given recorded temperature over a period of time (193 Values) and the Impulse Response (5 Values with n=0 corresponding to the middle value).
data : data.csv | h = [1/16 4/...
1
vote
1answer
159 views
Find coefficients of optimal Wiener filter of length 2
I need to find the coefficients (impulse response) of a FIR Wiener filter with length equal to 2.
I have a gaussian white noise signal that is generated using the Standard Normal Distribution (mean = ...
3
votes
1answer
136 views
Sound activated recording and advanced filtering on Raspberry Pi
I'm making a Raspberry Pi bat detector using a USB-powered ultrasonic microphone. I want to be able to record bats while excluding insects and other non-bat noises. Recording needs to be sound-...
1
vote
3answers
75 views
Detrending PPG signal
I'm filtering a raw PPG signal sampled at 100sps
After applying a bandpass filter my signal looks like this
As you can see, It has a trend (a low pass component which is not in the desired signal).
I ...
1
vote
1answer
23 views
How to apply an atmospheric attenuation filter in the freq domain and then convert the filtered signal back to the time domain?
This question is a part of a more general question the answer of which I don't know -
How to apply a filter in the freq domain and then convert the filtered signal back to the time domain? Well, I ...
4
votes
2answers
101 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 ...
0
votes
1answer
80 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/...
1
vote
1answer
57 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 ...
1
vote
1answer
34 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 ...
0
votes
1answer
41 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 ...
5
votes
4answers
660 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), ...
0
votes
1answer
88 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 ...
0
votes
1answer
38 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". ...
1
vote
1answer
167 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, ...
0
votes
1answer
84 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 ...
1
vote
0answers
62 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:
...
5
votes
1answer
63 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 $x(t)$. ...
0
votes
0answers
43 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
vote
1answer
49 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
votes
1answer
175 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
vote
1answer
84 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, ...
0
votes
0answers
16 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 ...
0
votes
2answers
74 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 ...
0
votes
0answers
27 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 ...
3
votes
1answer
120 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 ...
6
votes
2answers
287 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 ...
0
votes
1answer
37 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 ...
0
votes
0answers
135 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 ...
4
votes
1answer
267 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 ...
0
votes
2answers
219 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 (...
1
vote
3answers
106 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....
2
votes
2answers
65 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 ...
0
votes
0answers
18 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
vote
3answers
559 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....
4
votes
3answers
79 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 ...
3
votes
1answer
112 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?
0
votes
1answer
255 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
votes
1answer
130 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
votes
1answer
145 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 ...
2
votes
5answers
458 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 ...
