Questions tagged [filtering]
The filtering tag has no usage guidance.
327
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Bandpass filtering EEG and getting weird distortions, parameter issue?
I am trying to bandpass filter an EEG signal, nothing fancy but it's coming out pretty distorted.
EEG data is taken from forehead. Sampling rate is 250 Hz. Cutoff is 2.5 Hz & 120 Hz.
Tried in both ...
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Extract PVC feature from singal to train the ML model with PVC characteristics
I have ML model which is trained on Afib, Normal, Other - 3 class. Currently when I am testing the model with unseen database, sometimes it identify PVC singals as Afib class.
For example -
enter ...
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What highpass filter is implemented in Audacity?
When I selected highpass filter effect in Audacity (an open-source audio editor), it lets me choose the cutoff frequency and the roll-off but it doesn't specify which filter type is used (IIR ...
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FIR filter for flipping the phase in negative phase
I have built up a FIR filter based on least square approach.
I deploy the IDFT matrix F_inv in above document page 7 and the desired response for compensated is H_F, the objective is
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How to achieve a DC portable power source with low noise in 400 MHz frequencies
I am working on an SDR composed system that is plugged into a Raspberry Pi board powered by a 5V DC Power bank. The SDR is configured to measure a signal around 400 MHz.
The noise floor measured by ...
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What does frequency filtering actually practically mean?
I've got an electronics circuit which was filtering between a Passive HPF stage (1uF and 330K) and an Active LPF stage (4.7uF and 10K). As you can see it was filtering between 0.48Hz and 3.38Hz, and ...
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Method for splitting time-sampled signal into two signals
Update: the yellow area in the graph below can be ignored, it shows power produced. I'm only interested in the blue line, and how to separate power consumed by the heating system from the rest.
I have ...
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Selective Discrete Time Derivative Filter
I have hit a problem which could be probably solved via discrete time derivative filter able to calculate the derivative of two specific harmonics of the input signal (namely frequencies: $f_1 = 100\,\...
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What's the best way of modeling 3d target motion with only 2d angle observations?
A maneuvering target is flying in 3d cartesian space, but a sensor (passive infrared or mic array, etc.) can only observe it in polar coordinate with 2d orientations
(azimuth, elevation). For ...
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Approaches to work around differing signal lengths when using Kalman filter
I have a set of vector valued signals $\boldsymbol{y}_{1:T}$ where each $\boldsymbol{y}_k \in \mathbb{R}^{v_k}$. Each signal is potentially of different dimensionality. I'd like to apply filtering and ...
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Why does sequential update of Kalman Filter work when you have multiple sensors?
If you are using a kalman filter with multiple sensing sensors there are two ways to fuse them.
One way is doing a single observation step where you include all the sensors in a single vector and a ...
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Amplifier Placement in a Wireless Receiver
In the context of wireless receiver system design, what is the optimum choice of amplifier placement? Should the received signal be amplified first then filtered or should it be the other way round?
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144
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Applying 1D wiener filter radially to 2D image
I am new to image processing. Using python, I have constructed a 1D wiener filter from the power spectrum of a Noisy Image, with Noise as a function of k. They both have the same dimension which is ...
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How to design a phonographic sound filter in python?
I'm making a phonographic filter or simulator to make one of my songs to sound as if it was recorded on a phonographic cylinder.
Two important things about phonographic recoding is that sound gets ...
Lerian Acosenossa
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Real time processing in matlab
I have to extract a particular frequency range from an audio signal. For that I am using an FIR filter of order 50 and it is written in MATLAB as below:
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Combination of IIR filter with Hilbert transform
I am familiar with the combination of the FIR filter with Hilbert transform, leading to the analytic signal:
$$y_a(t)=y(t)+jH(y(t))=x(t)*h(t)+jH(x(t)*h(t))=x(t)*\left(h(t)+jH\left(h(t)\right)\right)$$
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image preprocessing(filtering) : before or after undistortion and stereo rectification
I'm currently working on a stereo visual-slam program (using OpenCV).
After I get the images, there are 2 preprocessing steps to be done :
A) Undistort the images + stereo rectification
B) Some ...
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How to implement the recursive FIR filtering of a signal with zero boundary condition?
Now I have a signal $f(k)$ with $k=0,1,\ldots, N-1$, and $f(k)=0$ if $k<0$ or $k>N-1$, that is, the signal satisfies the zero boundary condition. Then by convolving this signal with a symmetric ...
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Demodulate qpsk with gnu radio
I'm trying to demodulate a qpsk signal with gnu radio. The signal is from the meteor satellite on 137MHz https://www.sigidwiki.com/wiki/Low_Rate_Picture_Transmission_(LRPT).
I recorded the signal with ...
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Signal filtering with rrcos filter doesn't seem to work
I'm trying to learn some signal processing and recorded some iq data from the meteor satellite which transmits data with qpsk. I read the file with python and tried applying a rrcos filter on the ...
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Weird filtering result
Im filtering some ecg data for mainly just powerline noise (50 Hz), but get some weird result between the R-peaks (main spike). I have just done some tried with some basic filtering like this:
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How to remove the unknown intervention from the signal (Octave)?
we have a signal recording and there are always interventions, I think it is not a noise, since it is not continuous but occurs in intervals, with 25 Hz (please see below). It is not affected by the ...
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How to exclude diffuse moving features in a stack of images
I have some stack of grayscale reconstructed images represented as a 3-dimensional matrix DPC with dimensions [Nz,Nx,Nt]. A ...
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Savitzky-Golay filtering (not smoothing) in real time
I would like to filter some data in an online sense i.e.
$$y(t) = a0 + a1*y(t-1) + a2*y(t-2) + ... $$
the order not important.
My understanding of the SG is that it is really a smoother - I have to ...
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Filtering out correlated data from dropouts
I have two 10Hz signals coming from an analyzer. There is a correlation between dropouts in the current applied and the signal that it produces. The correlations occurs sometimes, but not all the time....
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Butterworth filter cutoff attenuation is not exactly 0.707(-3dB)
The documentation of scipy Butterworth filter says its cutoff attenuation is 0.707(-3dB). To validate this, I created a square wave signal, performed FFT and implemented a bandpass filter with a band ...
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Why is the second difference matrix of size n-2 x n in l1 trend filtering?
The l1 trend filtering is expressed by taking $||Dx||_1$ where D is the second difference matrix why is taken of size (n-2)xn rather than circulant matrix of size nxn. I have implemented in both ways ...
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153
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how to plot analog filter impulse responce and frequency responce?
I an new to signal processing, working on a UWB rada data this data has a shape of frames for whcih every frame (list) has 164 values, I want to pass a band pass filter with the 1hz and 5hz ...
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Need for rectification in cochlear implants
In cochlear implants, the input signal is fed to a set of bandpass filters and is then half-wave rectified and low pass filtered to estimate the envelope signal.
What is the need for doing ...
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The Effect of Spatial or Temporal Averaging on Noise Properties
I generate two noise images using MATLAB's function imnoise().
If I average the two noise images, the resultant image looks like the original noise
image but only ...
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BPF Filtering with DSP IIR Realtime C++ filter library
I am working with complex samples, I have a main signal at 630KHz, my Fs is 1.26MHz and BW is 12.6KHz.
If I plot a frequency-magntitude spectrum it looks like this:
As you can see along with my main ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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187
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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 ...
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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
...
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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 = ...
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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-...
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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 ...
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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 ...
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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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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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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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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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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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