Questions tagged [filtering]
The filtering tag has no usage guidance.
257
questions
0
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0answers
22 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:
...
0
votes
5answers
111 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
votes
1answer
41 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
vote
1answer
61 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. ...
0
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0answers
19 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
57 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
vote
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
votes
1answer
178 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
vote
1answer
63 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
votes
1answer
27 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 ...
0
votes
1answer
21 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(ā1), f(0), f(1)) = (ā0.5, 0, 0.5)$. How can we use it? Could ...
0
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0answers
39 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 ...
2
votes
3answers
140 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:
...
0
votes
2answers
82 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
votes
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 ...
0
votes
1answer
38 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 ...
2
votes
1answer
66 views
How to find the best Q format representation?
I'm currently working in a project in which I use the coefficients of a IIR Elliptical digital filter (9th order) and the voice signal from a recording of my cellphone but I'm having issues finding ...
-1
votes
3answers
43 views
what are some possible reasons of having duplicates in sensor signal? resulting in stair-step signal?
I am using an cellphone application to record cellphone gyroscope signal. I put the sampling rate to "fastest" which means the highest sampling rate the cellphone is able to do. What is strange is ...
1
vote
1answer
85 views
Reduce Jitter in Live Kalman Filter
I have a stream of data over time that I have fed into a Kalman filter. This data represents the vertical displacement in time of a vehicle's rearwheel as it travels over a bump in the road. The ...
0
votes
1answer
78 views
A filter with low phase shift or no phase shift at all? Which one? [duplicate]
I'm seeking a good advice for a filter. Can you help me?
Right now I made my own simple filter. Not sure what I'm doing, but it seems to work.
...
0
votes
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 ...
0
votes
1answer
19 views
How can I plot Wiener filter's behaviour for different taps (memory filter)?
What's the expected behaviour of Wiener Filter for different taps (memory filter) , when input signal is a sinusodial tone?
Do you have any idea how I can plot or simulate Wiener Filter's behaviour (...
0
votes
1answer
126 views
Filter: IIR Filter
How IIR Filter coefficients formula derived? for LPF, HPF, BPF, BSF there are coefficients formula for a0, a1, a2, b0, b1.
How it came? I would like to know the derivation for all those coeffs w.r.t ...
1
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2answers
178 views
3
votes
1answer
22 views
Image Filtering by Averaging Similar Areas of the Same Image - Patch Based Processing
I heard of filtering algorithms which, to filter an image specific area, find similar areas in the image and average them to reduce the noice of the original area. E.g. an edge of a house can be more ...
0
votes
3answers
90 views
I can't wrap my mind around the concept of filtering and the unit circle ? any help? [closed]
Can someone elaborate this theory where there is a link between the stability of a filter and the zeros or nulls being on the unit circle?
0
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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 ...
0
votes
0answers
63 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
votes
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 ...
0
votes
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 = ...
2
votes
1answer
258 views
How determine the delay in my signal practically
I am trying to practically determine filter group delay so that I can try to reduce or adjust for it. I have tried all kinds of methods but still can't get the right result. I know that theoretically ...
0
votes
1answer
37 views
How to get discrete values from a nosiy data set that have a trend?
I have a sensor that produces values over time (appr. 50/sec). I visualized these values (X axis is the time), this can be seen on the picture, measurement A and B - these are two independent ...
2
votes
1answer
74 views
Transfer function given as z-Domain fraction: gain calculation
I am stuck on a question regarding transfer functions. I have the answer and have attempted the question but am having trouble solving it.
Q: Given the transfer function of a digital filter is (5z-5)/...
0
votes
1answer
45 views
How to quantify phase distortion of a filter specific to a signal?
For example, a EKG input signal is filtered with a known transfer function that does not have linear phase. How do you quantify the phase distortion of the output signal given you have the input? I ...
1
vote
2answers
92 views
Meaningful output of FIR filter output
I have implemented FIR filter using tapped delay line method. I start getting output as soon as first input sample is passed to it, I am wondering from which sample I will get the proper output(...
0
votes
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 ...
1
vote
2answers
78 views
When to Apply Circular Convolution Formulas?
Context
I am studying the family of Discrete Trignometric Transforms (DTT): Discrete Cosine Transforms (DCT) and Discrete Sine Transforms (DST). And trying to understanding more their properties, I ...
0
votes
1answer
58 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 ...
3
votes
2answers
130 views
How to filter very low amplitude staircase signal from a background noise
I have a staircase signal of a specific pattern that is drowned in a background noise. The ratio of signal to noise amplitude is nearly $10^{-4}$. I have attached the image of both with this post. I ...
1
vote
1answer
166 views
DC Spur in DAC output
I have a design in which a signal from ADC is filtered and then played by DAC. In FPGA the real signal is converted to quadrature using DDS with 70 MHz frequency. After filtering, the baseband signal ...
0
votes
1answer
64 views
Filtering in the Frequency Domain - DIP [closed]
I am trying to do some filtering with a gray scale image in the frequency domain. I am just getting into matlab after some time away from any signal processing or coding and can't quite seem to get my ...
1
vote
2answers
186 views
How Butterworth low-pass filter can be applied on a digital signal (i.e. discrete representation of a signal)?
I would like to know how to apply a low pass filter (Butterworth) to a digital signal. So, I have some values of the signal, let's say $S(t)$. Those values are equally spaced in time. I have read the ...
1
vote
2answers
121 views
Cross-correlation of filtered random processes
I have a wide-sense-stationary (WSS) process $\{x(t)\}$ and two linear filters with impulse functions $h_1$ and $h_2$.
Let $\delta(\omega)$ be the power spectrum of $\{x(t)\}$ and $$H_1:\omega\...
0
votes
2answers
65 views
Downsides of higher order filtfilt's
I understand that with a standard filter, higher order will yield sharper frequency selection at the cost of increased phase delay. However, with so-called zero-phase-distortion filters like that ...
1
vote
0answers
121 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 ...
2
votes
2answers
97 views
How to apply discrete filters to a signal
Let's say I have a signal like x[k] = [-20 -50 -30 50 30 -60 60 -60 60 10 5 10 5 5], and I want to apply a lowpass and a highpass filter to this signal (separately). For example the impusle response ...
0
votes
1answer
133 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
votes
2answers
174 views
Is There Any Filtering Technique with Element Wise Product Only Instead of Convolution?
Generally we apply a filter to reduce noise from signal. For example if the received signal is $S$ we would get a signal $Y$ with reduced noise applying a filter $W$ with the operation Y= convolution(...
-1
votes
1answer
280 views
Real time FFT & IFFT with low pass filter
I am processing the signal from MPU6050. Applying FIR filter in the frequency domain and then taking IFFT to get filtered signal but getting some spikes in the output signal. Searched a lot about it ...
0
votes
1answer
56 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 ...
