Questions tagged [filtering]
The filtering tag has no usage guidance.
231
questions
2
votes
1answer
38 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
37 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
48 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
33 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
votes
2answers
50 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
44 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 ...
0
votes
1answer
53 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 ...
0
votes
1answer
125 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
38 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 ...
0
votes
0answers
18 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 ...
1
vote
2answers
69 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
62 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
38 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 ...
0
votes
0answers
49 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 ...
0
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0answers
77 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:
...
0
votes
0answers
12 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 ...
2
votes
2answers
73 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
46 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 ...
-1
votes
2answers
137 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
164 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
38 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
votes
1answer
33 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 ...
0
votes
2answers
68 views
Filter before or after multiplication of two signals?
I have two signals and want to multiply them, e.g. voltage and current are multiplied to get power. The result (e.g. power) shall be a filtered result, e.g. to see the average.
Is it better to filter ...
0
votes
0answers
14 views
Differentiating high frequencies if a signal
I have a power signal (in dBm) which contains lots of peaks (around -80 dBm) and most of the time is around -110 dBm which we can call it noise level (obviously with fluctuations). As you know, both ...
0
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0answers
20 views
remove \ minimize first side lobe ringing artifacts due to data truncation
I have a truncated data set that I need to transform, for example:
...
0
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0answers
112 views
Fusing like data from multiple sensors using kalman filter
I'm new to kalman filters and filtering, and I'm working on a personal project where I have multiple readings all providing the same data (3d position in space, provided via computer vision algorithms)...
0
votes
1answer
40 views
how does the Frequency spectrum of a signal change in the logarithmic space?
I am trying to implement basic homomorphic filtering but I can't seem to understand what happens in the frequency domain when you take the natural logarithm of the function.
In Matlab I'm getting not ...
2
votes
0answers
32 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 ...
0
votes
1answer
29 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
votes
1answer
80 views
What is the difference between domain and range filtering?
In the context of image processing, I have heard the expressions "domain filtering" and "range filtering". What do these terms refer to? What is the difference between them?
2
votes
3answers
187 views
Causal unstable system turn into stable anticausal?
I would appreciate it very much if someone would be able to provide some clarity, help or comment on this problem.
I have been reading several papers on time series identification such as
https://www....
1
vote
1answer
43 views
What is used to initialise difference equations that require data from the output?
Given some difference equation for a filter like
$y[k] = ax[k] + bx[k-1]+ cy[k-1]$,
how would you initialize it? Since it needs an old output value (feedback) to calculate the new output value, it ...
1
vote
0answers
56 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:
...
1
vote
1answer
93 views
Looking for a analytical formula to compute the central frequency of a signal analyzed by a discrete wavelet at a given scale
I am reading this paper by Han et al. (2014). In this article, the authors extract detailed information from geomagnetic data sampled at 1Hz using a daubechies 5 (db5) wavelet: they reconstruct the ...
0
votes
1answer
98 views
How do I find the frequency of a particular bin in a cosine transform, and two other questions
I have a discrete series of values and I have applied a Discrete Cosine Transform to it, obtaining values like:
...
0
votes
1answer
94 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) ...
5
votes
1answer
598 views
What type of low-pass filter to use for gyroscope filtering in control application?
I am using a gyroscope to generate a feedback signal that drives a motor to resist rotation, just as in a camera gimbal.
The gyroscope is sampling at 32 KHz with a bandwidth of 8 KHz, and my control ...
0
votes
0answers
30 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 ...
1
vote
3answers
195 views
How to filter my noisy square wave so that i can recover my signal using the Chebyshev Filter
I have a noisy square signal as input but it has a lot of noise.
I should use a Bandpass filter to recover my signal.
I know that the Chebyshev Filter is a bandpass filter; but it doesn't work. the ...
0
votes
0answers
50 views
how to do supervised NMF source separation?
I know how NMF works by itself (unsupervised), but I am now interested in learning how it works in the supervised way.
Suppose I have a clean isolated time domain signal of about 3 seconds in length ...
0
votes
1answer
2k views
What is zero-phase filtering and forward-backward filtering?
I am pretty familiar with IIR and FIR filtering and I have implemented them in my several projects. However, recently i found something called zero phase filtering. I have tried to understand it but ...
-1
votes
1answer
39 views
Applying window function to reduce out of band emission for a symbol in LTE simulation?
I have to apply a window to an IFFT'ed signal (based on LTE standards, simulated for 1 symbol - 100 resource blocks - 1200 subcarriers). I have a signal which I have simulated till the IFFT. Now I ...
-1
votes
1answer
40 views
filter multiple sources from each other
I am trying to supply a solution for recording a court room and then, use some smart algorithms in order to automatically convert the speech to text.
In order to do that I have three boom microphones,...
1
vote
1answer
180 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&...
1
vote
0answers
52 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 ...
0
votes
1answer
77 views
ARMA & MA methods: how do you know the error terms?
Reading the ARMA model for the first time, and I'm confused.
Let's say I have a time series
x = [1, 2.1, 2.9, 3, 4.1]
According to the ARMA model, $X_t$ is a ...
1
vote
1answer
780 views
How to remove ECG artifacts from EMG data?
I'm new to signal processing and try to analyze EMG data from pectoralis major and other respiratory muscles. Unfortunately, there are strong ECG artifacts in all recordings and I don't know how to ...
0
votes
1answer
125 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 ...
2
votes
3answers
703 views
How to Classify Image Filter as Low Pass Filter (LPF) or High Pass Filter (HPF)?
I am currently reading on the topics of image filtering and convolution kernels. While the process of convolution is clear to me, I do not understand, how one arrives at the statement, that a certain ...
1
vote
1answer
1k views
What are the advantages and disadvantages separability of Gaussian 2D filter?
I know separability of a Gaussian filter enhances the computational complexity from $\mathcal{O}(L^2*N*M) \to \mathcal{O}((L*N*M)$. How this really reflect on my program? I suppose the number of for ...
