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Questions tagged [filtering]

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1answer
140 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
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3answers
767 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
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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 ...
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2answers
2k views

Extended Kalman Filter (EKF) for Non Linear (Coordinate Conversion - Polar to Cartesian) Measurements and Linear Predictions

I'm new to Kalman filtering and state estimation and I'd like some guidance on EKFs. Currently, I'm trying to use a linear prediction model coupled with nonlinear measurements to estimate the state ...
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1answer
67 views

What do poles do for a filter?

What are the disadvantages of having too many poles? Thanks.
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1answer
92 views

When applying a bandpass filter designed in Matlab's DSP system toolbox, is it necessary to do any normalization?

I'm applying the next bandpass filter to the data of an impulse response coming from .wav; it fades data below 10 Hz and above 400 Hz: ...
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0answers
85 views

How to filter a sequence of frames?

I'm have a sequence of 2-dimensional MxN frames. I have concatenated these frames to form a 3-dimensional MxNxT matrix. Now i want to filter this 3D volume by 2 types of filters (a 2D log-Gabor in xy-...
0
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1answer
320 views

Implementing FIR/IIR “alike” filter in R

I am new to signal processing. I am trying to simulate something similar to IIR/FIR filter with $k$ delays to imitate acoustic echo reflection. The difference equations for FIR and IIR respectively ...
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3answers
1k views

How to use Kalman filter for altitude prediction based on barometer data?

I have barometer noisy data with known variance. I studied Kalman filter but I did not find an answer to this problem: My process model is: altitude is changed because of velocity that is changed ...
1
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1answer
132 views

Do integration/differentiation processes work as simple filters?

How these processes are different from simple IIR 1 order filtering, FIR filters in terms of amplitude and phase characteristics?
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1answer
4k views

Impulse response of ideal filters

I am aware that an ideal low-pass filter in both continuous time and discrete time has a $\mathrm{sinc}$ impulse response. What would the impulse response of an ideal high-pass or band-pass filter ...
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2answers
572 views

BIBO Stability and the convergence of the frequency response of a system

It is my understanding that an LTI system is BIBO stable if and only if its impulse response $h(t)$ is absolutely integrable. This also happens to be one of the Dirichlet conditions for the ...
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2answers
363 views

Bandpass filtering IQ samples from USRP

I have an USRP (B205mini) with an RX frequency of 900 MHz and a bandwidth of 100 MHz. I want to distinguish between two raw, unmodulated signals at respectively 875 and 925 MHz. My approach would be ...
3
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1answer
116 views

Use samples of Fourier transform as DFT?

Consider the LTI system given by: $H(z) = 1 - \frac{1}{2}z^{-1}+\frac{3}{4}z^{-2}$ Let $x[n] = (\frac{1}{2})^nu[n]$ be the input to the system. We want to find the output for $n = 0,1,...,N_a$, using ...
3
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1answer
7k views

Apply butterworth filter (lowpass) to a signal

I'm working on a DSP lab and I can't figure out how to apply the filter I've created to a sound. The only thing I found online that did something to my sound was ...
1
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2answers
2k views

What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...
0
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1answer
716 views

Extracting the carrier signal from AM

I am new to DSP and leaning about amplitude modulation. I am trying to demodulate a 5 Hz signal that is modulated by a 50 Hz carrier. I am trying to extract the carrier, not the the 5 Hz signal. A ...
1
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1answer
244 views

Real-time oscillation-like noise filtering

I am making real-time measurements, which are affected by some noise. This noise has oscillating pattern, i.e. the total signal tends to oscillate around the mean value. The examples of measurements ...
2
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0answers
107 views

Use of an impulse-response system to model sediment transport along a river reach

I am new to signal processing and have come into the subject from the study of rivers and basic geophysics. I am trying to test an idea previously put forward that the sediment transport response of ...
0
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1answer
540 views

How to eliminate negative frequencies from IQ signal

I have a 192kHz IQ signal from an RF receiver, and i'm trying to remove signals in the negative (or positive) frequency spectrum. I see that the negative frequency signals are -90 degrees phase ...
0
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1answer
118 views

Remove high resolution spurious peaks from sinusoidal signal

I have the current from a LEM transducer measured. The measurement is taken on the output of a transformer. The signal is a 50 Hz signal, measured at 100kHz. When the demand of the system is increased ...
1
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0answers
84 views

Processing digital sound in Audiokit to sound like the 1960's

I am looking to imitate 70's analog equipments sound. I was wondering is there a way to create tape saturation / distortion inside Audiokit? I want to add that and randomized tape crackles and ...
1
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1answer
3k views

Pre-emphasis filter for speech recognition

I'm trying to design a: $$H(z)=1 - 0.95z$$ FIR filter, for speech signal. I am using this arm_fir_example_f32.c code shown below. And I need to change the filter ...
4
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1answer
713 views

Polyphase Filter decomposition. It is not working

So, I want to do a polyphase implementation of a filter bank (I had problems with it since the beginning and I already asked for help to the community in the past, indeed: Norm MPEG-1 Layer III (Mp3) ...
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2answers
1k views

Convolution in Spatial Domain Is Multiplication in Frequency Domain

I have to prove convolution in spatial domain is equivalent to multiplication in frequency domain using two matrices. $$ x(m, n) = \begin{bmatrix} 1 && 2 \\ 3 && 4 \end{bmatrix} $$ $...
4
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2answers
101 views

Filtering without using any transforms

A composite signal is defined as $$x(t) = \sin(2\pi 10t) + \sin(2\pi 40t) + \sin(2\pi 60t) + \sin(2\pi 50t)$$ Separate the four frequencies without using any of the transform techniques.
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1answer
840 views

Implementation of the filter function (Matlab) C/C++

I am trying to apply some filtering in C/C++ code, I have designed an algorithm using Matlab and it works well, so now I am moving it to native code. I am ...
2
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2answers
67 views

Recommendation for studying filters

I have a project to do about what happens to a periodic function when we pass it through a low-pass, high-pass and band-pass filter. I have no expressions for the filters or the function, I just have ...
5
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1answer
316 views

Is there a $z$-transform like for variable sampling rate signals?

I'm working with signals with variable sampling rate (the time space between samples is not constant). I know the delay between samples but I don't wont to interpolate the signal. Is there a way to ...
1
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1answer
60 views

position of useful filtered data inside DFT based filtered output

I'm trying to filter a 400 samples signal with various bandstop FIR filters (constant group delay), one at a time to see which one gives me the desired result. Every filter was build using the Kaiser ...
1
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1answer
450 views

Image zoom out using Gaussian blur and downsampling

I am trying to implement a simple zoom out algorithm using two steps: The image is blurred using gaussian convolution of standard deviation $0.8\sqrt{{\tt zoomfactor}^2-1}$ as we saw in class. The ...
1
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1answer
1k views

How to perform a gaussian blur using FFT?

I am trying to implement a gaussian filter with matlab.Here is my implementation: So far All I get as output is a black image. Any hints? ...
0
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1answer
46 views

Buffering block and filter length in real-time processing

I have a signal sampled at 256 Hz, which I want to filter with a 50 taps long FIR filter in real time. Would it be a problem, if my data block size is only 32 samples? And should I then concatenate 3 ...
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1answer
364 views

Filter problems in python

I am recording a 30 second 1000Hz Sine wave, saving it to a list, splitting the list into 5 second sublists and I would like to apply a notch filter to each sublist to check when the signal drops out ...
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2answers
219 views

Filter Implementation

I am rather new to the world of signal processing, and am struggling to understand a fundamental concept: How are filters actually implemented? I have read a significant portion of this online book, ...
1
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0answers
142 views

Electromyography: is this interference from the heart/how to remove it?

I'm using electromyography to evaluate the activity of lumbar erector spinae at various levels of effort. For this I also intend to sample the activity at complete rest (in prone lying). In my first ...
2
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1answer
3k views

homomorphic filter - python overflow

I'm trying to implement the homomorphic filtering as implemented by this research article - step 4 (pdf) The original Matlab code, which I'm trying to translate into Python, is as follows (WARNING: ...
2
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1answer
246 views

Denoising short, non-uniformly spaced, bandlmited sequences

Consider a bandlimited signal $x(t)$ with bandwidth $BW$. Samples of this signal are observed at non-uniformly spaced sample points in the presence of noise: $y(t_i)=x(t_i) + n_i \qquad i\in\{0,1,\...
1
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0answers
36 views

Multitapering in time domain to obtain smoother filtered signals?

Suppose we want to approximate the instantaneous power $z(n) = |y(n)|^2$ of the discrete-time signal $y(n)$, where $y(n)$ is the result of filtering $x(n)$ with a given window $h(n)$, $y(n) = x(n) \...
1
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1answer
3k views

Does Higher Sampling Rate Increase SNR?

I have AM demodulated voice samples that come from a 14bit ADC that I will filter, process, and then send to a CODEC. I can choose a sample rate of 96kSPS, 64kSPS, 48kSPS, or 32kSPS at the CODEC. ...
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0answers
238 views

How to include phase noise in sinusoidal kalman filter model?

I am modelling simple sinusoidal motion using a Kalman filter from the following equation of motion: $ \ddot{x} = -\omega^2x $ So my matrix equation of motion is: $$ \begin{bmatrix} \dot{x} \\ \...
1
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2answers
86 views

Tracking unknown number of signals/coordinates

I have a time series data. Where for every time step I have a varying number of object coordinates. I want to track these over time. There might also be some missing coordinates for a few frames. ...
0
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1answer
44 views

Is this a robust method for analysing correctness of a filtered signal? Is there a more robust method?

I have a recorded signal which contains several frequency components with stochastic phase and amplitude changes and want to extract the true signal with the other frequency components and noise ...
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1answer
781 views

How can i create a low pass filter in matlab

i am trying to create a low pass filter in matlab for a project in signals and systems class but i couldn't. cut off frequency is 500 , sampling frequency is 10000 and the low pass filter's band width ...
2
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0answers
39 views

Filtering for Wright-Fisher HMM

I am trying to understand what filter may be suitable for the following HMM: The signal is a Wright-Fisher one-dimensional diffusion characterised by the SDE $$dX_{t}=\frac{1}{2}\left(\alpha(1-x)-\...
2
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1answer
134 views

Standard deviation is varying with change in amplitude of DC signal

I am trying to make sense of the below code. I am taking a large sample so that I get good estimates for standard deviation. ...
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0answers
90 views

Fastest way to subtract known music tracks from live videogame audio stream

I want to isolate video game "action" sounds from the video game soundtrack. Given all ~20 songs, I'd like to filter them out from any live audio stream during gameplay. What is a fast and robust way ...
1
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1answer
6k views

Differences between low-pass, band-pass, notch filters

I'm studying image processing and I know that there are different filters you can apply. I don't understand the difference between the low-pass/bandpass/notch filter (or high-pass/band-reject/notch). ...
4
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1answer
6k views

Simple software low pass filter

I am measuring voltages and currents of a 3-phase electrical machine and I need to calculate the power. Every interrupt (frequency between 30-70kHz) I get values (voltages, currents) from analogue-...
0
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1answer
280 views

Relative Computational Complexity for Channelizer Implementations

Suppose I want to separate a broadband input signal into multiple narrow subbands using an FFT-based analysis filter bank. The filter bank uses a prototype lowpass filter and is implemented using a ...