Questions tagged [filtering]

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12 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 ...
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10 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: ...
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18 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)...
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1answer
30 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 ...
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31 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 ...
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1answer
13 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 ...
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1answer
30 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?
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3answers
80 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....
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1answer
40 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 ...
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41 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: ...
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15 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 ...
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1answer
49 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: ...
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1answer
73 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) ...
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1answer
236 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 ...
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0answers
24 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 ...
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3answers
103 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 ...
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26 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 ...
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1answer
487 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 ...
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1answer
26 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 ...
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1answer
37 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,...
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1answer
113 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&...
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36 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 ...
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1answer
56 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 ...
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1answer
546 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 ...
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1answer
94 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 ...
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3answers
318 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 ...
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1answer
677 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
975 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
63 views

What do poles do for a filter?

What are the disadvantages of having too many poles? Thanks.
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1answer
65 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
62 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-...
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1answer
210 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
812 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 ...
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1answer
85 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
2k 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
417 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
222 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 ...
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1answer
107 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 ...
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1answer
5k 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 ...
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2answers
1k 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 ...
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1answer
563 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 ...
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1answer
172 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 ...
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0answers
102 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
381 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 ...
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1answer
108 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 ...
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0answers
68 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 ...
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1answer
2k 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 ...
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1answer
528 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
697 views

Convolution in spatial domain is multiplication in frequency domain

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