Questions tagged [noise]

In signal processing noise can be considered random unwanted data without meaning.

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Imitate noise audio file with math function

Is it possible to reverse engineer a short white noise audio file and imitate it with a function instead? The file doesn't contain pure white noise, there has been EQ applied to it, also some ...
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How to add quantization noise (SQNR) to thermal noise (SNR) in a total value?

How can I add the BAQ (Block Adaptive Quantizer) compression noise to the input SNR? In the end is a quantization noise to be added to a thermal noise. I got the following formulation, but I dont ...
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Random gaussian noise estimation from a given trajectory

I wish to estimate the noise of given trajectory from a measurement (data which is provided). I consider that the noise is random gaussian noise. I add here examples of two trajectories, one of the ...
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Stationarity Test on Dataset

I have a nice and clean noise signal sampled at a fixed rate for several hours. When I calculate the PSD I see it's pure flicker noise. But I don't know much about the process. I've seen some ...
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Power of noise signal through a matched filter (Digital Receiver)

I am studying matched filters and the sense of signal to noise ratio. In a question I was given, stated that: Show that a matched filter of a signal $s(t)$ maximizes the SNR of the output on a ...
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Simplest explanation of the relationship between gyro bias <> angle random walk (ARW) and accel bias <> velocity random walk (VRW)

We are discussing the errors to consider when using IMUs for navigation. I seem to have a problem wrapping my head around the general concept of the topic and need some help. I understand that the ...
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Reference for Wiener-Kolmogorov whitening procedure

In an old paper, accessible only for a fee, I found: (where the LHS of Eq (5) lack the symbol of derivative). What is the Wiener-Kolmogorov whitening procedure? I would like to study this procedure, ...
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Noise Reduction - noisy lines

I'm trying to reduce the noise in this photo. What type of filters/techniques should I use to cancel out the noise? I've tried using box filter and Gaussian filter to blur out some of the noise, but i ...
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Is there any data or theory about human visual system to identify details under noise?

For one clean image, one person can identify every details at first. Then white Gaussian noise is added to the image. With low noise level, one person can still identify every details even though ...
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Pop and buzz noises caused by the signal process

There is a measurement called waterfall effect in audio systems. When you apply a sweep signal starting from 50Hz to 20KHz, it shows how long the resonance of the speaker goes. For example in the ...
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AWGN continous time channel + colored noise

I'm working on an exercise but I'm stuck at the question where the noise becomes colored, can someone help me ? Let $\{\psi_1(t) = \mathbf{1}\{t \in [0,1)], \psi_2 = \mathbf{1}\{t \in [1,2]\}\}$ be an ...
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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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Extract a signal from noise, so I can view noise spectrum only?

I have a perfect modulated signal. I have the same signal but with noise, this noise is from non linear amplification. Is it possible, to extract the clean signal so it's just leaving the noise? The ...
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Simulating RF interference (noise) to captured RF signals

I have carried out an approach to clean my RF signal captured in order to perform classification on a set of devices. However, a further extension to this study I aim to achieve is to evaluate the ...
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Is a white noise always zero mean and uncorrelated?

It seems to be silly, but is it possible to deduce mathematically that a white noise is necessarily zero mean and uncorrelated? I have seen some people defining a white process as a zero-mean and ...
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How to optimize noise reduction to perform burst detection and detect oscillations?

Let be $\mu_k$ some univariate signals of time $t$. I am performing burst detection to detect oscillations in any signal $\mu_k$. I tested the following methods : Perform noise reduction on $\mu_k$ ...
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Convert filter coefficients at one sample rate to different sample rate

I was doing some research into dithering in audio, and I was always wondering what Audacity's "Shaped" dither was. Well, turns out it's noise shaping, with an FIR filter whose coefficients ...
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Which type of noise can we see from the given image signal and its abs of 2D FFT?

1. Background: I get an 128*128 2D one-channel noisy image as follows: I get the shifted absolute values of 2D FFT result by the following Python code: ...
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Thermal noise from circuit transfer function

Is it possible to compute the thermal noise of an electronic system given only it's transfer function (phase + magnitude)? In my case I have a black box circuit of passive elements. I can't measure ...
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Determine the noise energy $N_{0}$ of an averaged set of samples [duplicate]

Background I am trying to find a way to adjust the amplitude $A$ of a rectangular pulse of $n$ samples such that, in the presence of AWGN with $\sigma^{2}=1$, I may simulate for a specified range of $...
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Interpreting sensor noise data

Introduction :I am trying to create an EKF for an autonomous vehicle, and i need to model the error of the sensors. (I am a mechanical engineer so my knowledge on electric signals is limited). The ...
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Adjusting pulse amplitude against fixed noise variance to achieve a given Eb/No

Given a short duration pulse of $n$ samples out of a frame of $L$ samples, and amplitude of each of these samples being $A$, and an AWGN channel with variance $\sigma ^{2} = 1$, how can I derive $A$ ...
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Eb/N0 on a VLC simulation using OOK modulation

I have been doing a matlab simulation of a VLC (visible light communication) system that uses OOK for the modulator. I have to explain the basic knowledge behing the simulation and I´m having lots of ...
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Weird Pattern in the Power Spectrum diagram (i.e. the frequency domain of the signal)

I am quite a newbie to signal processing. I convert the time-domain signal to the frequency domain with the automated power-spectrum generator in the matlab app. The frequency domain has this ...
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why need de-correlated signal for measuring phase noise in laser

when measuring phase noise from a laser by using heterodyne method , we will get the output signal as de-correlated. why we using de-correlated output for phase noise mesurement. how it is related to ...
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Optimal methodology for analysis of noisy 3-dimensional (x,y,z) vibrations data

Details I have x, y and z data of some vibrations and a timeline of corresponding events that caused these vibrations. I want to analyze how events and vibrations are related, so that it can be stated ...
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removing stripy artifact from fMRI

I have fMRI images, some of which have a stripy artifact that looks like a Gabor filter. Removing this kind of noise is not, to my knowledge, a standard part of any fMRI processing pipeline. I am ...
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What is best filter to get 1/f(^alpha) that is linear on a log(PSD) vs log(Frequency) plot

I have a white noise signal that I plot on a log(PSD) vs log(frequency) plot. Now I want to filter that signal with several different filters to to get different alphas (0.5 to 3.0) in the 1/f^alpha ...
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How can I generate long time series data of band limited gaussian white noise in Python?

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How can I add white gaussian noise to get the required extinction ratio?

I need to add white gaussian noise to my signal in MATLAB so that I obtain 15 dB extinction ratio (ER). I know that ER is max power level to min power level. I use below code to calculate my signal ...
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How to generate wideband Gaussian white noise

I want to generate correlated complex white Gaussian noise signals in MATLAB. What I do is that I take complex Gaussian random variables with unit-variance and multiply them with the desired input ...
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Combining multiple signal acquisitions to produce one big FFT

I found myself in working with an FFT that does not have sufficient frequency resolution and I would like to increase this sensitivity. Since I have to perform this FFT on multiple noise acquisitions (...
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Removing very big peaks in a signal

I am analyzing a signal where I want to extract the peaks based on a threshold. My problem here is that there are some noise artifacts very high that are messing with my signal. I want to remove them ...
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Estimating quantification and sampling error

I have a signal sampled from $\mathbb{R}^2$ at a frequency of $2\text{Hz}$. It is quantized from $\mathbb{R}^2$ to $\mathbb{N}^2$, seemingly using the round operator. How can I estimate the error ...
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Correct Noise for NOMA system

I am trying to simulate a NOMA system with SIC, but I'm so confusing with the noise expression: $n_m \sim CN(0, \sigma^2_m)$, is zero mean complex additive Gaussian noise with variance at mth user ...
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Why does the variance of the Empirical Transfer Function Estimate not decay with increased sample points?

Please refer to Ljung's Lemma 6.1. In short, this lemma tells us that for a given LTI system $y[n]=g[n]*u[n]+v[n]$ where $v[n]$ is a stationary stochastic process with a zero-mean and a finite power ...
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Reducing Noise Floor by Sampling Larger BW or Noise Shaping White Noise

If I am sampling a sensor with white noise (Johnson) that is the noise floor of the system could I drive the noise floor down by sampling a larger bandwidth than I care about and then using a digital ...
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Does the error in the impulse response accumulate when applying a step-input?

Consider the model of the form $y[n]=0.9y[n-1]+x[n]+e[n]$, I forgot if this is called an ARX model but who cares, anyways assume $e[n]$ is a zero-mean white noise. I am applying a non-parametric ...
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Why can't quantum phase noise in radio astronomy amplifiers just be filtered out after down conversion, instead of down-converting first?

In the related Astronomy SE questions below and their answers, it has become apparent that radio telescope arrays down convert their highest frequency bands before the first stage of amplification. ...
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How to judge the percentage of white noise and color noise when using typical SDR enviroment?

Per this question,I understand different result when noise occurs in time domain and frequency domain. As to the system,has antenna+upconveter+USRPB210+laptop,...
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How to detect acoustic and/or network degradations in speech as early as possible before automatic speech recognition?

I'd like to learn about techniques and approaches to identify speech degradations before they enter automatic speech recognition system and cause false recognitions. For example, I'd like to detect ...
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How to determine the CRLB for FFT based estimator with MATLAB?

I am trying to determine the CRLB for FFT-based frequency estimation in MATLAB. For this, I am simulating a single sinusoid in white noise with different amplitudes and constant noise power. Here is ...
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How does the RMS value of noise varies with sampling frequency?

I have been trying explore the background rates due to thermal noise (instrumental) through a simulation (python). So, what I have been essentially doing is the following ...
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Optimal weighting in case of unknown noise variances

Let's consider $n$ multiple measurements $x_i[j]$ of the same desired signal $s[j]$ but with different uncorrelated zero-mean additive noise $n_i[j]$ with different variances $\sigma_i^2$: $$ x_1[j] = ...
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PSD of Poissonian shot noise

I have a signal $R(t)$ that is DC with shot noise. It has units of events per second. I am trying to understand this signal in a continuous-time picture. In time-domain, I can model it as a series of ...
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Are there Fourier methods for VERY low frequency repeating signals?

Suppose I have a very low frequency pattern of sound. For example a 10 second music file. Then 10 seconds of silence. Then the same 10 second music file repeated again. The whole sequence repeats ...
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How to interpret Allen Deviation with increasing negative slope

I was calculating the Allan deviation (utilizing the Python module allantools.adev, which relies on eq. (6) in https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50505). The expected behavior is a ...
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Adding AWGN into a positive real signal

I am trying to add a Additive White Gaussian Noise (AWGN) to a signal whose mean is 0.5. I am working with OFDM for Li-Fi communications whose signal must be real and positive. Normally, The AWGN is ...
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Inverse STFT causing unwanted noise spikes?

I have an (audio) signal. I am applying STFT continuously and after applying a certain magnitude threshold I am doing inverse STFT to reconstruct the signal. But I am getting some unwanted mini noise ...
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3 answers
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how to filter accelerometer data of small robot, remove movement noise

I have a small robot (4tronix MARS Rover) and have added a MPU9250 unit which includes accelerometer (and gyro and magnetometer). I have calibrated it to determine offsets in a static situation. My ...
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