Questions tagged [noise]

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

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What happens if you use the Fourier transform of the autocorrelation of a non-WSS process to compute power spectral density?

The Wiener–Khinchin theorem states that the power spectral density of a wide-sense stationary stochastic process can be obtained through the Fourier transform of the autocorrelation of the signal i.e. ...
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Bandwidth for Noise Calcuation FMCW Radar

I am trying to determine the thermal noise for a Frequency modulated continuous wave radar. The radar is the TI IWR6843 chip. Currently, I am using the radar to transmit a chirp with a bandwidth of 4 ...
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Trying a wiener noise cancellation code but not able to filter out the noise

I am performing noise cancellation using Wiener filter for a project. The project statement is "to record our voice and take it as desired signal, add a noise, use wiener filter to estimate the ...
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Finding the average probability of error for a transmission system using this signal constellation [duplicate]

We have a signal constellation with decision regions given in the figure below and symbols are equally likely to be transmitted. Now we have to find the average probability of error for a ...
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If add white noise to the signal, how much does the std of the noise affect the thd of the signal?

I'm an electrical department student studying signals and systems. The RMS value of the general AC electrical signal is 6.31V, and the first harmonic value is 6.30932V(rms). (THD is approximately 1.5% ...
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snr of awgn in matlab before and after filtration

I'm studying a system's transient characteristics with awgn added to an input signal and I need to calculate $\text{SNR}$ before and after filtration. Here is my code to generate input and output: <...
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How does applying a unity-gain Hann window to White Noise change its power?

What works: I generate real-valued white gaussian noise with standard deviation $\sigma$ I calculate the FFT of this noise. The Abs of the FFT is a flat noisy trace over frequency, as expected for ...
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Detecting and Removing Noise from Signal using Python

Through this platform, I want to ask that how can I remove unwanted noise from the signal when you do not have much information regarding the frequency at which they appear? Data is collected from an ...
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Noise with a positive or negative mean

I am working on calculating the SNR for my network model. Considering AWGN at the receiver with zero means, the SNR can be presented as $$\text{SNR} = \cfrac{P \cdot|h|^2}{\sigma ^2}$$ where $P$ and $...
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Calculate noise variance from a given SNRdB

I was analyzing the following code for the MRC scheme from the book MIMO-OFDM Wireless Communications with MATLAB. Here, I am not able to understand based on what logic the sigma value calculated <...
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Can FFT2 be used as a randomness test for image encryption?

Based on this link Is it possible to consider a model to introduce FFT2 as a parameter to determine how random the image is? (randomness test like Entropy) consider Lena's image and its FFT2: If we ...
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Is there a relationship between the entropy of the original image and the output of the 2D Fourier transform?

Is there a relationship between the Shannon entropy of image and the output of the 2D Fourier transform(FFT2) of the image?
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What's the FFT2 of white noise image?

I try to compute the FFT2 of the white noise image. I use this image with Entropy 7.995 and pixel scatter plot: based on this python code: ...
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Synchronization of two noisy sinusoidals signals

I have two noisy sinusoidal signals and I am currently investigating solutions to synchronize them using python. Here is an example I made to illustrate my goal, supposing that I generate these two ...
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Examine the operation of a filter, given its z-transform

I am given the z-transform of a filter $$H(z) = \frac{z^2 - 1}{(z-z_1)(z-z_2)(z-z_3)(z-z_4)}$$ where $z_1^* = z_2$, and $z_3^* = z_4$. I'm interested in the operation of this filter, and what happens ...
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How do I distinguish a 49.90 Hz sine wave from a 49.95 Hz one in a short audio recording?

I've read an article about "mains hum" forensics in http://hummingbirdclock.info/about and about Electrical network frequency analysis. The idea is to be able to measure the small variations ...
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Measurement of blocking artifacts in images

I want to define a threshold for maximal blocking artifacts in an image. What is a good key value to measure blocking artifacts? I have no reference image non natural image Example: I looked into ...
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Remove additive-zero-mean-Gaussian noise

I have 5 values, and each value is corrupted by Additive-Zero-Mean-Gaussian Noise with variance = 0.05. Each value is in the range from 0 to 1. Is there anyway for me to remove the noise?
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A self-supervised learning technique to denoise my specific signal

So I work in this domain of biophysics that has to do with a light-based detection for measuring small movement of molecules (nanometer and piconewton scale) via a Quadrant Photodiode. This signal ...
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Deconvolving while suppressing other known signals

Given a known impulse response $h(t)$ and an observed signal $y(t)=(h*x)(t)+n(t)$, my aim is to recover an estimate of $x(t)$ in the presence of unknown additive noise $n(t)$. If the mean power ...
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How to generate a first order Gauss-Markov process in Python

I would like to synthesize a first order Gauss-Markov process from a white Gaussian noise. I know from signal processing theory that it could be realized using a noise shaping filter designed properly ...
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Where does the following expression for stationary Gaussian Noise come from: $\langle \tilde{n}(f)\tilde{n}(f')\rangle = \delta(f-f')\frac{1}{2}S_n$?

First, the definitions: Definition (Gaussian process) A random process $X(t)$ is a Gaussian process if for all time points, $t_1,\ldots,t_n$ the random variables $X(t_1 ),\ldots,X(t_n)$ have a ...
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Fixing/up-rezzing images is easily possible these days in practice. Is there any analogous tool available for low-quality audio?

Tools like waifu2x and Anime4k (for the MPV video player) can already easily de-noise and up-rez low quality images to 4k quality pretty darn well. Similar tools like DLSS and FSR are used for video ...
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Understanding the following formula of Throughput?

In massive multiple input multiple output (MIMO) case, I came across the following formula of throughput: $\tau_{ij} = \bigl[\displaystyle\sum_{j\in \mathcal{U}}x_{ij}\bigr]^{-1}W_i\text{log}(1+\...
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How long can information be preserved with modern technology?

This might not be quite the right forum, but with access to "consumer grade" memory storage and modern error correction algorithms, how long (order of magnitude) can data be preserved before ...
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Period and wavelength of a noise signal?

How do I determine the wavelength of a noise signal like the one below? I find it easy to understand for sine waves, but it gets tricky for me when the signal is more complex like a noise signal. If I ...
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Calculating estimated ADC Noise Floor from given specifications

As per my current understanding, the ADC datasheets for modern high speed ADCs give the noise level measurements in terms of Noise Spectral Density (NSD) in unit of dBFS/Hz. Now to convert that value ...
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Pop sounds at intersection of overlapping envelopes

I am currently dabbeling with programming a real-time audio software and I already got a simple pipeline where notes can be played and released and each note has its own envelope so that the amplitude ...
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If I know the RMS noise/the variance of a DC measurement, can I simply subtract it from the measurement?

Let's say I have an electronic system that's taking a measurement. It provides a simple bipolar excitation current to a resistive load (bipolar square wave so as to cancel out thermal emf), puts it ...
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Do you append 00 or 10 when oversampling

Say I have an 8-bit ADC and I oversample at such a rate as to obtain 2 additional bits. So, before I apply the low-pass filter, I need to append two extra bits to the 8-bit signal of the ADC. Do I ...
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How to apply chi square formula if the expected value is 0?

My $H_0$ hypothesis is that the N signals I've collected are just white random noise, i.e.: $H_0: d(t) = n(t)$ I'm then asked to formulate the $\chi^2$ test for this. But according to the formula $\...
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In this question, what does μ stand for?

Let $X_i$ ($i=1,\ldots,N$) be random variables describing an unknown constant signal $S$ and a noise $n_i$. $$X_i = \mu_i S + n_i$$ In this question what does "$\mu$" stand for? Also, can I ...
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What is the Laplace Transform of the output power spectrum if the input signal is a white noise?

Let us consider a random wide-sense stationary process $n(t)$, which passes through a filter $h(t, \tau)$. Its autocorrelation function is $$R_{n^\prime}(t)=\int_{-\infty}^{\infty} \int_{-\infty}^{\...
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How to generate time-series from a given one-sided PSD?

Generating time series from a given PSD has been discussed in this and some other forums already (which I've referred some of them below) but almost all of them are mostly descriptive and none of them ...
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Noise impact on X-band signal amplification

I have a locally generated 10 GHz LO signal that should go into the LO port of a mixer. The LO signal strength is -1.7 dBm. The mixer has a required LO-drive of about 13 dBm. Before the LO signal hits ...
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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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