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Questions tagged [noise]

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

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Why is white noise uncorrelated for any two different samples?

Consider white noise with spectrum density $N_0/2$, it is known that the autocorrelation is given by: $$R(\tau) = \frac{N_0}{2}\delta(\tau)$$ Meanwhile the definition of delta function in the ...
Harry's user avatar
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Simultaneous removal of all noises in all channels?

Can MATLAB be able to look at all 16 channels of a bio-amplifier simultaneously and look for the common factor which is the noise which affects all channels simultaneously, and the noises removed from ...
Jtl's user avatar
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Understanding the additive white Gaussian noise (AWGN) representation

In my research work in wireless communication, I came across an equation of received signal wherein the AWGN is denoted by $n\sim\mathcal{C}\mathcal{N}(\textbf{0},\textbf{I}_L)$. Note that dimension ...
Pranu's user avatar
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Jitter model does not behave as expected after FFT

So I'm currently trying to understand the relationship between jitter and phase noise. To help my understanding I did write a little simulation in matlab. I used this model in the time domain, relying ...
Maci's user avatar
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Equalizing Standard Deviations of Sequences through Smoothing

I have several sequences with varying standard deviations, and I want to smooth them so that each sequence has approximately the same standard deviation, which I've predetermined. I'm open to any ...
Vlad's user avatar
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2 answers
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How does background noise affect the fft results for a pure tone

When I am recording a pure tone and conduct a fft, I receive a peak in the spectrum for this certain tone. Let's say the peak is 5 Now I am recording a pure tone with additional white noise. Does this ...
Stefan's user avatar
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Difference transformation and Stationarization of Moving Average

I have a temperature sensor data, I want to denoise it. The first thing that came to my mind was to take the moving average, it was very smooth but it is still not stationary. If I take the log ...
Clankk's user avatar
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5G BER vs SNR for QPSK, 16QAM, 64QAM

Recently been running simulations where I run through simulating passing random data bits through LDPC Encoding, Modulation (4, 16 or 64) and then AWGN. The code itself is 90% developed by myself with ...
Dudley008's user avatar
3 votes
1 answer
97 views

Does oversampling lead to colored noise?

Suppose we receive $R(t)=X(t)+W(t)$, where $X(t)$ is band-limited to $[-B/2, B/2]$ and $W(t)$ is white Gaussian noise with autocorrelation $R_W(\tau)=\frac{N_0}2\delta(\tau)$. If we filter $R(t)$ ...
syeh_106's user avatar
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Calculating variance of sensor readings from noise density

I do not know much about signal processing and would appreciate if someone could confirm if my calculations are correct. Here I have the Noise density of an accelerometer that has frequency 6400hz ...
misha7b's user avatar
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How can it be possible that I hear people voice from my computer speaker?

I searched on web and apparently can be due to truck drivers communicating at CB band which is around 20MHz. And apparently this communication may interference with the frequencies used by computer's ...
allexj's user avatar
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Is the noise at different sampling points related? [closed]

Given the power spectral density of noise, if the values at different sampling points of the same noise are added, what is the power spectral density at this time? Is there any correlation between the ...
fs s's user avatar
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How to produce a noise spectrum from an rms velocity specification?

For a dynamic model I am looking at the appropriate input to analyse the performance under the influence of floor vibrations. The norm is an ISO VC-C floor spectrum as displayed in the image. However, ...
Jan's user avatar
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2 votes
2 answers
105 views

How can I denoise this signal?

I have data captured by a wireless sensor that is noisy. It randomly jumps in value frequently, and I want to know what this signal will look like without these jumps. I am looking for an elegant ...
stochasticlover1's user avatar
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1 answer
64 views

Narrowband Gaussian Noise

Could anyone lead me on the right path on where I could get more information in regards to a narrowband Gaussian signal can be modeled as: $$ X(t)\cos(2\pi f t)+Y(t)\sin(2\pi f t) $$ where $X(t)$ and $...
SignalToBeLearnt's user avatar
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Kalman filter for multiple data sources, measurements from which have different characteristics of Gaussian noise

I am trying to use the Kalman filter for my task: During the time, I receive data from different sensors. The state of the model may change over time according to the Const Velocity model, or the ...
Leon's user avatar
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1 vote
1 answer
125 views

Interpretation of a non-canonical Allan Variance plot

I am currently working on characterizing the noise sources of a Global Navigation Satellite System (GNSS) sensor using an Allan Variance plot, which is commonly employed to analyze frequency stability ...
RoninAmibo's user avatar
1 vote
0 answers
26 views

Removing noise from data series of road surface data

I have a data series containing underlying noise, the plot of which is : The issue is to remove the noise leaving the pattern which is raised above the lower level. The lower level is road surface ...
Roy Jaques's user avatar
0 votes
3 answers
81 views

Output spectrum of the direct digital synthesis (DDS)

I have a question about the output spectrum of DDS, which consists of a phase accumulator and look-up table. Since the look-up table stores accurate information about sinusoidal waveform, I think ...
chicken's user avatar
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1 vote
1 answer
105 views

Shot noise at an imaging system - is it white?

Shot noise is generally a white noise. For an imaging system based on detectors the shot noise variance that scalers linearly with flux and time (details here and here): $$\sigma^2=I\cdot QE\cdot\...
Yair M's user avatar
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What duration of a white noise burst is required for it to be "white" at a given frequency or frequency range?

I am running white noise bursts (with very short ramps on/off to prevent discontinuities) through underdamped resonant bandpasses which are tuned to any given $f_0$ and an underdamped $Q$. Continuous ...
mike's user avatar
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1 vote
0 answers
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Is there a method to detect sum of sinusoidal signal?

Consider we have $N$ samples. In that $N$ samples we may have $M$ samples from sum of sinusoidal signal plus noise. Obviously $M<N$. In case $N=M$ we have only $N$ noise samples. Let us assume $M$...
Creator's user avatar
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How to accurately estimate the quality factor of a noisy signal

I'm currently interested in measuring the quality factor of a noisy signal. For the purposes of example, consider a single degree of freedom mechanical system excited by white noise: \begin{equation} \...
AnonymousPlatypus's user avatar
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1 answer
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How to mask part of signal?

I am trying to implement masking in 1D signal data, I saw in one paper that they are masking 70% of the signal as in the figure below: In another study, they have mentioned that the mask part is ...
S.EB's user avatar
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1 answer
247 views

How to generate covariance matrix of coloured noise

For standard gaussian white noise, the covariance matrix is a identity matrix. What about other coloured noises (generated from standard gaussian): Brown(red), Pink, Blue, Violet? Additional details / ...
sdnemina's user avatar
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0 answers
21 views

Filtering out chaotic noise from breathing sensor signal

I've got a signal from a respiratory sensor (chest strap, piezo sensor) and I need to extract (live) the breath-per-minute value. Now for a nice steady signal this is not such a problem, the problem ...
Dutchottie's user avatar
0 votes
1 answer
44 views

Why different noise terms are read at specific sampling interval in Allan Variance plot?

I was trying to identify Quantization Noise, Angle Random Walk, Bias Instability, and Rate Random Walk from Allan Variance plot which as Allan deviation on y axis and Sampling Time Interval ...
Mahesha999's user avatar
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2 answers
212 views

ADC response inversion to Gaussian noise

Assuming the input to an ADC is a Gaussian white noise signal, and being a bit idealistic in all senses, is there a theoretical expression that links input power to output power which can be inverted, ...
Albert's user avatar
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1 answer
58 views

Remove noise from lung sound wav

I am working in this dataset data.mendeley.com/datasets/jwyy9np4gv/3? aiming to develop a machine learning model for classifying various diseases based on lung sounds during both expiration and ...
Zayo's user avatar
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135 views

What is the event that repeats itself in sinusoidal signals

I am studying medical imaging and it has been stated that it is sufficient for Nyquist Theorem to hold for the signal to be Bandlimited. I am trying to understand what is the wave in a signal. What is ...
George Ntoulos's user avatar
-3 votes
1 answer
176 views

Assumptions of Nyquist sampling theorem [closed]

Hoping I can save the question and it doesn't get migrated to philosophy stackexchange as Hilmar said in any case I don't think it is a different question the question was always meant to be ...
George Ntoulos's user avatar
2 votes
2 answers
1k views

Why is energy zero at zero bandwidth?

From the video lecture on noise analysis by Razavi here. Can anyone explain in more detail what Razavi said here? Why is the energy at a single frequency (zero bandwidth) zero? Lets look at the ...
hana's user avatar
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1 vote
1 answer
130 views

Find the spectral density of the square of white noise with a limited bandwidth

I tried the following order of operations: Let's consider the spectral density of the square of white noise with with a limited frequency band. If $S_{x} \! \left( f \right)$ is the spectral density ...
Raist Majere's user avatar
2 votes
0 answers
43 views

Online Noise Reduction on Non-Stationary, Broadband Signals

im capturing ultrasonic waves using an analog MEMS mic and other components on a PCB. My signal is similiar broadband and non-stationary (see 2) and im trying to remove/reduce environmental noise. I ...
Tom's user avatar
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2 votes
1 answer
153 views

Correcting noise floor of DFT sampled signal

As mentioned in the slide below (full slides located here, starting at PDF page 29), the apparent noise floor on a DFT plot depends on the number of sample points $N$ used to calculate the DFT. The ...
Halleff's user avatar
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1 vote
1 answer
216 views

Relation of SNR and BER

I am working towards establishing the error rate of the communication system relying on on-off keying. I have trouble understanding the estimation of bit error rate (BER) performance when the ...
Humphrey Appleby's user avatar
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0 answers
53 views

how to choose sample frequency if there is alias frequency?

my circuit only need very low frequency of signal and cannot add anti alias filter in analog domain, so I adopt sample rate frequency hopping as follow: 1、use FFT to identify if there high value ...
ElectronicABC's user avatar
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1 answer
49 views

Noise (in dB) added to a signal but within range limits

I have a sine wave signal to which I add noise in terms of dB. This is based on https://stackoverflow.com/questions/14058340/adding-noise-to-a-signal-in-python The signal is sent to a DAC and there ...
Mart's user avatar
  • 195
0 votes
1 answer
55 views

Reducing 1/f-noise

I have some mems accelerometer (ADXL355 and IIS2ICLX) and i want to get a accuracy of 0,005 ° incline measuring by using the axis of it. I am measuring with arduino over I2C and have a Samplerate ...
Rayjay's user avatar
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3 votes
1 answer
89 views

The power of a sinusoidal component in noisy PSD

I am very new to signal processing and I have been doing a lot of reading on it but I don't seem to understand everything. I'm hoping you can help my confusion a little. I am simulating a lidar signal ...
IhmeKyselijä's user avatar
0 votes
2 answers
108 views

Visually identifying audio noise

I have an audio file consisted of a sole 440 Hz sinusoidal wave, which can be heard here. After some manipulation, I've added a noise to it, resulting in a second audio file, avilable here. The noise ...
JohnCalms's user avatar
3 votes
1 answer
176 views

Removing multiplicative noise (signal) in FFT

I've read up a little here on how to deal with multiplicative noise vs additive noise, with the most simple approach to take the logarithm of the signal to remove the noise. I'm wondering how this ...
user70478's user avatar
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0 answers
17 views

Removing fixed phase offset noise

This feels like a real basic question but I'm struggling to find a clear answer. I have PSK signal that subjected to a fixed phase shift noise, introduced between the transmitter and receiver - so the ...
Dr_Chris's user avatar
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0 answers
47 views

I need help deciphering an audio file .mp3 file to get an answer. From a game

I was given a .mp3 audio file needed to be deciphered however I don't know how. I found the spectrogram which outlines the words "youtube", so I suspect the final answer might have a youtube ...
max's user avatar
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1 vote
2 answers
97 views

Related to Additive white Gaussian noise (AWGN)

In my research work regarding wireless communication, I came across many research papers wherein AWGN is assumed to be modelled as "complex Gaussian with zero mean and unit variance". I ...
Heretolearn's user avatar
6 votes
2 answers
469 views

Modelling MEMS accelerometer noise

I am trying to compare two MEMS accelerometers in terms of their noise for ground motion monitoring applications. I would like to take some "clean" data (recorded by good quality ...
marco890's user avatar
0 votes
0 answers
19 views

Noise on microscopy data

I have to analyze beating cardiomyocytes. In order to do so, I have written a Matlab script to replicate the method found in Béland et al., Front. Physiol. (2022) (doi: doi.org/10.3389/fphys.2022....
Lorenzo's user avatar
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0 answers
33 views

Periodogram Formula for sampling noise

The formula I know for the periodogram is $$I\left(f\right)=\frac{1}{NT}\sum_{n=0}^{N-1}\left|x\left[n\right]\exp\left(-2\pi fjnT\right)\right|^2$$ but for this one question I have which states that $...
namo's user avatar
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24 views

Allan deviation correct with one-side noise but wrog with two-side noise. Why?

I'm developing a Simulink model for noise according to the description of the algorithm of Accelerometer in this page: IMU simulation model. My system takes the RandomWalk (defined in [unit], being ...
Xwang's user avatar
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2 votes
1 answer
101 views

Smoothening Noisy FFT

I've got the following FFT with a sampling frequency of 192 kHz that has around 17.000.000 samples. The signal is a hiss of escaping gas. This looks noisy and i want to determine the characteristic &...
Tom's user avatar
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