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Questions tagged [noise]

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

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0 votes
2 answers
83 views

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 ...
1 vote
2 answers
106 views

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 ...
4 votes
1 answer
3k views

How Does the RMS of White Noise Change with Sampling Frequency?

There is an analog system which includes the continuous-time linear equalizer (CTLE). With some .noise analysis the power-spectral density (PSD) of the noise in that system is provided. So let's not ...
24 votes
4 answers
7k views

How to distinguish voice from snoring?

Background: I'm working on an iPhone application (alluded to in several other posts) that "listens to" snoring/breathing while one is asleep and determines if there are signs of sleep apnea (as a pre-...
2 votes
1 answer
100 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 &...
0 votes
1 answer
40 views

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 ...
4 votes
1 answer
688 views

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 ...
12 votes
2 answers
482 views

What is the difference between 'de-noising' and what we commonly know as filtering methods to remove noise?

Pretty simple question - I am trying to figure out what exactly is different between 'de-noising' a signal, and simply filtering it (as we commonly know) to remove noise. Is this a case of lexical ...
1 vote
2 answers
144 views

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 ...
1 vote
0 answers
13 views

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 ...
0 votes
1 answer
308 views

Correlated phase noise

I am trying to find a mathematical model to understand the correlated phase noise. Here, I see the reference phase noise is almost the same after up-conversion and then down-conversion. How does ...
0 votes
0 answers
32 views

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 ...
0 votes
1 answer
42 views

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 ...
1 vote
1 answer
80 views

Frequency content of a noisy signal

To find the frequency content of a noisy signal (PSD), there are two methods below: #1 Take the fourier transform of its power signal (square the noisy signal) #2 Find the autocorrelation function of ...
1 vote
1 answer
127 views

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 ...
3 votes
1 answer
95 views

How to understand "independent sample rate" of windows?

A window metric called independent sample rate is given in a book that I recently read. It says that in spectral estimation, the variance of power-level estimates is inversely proportional to the ...
2 votes
1 answer
84 views

Thresholding algorithm for separating skin from clothes in python

I have an several images that look like the following: I would like to separate the skin from the trousers here without specifically training a segmentation model. Can anyone suggest any such ...
2 votes
1 answer
76 views

Kalman Filter - Gaussian representation

I'm trying to understand well the kalman filter, as a result i'm having this question : Why do we represent noise with a Gaussian ? what does this really mean intuitively ?
3 votes
1 answer
576 views

Estimate Image power spectrum of the noise

I want to implement Wiener filter. I have original image and image blurred with linear motion. The one thing I am lack of(to implement it) is Noise power spectrum. I know that it is hard task. I've ...
3 votes
2 answers
314 views

Power Spectrum Density and Frequency

if i have some random signals (sampling rate = 10Hz, 0.1s per data) Using python library i transformed it to power spectral density power spectral density forms = f, psd (using mlab.psd) I'm really ...
0 votes
0 answers
10 views

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 ...
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 $R(t)$ ...
0 votes
0 answers
86 views

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 ...
2 votes
2 answers
60 views

Noise reduction for 2D advection scheme

I am modelling the path of a rock deposited onto a glacier and its englacial flow with the ice within the glacier in MATLAB. I am doing this with the 2D advection equation. However, I do get some ...
1 vote
0 answers
57 views

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 ...
0 votes
1 answer
44 views

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 ...
3 votes
1 answer
782 views

White noise generation in frequency domain (stfft) produces a periodic pattern

I have created a set of spectral processing modules for SynthEdit next to be released, implenting short time fft, so I am now quite experienced with the matter, but recently encounteted an unexpected ...
5 votes
4 answers
3k views

Numerically generating noise time series from spectral density

I'm trying to figure out a way to construct (numerically) time series of random variables given some spectral density $S_{xx}(f)$. I'm interested in various types of spectral densities (flat, ...
0 votes
2 answers
355 views

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 ...
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 ...
0 votes
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 $...
0 votes
0 answers
17 views

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, ...
1 vote
1 answer
124 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 ...
0 votes
0 answers
19 views

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 ...
1 vote
0 answers
92 views

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 $M$...
2 votes
1 answer
63 views

Estimate Local Noise Intensity in an Image

Noise can be assessed in uniform regions of an image, by subtracting a lowpass-filtered version of it. Then from the histogram of intensities, a global measure can be obtained (such as the average ...
0 votes
1 answer
68 views

DSM Model Not Producing Expected Noise Shaping

I am trying to design a 2nd Order CIFB DSM ADC on Simulink based off the values I have extracted from Richard Schreier's Delta Sigma Modulation Toolbox. However, when I ran the model according to the ...
0 votes
1 answer
52 views

Noise only from TDM input from ICS-52000 MEMS mics on board NotWired NW-AUD-ICS52000

If this is not the right StackExchange group, please advice. I seem to have the same problem as 1 (2019, on the miniDSP forum, unanswered) with the NotWired NW-AUD-ICS52000 boards. I have had no other ...
0 votes
1 answer
115 views

AWGN model of Quantization Noise

[Edit answer moved from OP edit to "Answers" as per comment suggestion] I'm trying to create a simple model of a signal chain (image sensor) that includes an ADC but I'm failing to observe ...
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 ...
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 ...
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 ...
1 vote
1 answer
104 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\...
1 vote
0 answers
90 views

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 ...
1 vote
1 answer
124 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 ...
5 votes
2 answers
283 views

Minimum statistics noise estimate - how to calculate the underestimation factor?

I have implemented a basic noise estimator using the minimum statistics method. Noise power estimate is obtained as a minimum of the short time power estimate within a window of subband power samples. ...
-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 ...
0 votes
2 answers
1k views

How can I remove noise from heart sounds?

I have .wav files acquired through putting an Android cellphone microphone directly on the chest of a person. For feature extraction, I have to make them noise free. These recordings were taken in ...
0 votes
1 answer
99 views

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 ...
0 votes
0 answers
76 views

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} \...

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