Questions tagged [noise]
In signal processing noise can be considered random unwanted data without meaning.
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questions with no upvoted or accepted answers
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detect what is noise in audio signal
I'm trying to filter noise from an audio signal. The signal was and is going to be recorded in a city environment which always contains some white/pink noise.
At this moment I'm using two options to ...
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frequency spectrum of a sampled signal, PSD and power discussion
Before I go into my question, I first want to review the basics of sampling a signal and at the same time I build the basics of my questions so that they make more sense. I know I have asked couple of ...
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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 ...
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Relative beat detection for two audio recordings
I'm trying to synchronize (overlap) two audio recordings of the same song: a complete HQ version, and an incomplete, noisy version (phone recording for example). The noisy recording may have had its ...
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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 ...
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How to extract human voice from cluttered signal?
I have a signal which has human speech, background voice and noise as it can be seen in below figure.
I have calculated its power spectral density (PSD) using many different methods which can be seen ...
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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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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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What is the difference in the algorithm for noise reduction in SoX and Audacity?
I've looked at this question, and I understand that SoX works way FFT of the noise, then subtracting that from the FFT audio, and then resynthesizing using FFT, but I don't quite understand how this ...
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2
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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 ...
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Energy Detection in Presence of Colored Gaussian Noise
Before asking my question, let me introduce the context:
For spectrum sensing based on energy detection, which has been widely studied in presence of AWGN, the optimal detection threshold is computed ...
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Connections between quantum field theory and signal processing
I've been working with quantum field theory on the basis of it being a stochastic signal processing formalism for a number of years. The projection to fourier components within the forward light-cone ...
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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 ...
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Remove the extra peaks by lag
Suppose that we have some peaks of a signal and we know the time lag between dominant peaks. How is it possible to remove the extra peaks by applying time lag ?
Lets say it in MATLAB
...
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Why PSNR decreases for Ultrasound Images?
I am working different types of filters to remove speckle noise in ultrasound image. I have taken the below paper as my base paper and trying to reproduce the results of this paper:
My Base Paper
I ...
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Calculation of an autocorrelation function
A sample of a random process is given as:
$$
x(t) = A\cos(2\pi f_0t) + Bw(t)
$$
where $w(t)$ is a white noise process with $0$ mean and a power spectral density of $\frac{N_0}{2}$, and $f_0$, $A$ ...
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dimensions of the autocorrelation function of white noise
My question concerns the dimensions of the autocorrelation function of the white noise.
First is a short summary of what I understand about the random signals. If we have a stationary random signal $x(...
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Extracting transfer function from output measurement
Let's say I am generating pure sine oscillations with a laboratory instrument on which vibration frequency and amplitude are tunable (there are uncertainties +/- 1 % with my inputs), and I get my ...
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2
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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 ...
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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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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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White noise does not contradicts Wide Sense Stationarity?
I am studying White Noise. But I am really beginner level, so I have a confusion with its construction.
White Noise is usually defined as a Wide Sense Stationary process $N=\{N_t\}_{t\in T}$ (for $T$ ...
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Black dots in spectrogram
Whenever I zoom in on the spectrogram of a recording I made with my phone I see these strange dark dots, unfortunately I cannot try another phone. What is causing them?
They seem randomly distributed ...
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Estimating shot noise - what's the origin?
If I have some photon detector, say a CCD, how do I estimate the error introduced by shot noise correctly? Typically, sources found on the internet say that the shot noise is the square root of the ...
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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 ...
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What is the variance of DFT of Fourier coefficient of difference of a vector of white noise?
Consider $\big\{x[0], x[1], \ldots, x[N-1]\big\}$. Suppose,
\begin{cases}
x[n] \sim \mathcal N\left(0, \sigma^2\right)\\
\big\langle x[n], x[n-1]\big\rangle = \frac12 & \forall \ n\\
\big\langle x[...
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How to find the noise power in my simulation
I am currently working a tricky communication chain that I want to simulate into Matlab.
The chain is like a classic BPSK modulator/demodulator chain, but where the BPSK modulated signal has been ...
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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 ...
user7657
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How to remove varying noise from strain data in MATLAB
I'm very new to signal processing. I have some data measured over time at 800 Hz. I'm interested in the high frequency signals. You can easily identify them in the image below (in this case, 3 signals)...
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Simulating Phase Noise: How to do it?
I have a system that I am simulating, and I want to add phase noise to the process. I didn't know how to do it, so I have been conducting an literature review.
I found a good reference with an "...
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Phase noise definition
I have some problem with understanding the phase noise definition formula.
please see this image:
I can't understand the paragraph that I show ? near it. How is it possible to get phase noise > 0 ...
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Detection over AWGN analysis disagrees with Monte Carlo simulation
I have a fixed vector $\mathbf{s} \in \{\pm1\}^m$ and a random vector $\mathbf{d} \in \{\pm1\}^m$.
I send either $\mathbf{x} = \mathbf{x_1} = [\mathbf{s}\space\mathbf{d}]$ or $\mathbf{x} = \mathbf{...
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Modelling of quantization noise with logarithmic steps
I have to modell the quantization noise of ADC.
I only know that the maximum relative error is 1 dB.
Since this is logarithmic, I find it hard to formulate an appropriate model for the quantization ...
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Check if I has right: Is this the Extended Kalman Filter
I have learn the Kalman-Buncy filter for the LQG controllers. I know that this is a signal processing forum and not robotics not math forum. But Extended Kalman Filters are daily discussed here.
...
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AWGN Build vs Randn noise do not match
I am generating noise in two different cases with the same SNR once using AWGN command which is a built in command and second time using randn function with the correct scaling however I am getting ...
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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 ?
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Kalman filter to filter noise from acceleration data
I would like to apply a Kalman filter to remove noise from my measured acceleration data. The idea is then to compare the results obtained in this way whit the results obtained by applying a low-pass ...
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1/f noise generation
Recently I was reading a paper about the pink noise generation. But I don't have any background of this field.
I am confused with some part in the paper.
First, the Voss's algorithm generated a ...
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Purple Noise Modeling / Differentiated White Noise (Kalman Filtering)
I am designing a Kalman Filter for a signal which features a certain kind of noise and I do not know how to model it properly in the filter.
The noise is constructed from a white noise source, called $...
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Noise analysis with periodogram. problem with different resolutions
I don't understand what happened in my simulation.
I would like to perform a trade off between 2 ways to estimate power in frequency bands. I want to detect spurious frequencies.
First method:
I ...
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Adding shot noise in frequency domain
I have a current signal represented by an array in python, which I would like to add shot noise to. Shot noise is defined as
$$
σ_i = \sqrt{2qI \Delta f}
$$
where $q$ is the elementary charge, $I$ ...
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Extended kalman filter for accelerometer data on shaking table
I am using an accelerometer to record the motion of a shake table (a rocking table) which moves forward and backward in one direction. The signal is very noisy and decided to use Extended Kalman ...
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Smoothing data from a 3D camera
The camera uses two cameras and reflective infrared markers to compute 3D positions. For recognized marker configurations, the camera computes a translation and an orientation (quaternion). For stray ...
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Equivalent number of looks (ENL) calculation
As stated in gagnon1997speckle in paragraph 2.2, under the unit-mean noise assumption one can say that:
\begin{equation}
ENL = \left(\frac{\bar{y}}{\sigma_{y}} \right)^2 = \frac{1}{\sigma_{n}^2}
\end{...
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Finding circle in binary image (R, not matlab)
How would I extract the circular area of a binary image which looks like:
The two rods emerging from the side of the circle are noise.
I know of the hough transform in Matlab. However, I am using R ...
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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 &...
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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 ...
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Help figuring out how to extract audio content correctly from a file that produces spiky waveform with audible hiss/noise
I'm trying to extract PCM wave sequences from different files (files that are NOT audio files but contain audio data, and other data all in one file), and while this code does extract the expected ...
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Determine Noise Level by Convolving N Signals
I using a microphone to determine (air) leakage characteristics. The signals need to be filtered to reduce the noise level and i thought of using the Spectral Subtraction Technique. Since im having 4 ...
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Noise color in multidimensional frequency space - is there an angular effect or dependence?
I understand that if there is a non-constant level of noise in one-dimensional frequency space, e.g. noise variance increasing linearly with frequency gives "blue noise" in the iFFT space. ...
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