Questions tagged [noise]
In signal processing noise can be considered random unwanted data without meaning.
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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....
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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 $...
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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 ...
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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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How to detect faint, dense grains on an image?
I have a bunch of images similar to the following:
As you can see, there are faint grains in a roughly ellipse-shaped area, along with a few bright ones. I need to identify the location and density ...
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Proper audio noise and artifact detection approach
I'm working on developing an audio device testing suite (for speakers and like). I'm looking for approaches to detecting two types of noise: static such as white or pink noise and artifacts such as ...
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Can white noise be correlated to a random signal
For an random signal $X$ (does not matter if it is correlated or uncorrelated), given lag $τ$. If white noise is added to this signal, then can the summation of them be a correlated signal? Also, even ...
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What's the distribution of the DFT of a real-valued, zero-mean, normally distributed random vector?
Suppose $X$ is a real-valued N-dimensional Gaussian vector, $X \sim \mathcal{N}(\mathbf{0}, C_X)$. The discrete Fourier transform can be obtained by left-multiplying with the unitary DFT matrix, i.e. $...
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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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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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How to convert the phase noise spectrum density to frequency spectrum density?
Following the answer in this post: Phase noise and frequency noise relationship, I can calculate the phase noise spectrum density with the unit from $\frac{dB_{c}}{Hz}$ to $\frac{rad}{\sqrt{Hz}}$. ...
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PSNR decreases while denoising
I currently am trying to portray PSNR's ability to measure noise in an image. The PSNR is said to be high (around 40 dB) if there is a low amount of noise in the 2D signal.
In my experiment I have ...
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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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How to calculate The Signal-to-Noise Ratio (SNR) in dB (different units)?
Recently, I've ventured into a new domain that I intend to incorporate into my work. After thorough research and consultation, I've found this model to calculate the data transmission rate (Capacity).
...
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Time-varying shot noise generation
I'd like to model the behavior of photodiodes, the input is like data bits (0 & 1) where each bit is represented maybe with 100 samples / bit and the bit rate is $B$ bits/sec with period $T_{bit}=\...
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Generating time-domain noise from PSD
I have a question regarding generating a time-domain noise from the power spectral density (PSD), this was addressed in this question (How to generate time-series from a given one-sided PSD?) but I ...
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Noise spectral density and windowing
I am wondering about the definition of Power Spectral Density, in the context of measuring noise, i.e., Johnson-Nyquist (thermal) noise.
Usually a windowing method, like Welch's method, is used to ...
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How to determine Transmission Rate for Task Offloading in edge computing?
I am new to communication systems and am working on a model for task offloading on edge computing. One key parameter I'm aiming to determine is the data transmission rate. While I am familiar with ...
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What am i doing wrong?
How do I remove the noise (long vertical lines) from signal? I am applying AC voltage via function generator which is amplified by the power amplifier to a 6mm thick steel specimen. The signals are ...
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Difference between ADC dynamic range and voltage resolution?
Say I have a 10-bit SAR ADC with a $5 \ \text{V}$ reference. I calculate its resolution to be
$$\Delta V_\text{lsb} = \frac{5 \ \text{V}}{2^{10}} = 4.88 \ \text{mV} \approx 5 \ \text{mV}. $$
So for a $...
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Power spectral density convergence for finite samples
Suppose a sequence $\{a_k\}_{k=0}^{\infty}$ has power spectral density
$$
S_{\mathbf{a}}(f) := \lim_{n\to \infty}\mathbb{E}\left[\frac{1}{f_0 n}\left| \sum_{k=0}^{n-1} 2\pi f_0 a_k \exp(-2\pi ikf/f_0) ...
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Audio Classification
Most of the paper about audio classification has worked like this they have specific sounds class wise and the did classification. What if the audio files i have collected have two different sounds at ...
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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 ...
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PLL in noise-free and noisy channels
I'm trying to evaluate the performance of PLL in compensating the phase noise in the absence and presence of AWGN noise, and the counterintuitive result I consistently get is that PLL performs better ...
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Probability distribution of phase of fourier transform of white noise, colored noise (1/f noise in particular)--- Definitions and standards
What is the probability distribution of phase of fourier transform of white noise and colored noise (1/f noise in particular) ? Is there a standardised definition?
Often, the colored noise is derived ...
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removing spikes from spectrum
I am working on 50 samples obtained from time domain signal by FFT. It appears at certain frequencies which are -- according to our experimentalist -- due to some issues with their oscilloscope. What ...
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noise synthesis arbitrary PSD
I have noise measurements for a circuit, in units of noise power (measured in Watts against a known load), per frequency bin.
For simulation purposes, I wish to synthesize noise with the same spectral ...
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Will a DC offset drift create any noise?
Transducers have a certain DC offset and it can drift relatively quickly. After a high-pass filter is used (say 0.1 Hz) will there be any noise in the frequency bands of interest (eg. 30Hz-200Hz) ...
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Instability parameter from Allan Deviation when noisy
I have some simulated outputs from a model of a sensor that a teammate wrote. I'm attempting to verify, using Allan deviation, that random walk and bias instability were modelled correctly.
To do this,...
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How does downsampling decrease the noise power?
I read one equation from a technical document, i.e., assuming the time-domain white Gaussian noise samples with variance $\sigma_{TD}^{2}$ in dB are sampled using ADC with sampling rate $f_{s}^{ADC}$, ...
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Noise variance of DT samples from CT track-and-hold signal
(I will be referring to info from these slides in this post, for your reference.)
Consider first for comparison a typical CT low-pass filter, without any sampling, for example implemented by the RC ...
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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 ...
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Noise is not showing in FFT
The below is a graph my designed constant current source.
You can clearly see that there are some noise in the values.
But when I take the FFT, the noise is not actually showing in graph.
Could some ...
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Signal averaging of a digitized noisy signal
If I have a signal that is lower than the noise power, I may want to use signal averaging over time to increase SNR.
However, when the signal has been obtained after digitization, there is ...
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What is the relation between the 1/f spectral noise density and the Allan deviation noise floor? (I found a value of $\frac{5}{3}$)
I have some noise density that consists of 1/f noise and white noise like so:
I then select an arbitrary sampling frequency $f_S$ and data length $n$ and compute a time domain noise data vector like ...
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1/f noise: Why does the Allan Deviation remain constant, while standard error of mean keeps decreasing for long averages?
It is a rather well-known fact, that measurement precision is limited by the 1/f noise of a signal [1]. One way to show this in a concise fashion, is to plot the Allan deviation of the signal. For ...
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Adding noise to ECG to mimic Electrode Motion Artifacts, Muscle Artifacts, and Baseline Wander in Python
I have clean ECG signals and I want to add noise to them. Specifically, I want the noisy signals to be closest to "real life" type of noise.
Reading this paper, I noticed that the ...
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Which probability density functions to use in a likelihood ratio test for the radar detection problem?
I am trying to understand the radar detection problem in the form of the generalized likelihood ratio test and am having a little trouble with understanding the noise distributions. Perhaps this will ...
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Introducing periodic jitter to a clock
This question is about the ideal digital clock. Lets consider an ideal clock with 0 raise time and 0 fall time i.e. perfect square wave. As shown in the diagram below. Let the original clock period be ...
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Solving Inverse Problem of Multiple Pulses Over Multiple Channels with Convolution Kernel and Cross Channel Mix
Before I start, let me note that I have 0 experience with signal processing, so please bear with me:
My System
My system can be represented as an $m \times n$ matrix $X$ (input) where each
column ...
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Any alternative implementations for (overlapping) Allan deviation calculation than "allantools"?
We have the need to calculate the overlapping Allan deviation on possibly some billion data points (for long-running measurements). While alantools.oadev() is ...
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Improving Modeling of Thermal Noise Behavior at Antenna
Background
I recently asked this question over on Electrical Engineering Stack Exchange. On the advice of some commenters there, I've broken off those pieces which are appropriate for asking as ...
