Questions tagged [noise]

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

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35 views

PSD from autocorrelation in MATLAB

I am trying to simulate a simple stochastic process defined by the equation: \begin{equation} \frac{1}{v}\frac{db}{dt} +\Gamma_0 b= \sqrt{\sigma}R(t), \end{equation} where $R(t)$ is a zero-mean white ...
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1answer
67 views
+50

Which Noise Reduction Algorithms Are Used in Commercial RAW Image Processors?

I'm trying to guess what noise reduction algorithms are used in commercial processors for raw images from digital cameras. I find this fairly easy to do for the sharpening algorithms (most use unsharp ...
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1answer
27 views

Correct way of viewing negative voltages in units of dB for noise analysis

I have a voltage signal, on top of which there is some noise. I am interested in the noise components so the way I am trying to do this is to fit the known signal to the data and look at the residuals....
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2answers
68 views

Noise and AutoCorrelation Function

I would like to find a way to identify whether some components of a signal I have are "noise components" or not. Given the fact that the (normalized) autocorrelation function of white noise is a ...
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1answer
65 views

Generate signals with a particular variance and SNR

Consider a system model of the form: $y_n = ax_n + v_n$ where $x_n$ is the input that is corrupted by $v_n$ which is an Additive White Gaussian Noise of zero-mean and variance 1 for $n = 1,2,...,N$ ...
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2answers
58 views

White noise and its phase after narrowband bandpass filtering

Suppose $w(t)$ is a white noise with uniform spectral density $N_0/2$. It is bandpass filtered to get a narrowband white noise $n(t)$ for $f_c - B_T/2 \leqslant |f| \leqslant f_c + B_T/2$. We write ...
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1answer
66 views

On generalizing Gabor-Heisenberg uncertainty in a noisy environment

The Gabor-Heisenberg uncertainty represents the fundamental limit of time and frequency resolution one can extract from a signal. $\sigma_t \sigma_f \geq \frac{1}{4\pi}$ My question is: what happen ...
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31 views

Moving noise floor spectrum after decimation

Currently I am working in a spectrometer with a stage of decimation previous the fft. In particular I am decimating with a factor of 16 in two stages of 4 each one. I attach a diagram of the model (I'...
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1answer
27 views

How can we prove that Spectral density of In-Phase component and Quad-Phase component of a sample function of narrow-band noise have same definition?

Suppose we have a narrow-band noise $N(t)$. We analyse this to In-Phase and Quad phase components by the equation: $$N(t) = N_I(t) \cos(2\pi f_c t) - N_Q(t) \sin(2\pi f_c t)$$ Now a book (by Simon ...
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1answer
52 views

Model-based Kalman filtering a noisy signal

In a healthcare application, I need to calculate urine flow by differentiating the mass of urine emitted by a person over time. The measuring instrument consists of a load-cell under a fluid container,...
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0answers
28 views

how to cut off frequencies above 10 Hz with Welch method

This is the first time I have worked with any code so I am rather unfamiliar with all the lingo and processes involved. I am trying to convert a signal to the frequency domain and want to find the ...
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1answer
59 views

How does spectral density of a power signal change when it is multiplied by $\cos(2\pi f_ct)$?

Suppose we have a power signal $n(t)$ whose power- auto-correlation function is: $R_{n}(\tau)$. Now we multiply the signal by a cosine as $$\cos(2\pi f_ct) \cdot n(t)$$ whose auto-correlation is $R_{...
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1answer
108 views

How would you use machine learning for peak detection?

I have a noisy signal and I'm trying to find a way to detect peaks with ML. The "peaks" are easy to find as human because they are rhythmic and have the same "general" shape but the amplitude and ...
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1answer
30 views

high & low pass correlated dither noise question

I read a pretty cool article the other day: https://www.digido.com/ufaqs/dither-noise-probability-density-explained/ It says that if you have two dice (A and B) that you can roll both dice and then......
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24 views

Spread Spectrum (CDMA) signal phase noise measurement

A CDMA signal is considered for this application. I would like to have an information on the generated signal oscillator's quality using a phase noise measure. If the signal was a pure carrier, it ...
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21 views

Automotive Radar Simulation

I am looking to simulate a radar channel and a waveform to test some ideas from other signal processing domains on automotive radar. However, I have no experience with the typical automotive radar ...
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42 views

Cross Correlation as Noise Reduction, is this possible?

If I have two sensor measuring the same signal but from two different locations from the source, and I get two different readings of the signal, each with slightly different noise. Is there a way to ...
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14 views

Differentiating high frequencies if a signal

I have a power signal (in dBm) which contains lots of peaks (around -80 dBm) and most of the time is around -110 dBm which we can call it noise level (obviously with fluctuations). As you know, both ...
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1answer
34 views

Peak Detection on ECG signal

I've been working on a ECG signal collected during exercise through my chest mount heart rate monitor. My goal is to accurately detect the location of the R-wave; R-wave is the narrow peak similar to ...
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0answers
26 views

additive white Gaussian noise -ask fsk psk

i want to simulate a system that uses ask,fsk ,psk in Matlab with additive Gaussian noise for each mode . figure shows the system propti and Eb/N0=6db my question is how to calculate the standard ...
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1answer
32 views

How to interpret PSNR value?

Say, I have original image, noised and denoised. By PSNR value I want to find out how good does my denoising algorithm works. For which pair of the images should I calculate it? I've tried it for ...
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1answer
50 views

Recommendations for SINAD equipment

I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup: Signal generator (generating 1kHz FM signal ) $\rightarrow$ ...
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Any recommendations for buying SINAD measuring equipment? [duplicate]

I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup : Signal generator -> attenuator ->HackRF connected to PC with SDR# ...
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1answer
38 views

Find the noise settings to reproduce it

I work on images that contain shot noise (Poisson) acquired from a microscop. On few images, I have a "flat" zone that is supposed to have the exact same intensity, but it's not because of the noise. ...
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1answer
50 views

How to calculate SNR with sample noise and noisy signal only

I want to calculate the SNR for a speech signal recorded within a noisy environment. I also sampled purely the noise within the environment. The SNR is based on the ratio of power of clean signal ...
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2answers
89 views

How exactly does one apply a Hanning Window for a spectral estimate?

PREAMBLE I am a graduate student researching evolutionary ecology. My supervisor and I have been trying to learn how to simulate colored noise, discretely, by the $\frac{1}{f^\alpha}$ power law for $\...
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1answer
62 views

Overview Noise Reduction Techniques

I am trying to learn signal processing and when I research about ways to reduce noise in different situations it's so easy to get lost in one solution or go down the wrong path for example, is your ...
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0answers
29 views

Threshold for CAF Surface

I am calculating a time partitioned Cross Ambiguity Function (CAF) by adding the surfaces of different time-sectioned CAFs together. Meaning, I calculate a CAF using 10 seconds of IQ data, calculate a ...
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0answers
18 views

Ideas to eliminating noises in baseline of Korotkoff sound signal?

I am currently researching and designing an automatic blood pressure detection based on Korotkoff sound phenomena. I have acquired data that look like this : I thought that thresholding a signal will ...
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0answers
15 views

Generating a phase modulation frequency spectrum with jitter

I would like to produce a frequency spectrum plot like this: (from All About Circuits) I know that one can take the modulation frequency and multiply it by a given order and scale by the modulation ...
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0answers
26 views

How do you evaluate a denoising algorithm when all you have is the noisy data?

I'm currently working on denoising acoustic signal used in leak detection so that the leak detection could be more accurate. The thing is noise can come from various sources (Car or people passing by, ...
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1answer
123 views

Relation between constellation SNR and baseband SNR

Let's say I have an I/Q modulation, ie. QPSK. I can simulate an the effects of an AWGN channel by adding to my QPSK symbols the realizations of a complex normal. $\mathcal{CN}(0,\frac{1}{\mathrm{SNR}...
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25 views

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 ...
2
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2answers
263 views

Time series of Poisson Process

I want to run a numerical simulation of a system (eg first order low pass filter) that is stimulated with a photocurrent-like signal. My preferred language is Python. I'm failing to understand how to ...
0
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0answers
29 views

Remove constant noise from Goertzel output

I'm trying to analyze a signal recorded from an analogue phone line and do DTMF recognition using a Goertzel algorithm. However, due to a fault in the hardware, there is a constant 50Hz power line ...
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1answer
35 views

Denoising Oscilloscope data the right way [python3]

I need to plot large oscilloscope data sets. They are too large (100 million Values) to plot all of them in a for loop. If I try to do that it results in a ...
0
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1answer
69 views

Why do we need to write the noise as randn(2,1)./sqrt(2*SNR) instead of randn(1,1)/sqrt(2)?

I saw this code, about the error probability of on/off signal ,on the internet ...
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2answers
103 views

Question About Sampling White Noise

Assuming that we have a continuous signal $v(t)$ $$v(t) = \int_0^t g(u)\, \mathrm du\tag1$$ where $g(t)$ is white noise.Then take the derivative of it. $$\frac{\mathrm d}{\,\mathrm dt} v(t) = g(t)\...
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0answers
18 views

Getting SNR of reconstructed signal in MATLAB

I am trying to run code to compare the efficiency of various basic sampling methods such as ideal sampling, natural sampling and so on. I want to then use average power to see how accurate the ...
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1answer
39 views

How to achieve a smoothed frequency phase response with no outliers

I have two sampled signals, which I then perform wavelet analysis on, by synthesising the Filterbank, perform the dft on each kernel, and the dft on the sampled signals, and multiply together. ...
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1answer
33 views

Coefficients for half-order filter

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23 views

how to calculate a SNR?

i had some question.i have do some some filtering FFT using a matlab program.but,i need to compared the original signal,noise signal,and filtering signal based on SNR.but i dont understand how to ...
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1answer
47 views

Downsampling by block averaging

Many spectroscopic detectors used to study light absorbance as a function of time. These detectors cab sample data at 160 to 250 Hz. There is an option of choosing lower sampling rates such 80, 40, 20,...
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1answer
49 views

Intelligent Noise Removal in Data

This question is linked to this question: I have this data: ...
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1answer
70 views

PSD subtraction

I am interested seeing the difference between two power spectral densities (PSD) as a noise reduction exercise The blue line is the psd of my signal, and the the orange line is the psd of the ...
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0answers
18 views

Signal ECG , collecte & visualize data

I am currently working on a sensor that visualizes an ECG signal and visualizes its data. Its principle is that it has 3 electrodes that must be placed in specific parts of the body .... I would like ...
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1answer
27 views

What does "noise power is assumed to be the same at all nodes

I was reading a paper about communications between nodes, and in the simulation section they gave the condition of the simulation as follow : "...The noise power is assumed to be the same at all ...
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0answers
43 views

processing a very noisy signal

I work on an ECG signal that I collect from a sensor, and it is very noisy. Having researched it above I read that FFT or so Nyquist-Shawon's casting theories were advised, being novice in the field ...
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0answers
32 views

Should I increase the mean or the variance of Gaussian noise?

I am new in DSP. I am currently working with a project and I want to try which algorithm works better given different image noises. To test it out, I have been using the Gaussian noise in images. ...
2
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0answers
27 views

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)...