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

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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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1answer
25 views

Estimating the variance of noise using median function (?)

By investigating the implemented code of an accepted paper, I encounter with following relation to estimate the variance of noise in an image: $$ \sigma = \frac{median ...
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1answer
23 views

Why does DPSK constellation shrink when noise is added?

I am generating a DQPSK waveform at complex base band with constellation points on the unit circle and when I add AWG noise the constellation shrinks. The noisy constellation "blob" migrate inside ...
2
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0answers
45 views

Measuring noise floor in an impulse response

Say I have an impulse response... (an envelope of the actual IR obtained using the Hilbert transform) ... question: how do I calculate the surrounding noise level? Visually this looks to be ~ -54 ...
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1answer
24 views

What is the spectrum of modulated noise?

I use a white-noise generator in an rf bridge to measure antenna impedance. The receiver is an ordinary AM/CW/SSB communications type, nothing fancy, nothing 'coherent'. As I approach the null of the ...
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0answers
24 views

Extract voice from magnetic tape

There is a recording which contains very noisy voice. (voice with a low Signal-to-Noise ratio). It is a female voice of a stationary speaker (right in front of the microphone) and there are many ...
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1answer
33 views

Generating a noisy sine wave in Python, efficiently

(Questions after code block.) For now, I am generating the sinusoid and the noise separately and then normalising the amplitude so I can write the signal to a .wav file (16-bit, 16kHz). ...
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0answers
43 views

Spectral density of 1-bit nonlinear detector in terms of analog spectral density

Suppose we have a time dependent noise signal $\theta(t)$. We sample $\theta(t)$ with a device which has 1 bit of resolution and is itself stochastic in the sense that the readout value $u$ of the ...
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1answer
27 views

How can I extract a sinusoid from a very noisy signal for computing the phase shift?

I have done some measurements and I got two very noisy signals. I want to extract a certain sinusoid from the signals and I want to compute the phase shift between them. I made some simulations and I ...
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1answer
32 views

simulating noise with Yuler and burg

I want to simulate short term white noise with Yuler and Burg. It's said that it can give better results than Gauss-Markov. The problem is that each time the series diverge. Do you think that I made ...
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22 views

probability distribution of complex Gaussian column vector and conditional probability of complex Gaussian column vector

I have column vector $\vec r=[r_1\ r_2]^T$. $$\vec r =hA\vec s +\vec n$$ where $h$ is a complex number , $\vec n \sim \mathcal{C} \mathcal{N}(\begin{bmatrix} 0 \\ 0 ...
2
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1answer
55 views

Sampling of band-limited white noise

The context is communication where we have a front-end that samples a signal and a noise (but here we focus only on the noise). My goal is to determine the noise power that I should use to simulate ...
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1answer
20 views

Maximum Likelihood carrier phase estimation of $Acos(2\pi f_ct)$

This question refers to the example 5.2-1 of the book "Digital Communications, 5th Edition by John Proakis, Masoud Salehi" (example 6.2-1 in the 4th edition of the book) which asks for the estimate ...
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1answer
47 views

Complex normal Gaussian noise

I would like to create complex normal Gaussian noise with dimensions (M,N) The noise should be zero mean and the variance should be equal to one. How can I do so? thanks
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1answer
33 views

How does spatially white noise differ from diffuse noise

In noise reduction, having read that directivity index is used to reduce diffuse noise and white noise gain reduces spatially white noise, I would like to know the difference between both the noise ...
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0answers
5 views

How can you test Gamma in ISP for test?

In CMOS image sensor, there are gamma processing block in the so many ISP chains. Is there any one know how to test the gamma block only whether working good or something wrong? How can you test ? Is ...
2
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3answers
94 views

why the ultasound image is noisy by speckle noise?

My first question : I want to know why an image is noisy ?. why the ultrasound, SAR and Laser... images are noisy by a multiplicative noise not an additive noise? Another question : So the ...
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0answers
28 views

Remove noise from Binary image, License Plate noise removal (MATLAB)

How can I remove noise form Binary license plate? example images: http://s1.upload7.ir/downloads/XB6RfCQnJz5dyJgXPrg2Co5OmAFSkmO8/Untitled.png source file : ...
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0answers
29 views

noise in signal

I am trying to add phase noise in signal. However, when i see the graph in frequency domain the spectrum is not broading. Can anyone tell me what mistake i am making? ...
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0answers
19 views

Use the line function commend matlab of PDE toolbox in image processing

I want to use the line new command of PDE toolbox as Matlab R2015a to restore a noisy image with gaussian noise. The PDE is : \begin{eqnarray} \nabla.(\frac{ \nabla u}{\sqrt{1+|\nabla u|^2}}) ...
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59 views

Why is generating $1/f^\alpha$ noise so complicated?

Why can't I just take the square root of the power spectrum $P(f) = Cf^{-\alpha}$, multiply with $e^{i\theta_n}$ ($\theta_n$ being $N/2$ random phases in $[0, 2\pi]$), and then do an inverse Fourier ...
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0answers
19 views

Identify correlated colored noises that affect a signal

In the process of signal + noise, which is not stationary. In this case how could I a. determine what autocorrelated noise colors affect a signal. b. What mix of correlated colors affect the signal ...
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23 views

what is the difference among noise,blurring and contrast? [closed]

I want to know the following what is the difference among noise,blurring and contrast ?
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36 views

Advice for creating differential microphone array

For a school project I'm required to create a differential microphone array that can filter out background ambience, so a clear voice signal can be recorded in noisy environments. The plan was to use ...
3
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1answer
110 views

What is the connection between analog signal to noise ratio and signal to noise ratio in the IQ plane in a quadrature demodulation system?

We would like to compute the quantitative relation between analog noise near the LO frequency and the statistics of points found in the IQ plane after IQ demodulation. In order to completely ...
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3answers
83 views

EQ - Calculate the power per Octave of a signal through FFT

I'm working on a audio Equalizer, and I'm not sure if the way I obtain the power per octave of my signal is good. Here is the code I have : (I use the third octave bands, which is initialized earlier ...
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1answer
26 views

What noise will change the frequencies components of a signal?

Normally, when talking about adding noise to simulation data, the choice are AWGN, pink noise and so on. However, in practice, the noise in the experiments changes the locations of frequency peaks as ...
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0answers
25 views

How to detect impulse noises in audio recording?

How do you detect impulse noises in audio recordings of speech? By "impulse noise" I am thinking about noises like: Typing on a keyboard A door slamming Somebody bumping into a table Tapping on a ...
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0answers
39 views

SDR Signal processing - noise filtering

I'm looking for an advice with noise filtering using digital singal processing. I've been pointed here in my original question posted on Stack Overflow. So whats the problem: 1. I am using my SDR ...
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1answer
46 views

What is the statistics of the discrete Fourier transform of white Gaussian noise?

Consider a white Gaussian noise signal $x(t)$. If we sample this signal and compute the discrete Fourier transform, what are the statistics of the resulting Fourier amplitudes?
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1answer
57 views

Spectral density of modulated noise process

Suppose we have a noise process $F(t)$. Suppose $F$ is stationary and we know its autocorrelation function $$\rho_F(\tau) \equiv \langle F(0)F(\tau) \rangle$$ where the average is over realizations of ...
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1answer
49 views

Can realizations of a filtered Gaussian white noise process be represented as a Fourier transform?

Suppose we have a noise process $V(t)$ which is the result of passing Gaussian white noise through a filter with frequency response function $H(\omega)$. Can we represent realizations of this process ...
2
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1answer
38 views

Removing a non linear noise trend from data

I have a dataset that looks as follows Now, this is from an actual measurement (of the reflection coefficient of a microchip with four LC resonators connected in a periodic fashion) so there is ...
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1answer
49 views

How to remove gaussian noise and poisson noise?

I want to remove the noise gaussian and poisson noise. But I'm unfamilier with noise remove methods but from my understanding it's similler to average filter which is median filter. But I want to know ...
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25 views

What is difference noise reduction technic on additive gaussian noise and poisson noise?

As I know the camera noise are consisting like poisson noise and additive gausian noise. I want to know about What is difference noise reduction technic on additive gaussian noise and poisson noise? ...
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67 views

ECG noise filtering using FIR Bandpass Filter

I am new to signal processing and examine ECG data corrupted with noise. The clean data has a frequency spectrum like this. And the corrupted one looks like this (sorry for the different scale) ...
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1answer
33 views

Smooth (not) equally-spaced signal strength data

I'm currently trying to reduce the noise in/smooth sampled signal strength data. The context is that I collected data from a transmitting device using bluetooth - the available data is basically a ...
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1answer
47 views

How to form Kalman filtering matrices for a problem with variable acceleration?

Assuming we have time vector $T$ with constant time step $dt$ position vector $X$ velocity vector $V$ acceleration vector $A$ All vectors $X, V, A$ have noise on their measurement ( $n_x$ , $n_v$ ...
2
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1answer
167 views

What is the difference between i.i.d noise and white noise? [closed]

I want to know the difference between independent and identically distributed (i.i.d) noise and white noise. In my short knowledge, i.i.d is that there is no relationship about time dependancy. White ...
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1answer
104 views

What does clipping gaussian noise mean?

I found the subject at here like this "Does clipping noise colour the spectrum" When I researching for clipping noise. But I can't understand because typically something has clipped means something ...
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1answer
65 views

What does standard deviation of noise 1 mean?

In theory of noise,Typically, the standard deviation of noise has 1 and mean has 0. I think that the reason of noise mean has 0 that we can assume that all noise signal go to zero when we sum it all. ...
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1answer
96 views

What does zero-mean noise mean?

I don't know where to start from. and this question might be very silly, I have found such as comment from someone at here, "I think if you noise is zero-mean it doesn't matter, if not it does (you ...
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1answer
77 views

Kalman filter - understanding the noise covariance matrix

What is the significance of the noise covariance matrices in the Kalman Filter framework? I am referring to: process noise covariance matrix Q, and measurement noise covariance matrix R at any ...
0
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1answer
56 views

Does clipping noise colour the spectrum

Does extreme clipping white noise colour the audio spectrum? I thought (and hoped!) not on the basis of this from research.net Clipping is mathematically equivalent to the addition of impulse ...
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0answers
41 views

What is spectral subtraction? [closed]

I have to write some simple examples in Matlab which use spectral subtraction. These examples will be included in a paper to help a friend understand spectral subtraction. But I don't know where to ...
0
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0answers
21 views

Simulate noise on the x axis for raw time-of-flight mass spectrometry signals

I am analyzing raw mass spectra produced by a time-of-flight mass spectrometer. These spectra are 2 dimensional signals that consist in intensity values with respect to mass/charge values. Here is an ...
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2answers
203 views

Noise removal from audio using FFT/Spectral editing

I have a noisy recording with some letters spoken out loud. I've noticed that the noise is easily recognizable when looking at a spectrogram of the audio. Is there anyway to set a power/frequency ...
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1answer
148 views

What do we espect Likelihood function used for?

In my understanding, I let make a example. For example, you can see in the following picture. Consequently, We want to find ^sigma. and We have already known the observation data(which is random ...
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2answers
33 views

FIR Filter matlab command

i'm trying to understand the fir1 filter but i still don't get it. For example here i got an audio signal that i consider noise, i'm passing it through a low pass filter. ...
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49 views

time domain non stationary time series individual colored noise identification algorithm

One of the methods for identification of modulated colored (stationary) noises is that of lag 1 autocorrelation power law noise identification algorithm. This method can determine the dominant noise ...