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

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What is mismatched noise?

Can anyone simply explain what mismatched noise is? And what is the noise that is not mismatched noise? Thank you!
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26 views

Using Matlab xcorr to find a signal hidden behind noise

I am trying to develop some code to find a transient signal in a data set I have. Before I get there however I am trying to write code using simulated data. I first am creating a signal with a ...
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62 views

How can I reduce noise errors when detecting DTMF with the Goertzel algorithm?

Thanks a lot to whoever downvoted my question for no good reason. I wrote an implementation of the Goertzel algorithm in JavaScript and made a demo that detects DTMF dial-tones. You can find the ...
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27 views

understanding 1D wavelet analysis

i would like to understand how should i use following code for code for detection of uknown frequencies?let us consider following signal ...
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19 views

Correcting outliers using the standard deviation of a two-point different function?

I recently read a research paper that discussed how to correct lightcurve data (flux vs. time) by using the method as explained below: We have considered as outliers in the datasets the individ- ...
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56 views

denosing given signal using wavelet

let us suppose that we have given following model $y(t)=A_1 \sin(\omega_1*t+\phi_1) + A_2 \sin(\omega_2*t+\phi_2) + A_3 \sin(\omega_3*t+\phi_3)+ \ldots +A_p \sin(\omega_p*t+\phi_p)+z(t)$ where ...
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54 views

Finding a signal in noisy data

I have a large data set that was collected by a 5 GHz oscilloscope, so I basically have an array of voltages with each index being a very small time step apart. I am looking for a specific signal in ...
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90 views

Audio signal dither and noise shaping

I'm trying to get a handle on the importance of the error feedback term in noise shaping operation in typical audio dither algorithms. I'm thinking in terms of four signals. The original signal, the ...
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92 views

How to understand the type of noise

Suppose that I am receiving RF signals contaminated with noise through antenna. This signal is digitally sampled. How can I understand the type of noise(Gaussian,Uniform etc). Any algorithm is there ...
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18 views

Finding correct values based on information from two arrays

Consider the following scenario: Say, one machine is sending out a beep signal every 10 seconds in a very noisy environment. I have two sensors which detects these beeps independently. Device A is ...
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1answer
53 views

Autocorrelation of noise - negative correlation

I am investigating autocorrelation of electrical noise as part of an undergraduate experiment (as detailed in http://physlab.lums.edu.pk/images/a/ab/Correlation.pdf). I sampled noise voltages using an ...
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1answer
40 views

Best Guess Rectangle

I am using openCV to find a particular object, and am trying to find a way to make it locate the object consistently. The object's location will be determined by taking 30 frames and trying to find ...
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57 views

ARMA models for non stationary signals

let us suppose that we have non stationary signal,whose value is given by ...
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4answers
109 views

Is there an algorithm for second order filtering of data where the filter frequency is not known a priori?

It is well known that a moving average algorithm done in the time domain is equivalent to a filter with frequency response $\mathrm{sinc}(\omega\tau)$ where $\tau$ is the averaging time. (see this ...
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70 views

Image Noise Detection Using MATLAB

I want to implement the following algorithm. Let I denote noisy image and for each pixel of I is represented by I(x,y). A Sliding window of size 3X3 centered at I(x, y) is defined. At first ...
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2answers
397 views

What is the math behind median filter's noise reduction property?

I am interested in understanding the mathematical reason for why does applying a median filter on an image (or signal) result in reduction of noise.
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50 views

Is the quantization noise white here?

If I have the following power spectral density of the quantization error can I tell that quantization noise is approximately white? Can you please provide some justification?
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41 views

Common mode rejection (in software) without a reference channel? EEG data

Summary I need to remove artifact that appears strongly on all channels in my EEG data. It's already recorded (from another lab) so I can't use hardware solutions. Also: band overlap and no reference ...
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2answers
58 views

Using Total Variation Denoising to clean accelerometer data

I know this is maybe a very basic question but I am doing this as a hobby and I can't find a solution to this problem. Basically I am trying to remove some noise from data I am reading from an ...
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13 views

Confusion related to effect of noise on dynamical entropy

There are various ways of calculating the Kolmogorov entropy (KE) http://www.scholarpedia.org/article/Kolmogorov-Sinai_entropy of dynamical system. According to Pesin's theorum, it is the summation ...
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295 views

noise of zero mean and variance?

It might be a very silly question, however I'm facing problem with it. Now, the Gaussian noise is a signal with zero mean and variance. I understand what the mean and the variance mean however, I'm ...
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1answer
102 views

Relationship between entropy and SNR

Dynamical entropy Kolmogorov entropy is defined as the supremum of the Shannon entropy over partitions of the phase space. In general any form of enropy is defined as uncertainty or randomness. In a ...
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2answers
90 views

Using filters on an 8 bit song has absolutely no effect after saving

This seems like such a trivial problem but there is no answer anywhere. I'm trying to convert a 16bit song to 8bit so I can play it with a microcontroller. This creates a lot of noise. Every time I ...
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4answers
144 views

Why does the high frequency component of an image contain more noise?

I am working with wavelet transforms. When we apply a discrete wavelet transform to an image, it decomposes into four components named the approximation component, thevertical component, the ...
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1answer
67 views

Effect of sampling interval length and Gaussian noise on the frequency-spectrum

Suppose you have a signal $s(t)$, corrupted by Gaussian noise of $\eta(t)$ with zero mean and standard deviation $\sigma$. So that the measured signal is $f(t)=s(t)+\eta(t)$. I now want to calculate ...
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39 views

Estimating device height from 3-axis accelerometer data (possibly by supervised learning)

I'm trying to estimate the height of my device using an cheap integrated Freescale accelerometer. First, I estimate the earth direction when measured acceleration is close to 1g, then I project the ...
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58 views

Inverse of Wavelet Transforms - Background and Noise Removal

Main Problem: How can you inverse Wavelet Transforms (Using the data given by signal.scipy.cwt) I was wondering if anyone understands the ...
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1answer
73 views

Colored noises: Stationary or non-stationary?

I know for sure that white noise is considered as a stationary sound, but is that true for the rest of them? http://en.wikipedia.org/wiki/Colors_of_noise Also, can we meet some of these sounds in ...
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142 views

Which domain used for denoising additive and multiplicative noises

I want to know what is the difference between additive noise, multiplicative noise.. In what domain these noises are handled to remove? I am interested particularly in image dataset Does different ...
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1answer
62 views

How to extract the maxima and minima of a noisy period input signal

I have a (rough) known period sine wave coming in, held in an array, with superimposed noise. I need to find and count the maxima and minima (in C). Any suggestions or algorithms? The signal has ...
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45 views

Common mode noise from two ADC results

I am sampling two sinusoidal analogue signals that are phase separated by $\frac{2\pi}{3}$, and there appears to be a significant amount of common mode noise in my samples. What, if any approach can I ...
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2answers
75 views

Generate noise with arbitrary covariance

I am doing a time series change detection experiment. One of the experiments includes generating some artificial data for model evaluation. I came across a problem in generating noise data with ...
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26 views

Using output error model to model colored noise (using a prefilter)

I have a "black box" SISO system. I use zero input to measure pure noise on the output. After preprocessing (peakshave and removing DC) I try to model the noise using AR (and also ARMA). When ...
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1answer
78 views

How to compute the statistics of the DFT of noise?

I would like to know how to compute the statistics of the discrete Fourier transform of a noise signal. To illustrate what I mean, I will first explain in detail a computation I have managed to do ...
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48 views

Algorithm for spectral noise gating

Are there any freely available libraries or command line tools for the spectral noise gating algorithm? In essence, this method reduces unwanted frequencies over whole sample based on a given noise ...
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40 views

How to determine brown noise variance from samples?

To be correct I want to determine variance of white noise before integration (brown noise is white noise after integration) For example, I have a following model (in Matlab) of noises acting on my ...
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91 views

Why is random noise amplitude inversely proporional to the frequency?

http://astarte.csustan.edu/~tom/SFI-CSSS/info-theory/info-lec.pdf compares a bacteria DNA vs a random string: My first step was to generate for myself a "random genome" of comparable size to ...
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1answer
458 views

SNR calculation with Noise Spectral Density

I am having difficulty in calculating the SNR for the following scenario: In a cellular network Transmit power=36dBm Noise spectral density=-174dBm/Hz (AWGN) Bandwidth=10MHz I have some other ...
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1answer
56 views

Why do I have to use variance and not mean value to calculate noise?

Why, when I have to calculate some types of noise (for example shot noise and others which are in the denominator of SNR ratio) or attenuation from turbulence, I have to use variance of the of the ...
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26 views

Discretization of Sensor Noise for Robotic Simulations

What is the best way to perform discretization of sensor noise for simulations in Matlab? I have a MEMS accelerometer and the datasheet specifies the following: ...
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89 views

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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2answers
140 views

Convolution for non-signal-processing background

I am a civil engineer and am analyzing traffic data recorded by capturing vehicle movements over a highway for a specified time period. The database I am dealing with contains observations at every ...
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255 views

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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1answer
95 views

MATLAB gradient derivative troubleshooting

I have an array $A$ having the next 145 values I would like to calculate the $\frac{dA}{dX}$, having a 1D grid, $x$: 1:286:41468 I use the function gradient: ...
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2answers
70 views

Signal amplification when summing low SNR images

I'm trying to add up a few black & white images of the same object in order to amplify the SNR. I'm working on relatively low SNR images (about 1.1) and I wish to amplify it somehow. My first try ...
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1answer
79 views

Most accurate method of Voice Activity Detection?

What is currently the most accurate Voice Activity Detection algorithm with high levels of background noise? I would also appreciate if it does not require any manual calibration. Bonus points for ...
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103 views

Noise Equivalent Bandwith of IIR and FIR Filters?

How do you calculate the noise equivalent bandwidth for an IIR or FIR filter?
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113 views

Do waterfalls generate pink (1/f) or brownian (1/f^2) noise?

Does anybody know if natural waterfalls generate pink noise or brownian noise? I have tried to search about this but the matches are non-scientific and contradictory. For example Livescience.com ...
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1answer
155 views

Gain of FIR/IIR filters

What are the formulas for signal and noise power gain of digital filters (FIR and IIR)? For a FIR, I've seen in Harris' windowing paper that the DC gain is the sum of the filter weights. $$ G = ...
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460 views

Bilateral filter vs anisotropic diffusion

What are the advantages / disadvantages of bilateral filter and anisotropic diffusion for noise reduction? EDIT: To be more specific - what are the practical differences in terms of quality, speed or ...