Questions tagged [noise]

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

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41 views

Ambient noise levels in desert and recording studio

Are there mathematical models which suggest which of the two - desert or recording studio - is likely to be quieter? I would think a recording studio would be quieter than a desert. Is there a ...
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24 views

ICA for Noise Reduction over a Dataset

Suppose my dataset consists of $N$ example vectors $\mathbf{x}_{1}, \ldots, \mathbf{x}_{N}$ where $\mathbf{x}_{n} \in \mathbb{R}^{p}$ $\forall n$. I assume that each vector $\mathbf{x}_{n}$ is ...
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516 views

Removing background noise algorithm

What is the algorithm for removing background noise from an audio clip of human speech? Say I have a 10 second audio clip of somebody talking, and there is background noise of them tapping on their ...
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102 views

SINR is 3-tap zero forcing filter

I have a following toy example: received signal: $y[n] = x[n] - x[n-1] + z[n]$ and with $\text{Pr}(x[n]=1)=0.3=\text{Pr}(x[n]=-1)$ and $\text{Pr}(x[n]=0)=0.4$ and $z[n]$ is a Gaussian distribution. I ...
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222 views

Detection Bandwidth for Noise Power Calculation

I am trying to calculate the $P_{noise}$ in an experimental setup, such as given below. The DUT is excited at a predefined frequency, $f$ , with power $P_\text{in}$. The total power is measured by the ...
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294 views

How to find out the noise level of a signal

Is it possible to find the amount of noise or SNR of a signal from its time series output? For example; let x = randn(100,1) and ...
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1answer
142 views

Gaussian signal generation

Edit: Could the following be the answer? Generate WGN-like-signal which is centered around a set dBm value. Treat that signal like it was a frequency domain representation of an unknown X time-domain ...
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1answer
159 views

Kronecker delta instead of dirac delta as correlation function of white noise

From my understanding, if you have a sample $x_{t_1},\dots,x_{t_n}$ of $X_{t_1},\dots,X_{t_n}$ which are iid $N(0,1)$, then $x_{t_1},\dots,x_{t_n}$ is a sample path of Gaussian white noise. However, ...
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61 views

Comparing the performance of a digital communication sim against a reference

I have a complex baseband simulation of binary FSK modulation and demodulation. The modulated signal $s[k]$ is computed as $$ s[k] = e^{-j2\pi f_ik/f_s} , i \in [0,1] $$ where the sampling rate is $...
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54 views

start of packet detection

With the current lockdown, I'm spending some time in understanding L1 PHY development and have some questions on the start of packet detection in an IQ capture Let's say I have a WiFi IQ capture ...
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45 views

Can someone explain or elaborate on the channel estimation and noise variance estimation algorithms used in HF receiver?

For different type of communication, there is different type of algorithms to acquire CSI. For instance 4G (LTE) network have SRS or DMRS to estimate the channel based on pilots. I am designing a ...
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1answer
889 views

What happens to the standard deviation of a white Gaussian noise after low pass filter?

If I apply an ideal box-car low pass filter on a random signal with white Gaussian noise, what happens to the Gaussian distribution's $\sigma$? I know that the auto-correlation function becomes a sinc(...
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45 views

Measure how Straight/Smooth the Borders are Rendered in an Image

I have two images: I want to measure how straight/smooth the text borders are rendered. First image is rendered perfectly straight, so it deserves a quality measure ...
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1answer
192 views

Power spectrum of uniform white noise

Given a white noise image $W_{i,j} \sim U[a,b]$ where each pixel is distributed uniformly in $[a,b]$, how would I go about computing its power spectral density? That is, I want to find $E[|\hat{W}_{i,...
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74 views

Least square error channel estimation in the presence of AWGN noise

I want to implement Least Square (LS) channel estimation method in the presense of AWGN noise in MATLAB. $y(n) = x(n) * h(n)$ $Y(k) = X(k)H(K)$ Y(k) is the received signal in frequency ...
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27 views

Dirty Image Quality Assesment Measure

I was looking for a way to measure how dirty is the document in image processing. Example images below: a. Dirty Backgrounds b. Dirty Backgrounds with Text Can someone give me an initial idea to ...
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2answers
247 views

Is noise figure dependent on input noise power?

I was reading about Noise Figure on Wikipedia (https://en.wikipedia.org/wiki/Noise_figure). There, I saw the following definition: The noise factor is thus the ratio of actual output noise to that ...
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111 views

How to simulate (in matlab or c) power spectrum of random brownian noise signal?

I have a semi random noise signal, it does have some periodicity however. I can estimate the power spectrum (of the blue signal, I thought that it would be more clear, because white noise is flat, ...
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1answer
79 views

How do I find variance from the PSD of a stochastic process?

I have a time series that consists of noise and a signal, shown here windowed and Wiener filtered: and the PSD of just the noise (used in filtering): I want to find the variance of the noise using ...
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1answer
133 views

why does my integrator perform noise shaping?

I am designing (in matlab) a simple system with a DC signal at 0 Hz and some added noise. I am performing a differentiation of the signal (by simply subtracting the last values from each other), next ...
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1answer
73 views

How to add a particular noise on a signal?

I have a simple ADC model (an input signal == sampled signal ). The adc should be modelled as with following values: 1.5 V (peak to peak).. meaning --> +1.5 V --> 0 dBFS ... how to do this ? The ...
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21 views

What happens to crosscorrelation of two noise generator if one of them were to be inverted

I have two noise generator u1 and u2 and their crosscorrelation is given, what will happen to this crosscorrelation if u2 or u1 were to be inverted?
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44 views

Whitening Filter for Noise Estimation

The signal I'm working on includes some noise which is I assume Gaussian white noise with zero mean and an arbitrary variance. So, it is like; ...
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1answer
117 views

Torque signal fft

I have the following torque signal picked up with a 10.240Hz sampling rate from a testbench. I am studying its fft which I create on Octave with the following code: ...
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1answer
280 views

Ouput SNR of an integrator

Say I have an integrator with transfer function $\dfrac{\mathrm{F_s}}{s}$. This integrator has an initial condition zero and integrates from $t=0$ to $t=\dfrac{1}{Fs}$. If I apply a constant $V_{...
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3answers
403 views

best technique to remove noise from bio signal data

I'm still learning about signal processing so sorry if this is an intro problem. I want to remove noise from the following data so I can separate each wave and run analysis on it. The data is sampled ...
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47 views

Acceleometer Noise and FFT

Background: I'm fairly new to signal processing and sensors, etc. I'm working on my thesis, which involves the use of an MEMS acceleration sensor as a vibration measuring device (for rotating ...
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2answers
821 views

Formula to calculate/generate gaussian noise?

What is the formula to calculate gaussian noise, given we have variance and mean? I am trying to search google for formula but i am unable to find any much relevant result. If for example i have mean ...
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1answer
204 views

Meaning of AWGN complex and real noise under BPSK Decision Scheme

I'm currently studying error correcting codes and decided to replicate some common Bit Error Rate curves under BPSK modulation. I initially had trouble to convert SNR to a Gaussian $\sigma$ because I ...
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1answer
44 views

Random 2D noise generated in spectrum domain always have maximum at (1,1)

I want to add a noise made of harmonic functions to my 2D matrix. I thought it could be made by adding random amplitudes to modes in Fourier domain. I keep Hermitian symmetry of the matrix so that the ...
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2answers
43 views

Channel noise - A misnomer?

I was discussing with a colleague with background in communication about white Gaussian (WG) channel noise. He said noise is not added by the channel and it's just a misnomer. Noise, which is thermal ...
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2answers
790 views

Fourier transform of a noisy signal

Let's suppose i have a sensor that measures the output of a process and this cause a not negligible noise that affects my signal. My goal is to analyze the process signal in order to find faults. How ...
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63 views

lock in detection based denoising using matlab?

What are the limitations of implementing the lock in detection technique in matlab? I have time varying data with known frequency with huge background noise. The reference signal is also available. ...
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1answer
343 views

Does mixing brown noise and white noise create pink noise?

What happens if you take a white noise generator, run it through a one-pole LPF set to a low cutoff frequency, and then mix the two together? Do you get pink noise? Say you have this code: ...
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1answer
213 views

Normalizing white noise to match pink noise's amplitude at a given frequency?

I have a pinking filter which I am running white noise through to get pink noise. I would like to then mix the white noise with this pink noise, where the amplitude of the white noise will match the ...
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1answer
213 views

Difference between "scaled white noise " vs. "unscaled white noise"

I have been searching Matlab user-guide for Wavelets. In their graphical user interface for denoising, there is an option for "unscaled white noise" and "scaled white noise" for the noise structure. ...
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104 views

What is the type of each 4 different noise signals that are shown below?

Dear signal processing experts, I am looking at four different noise signals.I got them in a time domain and they are different. I went to the frequency domain and found the fft for all four signals....
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1answer
89 views

Positive slope of BER with a greater frequency deviation?

I am trying to implement a frequency-modulated communication channel on MatLab. However, there is something I don't understand about the sensitivity of the frequency modulator (or the frequency ...
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1answer
250 views

Adding White Gaussian noise to a voice signal

I'm trying to add White Gaussian Noise to an audio file. However; the energy of the noise should be 1/10th of that of the signal. My first attempt is as following: ...
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1answer
73 views

SNR estimation prior to demodulation?

What are the standard ways to measure SNR, particularly before demodulation/synchronization?
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1answer
93 views

Auto-correlation of C/A code with 30dB noise

I've a C# program that generates a GPS C/A code consisting of -1s and +1s. Auto correlating the code with rotated versions of itself shows that the peak is 1023 and the next maximum value is 63 which ...
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2answers
85 views

Transforming digitized noisy signal before applying cross-correlation

I'm trying to grasp the concept of cross-correlation as it applies to CDMA in the GPS C/A signal where noise is involved and the SNR is low. My understanding is that before calculating the cross-...
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1answer
223 views

Adding Poisson noise to a time series signal

I'm working on a radiation detection problem. I have simulated some measurement count data and want to add an amount of Poisson background noise to achieve a certain SNR. Radiation count measurement (...
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56 views

Minimum statistics noise estimate - how to calculate the underestimation factor?

I have implemented a basic noise estimator using the minimum statistics method. Noise power estimate is obtained as a minimum of the short time power estimate within a window of subband power samples. ...
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66 views

FFT response for noisy signal, averaging the response and

I try to analyze a system's state with acceleration sensors by measuring the frequencies and amplitudes. Since a cheap sensor is used, I have a noisy signal in the beginning (up to 40Hz - see below). ...
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1answer
88 views

How to measure the "correctness" of a pink noise generator?

I've implemented a pink noise generator for audio applications. How can I measure how close of an ideal pink noise is my output? I do not have access to Matlab or Mathematica. I would prefer a ...
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2answers
998 views

Understanding Voss-McCartney pink noise generation algorithm

I'm implementing the Voss-McCartney pink noise generation algorithm. If you follow the link above, you can read: from James McCartney 2 Sep 1999 21:00:30 -0600: The top end of the ...
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1answer
136 views

Variance of a signal

How to calculate the variance of noise samples modeled as follows: $n_a(t)$ is a Gaussian zero-mean white noise process with (two-sided) power spectral density $\frac{N_0}{2}$. $n_a(t)$ is passed ...
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116 views

Randomly Generate Synthetic Noise in an Image Text Document

I'm working on denoising dirty image document. I want to create a dataset wherein synthetic noise will be added to simulate real-world, messy artifacts. Simulated dirt may include coffee stains, faded ...
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1answer
81 views

How exactly is analog Signal to Noise Ration (SNR) defined?

Say, my ADC reads noise signal only, not sure how to define a threshold. Let's say my noise is sitting at 0V (zero mean), oscillating between +5 mV to -5 mV, so Vnoise = 10 mVpp. I'm looking for 20 dB ...

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