Questions tagged [noise]

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

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30 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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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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1answer
42 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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49 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
57 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
47 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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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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Generate PCMU/PCMA noise samples

I'm attempting to test an Real-time Protocol library and would like to be able to transmit white noise. The part of the library I'm testing doesn't have access to the codecs. How do I generate PCMU ...
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Techniques for removing noise aside from Spectral Subtraction/Statistical Method?

I am studying how to remove noise from speech audio and I figured the most common error in spectral processing comes in the form of musical noise. Now what are the techniques on reducing this ...
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1answer
25 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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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
123 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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Measure how Smooth the Borders are Rendered in an Image

I have two images: I want to measure how smooth the text borders are rendered. First image is rendered perfectly smooth, but the second image is rendered with a lot of curves. How will I measure it ...
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1answer
53 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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The dependence of signal / noise on the distance to the cover

I am using the K-LC6 microwave module. He has two outputs I and Q The device is in the case and is closed by a cover made of polycarbonate material. I noticed that if you slightly change the distance ...
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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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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
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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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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
26 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
39 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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How can I calculate time gap in different waves

I want, calculate the time gap between two signals .but that signal has frequently changed the frequency range. I want to combine with these two signal including phase shift I have a circuit for ...
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1answer
30 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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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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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
45 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
130 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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How to build intuition for tuning a Kalman Filter?

I'm working on designing a Kalman Filter for more accurately predicting the position of a ultrawideband RFID tag in an indoor space. Before testing with live data, I've been playing with randomly ...
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Wireless Channel Modelling - LOS

Let $T$ a transmitter and $R$ a receiver in a wireless scenario. The two entities are in an outside scenario with Line of Sight. The transmitter $T$ sets its maximum power transmission $P_{TX}$ and ...
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3answers
69 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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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
112 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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Grading Images According to the Noise It Contains

I have collected a lot of dirty blank pages and each image is varied in the noise it contains. How will I grade images according to the noise it contains in terms of amount, and other aspects? What ...
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1answer
21 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
35 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
40 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
67 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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0answers
36 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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0answers
34 views

Information entropy of Poisson noise

I would like to calculate the information entropy of the channel with additive Poisson noise. The model consists of an input signal, an optical image, an image acquisition device, and the output ...
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0answers
18 views

Filtering noise from periodic time series

Apologies if this is answered elsewhere, but I'm not a signal processing expert and am probably not using the right words to describe my problem or search for answers. I'm tracking people's feet ...
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1answer
187 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
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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
54 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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1answer
39 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
76 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
70 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
37 views

SNR estimation prior to demodulation?

What are the standard ways to measure SNR, particularly before demodulation/synchronization?
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36 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
39 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
36 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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