Questions tagged [noise]

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

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Averaging data from 2 sensors

Suppose we take a reading of a single rotating axis using 2 identical sensors. Intuitively, I think that averaging the outputs of both sensors will yield a less noisy result. But what if sensor A has ...
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2answers
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How to detect defects at a contour?

I am detecting a contour of a smooth metal. I do binarization first then use openCV contour function. But sometimes the metal has defects such as dots or dusts at edge. This leads a unsmooth edge. Is ...
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Given a -3dB/ octave filter that makes Pink Noise, how can I make a +3dB/ octave filter that makes Blue/ Azure Noise?

I learnt from here that the following filter can turn white noise into pink (-3dB/ octave). ...
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Seeking advice on how to denoise a video from poor CCTV lighting

I have grainy CCTV footage that will need some amount of clean up. I request for ideas on the best way to clean out the noise. I am attaching a frame extracted from the video here for hints on the ...
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1answer
47 views

Why do I keep seeing this equation for $E_b/N_0$

I keep seeing $$\frac{E_b}{N_0} = \frac{E_\text{s}}{\rho N_0}; ~~ \rho=\log_2{M}$$ But my own calculation is: $$\frac{E_b}{N_0} = \frac{E_s}{N_0}\frac{1}{k}$$ Where $k = \frac{\rho n}{ms}$, where $\...
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Removal of parallel-line like streaks

Just wondering what image processing techniques can remove some artifacts of parallel-line like streaks, which are shown in the red box in the above picture. I was thinking about removing it from ...
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1answer
35 views

Noise removal in discrete signal

How do i remove these kinds of noise from the discrete signal in python?
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2answers
238 views

Increasing SNR and Dynamic Range using Oversampling

How much gain in dynamic range and SNR can be expected if we are to oversample a signal with fixed analog input bandwidth. For Example if I have a analog filter at the input which limits the bandwidth ...
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1answer
83 views

How is signal to noise ratio actually measured by receiver equipment?

This sounds like quite a basic question but it surprised me, how is SNR actually measured? You have the incoming signal: It seems like the SNR is just the visual comparison of the peak signal '...
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2answers
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Determine the Signal Curve from Parameters of a Power Curve by Noisy Measurement

I have a class of signals described by function: $$ f(inc,d,t)=inc\cdot t^d $$ where inc and d have a finite set of values like 1, 2, 3, i.e. $$ inc, d\in \left \{1,2,3 \right \} $$ and $$ 0\leq t<...
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Wavelet denoising. Simple explanation

I am studying wavelet transform. In the matlab in the "wavemenu" package, I use "SWT denoising 1-D". I loaded my signal, performed a Haar 5 wavelet squelch. I got a good result. I ...
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How can I add any kind of noise to image for a given SNR?

What is the best way to add any kind of noise (not only Gaussian noise) to 2D signal (image) for a given SNR?
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Additive noise meaning

What is additive noise? What actually additive means? I have tried to search in the internet but the only answer that I get is the noises gets added therefore it is additive, which make me think that ...
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Colored noise and adjusting covariance matrix with change of frequency

Assume a signal sampled at 2Hz. Assume it is a colored noise with known PSD. The measurement equation to be used in a Kalman filter requires a covariance matrix. If I want to sample at 9Hz (for ...
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1answer
93 views

Finding Minimum SNR or Minimum Detectable Signal Based on Noise Spectral Density

Imagine I have an $n$-bit sensor, whose noise spectral density is $V/\sqrt{Hz}$. $V$ is an exemplary measurement unit. The desired measurement bandwidth is also known. Is there a mathematical way to ...
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Decoding packets in Long Mode Range

Im using CC1350 launchpad microprocessor of Texas Instrument that I configure my transmitted packets using SmartRF studio Im trying to decode my packets for verifying if my transmitted packet is valid ...
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1answer
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awgn function in MATLAB

I'm using 'awgn(input_signal,snr_db,'measured')' function in MATLAB to add white noise to the input signal. Here is the simplified script. Does zero padding the input signal affect the behavior of ...
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1answer
138 views

Generating digitized white noise: uniform vs normal sampling

Consider the following two ways of generating noise in the time domain for audio applications: Generate samples from a uniform distribution [-amplitude, +amplitude]...
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1answer
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SVD based noise filter

Given a sequence of length $2N$ $$ x[1], x[2], \dots, x[N], \dots x[2N] $$ We can construct the following matrix along with its SVD. $$ M = \begin{pmatrix} x[1] & x[2] & \cdots & x[N] \\ ...
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What is the point of smoothing an FFT or spectral density plot, and how does that affect the noise floor?

It appears that smoothing the FFT or spectral density plots of a noisy signal is a common practice. I see that common tools like MATLAB and Python have functions built in to their FFT tools to do just ...
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1answer
57 views

How many bins to include when calculating SNR from FFT?

I'm a scientist conducting an experiment that requires some signal processing. My expertise is not in signal processing, thus here I am. We've basically re-created an experiment conducted by other ...
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How can a thresholding method in discrete wavelet transform be adaptive and denoising is performed level independent?

I am a bit confused regarding the thresholding methods and noise estimation options found in Matlab regarding Discrete Wavelet Transform. Please correct me if I am wrong. I am understanding that noise ...
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2answers
107 views

Find the Equivalent Noise Bandwidth

I have already asked (in another thread) how to quantify (specify) the window function I have created. One figure I need it seems is the Equivalent Noise Bandwidth (ENBW) Or Noise Equivalent Bandwidth....
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Why my signal is so noisy?

I have started analyzing a signal from a MEA experiment that consists of reading from electrodes inserted in a brain slice. Anyway, the signal is sampled at 2 KHz but the readings we have are very ...
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538 views

Quantization SNR of sine wave doesn't match 1.761 + 6.02 * Q

I am trying to show with numpy that the quantization noise of a sine wave matches the SNR formula of SNR = 1.761 + 6.02 * Q. The numpy code is simple: ...
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Signal processing on hourly atmospheric temperature, wind speed and humidity data for solar panel maintenance

I am working on a machine learning problem, where i have to predict if a device connected with solar panel at a specific block has been damaged. I have many factors to consider, out of which ...
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2answers
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How to plot thermal noise in the “time domain”?

$P = 4kT$ (where $k$ = Boltzmann’s constant, and $T$ = temperature of the instrument ($K$)) And the mean voltage is thus, of course, $V^2/R = 4kT$ And the voltage is distributed as a Gaussian around ...
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1answer
58 views

Removing Gaussian Noise from a Signal to Get Minimum Value

I have a signal that has a minimum value that I'm trying to read. The issue I'm having is that the signal is spread out by gaussian noise. I have the signal at a lot of timesteps (and expect the ...
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2answers
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Recover an OFDM signal affected by AWGN

I have an OFDM signal affected by AWGN, if I know the power of the gaussian noise, can I recover the OFDM signal? Can I perform deconvolution to recover the original signal? thanks
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1answer
167 views

DC bias from ADC in frequency detection scenarios

In real-world applications where a frequency or multiple frequencies need to be detected from a digital signal that comes from an analog-to-digital converter (ADC), what are the typical 0 Hz (direct ...
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1answer
55 views

Es/N0 with roll-off

I was trying to figure out if the relationship between SNR and Es/N0 changes with roll-off factor. $W$: RF bandwidth. $B$: Base band bandwidth. $W = 2B$. $E_s$: Symbol energy. $P_s$: Symbol power. $...
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87 views

Why is the relationship between Es/N0 and SNR different for complex and real signals?

I try to use the AWGN Channel model of MATLAB to build my simulation model, but the explanation of the relationship between Es/N0 and SNR in the official manual of MATLAB makes me confused. It says ...
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19 views

Filtering a noise of F[sig] frequency [Example 20Khz] in measurement system

I am developing a system where there is inherent noise of F[sig] frequency. This is a DC measurement system and want to get rid of the noise by sampling at F[samp] samples per rate and taking multiple ...
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1answer
76 views

noise floor of attenuator

NF of attenuator is same as the attenuation value as the noise floor remains same but signal level gets attenuated? But NF of amplifier depends on the device as it increases both signal and noise?
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“How is the noise floor of RF section is mapped to ADC noise floor for a 10MHz BW?”

My interpretation is if a gain of 40 is used before AGC -40 dBm become 0 dBm and -121dBm (noise level) becomes -81dBm SNR remain same (assuming NF =0 for theretical purposes). Noise floor of ADC is (6....
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Legacy LongRange Mode information (mode 1 in the my attached link)

Mode 1- Legacy Long Range Packet Format and Im attaching a photo of ti reference: link for more information about this mode category : TI SWRA642 I want to understand the packet format, what's my ...
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Why does this maximum entropy method for noise removal not work?

I am trying implement the maximum entropy method (MEM) for image reconstruction or spectral filtering (based on various papers, e.g. "Image Restoration by a Powerful Maximum Entropy Method" ...
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1answer
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Conceptual Questions on Colored Noise Process

I am having a tough time finding answers to some specific questions and finding references where there is information regarding Brownian noise or Red Noise. I'm referring to white and colored noises ...
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1answer
63 views

Respiration (breathing) signal movement artifact removal

Situation: I have breathing data of participants who have done different things during the study which caused their breathing change; watching mindless video to which resulted in unconscious regular ...
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1answer
77 views

How to calculate variance of noise on a noisy image (Noise+Signal)

I have a long exposure image captured at 70ms. (I1) (As attached) I also have another image captured at 0.7ms with Gain24. (I2) (As attached) This image has both noise and signal together. I would ...
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How to check my CRC of my RF packet? [duplicate]

The "problem" is that I want to validate if my received RF packet is valid or not valid, in other words I want to validate if my RF packet corrupted or not corrupted . the transmitter that ...
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3answers
348 views

Is white noise WSS by nature or not?

I want to know what is the difference between white noise and WSS white noise. is there any difference between them or they're equal? and what about white Gaussian Noise?
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LPF Filtering without changing DC value of signal

I have sampled my transmitted signal, it's looks like sinusoidal , frequency sampling is =2048Khz, bitrate of transmittion=100Kbaud , and my problem is that I have designed in matlab my LPF filter ...
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1answer
58 views

Low pass equivalent of bandpass white noise

Let $$n(t) = Re\{z(t)e^{j2\pi f_ct}\},\ $$ where $z(t)$ is the low pass equivalent of white noise $n(t)$. We know the autocorrelation of $n(t)$ is $$R_n(\tau) = \frac{N_0}{2} \delta(\tau),\ $$ $\delta(...
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1answer
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Matched filter for recieved RF digital packet by LPF

Im transmitting by cc1350 launchpad microprocessor digital RF Packets, transmitted modulation FSK. bit rate of transmitting is 50Kbouad, frequency of transmitting is 868MHZ . Im sampling the signal(...
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1answer
27 views

How does filter works in noise reduction?

On page 22 of the slide, the 1D array is [1, 1, 1, 1, 1], but the dots are uneven. Then why their values are the same? What's the value of the point that the arrow is pointing at? Though it gives ...
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filtering my received Signal by LPF

I've received my transmitted signal that I sampled it on 20480000 frequency , transmitted frequency 868MHZ , bitrate 100KHZ , I see the "bits" that Im transmitting in my plot in matlab it ...
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Converting Received RF packets to binary file that RF packets sampled by dongle rtl-sdr

Im using #SDR software that I transmit packets from cc1350 launchpad to the air and I want to validate that if those packets are valid or not by checking its CRC. my problem is actually the step to ...
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1answer
31 views

Plotting a Time Frequency contour/colormesh plot of a Discrete Wavelet Transform

I have a pressure vs time data of a noise on which I wish to perform discrete wavelet transform. I have divided my frequency range into 1/3rd Octave Bands and have calculated sound pressure level at ...
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1answer
66 views

Showing that the sum of zero-mean noise is zero. Then computing the convolution of zero-mean noise with a given function

This is likely to be a quick fix for people with experience in stochastic processes. Let $ \eta[k] $ be a sequence of Uniform noise, $ \eta \sim U([-M,M]) $. I want to test if the following is correct ...

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