Questions tagged [noise]

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

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27 views

How to use a boxcar averager in conjunction with lock-in amplifier

Suppose there exists a temporal voltage signal composed of short pulses, modulated by a sinusoidal envelope. One desires a hardware-based signal processing scheme to maximize signal to noise ratio (...
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58 views

The Effect of Spatial or Temporal Averaging on Noise Properties

I generate two noise images using MATLAB's function imnoise(). If I average the two noise images, the resultant image looks like the original noise image but only ...
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76 views

Calculating complex AWGN in BPAM and QPSK

I was trying to add complex AWGN in a BPAM and a QPSK signal, manually. However I started using formulas as it is shown below (e.g. in BPAM) but the result was not the expected (also using as a ...
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Filtering out motion noise from ECG

I have some ECG data that have some noise from motion in it. I also have have accelerometer data sampled at the same time. The idea is to use the accelerometer data to filter out motion noise from the ...
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60 views

How Can I correct amplitude and smoothness of FFT?

I am trying to create 10 individual signals with on-off keying modulation format, add them up to have a final signal, and then take a Fourier transform of that signal. I tried to zero padd the final ...
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1answer
44 views

How does sampling jitter affect state estimation?

Suppose I have some process which is governed by: $$ \vec{x_{k+1}} = A\vec{x_k} + B\vec{u_k} + w_k$$ where $u_k$ is the input, and $w_k$ is process disturbance. This process is continuous time in ...
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25 views

Estimating change in RMS of noise given FIR filter coefficients

Filtering noise leads to a change in the overall RMS of the noise as demonstrated by the following code-block. which uses scipy's firwin2 to calculate the taps. The ...
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2answers
305 views

Conversion of dBm/Hz into watt

I have a noise power density of -174dBm/Hz and a bandwidth of 180kHz. How to convert the resultant noise into watt. I am confused. First, multiply (-174dBm/Hz) by 180000, then convert the result into ...
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1answer
51 views

Could alternative SNR definition be converted into dB unit?

There is alternative definition for SNR that mention in this wiki page It is: i.e. mean per standard deviation, Is it possible to convert this SNR value into dB unit? without knowing the power of the ...
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What is the best approach to cancel realtime noise from a participant audio for conference purpose?

I am new to audio signal processing and I wanna do real-time noise cancelation for a participant in a conference. I am capturing audio at 16bit, 16khz, little-endian config. I tried to use the webRTC ...
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1answer
51 views

Simulating Es/N0 by adding noise to analog signal

I believe I am familiar with simulating $E_s/N_0$ by adding noise to the output of the matched filter, but what would be the correct way to simulate $E_s/N_0$ starting with the analog signal at the ...
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Eliminating shadow-like noise from wafer map images

I'm trying to eliminate a shadow-like noise from the wafer images and only leave the most prominent defects as shown in Image1 below. I thought I could treat it like salt-and-pepper noise. Hence, I ...
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61 views

White noise does not contradicts Wide Sense Stationarity?

I am studying White Noise. But I am really beginner level, so I have a confusion with its construction. White Noise is usually defined as a Wide Sense Stationary process $N=\{N_t\}_{t\in T}$ (for $T$ ...
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How plausible is undetectable (covert) radio communication?

Ever since I found out that coding gain allows you to receive a signal that is well below the noise floor I have been fascinated with the idea of covert radio signals (low probability of detection). ...
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61 views

dimensions of the autocorrelation function of white noise

My question concerns the dimensions of the autocorrelation function of the white noise. First is a short summary of what I understand about the random signals. If we have a stationary random signal $x(...
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Removing noise from an audio file only in time domain?

Hello I am doing some work for a course and I need to take an audio file and remove the noise from it. So far I've removed the noisy signal which is a 1000Hz pure tone using the frequency domain. I ...
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1answer
34 views

Why the received SNR increases with bandwidth?

I am performing the following simulation: Complex chirp signal with bandwidth [-B, B] is transmitted through a multipath channel which has $N$ taps all being complex Gaussian variables (i.e., ...
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59 views

Black dots in spectrogram

Whenever I zoom in on the spectrogram of a recording I made with my phone I see these strange dark dots, unfortunately I cannot try another phone. What is causing them? They seem randomly distributed ...
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1answer
27 views

Too low measurement error Q (much lower than real measurement noise) in Kalman Filters

What do we expect by setting a too low measurement error in a Kalman Filter model, much lower than the noise existing in the measurements? And why? Let's say we simulate some measurements and we add ...
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1answer
543 views

Is Allan variance still relevant?

I've been working with Allan variance for a while and I'm not really super excited about is purpose. I understand that noise time recordings, if they include flicker noise, diverge in time. In other ...
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44 views

Measuring level of background noise in a recording of a known audio file being played in an environment

I'm trying to solve the following scenario: A digital music player plays audio in a public space I have a microphone recording that audio in the space I want to compare the noisy recording and the ...
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11 views

How to use numpy covariance result to get a correction factor and make my second signal to exactly overlap on my first signal?

covariance = np.cov(y1_interp, y2_interp)[0][1] print('covariance is', covariance) covariance is 0.00010861874695023591 This number shows how different my signal 2 ...
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$\frac{\mathbb{E}[P]}{\mathbb{E}[N]}$ vs. $\mathbb{E}\left[\frac{P}{N}\right]$

This is a very simple question arised from my considerations in here: Log-normal shadowing and mean power. I have understood that SNR is often defined as $$\frac{\mathbb{E}[P]}{\mathbb{E}[N]},$$ but ...
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51 views

How to remove noise from the signal? [closed]

I'm new to DSP and currently working on time-series data. The mentioned time series (of Toe) is extracted from a video tracking various body parts of an athlete. Ideally, there shouldn't be any ...
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1answer
77 views

Noise Variance and Sampling in the Linear Regression Context

I am new to signal processing, so please bear with me. My question applies to any general problem of estimation from noisy measurements but I will like to understand this through a problem given here. ...
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1answer
122 views

Generating violet noise with a specific PSD coefficient

I am trying to generate a time-domain violet noise signal with the following power spectral density (PSD): $$ S_n(f) = A^2f^2 $$ Unfortunately, I am having trouble finding the right amplitude ...
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Estimating shot noise - what's the origin?

If I have some photon detector, say a CCD, how do I estimate the error introduced by shot noise correctly? Typically, sources found on the internet say that the shot noise is the square root of the ...
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1answer
61 views

Help generating non-Gaussian noise

I'm trying to add non-Gaussian noise to an image. The purpose is to synthesize realistic camera noise. I am doing the following: Obtain a noisy image sample by subtracting a low ISO photo from a high ...
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2answers
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What kind of noise features should I know before removing them programmatically?

This is my first question here in DSP StackExchange and honestly speaking I don't have any experience in this field, but one of the school project I'm currently working in is building an application ...
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1answer
48 views

Time warping / frequency modulation natural examples?

"Time warping" defined as $$ x(t) \rightarrow x(t - \tau(t)) $$ where $|\tau'(t)| < 1$ ($=1$ is time stopping, $=0$ is time shift, $>1$ is time reversal). Where can this occur? A ...
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59 views

How to smooth wiener deconvolution result in Python?

I'm wondering if it is possible to smooth the estimated response from a Wiener deconvolution in order to have a better representation of the original signal and to remove the side lobes. (Here an ...
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1answer
45 views

Noise model as Sinc function

In "Fundamentals of signal processing: estimation theory", example 3.13 Kay has used a model of band-limited Gaussian noise with a uniform PSD and a sinc autocorrelation function. I expected ...
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How to convert SNR to Eb/N0 in Chirp Spread Spectrum modulations

This question is related to Conversion between Eb/N0 and SNR in spread-spectrum modulation like LoRa CSS?. However I couldn't solve my issue. I'm simulating a Binary Orthognal Chirp Keying ...
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1answer
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A filter removing forbidden information in the stop-band

Is it possible, and how could it be done, to make an extension of filters that converts the signal in the filter's stop-band into noise with no information content or at least with zero correlation to ...
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1answer
61 views

Impulse response $h[n]$ of a non linear I/O equation

my question concerns an assignment that was given to us at school. We have been given a list of I/O equations and it is required, for each of them, to find the impulse response $h[n]$ and the ratio ...
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1answer
50 views

Having trouble working understanding a noise shaping filter

As context, I'm trying to understand and implement this Von Karman turbulence model in a simulation I'm working on. In order to generate turbulence velocities on the fly using the model, a ...
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1answer
87 views

How to predict the final noise after adding two or more noisy discrete signals?

Is it possible to accurately predict the noise level if we add two or more noisy signals. For the sake of simplicity, let us say, the noise is independent and Gaussian. Suppose we wish to add signals $...
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1answer
84 views

Phase Noise and Multi-carrier Frequency conversion

I have a oscillator with a phase noise mask that was represented in dBc at specific offsets from a carrier. Two options for a multicarrier signal going into a converter, apply the phase noise mask (...
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1answer
43 views

Is "Introduction to Statistical Signal Processing" by RM Gray good for starting?

I am working on noise processes in electronic devices for my studies, by now Ive been doing a fairly large amount of processing of time measurements, like calculate PSD, estimate thermal, flicker ...
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2answers
83 views

Why does adding white noise improve the calculation of frequency of a sine wave in the time domain?

I created short audio files with a sine wave (tone) having a set frequency, and added varying white noise to it generated by a random number generator. I wanted to code and test the simple algorithm ...
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1answer
82 views

When to zero-mean a signal?

I have two sets of signals. The first is a noisy sinewave, which I zero-mean before taking the FFT since I need to find the amplitude. The other is essentially noise with a gaussian distribution. I'm ...
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56 views

How to reduce phase noise in radar?

Instability of oscillator can introduce phase noise to the signal received by radar [1]. Are there commonly used digital signal processing methods can reduce the phase noise? [1] Aubry, Augusto, et al....
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1answer
43 views

Reduce signal length while maintaining properties?

I am new to DSP. So I have a noisy signal with some high-frequency components. I was able to characterize the statistical properties of this signal through a gaussian distribution. My aim is to run a ...
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1answer
94 views

AWGN noise variance in upsampled BPSK signal

When I simulate BER for basic PSK schemes, I set the IQ complex noise variance to $\sigma^{2} = \frac{E_{s}}{2*R_{m}*R_{c}}*\left( \frac{Eb}{No}\right)^{-1}$ where $E_{s}$ = Energy per modulated ...
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1answer
57 views

How this convolution integral is solved to obtain autocorrelation function of current for shot noise?

I am studying shot noise characteristics from this source: Here the author writes that autocorrelation function is given by: $$R_I(\tau)=\bar{h}*h*R_Z(\tau)$$ where $R_Z(\tau)=q^2(\lambda^2+\lambda \...
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17 views

Calculating threshold in white noise for multiple pulses

I want to calculate the threshold for a given probability of false alarm (PFA) in a system, in which the noise is given by a coherent summation of three white Gaussian noise signals. Of course, there ...
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Remove Noise from Discrete Signal with given Noise Model

I am interested in finding the true signal $p \in \mathbb{R}^D$ of an observed discrete signal $t \in \mathbb{Z}_{+}^D$. I know that each observed $t_{i}$ with $1 \leq i \leq D$ is the result of a ...
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1answer
123 views

The power of signal processing when faced with hardware constraints

I am currently studying interferometry, but I have only just begun studying signal processing. I want to better understand the effect signal processing can have in maximising signal detection from ...
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1answer
34 views

Classification of very noisy EMG signals

I'm an absolutely newbie to signal processing. I'm trying to classify EMG signals which are very noisy (decibel values are more than -70 dB in some cases). After applying EMD technique these values ...
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1answer
88 views

How to extract noise from a signal in order to get both noise power and signal power

I have to implement a function to get an accurate SNR value. For that, I would need a separate noise signal to get the signal power and noise power but I have only one noisy signal (a .wav file.) ...

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