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Questions tagged [signal-analysis]

The processing of signals for the purpose of extracting a parameter or property embedded in a signal. Signal goes in and far fewer numbers come out.

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6 views

How to utilize product graphs in graph signal processing?

I'm working with dynamic graph signal processing. How to plot time variation and spatial variation separately and take the cartesian product of those two graphs? Any relavant Matlab codes?
2 votes
2 answers
206 views

Detect and Localize Abrupt Changes on a Noisy Non Periodic Signal

I have a set of some 5000 x,y datapoints. They plot a smooth curve with large gradient and curvature at the right. There is high-freq noise that varies in amplitude from dataset to dataset, but the ...
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2 answers
60 views

Can Autocorrelation be used to Differentiate Signal Quality (High, Medium, Low, Very Low) for Periodic Signals?

I'm working on a project to classify the quality of periodic signals into four categories: high, medium, low, and very low (noisy). I was initially exploring autocorrelation as a potential feature for ...
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1 answer
69 views

Simulation of Doppler shift in C/A code

I am trying to simulate C/A code under the effect of a doppler shift. Let's say the doppler shift is 5000Hz. I am assuming an ideal scenario where I can down convert the GPS to its baseband of 1....
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24 views

Power spectrum: $uV^2$ scale

I was reading a paper and found this figure: The paper defines slow wave activity as the mean power in the slow wave frequency band (0.4 to 5 Hz). I'm used to seeing power measured in "raw power&...
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1 answer
54 views

why are the coefficients different when I design an IIR bandpass filter using butter compared to using the Filter Design Toolbox?

In matlab, for the same parameters, why are the coefficients different when I design an IIR bandpass filter using butter compared to using the Filter Design Toolbox? When I run a command in matlab <...
0 votes
1 answer
246 views

Can someone explain me how the phase spectrum of trigonometric fourier series is related to phase spectrum of exponential fourier series of a signal?

Suppose we take a periodic signal and perform fourier analysis over it . Now we have two ways of representing the fourier series of this particular signal , one is trigonometric fourier series and ...
6 votes
2 answers
4k views

How to measure the smoothness of a signal

so how can i determine if a signal is smooth or not ? And if its possible to get something indicating the level of the smoothness of my signal. I looked at the r-squared and hurst exponent but i ...
1 vote
1 answer
36 views

Will open, edit, store from/to lossy audio format significantly degrade quality?

Say I have files only available as "ogg vorbis", 44.1kHz at 128 kbps vbr - which are meant for archival, but not much storage for lossless was available at the time. These are to be kept for ...
1 vote
1 answer
2k views

Order analysis on sample vibration data to detect unbalance in python

My main goal is to figure out how to do an order analysis in Python. For this I'm trying to do an order analysis in python to some sample vibration data I found here (with and without unbalance). I ...
-1 votes
1 answer
30 views

Statement on detectability based on relative height of abs max of spectrum

I have $2$ signals $s(t)$, $z(t)$ with the same energy $E(|s(t)|^2)=E(|z(t)|^2)=1$. However, the maxima of the signal spectra obtained with Fourier transforms verify: $\max(|S(f)|^2) \leq \max(|Z(f)|^...
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I want to generate a real time fft of vibration data from a triaxial MEMS accelerometer

I have been trying to generate a real-time FFT plot for my final year project on Condition Monitoring using a MEMS accelerometer (an MPU 6050) and an Arduino UNO. My goal is to generate a real-time ...
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1 answer
56 views

Is the analytical fourier transform of an exponential decay the same as the FFT of a time series of the same signal?

Analytical Fourier Transform of $e^{-t/2}$: FFT of a time series representation of $e^{-t/2}$: I'm trying to find the decay coefficiencts in tri-eponential decay signals, and as a logical starting ...
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1 answer
42 views

How single-tap equalization can be performed in OFDM for perfect channel estimation?

If I have for example IFFT length of 3 with cyclic prefix length of 2 and 3 channel taps, how can I illustrate the frequency domain equalization in OFDM? For example as far as I know, it's elementwise ...
1 vote
0 answers
44 views

How to improve quality of the recovered image in compressed sensing technology?

I was trying to use compressed sensing technology in image processing. Basically, I did a code in Python(Spyder IDE) which takes an image, compress the image and reconstructs it. I tried with the ...
1 vote
0 answers
42 views

ML-Classification of Motor Imagery EEG data only at 50% in MatLab

I'm trying to do ML-classification on some Motor Imagery EEG data and for a long time now I've been stuck at ~50% being correctly classified. This is my first time working with EEG data and signal-...
1 vote
1 answer
87 views

Removing DC bias

I have a signal that I have recorded from a AirSpyHF and want to remove a unwanted narrow signal with a notch filter (see figure). The spike in the image below appears to be a center spike, however it ...
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0 answers
40 views

Generating a whitening filter using MATLAB cceps() function

I have a few thousand realisations of a discrete stochastic process. I am trying to generate a whitening filter from these realisations. I am expected to use the MATLAB cceps() function to generate ...
2 votes
4 answers
2k views

Sawtooth wave Fourier coefficients

I have to calculate the Fourier coefficients of this signal. I found that signal equation is $$ y = \frac {A(2t-T)}{T} $$ To find Fourier coefficients I wrote $$ x_k = \frac{2A}{T} \int_{0}^{T/2} \...
5 votes
5 answers
2k views

Is it possible to find the FFT of a 1024-point signal by taking 8-input points at a time and calculating the FFT of those 8-points until the end?

Suppose the input signal has 1024 samples, and I want to take a 1024-point FFT. Can I instead take the 8-point FFT of the first 8 input samples then another 8 samples and continue this till the end? ...
0 votes
1 answer
84 views

Based on the eigen structure, What applications of discrete sine/cosine transformations can be found?

I am a PH.D in mathematics. I am interested in finding some applications of discrete Sine/Cosine transformations (DTTs) that are based on the eigenvectors. I have found some results concerning ...
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2 answers
98 views

How to remove known noise from acquired signals

what is the question: I have some time sequences(sampled at 0.5s and 3kHz which means every one of them has 1,500 points) from my force sensor. But I find the signal fluctuates wildly under no load, ...
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2 answers
533 views

Improvement of SNR by sampling different number of cycles using FFT of a fixed length singal

My question relates to Fourier transform of signals with different lengths in time but the same fixed length of the digitized signal with different sampling rates. Specifically, how does the number ...
0 votes
1 answer
244 views

Compute SNR of a signal with not clear fundamental frequency in PSD

I'm trying to compute SNR from a signal in which by visual inspection I can guess the SNR but I cannot compute it because I cannot find the fundamental frequency of the signal as I should be. On the ...
0 votes
1 answer
154 views

How to find frequency , location and phase of two sinusoid signal buried in noise?

There is a data set which has two different sinusoids buried in noise. Data record has following properties: A data records with a total data length of 2048 points. The sampling frequency is 100 Hz. ...
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32 views

Getting amplitude from messy signal

I'm working on analyzing some data from a grain boundary in an atomic simulation. I've got a lot of similar data to go through and am trying to determine a reliable way to get the amplitude of my ...
3 votes
2 answers
86 views

Maximum of the sum of different sinusoids

How to find the maximum sum of several (more than two) harmonic sinusoidal oscillations of the form $$y_n(t) = A_n\sin(2\pi f_nt+\phi_n)$$ with different amplitudes $A_n$, frequencies $f_n$ and phase ...
0 votes
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31 views

Can I get a resonance frequency from FFT power spectrum result?

I'm going through vibration analysis of cantilever by using FFT device but impact hammer input data isn't showing for some reason. So instead, I'm trying to get the resonance frequency by acceleration ...
0 votes
3 answers
74 views

very basic confusion about the bandwidth of constant signal function

I have a very basic question about bandwidth of constant function $f(t) = K$. As the Fourier transform of a constant pulse is a delta-function centered at zero frequency, the bandwidth (maximum value ...
0 votes
1 answer
97 views

Abnormal Y-axis value after performing FFT

I have an UFF file which consists of Vibration data. The objective is to convert the timewaveform signal to frequency domain. I have written a python script to convert the timewave form signal to ...
2 votes
1 answer
71 views

Frequency components in graph signal processing

As a mathematics researcher, I've delved into the intriguing realm of graph signal processing, yet I often find myself tangled in mental conflicts about certain aspects of this field. Any insights you ...
0 votes
0 answers
24 views

Spectral Theory: A Key to Unlocking Efficient Insights in Network Datasets

In the context of directed or undirected graphs, matrices such as adjacency and Laplacian matrices are commonly used. The eigenbasis of these matrices addresses some practical implications, such as ...
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1 answer
22 views

How to reorder the OFDM index before computing IFFT for CFR?

I used Intel 5300 NIC and the CSI tool to get CFR. I also want to apply for a IFFT to get CIR. Do I need to rearrange CFR before I apply ifft? The OFDM subcarrier indexes (for 20MHz) are: ...
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1 answer
988 views

what the difference between spectral density and the power spectral density?

What is the difference between the spectral density and the power spectral density, Or they are the same thing? In fact, I find this term in the book of GODA 2000.
1 vote
1 answer
77 views

Power Spectral Density and Total Power Calculation for Signal

I am currently working on analyzing a signal with the autocorrelation function given by: $$R(\tau) = 100 \cos( 10000\pi\tau) (Λ(2000\tau))^2$$ I need assistance in plotting the power spectral density ...
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31 views

DT System with input initially at rest

This is the very basics of Signals but my lecturer has provided barely any notes and I cannot find answers online (not just to this, but most of signals for some reason) Dealing with DT system: y[n]=y[...
1 vote
1 answer
351 views

How to calculate phase rotation of I/Q reference samples for Bluetooth Angle of Arrival

I am trying to compensate phase rotation due to carrier frequency offset (CFO) for Bluetooth Low energy (BLE) Angle of Arrival (AoA). In BLE AoA the adv. packets carry a Constante tone extension @...
2 votes
1 answer
2k views

Why does frequency sweeping double the frequency?

You can generate a signal with frequency f with sin(2*pi*f*t) where t is time. Yet, when I ...
0 votes
1 answer
36 views

How to reliably find audio interface recordings in mobile phone recordings

For scientific research, I recorded a few singers with several devices in a recording room. Two of these devices were proper microphones connected to an audiointerface, and they were positioned right ...
0 votes
1 answer
57 views

Frequency doubling of a signal with noise and without

I've been given a task to simulate a real-world scenario, in which a system receives a signal with a carrier frequency of 3.75 MHz. To filter the signal, either a very sharp and resource-intensive ...
0 votes
1 answer
66 views

Why the Discrete time fourier series coefficients of a real discrete time periodic signal are not symmetric about y axis?

If the signal is something like cos(πn/3) , we get the two DTFS coefficients that are symmetric about y axis and the resulting frequency spectrum is an even function . Now take the example given in ...
1 vote
1 answer
30 views

Amplitude Modulation in Scipy Documentation on Hilbert transform

I was reading the documentation on the scipy.signal.hilbert and an example was given there to illustrate the principle. To make it easier to understand, I copied ...
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1 answer
87 views

Is the magnitude spectrum of the Discrete Time Fourier Series of a Discrete Time periodic Signal , an even Function?

We know that the magnitude spectrum of a continuous time fourier series representation of a real periodic signal is an even function (i.e. symmetric about y axis). Does this hold true for discrete ...
0 votes
0 answers
21 views

Why is my target showing up with a non-zero centered velocity? I captured this data using the IWR6843A0P using a stationary corner reflector

I need help understanding what I should do to determine why my target is showing up in my Range doppler map with a non-zero centered velocity when I captured my measurement using a stationary corner ...
0 votes
0 answers
15 views

Real-world examples of unweighted directed graphs

Social Networks, Internet Traffic, Citation Networks, Transportation Networks, and Biological Networks exemplify real-world instances of unweighted directed graphs. Within these domains, the Graph ...
2 votes
0 answers
55 views

Baseline correction for XRD data in Origin

I have been trying to process the XRD data for a material, in Origin. I am an undergrad, new to the software, and while I have learnt to perhaps plot the data, I am not able to perform baseline ...
1 vote
1 answer
626 views

How do I get various peak values from a 2-D array or a matrix?

I'm working on 2D array analysis or an image analysis and get to know the different block of peak values marked "circle" in attached plot [e.g. 2*2 matrix] of the 2D array [as shown in Fig. ...
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39 views

Related to SNR in wireless communication

I am working on a research paper related to wireless communication, wherein I am facing some doubt while writing expression of SNR (which is a ratio of Signal variance in numerator to Noise variance ...
0 votes
0 answers
25 views

Fourier transform processing of iq data

I want to perform fourier transform on the iq data that is taken from spectrum analyzer. The purpose is to estimate phase noise from iq data.
5 votes
1 answer
103 views

The Amplitude of the Correlation Function Peaks After Matched Filtering

I have 2 signals: $s_1(t)$ and $s_2(t)$. The autocorrelation functions are given by $R_{s_1}(\tau)$ and $R_{s_2}(\tau)$ with $|R_{s_2}(\tau)|<|R_{s_1}(\tau)|$. I would like to know if the previous ...

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