Questions tagged [signal-analysis]

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If you would write the frequency-response in terms of projections through inproducts. How would you do it?

While studying for signals and systems I realised that the most intuitive way of understanding Fourier Series for me, was to see it as a projection (through inproducts) of a signal onto the orthogonal ...
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3answers
5k views

Interpreting the FFT results of a structural vibration problem

System: Cantilever beam type models, with an accelerometer on the end. The beam base is excited at various frequencies in harmonic fashion on a shake table. This results in vibration in the beam. The ...
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1/3 Octave Analysis

Good Morning! I am new in signal processing and I am trying to do a work in noise control of an electronic steering lock device (ESL). My aim is to calculate the loudness (Zwicker Method- ISO 532 B) ...
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1answer
140 views

Wavelets and bank filters

The wavelet transform has a problem as it gives poor time resolution for low frequencies and poor frequency resolution for high frequencies according to uncertainty conditions. This appears well ...
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1answer
55 views

Beamforming but only for total power?

Is there a method to speed up beam-forming if you only care about the total power in a given direction, or total power in frequency groups? I've googled this, and can't find anything. My intuition ...
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1answer
2k views

Computing the Power Spectrum Density (PSD) on a CSV File in Python

im quit new with signal processing and im trying to calculate the PSD of a signal im sampling. the signal is an output of a DC buck converter this is the code im using and this is the plot im getting ...
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2answers
185 views

Prove that, in DFT, Upsampling in time domain is equal to replication in frequency domain

Given: $x[n]$ is an $N$-point sequence whose DFT is $X[k]$ $$x[n]\xrightarrow{\mathcal{DFT}} X[k]$$ then, Prove that: DFT of the same sequence after insertion of $(M-1)$ zeroes between successive ...
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1answer
417 views

Recover IQ samples from signal

I have a data acquisition device that provides me with an array of integers that represents a modulated signal (let's say QAM16). I would like to recover the I and Q samples from the raw time-domain ...
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2answers
19 views

transmitting the real/imaginary parts of pass-band signal

As I know, the transmitted pass-band signal whose carrier frequency is $f_c$ can be written as follow: $s_1(t) = \text{Re}(a(t)e^{j2πf_ct})$ , where $a(t)$ is the complex modulated base-band signal. ...
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1answer
34 views

What is the difference between positive matrix coefficients and negative matrix coefficients of an audio?

I have turned an audio file into an one dimensional array by using audioread function in matlab and found several positive and negative fractional coefficient values.What is the basic difference of ...
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16 views

Showing specific values in an STFT plot

I have a short term fourier transform plot that I plot using matplotlib's pcolormesh() function: If I zoom in the plot, I see this: Now, I want the plot to just ...
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Maximum Value of DSNR in Detection of Signals in Noise Second Edition

I am interested in problem 8.5 of Detection of Signals in Noise, Second Edition. The problem calls for finding the maximum value of DSNR. I have done so, but my solution does not agree with the ...
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1answer
118 views

application of wavelet to vibration signal

I ask you to help me to interpret this figure corresponding to a diagnosis of gear failure using CWT (Haar); I have already worked on the analysis of the vibratory signals using the FFT; But since the ...
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1answer
134 views

Distinguish between sinusoidal oscillations and rythmic pulses

I want to distinguish between a sinusoidal oscillations and rythmic pulses. Which method can i use to do that? I want to implement a detector that can distinguish between this two types of signals. ...
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1answer
91 views

GPS Code Phase usage

During Cross-correlation process: xcorr=ifft(fft(a)fft(b)∗) we have frequency offset and code phase offset. How is it used later in the process of finding a ...
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1answer
180 views

Overlapping power-of-cosine windows with constant weight

I would like to refer you to a relevant question I posed on the Math StackExchange: A generalisation of the Pythagorean trigonometric identity. As can be seen from the question and the answer, what ...
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1answer
53 views

Measure 3-D length using smart-phone's accelerometer

I'm wondering if we can measure 3-D length only by our smart-phone's accelerometer. And we all know these low cost IMUs are not accurate. You can model accelerometer's error this way: $$ a = f*a' + g ...
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1answer
101 views

Separating/recovering base signal from two mixed signals, given phase information

I have collected two signals, $B_1(x)$ and $B_2(x)$. The signals start and end at the same $x$-values. Each signal $B_i(x)$ contains: a base signal $b(x)$, which is the same for both, and a signal, ...
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1answer
532 views

MFCC Classification

I'm working on gender estimation from speech signal and I completed MFCC feature extraction. So now I'm trying to estimate gender from these features. But I have frames for an audio file and I ...
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1answer
66 views

Finding the Sections of Signals that are the Most Similar

I have two discrete signals, $A$ and $B$ (both with $L$ values). I want to look for the section (of a certain length $R$) on each signal ($[A_1:A_1+R]$ and $[B_1:B_1+R]$) where they are the most ...
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1answer
36 views

Different number of modes while performing the EEMD (Ensembled Empirical Mode Decomposition)

I am performing an Ensemble Empirical Mode Decomposition (EEMD). I wrote a MATLAB routine to perform the EMD. I noticed that when adding white Gaussian noise to the input signal, sometimes I obtain a ...
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1answer
46 views

How to determine the shape along which an object is moving [closed]

The object moves as it pleases and receives its GPS coordinates. How to determine which shape the object is moving along? For example, we accumulated 10 points, processed them and produced the result: ...
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26 views

Remove noise from VGA image

I have 2 color images generated from same X-ray machines, but one of the image is obtained using VGA cable. Therefore the RGB intensities differ in the 2 images. I am using Object detection to detect ...
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1answer
46 views

Frequency Domain Distribution

I have a complex signal in the time domain normally distributed. What will be its distribution in the frequency domain? I assumed since the frequency domain is a linear transformation the distribution ...
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1answer
271 views

Phase Modulation and Intermodulation Anomaly ? (Spectrum plots inside - **Updated**)

I have a MATLAB script for modelling a two tone signal (a sum of two sinusoids) going through a non linear transfer function (such as an amplifier). The amplitude of a signal is amplified non linearly,...
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36 views

Reconstructing a signal from multiple filtered copies using overlapping tapered windows

I have an audio signal that I need to process and analyse in blocks. I've now decided to process it using overlapping non-symetric Hanning windows of length M = 9600 and a hopsize of R= M/2. I zero ...
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5answers
4k views

Why complex numbers are represents as a+ib and can't be as (a,b)?

I am confused as why do we need to represent the complex numbers with the imaginary y-axis if we can simply represent them as (x,y) ? I've read that Multiplication by i is an anti-clockwise rotation ...
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1answer
90 views

Audio from multiple microphones mixed to mono and ASR

I am trying to do speech recognition on an audio file which has 1 channel (mono). My problem is that the channel is comprised of the signal of 3 microphones which have captured the audio at different ...
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23 views

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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2answers
143 views

Augmentation for EEG signal classification using Deep Learning

Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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1answer
341 views

How to make sense of audio file's $\textrm{dBFS}$?

I'm trying to build a song visualizer using the FFT method. When I analyze the audio, I get the $\textrm{dBFS}$ value for each frequency range. From my understanding, $\textrm{dBFS}$ is in the range ...
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1answer
122 views

How to apply baseline methods to MNE preprocessed raw EEG signals?

I am new at EEG preprocessing and classification. I have followed Clemens Brunner's blog https://cbrnr.github.io/2018/01/29/removing-eog-ica/ as a tutorial for MNE. This is how I have preprocessed ...
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1answer
35 views

Calculating SNR of a complex-valued signal correctly

I have an array of complex-valued data. I would like to modify the array by injecting an artificial signal at a chosen Signal to Noise ratio. I have seen the signal to noise ratio for complex-valued ...
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53 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
37 views

What is the actual format of this audio file?

I am collecting some data from jotform .wav widget. All the audio files are in .wav format. But when I tried to open the file using python ...
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3answers
147 views

Signals - question due to sampling

I don't have an idea how to start it. Help pls :) $$m = z(t) + \frac{\operatorname{Sa}(t-T)}{4}$$ We have some signal $z(t)=\left(\operatorname{Sa}(\frac{t}{T})\right)^2$. How often the m signal ...
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16 views

MPEG Audio Constant bit rate conversion

I am trying to convert few .wav files to .mp3 format The desired .mp3 format is : I tried with FFmpeg with this code : ...
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0answers
26 views

How to measure EVM?

I am trying to understand the concept of EVM and how it is measured at different points in transceiver. I have a basic understanding that the error difference is calculated between two vectors (i.e. ...
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2answers
148 views

Autocorrelation and Spectrum Density

Wiener–Khinchin theorem states that autocorrelation function and power spectral density are a Fourier-transform pair - see Wikipidia (and lots of other resources). That means autocorrelation should be ...
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1answer
224 views

How to detect the maximum resolvable spatial frequency of camera?

I am trying to calculate the minimum line pixel width that can be distinguished from noise as shown in the camera test chart in Figure 1 where the thinner lines on the left are getting more and more ...
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32 views

How to implement Walsh demodulation in matlab?

1 1 1 1 ==> 0 1 -1 1 -1 ==> 1 1 1 -1 -1 1 -1 -1 1 I have this sequence of walsh spreading ...
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1answer
28 views

Having Problem about DownConversion

I hope, you are doing well. I want to ask question about baseband conversion. Background: I generated two AM signals in MATLAB, which one of them is shifted in time. I multiply the signals with $\cos(...
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1answer
57 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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1answer
59 views

How to make signal smooth using filter?

I have measured the output of a mechanical system and obtained the signal shown at the attached image. I want to make it smoother by removing the chattering (I think it is called chattering). In order ...
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1answer
39 views

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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2answers
70 views

Output of marginally stable systems

In' b.p lathi's book of systems and signal it is written that "marginally stable systems have one important application in the oscillator, which is a system that generates a signal on its own ...
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2answers
209 views

Significance of sequency ordering in Walsh-Hadamard matrices

So I've been doing some reading into Hadamard and related matrices (Slant, Walsh, , and have observed that there are three typical "orderings" of the rows based on various criterion. E.g. "Natural", "...
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1answer
61 views

Similarity or Relation between Walsh Hadamard Transform and Slant Transform

Is there any relation between Walsh Hadamard Transform and Slant Transform? Or is there any common property or similarity?
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1answer
85 views

About the variance of the coefficient of narrowband noise when using signal-space representation

Assume that n(t) is a white Gaussian noise process with zero-mean and power spectrum density $N_0/2$. By using the signal-space representation, it can be expressed as: $$n(t) =\sum_{j=1}^N n_j \phi_j(...
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1answer
133 views

A-weighted Digital Filter for 1/3rd Octave Band Analysis

I want to do a 1/3rd Octave band analysis on a noise signal. But the sound pressure levels should be in dB(A), i.e., and it should be A-weighted. For this, I am using the A-weight function from this ...

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