Questions tagged [signal-analysis]

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1answer
712 views

Upsampling and zero order hold

Maybe to someone this question may seem quite easy but I have a problem grasping it. Namely, assume that we have two systems A and B with sampling rates $f_A$ and $f_B$ where $f_A>f_B$ and $R=\frac{...
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1answer
149 views

How to represent multiple related signals via mathematical function?

I have three data sets from same source. I know they are interdependent and stochastic also. The datasets are of very high frequency (see the graph, X axis is time and Y axis is value). I want to ...
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1answer
1k views

Short term energy signal explanation

I'm trying to calculate the short term energy of a digital signal in python, using a rectangular window, but don't understand the basics of how this works, a pointer to any good explanation would be ...
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2answers
68 views

Goodness of fit for complex valued curves (i.e. frequency responses in frequency domain)

My apologies for perhaps the stupidity of this question. Presume that one has the 'frequency response' $Y_{data}(k)$ of a system and also has an estimated model $Y_{syn}(k)$ that fits the data. How ...
2
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1answer
2k views

Onset Detection for Audio Signals

I am having a problem understanding how the author gets the onset envelope of an audio song in this paper. The entire section in question has been quoted below: First the input sound is resampled ...
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1answer
2k views

Determining the fundamental frequency/pitch of a note

What I am trying to achieve is getting the fundamental frequency of a note played by an instrument. What I have already done is performing an FFT on a samples of audio file, and here's what I get: ...
2
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2answers
799 views

How to detect decaying oscillations in a signal

I have a sampled signal which contains (among other things) some damped oscillations. From the underlying theory I have reasons to believe that it can be characterized by some specific frequencies of ...
2
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1answer
184 views

Definition of energy of a signal

I was wondering why the energy of a signal is defined as $$E=\int_{-\infty}^{\infty}|x(t)|^2dt$$ I mean, I know that it is a definition, but is there a physical reason for it being defined like that?...
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1answer
130 views

Which is the total energy of the product of two discrete energy signals

Assume that I have two signals with finite energy. The first, $x_s$ \begin{equation} E_s = \sum_{i=0}^{N} |x_s(i)|^2 \end{equation} and the second, $w$ \begin{equation} E_w = \sum_{i=0}^{N} |w(i)|^...
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3answers
388 views

Acoustic Scenarios With Negative SNR

For all the practicing engineers out there: Where have you encountered a negative SNR? How negative, in dB, was it or estimated to be? Where would you expect to encounter a negative SNR? Note: I ...
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1answer
113 views

Confusion with regards to units in Sinc pulse

I am currently reading a section in the Handbook for MRI Pulse Sequence book where it says that the time-bandwidth product for a SINC pulse is given by: $$ T \Delta f = Z $$ where $T$ is the length ...
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1answer
203 views

Map the Amplitude Envelope from [dbmin,dbmax] to [-inf,dbmax]

I would like to map the envelope of a sound (which has max dB level = dbmax, and min dB level = dbmin) from [dbmin,dbmax] to ...
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0answers
222 views

How do I find amplitude modulation effects in natural signals

It is relatively easy to discover overlaid (additive) signals in natural phenomena using wavelet decomposition, Fourier Transforms, CEEMD, etc, because addition in the time domain is the same as ...
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2answers
139 views

Filter Design in Matlab

I want to design a filter to remove all frequency components from a .wav file except those within $\pm 25\,\text{Hz}$ of $523\,\text{Hz}$ as well as its harmonics (up to the Nyquist frequency). ...
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1answer
2k views

Plotting Power Spectrum (Matlab)

I want to make a plot of the power spectrum for a .wav sound file, over the frequency range from -2000 to 2000 Hz. Attempt: I used the following code, but the resulting plot is one sided. It doesn't ...
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2answers
80 views

A question about the concept of the time

$\delta[n+1]$ equals to one only $n+1 = 0$ ? If the 1. is true, so what does a signal $x[n+1] $ stand for? Is this signal causal or anticausal? I mean, if 1. is true, $n = -1$, so is this signal ...
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1answer
6k views

How do I generate sound using MATLAB?

I want to generate and play sound for tones with frequency 100 Hz and 200 Hz for 10 sec and 5 sec respectively using MATLAB with sampling frequency equal to 20500 Hz. Also I want to plot their ...
3
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1answer
928 views

what are the Pros and Cons of ESPRIT and MUSIC algorythms?

On wikipedia there are only 2 lines about ESPRIT: Estimation of signal parameters via rotational invariant techniques (ESPRIT)... MUSIC doesnt have an entry in the music disambiguation page, other ...
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2answers
4k views

What is the difference between a'mixer' and a ' multiplier' used in modulation process?

I am not sure if it is valid to conclude that a mixer produces a difference/sum of frequencies at output ,while multiplier produces multiples of frequency at its output. I am keen to know how far I ...
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2answers
665 views

Power of a speech signal

I have been asked to calculate the power of a speech signal given by the following: $$\ p(x)= \left(\frac a2\right)e^{-a\mid x \mid}$$ I know the formula for the power of a signal to be the ...
2
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1answer
119 views

The signal in MRI

I am trying to understand the signal formation in MRI and have a confusion. I understand that in the presence of the external magnetic field $B0$, the protons are precessing at the frequency given by ...
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2answers
4k views

detect to rising, stable and falling point in non-smooth rectangular wave

I am working on basic signal processing problems in MATLAB. I have found a signal from the internet (i don't remember the site exactly). The data is organized in column wise. 1st and 2nd column is ...
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1answer
422 views

Periodogram frequencies not matching with signals

I am new to signal processing world. I am working on a project where we have to find change points using spectral densities. I am running some simulations where in I created a wave which is a linear ...
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1answer
158 views

Showing a system is always controllable?

I need to show that the following system is always controllable: \begin{align}A &= \begin{bmatrix} -\alpha_1I_{k\times k}& -\alpha_2I_{k\times k}& \cdots &-\alpha_{n-1}I_{k\times k}&...
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0answers
310 views

Is GNU Radio a good choice still? [closed]

I'm a newbie at DSP. I am starting a hobbyist project where I plan to monitor 100's of wildlife radio collar frequencies (at my job) and record how many "beeps" per minute are received. My software ...
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4answers
3k views

What does the exponential term in the Fourier transform mean?

We know that Fourier transform $F(\omega)$ of function $f(t)$ is summation from $-\infty$ to $+\infty$ product of $f(t)$ and $e^{-j \omega t}$: $$ F(\omega) = \int\limits_{-\infty}^{+\infty} f(t) \ e^...
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2answers
3k views

Pre-emphasis filter design

I am using the standard MATLAB filter function to design pre-emphasis filter. However, I am getting the wrong results back! I have the ground truth so I can check ...
1
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1answer
172 views

Why Fourier transform and Stockwell-transform retain the absolute phase information of one signal?

Hello friends am studying the topic of signal processing and the Fourier transform and the s-transform and in most books as for example "Time-Frequency Signal Analysis and Processing. 2nd" of Boashash ...
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2answers
862 views

DFT of real sinusoids - why sum over -$N/2$ to $N/2-1$ as opposed to $0$ to $N-1$?

I'm going through a Coursera course on signal processing, and we're just introduced to DFTs. We are told that if you have a complex sinusoidal signal $x[n]$ where $n=0,1...\ N-1$, its DFT is given ...
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3answers
181 views

Phase shifting a noisy signal

I have a signal of the form $s(t)=A(t) \sum \cos(\omega_i(t)t +\phi_0) + n(t)$, where $n$ is gaussian noise. I can only read the signal+noise and thus can not separate them. I want to phase shift ...
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3answers
2k views

Determine whether a signal is increasing or decreasing over time

I have a signal (x-axis: Time, y-axis: Data) which has more than 10000 samples per second. The signal itself represents some physical data (e.g. speed, acceleration, etc.) and has some noise on it. ...
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1answer
149 views

How to measure noise, consonance, dissonance of a sound?

How can I make a graph of the noisiness of some audio durations of 100ms - 10s with 100% being white noise and 0% being a sine wave. I have FFT at the moment, are there other ways to know the ...
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3answers
2k views

Removing unwanted peaks from signal

I have a signal which looks something like: The 12 main round peaks is what I'd like to keep. However, the peak detection algorithm I apply is picking up the in-between noisy peaks. Any strategies I ...
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4answers
3k views

What is the real difference between DSP and AI/data science?

I am very much into DSP, but lately everybody is talking about "Data science" and ...
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3answers
4k views

What are the spike removal techniques in matlab without using filters

output from wavelet filter using daubechies 4 wavelet. Using wavelet filter this is the output obtained. The problem is elimination of the spikes at 0.023,0.043,0.063 and so on. Please note: no ...
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0answers
523 views

Sampling and zero crossing

I am sampling a sine wave of 50Hz(stepped down from 230V) at the rate of 500KHz. For identifying disturbances in the wave, i was thinking of comparing a cycle of incoming sine values with reference ...
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1answer
150 views

difference between wavelet filters

Some may think this question is little primarily,I just want to know the differences between different wavelet filters like decomposition high pass,low pass,reconstruction high pass,low pass filters.....
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0answers
32 views

connection between theory that is done in $L^2(\mathbb{R})$ and its application on discrete signal

I have problems understanding connection between theory that is done in $L^2(\mathbb{R})$ and its application to discrete signals. Look at this paper: http://home.ustc.edu.cn/~zhanghan/cs/...
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0answers
424 views

Discrete Fourier Transform for text analysis?

I would like to determine the number of text-blocks verifying a roughly similar pattern. I have the intuition that I could do it using some Discrete Fourier Transform (DFT)-like methodology. Example: ...
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0answers
40 views

how to design wavelets from splines

Can any one tell me how to design wavelets from splines using matlab. whether we can make wavelets from higher order splines or only with B splines
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4answers
355 views

Sampling Theorem: How to know the value between two samples of a Signal

According to Sampling theorem, in order to reconstruct a signal we need to sample it at the rate => twice the highest frequency component of that signal. (provided signal is band limited). Let's say, ...
1
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1answer
209 views

What is the right algorithm to detect segmentations of a line chart?

To be concrete, given 2D numerical data as is shown as line plots below. There are peaks on a background average movement (with small vibrations). We want to find the values of pairs (x1, x2) if those ...
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1answer
673 views

Is this waterfall characteristic of QAM or OFDM (or something other) modulation?

I recorded this signal at 2.45GHz, it is coming from a camera. Is this QAM or OFDM ? Based on those side-lobes I would guess OFDM but I am not sure. Also there seems to be an interesting preamble ...
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1answer
101 views

Narrowband Signal Decomposition

Why do the in-phase and quadrature components of a narrowband signal each have half the bandwidth of the signal?
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1answer
664 views

Daubechies wavelet transform

i have N samples obtained by sampling a signal with lot of frequency contents. How will i apply daubechies wavelet transform to obtain the frequency and its location? i need to write a program which ...
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1answer
277 views

MATLAB fvtool: Setting the passband ripple below 0dB for a FIR Filter

I'm new to using filter tools in MATLAB and I'm having a bit of difficulty. I'm designing a lowpass FIR filter and I'm trying to keep the passband ripple below 0dB in the magnitude response. So far, ...
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1answer
95 views

Denoising / thresholding via wavelets

When I apply differerent thresholding, wavelet denosing functions to non stationary time series which has been detrended via Loess regression and demean it. I expect that when this processed series ...
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2answers
395 views

How to Extract Nonorthogonal PCA Principal Components

My problem is essentially a 'blind source separation' problem. I have 3 non-orthogonal sources (or basis functions) and $N$ random linear combinations (mixes) of said sources. My problem is to obtain ...
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1answer
503 views

A problem about whitening of a signal

I intend to whiten the spectrum of a time series using a point-wise normalization in the frequency domain. In my first test, it looks pretty good. ...
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1answer
856 views

How to analyze reverb in existing sound recording?

I'm wondering if there is a technique by which to analyze an existing sound recording and extract some details of the reverb and echo that are present (either due to natural environment, or added ...

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