Questions tagged [signal-analysis]

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1,265 questions
103 views

Measure of intermittency/continuousness of a signal

I have three signals (below) each having the same standard deviation, however, are clearly very different temporally. Is there some such metric that could be calculated for each of these signals to ...
539 views

Gain function calculation (frequency response)

Define moving average process $y_t := 0.5 x_t + 0.5 x_{t-1}$ where $x_t := e^{i2 \pi t}$. Its frequency response is then: $$H(f) = 0.5 + 0.5 e^{-i2\pi f}$$ Recall that the frequency response in ...
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How to calculate the energy levels of frequency intervals of an audio signal?

Using the Fourier transformation I can translate a signal from the time-domain to the frequency-domain. If I divide the frequency axis into intervals, how can I calculate the audios signals energy for ...
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Are there any measurements or test for whether an audio signal is stationary?

I need to divide an audio signal into frames in which the signal can be assumed to be stationary. How can I measure whether an audio signal is stationary in a frame?
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Contradiction while using the convolution sum for a non-LTI system

In a recent quiz, we were given the following problem: The cascaded LTI systems $\mathcal{T}_1$ and $\mathcal{T}_2$ respectively have impulse responses $h_1[n]=\delta[n+3]$ and $h_2[n]=\delta[5−n]$....
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Significance of modular arithmetic in DFT?

In what ways does modular arithmetic plays a part in DFT? Why is it a so integral part of DFT?
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Baby Cry recognition robust against the distance [closed]

I am building a baby cry detection system using deep learning algorithm, Raspberry Pi and a microphone as the sound sensor. When the baby starts crying then the system should detect the cry. It is ...
55 views

Maximum of cross-correlation not moving

I already asked this question here yesterday, but it was very poorly worded I think. I made a much more detailled post explaining my problem of stackoverflow, as it might also be a code problem. Here ...
114 views

Any better way to detect Signal with ADC Overflow problem?

I am trying to create an algorithm to detect signal with "ADC overflow" as shown in picture on lower right. It happened because someone had incorrectly down converted an int16 signal into int8 signal. ...
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Parseval's Theorem for discrete series

I need to use Parseval's Theorem to find \begin{equation} S\:=\:\sum _{n=-\infty }^{\infty }\:\left[\left(\frac{\sin\left(\frac{\pi }{4}n\right)}{2\pi n}\right)\left(\frac{\sin\left(\frac{\pi \:}{6}n\...
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Array Signal Processing: What are snapshots in Direction of Arrival estimation?

I do have an overview of basic radar signal processing chain [Data cube, 3 stages of FFT, Range, Range-Doppler map, coherent/non-coherent integration, coarse DoA etc.]. I am now trying to understand ...
555 views

How to account for multiple signals in the input to a Kalman filter

I am interested in using a Kalman filter to track an oscillating signal due to a physical oscillator in a signal which contains the signal from multiple such oscillators oscillating at different ...
348 views

Predicting account balance based on historical data

Given the values of a bank account balance over time (see figure below as an example), how can one predict the account balance at a given date in the future ? Should I just fit one linear regression ...
1k views

What is the purpose of a window function?

I've read that a window function is a mathematical function that is zero-valued outside of some chosen interval. Can someone please explain what this really means?
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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 ...
1k views

Cyclic prefix vs. guard interval. Why use one over the other?

I'm currently studying some OFDM techniques, and have found that in order to avoid Inter-Symbol Interference (ISI), there needs to be some space in between symbols. Lets assume this length to be $\mu$....
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Proving conditions for controllability

Let's say I have the following LTI system: $$\dot{x}(t) = \mathbf{A} x(t) + \mathbf{B} u(t)$$ I need to somehow show the following is true or false (proof): This system is controllable if and only ...
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Is sub-sampling delay estimation possible without interpolation?

I want to estimate time delay between two complex narrow band signals. I can use any correlation method. There are several methods in the literature about sub-sample time delay estimation. Generally ...
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How to simplify this sequence

So I had this question (f) at my last exam that I failed and I'm now studying for my re-exam, the problem is that I still don't know what the answer is supposed to be in this question (f): Do you ...
83 views

Time-Frquency Resolution issues

While Im studying wavelet transform, I have this questions in my mind which can't find it's answer: I understand that when we take longer time windows and take the fourier transform we would suffer ...
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Must OFDM signal be time-division in a multiple-transmitter and SFN system when the signal is free of spread-spectrum?

The OFDM baseband signal can be demodulated since each subcarrier is orthogonal to another. But In SFN system, i.e., Single Frequency Network, all OFDM signals from several transmitters are in the ...
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Teager-Kaiser Operator vs. Hilbert Transform

Since a couple of months I started working on the extraction (estimation) of signal frequency and amplitude components by means of two different time-frequency approaches, namely the Hilbert transform ...
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Is a negative Es/No for an SCPC RF signal possible, and what would such a value signify?

I apologize if this isn't the correct Stack on which to ask this question, but it seemed like the best fit. I've tried to Google an answer, but I haven't been able to find anything that applies ...
446 views

Normalization purpose in signal processing

What is the purpose of normalizing the signal? If we have two signals on hand, how is it used when comparing these two signals?
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Audio Recognition and Learning

I'm a beginner with absolutely no experience in signal processing, but it has been a long-term goal of mine to do something that mixes music (a hobby of mine) and computer science (my "expertise"). I'...
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I used the continuous wavelet transform (CWT) to analyze the behavior of a 1-D smooth signal (extracting its modal property, damping and frequency components) in my research. Now someone asked: Why ...
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Variance of an Implicit Function of Kalman State Vector

Given a state vector given by $x = {[r, v, a]}^{T}$ (Range, Velocity, Acceleration) the Time to Hit is the the time which holds the following: $$r + v {T}_{tth} + \frac{a {T}_{tth}^{2}}{2} = 0$$ ...
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Preprocessing audio signal for neural network classification

I need to identify certain features of the audio signal recorded from microphone in stethoscope. These sounds are only samples i've found, but the final signal will be probably a bit noisier (maybe ...
1k 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 ...
1k views

Order analysis or order tracking

Last week I've been trying to implement the Order Analysis in MATLAB in vain. I've read a lot of docs about it like this one , but I still can't figure it out. This will be my last shot. Say I have ...
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Morlet wavelet time and frequency resolution

I want to calculate Morlet time and frequency resolution. the Morlet wavelet function is define as : $\psi(t)=\frac{1}{\sqrt{\pi f_b}}e^{j2\pi f_c}e^{-t^2/f_b}$ Note: I know the answers, but I don't ...
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use wavelet transform to extract frequencies from given signal

let us suppose that we have following signal values,which consists by deterministic components and random noise(white noise) ...
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Concept of Orthogonality and Orthonormality

Please explain me the concept of Orthogonality and Orthonormality. I understand that the mathematical definition of orthogonality between two vectors is that their dot product is zero. It means that ...
172 views

Detect signals degree of imbalance

I have got this question: let's suppose that I have three signals, representative of the same variable, but taken on three different component of a same device; in my case, three load signals, ...
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Possible to break out complex WiFi signal?

Is it possible to break out the i and q of a complex WiFi signal? If I have a laptop with a standard WiFi card in it, could I break out the i and q in analog, or upon sampling in an FPGA via digital ...
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What kind of power spectrum implies uncorrelation in time?

I am new in signal processing field, and actually I just need some basic tools for what I am working on. I've learnt that the autocorrelation function is the inverse Fourier transform of the signal's ...
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How to identify the beginning and the end of a signal using MATLAB

I have multiple signals as shown in this image. I'd like automatically detect time for the earliest detection of the signal (approx 0.7e4 in S1-B3-B (orange)) and last detected occurrence of the ...
81 views

Frequency estimation on chaotic waveform

The target signal is generated by the following analytically solvable hybrid chaotic oscillator \begin{equation}\label{eq:1} \ddot{u} - 2\beta \dot{u} +(\omega^2+\beta^2)(u-s)=0 \end{equation} ...
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What Is the Difference between Parseval's Theorem and Plancherel Theorem?

Wikipedia gives Parseval's theorem as follows. Parseval's Theorem , is the Fourier transform of x(t). And Plancheral's theorem is given as , where is the fourier analog. Plancheral ...
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Error due to downsampling an image

I have two images $I_1$ and $I_2$ suppose $I_2 = downscale(I_1)$, so for example if $I_1$ has resolution 1024x1024 $I_2$ could be 512x512. How can I measure how much quality I've lost during this ...
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I have a complex observable series $Y(t)$ which is the result of summing two complex r.v $X(t)$ (unobservable) and a $\epsilon(t)$ (unobservable). $$Y(t)=X(t)+\epsilon(t)$$ Assume that $X$ and $\... 1answer 107 views Linear Predictive Coding for general signals I have a signal that's monotonic and roughly linear and have been looking at using Linear Predictive Coding to encode information and compress my signal. I guess my first general question is if this ... 1answer 121 views Gaussian Equivalent of Convolving an Image 50 Times with a Box Filter I have a image that I'm convolving 50 times with a box filter, and I like to replace this with a single gaussian filter. Because both box filter and gaussian filter are separable I can just study the ... 1answer 246 views Cross-correlation, sharp peak at 0? First of all, I have to stress that I am not a professional of coding, no more than a professional of signal processing. I am a chemist that happen to be working on a project involving both. So in ... 1answer 176 views consecutive filtered blocks with filtfilt I'm doing basic signal processing in Python. I'm filtering consecutive blocks of a signal with scipy's filtfilt (to get zero phase). I would like to concatenate several blocks after filtering, however,... 1answer 121 views Changing the number of cycles of an sinusoidal input signal Imagine we have an ultrasonic sensor that transmits a multiple cycles of sinusoidal signal/waveform that can travel up to a specific distance/range. Can we achieve more distance coverage using more ... 2answers 455 views Room impulse response 'noise' I am working on getting room impulse response(RIR) and the first order reflections of a room. For now I am stuck at getting proper RIR. I followed Joseph's work and implemented on my own. My setup ... 1answer 290 views Vibration Analysis by using FFT I have 6 column vectors$(\mathbf A_x,\mathbf A_y, \mathbf A_z, \mathbf G_x, \mathbf G_y, \mathbf G_z)$taken by accelerometer to analyze the vibration of a construction. Each column is a$64998\times ...
An FSK-signal with a frequency-shift $\Delta F$, a symbol-stream $x$, $x(n) \in {\{-1,1}\}$ and symbol duration $T$ has the complex envelope: f[x](t)=\exp\left(2 \pi i \Delta F T \left(\sum_{l=0}^{...