Questions tagged [signal-analysis]

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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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376 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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91 views

Audio transient characterization of instrumental music

Some time ago, I seem to recall hearing or reading of an audio experiment where the very short initial transients of one musical instrument (A) were spliced in front of the much longer steady state or ...
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1k views

How do we calculate Power Spectrum Density (PSD) which is given in dB/Hz and not just dB?

I found many definitions for this quantity, PSD. In a document on signal analysis by National Instruments say that it is the amount of power in a unit bandwidth. Let's say P(f) is the power of the ...
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76 views

Is negative frequency important in calculating Spectral Moments

A follow on question form this one (What is meant by "spectral moment"?) In answers to the above referenced question spectral moment is defined as: $$ m_k=\int_{-\infty}^{\infty} f^k|X(f)|^...
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671 views

How to process the .wav file to get meaningful information like the number of inhales/exhales

The plot of the data from the wav file. Link to the sound file - https://drive.google.com/open?id=0BxAPlY66uX7qWWtDZUw3WkpjSGs&authuser=0 Also the FFT plot is like this I am new to the field of ...
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27 views

Aligning frames with common elements

I am new to image processing and had the following question: I have take some 512-px grayscale images. The images were take in such a way that all images were of the same spot, but there was some ...
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107 views

Removing the mean in finding PSD

Does removing the mean value of the signal effect the estimation of power spectral density(PSD)? If it effects, how? What is the advantage we can get by removing the mean of the signal in estimating ...
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1k views

In a signal there is a peak, I want to find the start of the peak and the end of the peak

I want to the start time and end time for the peak shown below. The start and end are shown by the marked circles in the fig As there are number of such plots and want to know start and end time for ...
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72 views

Interpolation methods for radar and acoustic imaging and potential pitfalls

A) What are the most common methods used to remap data for current generation imaging radars and acoustic sensors? B) What are some of the pitfalls in these methods? For example, in the past, at ...
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106 views

How to replace Hadamard Product and Column wise addition with new Matrix operation?

Let $$ A= \begin{bmatrix} a_{1,1} & a_{1,2} & a_{1,3}\\ a_{2,1} & a_{2,2} & a_{2,3}\\ a_{3,1} & a_{3,2} & a_{3,3}\\ \end{bmatrix} $$ and $$ B= \begin{...
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125 views

Time delay analysis in different binary sequences

I am extracting a property of a signal which I represent with either a 0 for absent or 1 for present. This property is extracted for each data point in a time series and in the end I am left with a ...
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104 views

How to synchronise two audio files using a marker

I'm working on a project on which we use WebRTC and the RecordRTC library to record audio files. I would like to be able to process the audio files server-side to ensure a good synchronisation. To ...
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2answers
2k views

Creating 2D array to play audio in left and right channel in matlab

I'm new to matlab sound processing and I am trying to create a 2D array for the sound code below. I have to make the sound have 400 samples(i.e 10ms) at 20hz, but having trouble getting the code to ...
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381 views

Extracting features from a signal: a 21st century approach?

I have a discrete signal of random length (let's say between 500 and 800 in time). This signal has an important information which I want to collect and to put it together in a feature vector to train ...
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216 views

Yet Another Peak Detection Request

I looked over the other entries regarding peak detection and none seem to answer my question. I'm working with Fourier spectra of digitized audio that can't be measured again. There are no ...
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712 views

how to compare two audio signals

I have two audio signal that I want to compare using Matlab, my problem is that I can hear the difference between both loud and clear, but when use the function ...
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35 views

select meaningful part out of a signal (for goertzel)

I have an on going input signal, most of the time with no activity. Once in a while there is an activity (oscillations in different freq). I need to take good 205 samples out of the signal. what i ...
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308 views

Definition of LPCC

would you please tell me what does LPCC exactly do?How can we calculate the coefficients of LPCC? I need to know clearly what is it so i can implement it. I dont know if i am asking this question ...
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216 views

Use of USRP SDR to process sonar?

I have ordered a USRP kit to do radio signal processing in software. Is there a way to use the same device to process sonar data? What would I do upconvert the sonar to 50 MHz?
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123 views

Calculate a Kind of Equivalent Baseband Signal by Examining the Zero Crossing

I have a device (whose behaviour I can't change) which does the following signal processing: The incomming signal contains two frequencies $f_1$ and $f_2$. One has a huge amplitude, the other a ...
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650 views

What is the best pitch (frequency detector) for a Voice Activity Detection Algorithim?

I am programming a Voice Activity Detection algorithm. After researching several methods, I implemented a simple method that determines whether or not the person is speaking based off the RMS of the ...
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3k views

Prony method for frequency estimation in matlab

i am interested if where can i find matlab code for Prony method for frequency estimation.there is pdf article about prony https://www.google.ge/#site=&source=hp&q=prony+method+for+...
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1answer
618 views

Apply band pass filter (BPF) before calculating the power of a signal (PSD)?

From my understanding PSD tries to give a good estimation on the power each frequency attributes to the overall signal power. If I am only interested in a frequency range $(\omega_0 \leq \omega \leq ...
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1answer
661 views

window for short time fourier transform

When we implement the 1D-short time fourier transform, the formula is as such: $$ Sf[m,l]=\sum_{n=0}^{N-1}f[n]g[n-m]\exp\left(\frac{-i2\pi l n}{N}\right). $$ the window $g$ used is normally ...
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27 views

ADSR parameter identification from envelope data

I'm trying to work out how to identify (or predict) ADSR parameters (attack time, decay time, sustain level and release time) from envelope data of real signal (or 'raw' data, but I think getting it ...
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28 views

FSK carrier frequency estimation in non equiprobable data

We know that in equiprobable data,change in phase over a time interval, this result will be directly proportional to frequency: f∝Im(s(n)s(n−1)∗) Where s(n) is the normalized complex FSK time domain ...
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24 views

How to tell, which coefficient corresponds to which frequency while computing wavelet transform?

I am applying wavelet transform on functional Near Infrared Spectroscopy (fNIRS) signal. My aim is to get the info that which coefficient corresponds to which frequency in the signal. Is it possible ...
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1answer
19 views

Total Harmonic Distortion THD for the rectifier

I have a circuit with rectifier and this cause the non-linearity and consequently harmonic. I show it on the oscilloscope and then collect the signal from the oscilloscope to the computer by using the ...
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26 views

Strange signals in wifi channel

I am currently working with a USRP B200 mini-i to receive 802.11 signals from various usb wifi devices. When sending packets with the USB device over a channel, lets say 2.412GHz, i can't really see ...
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3answers
46 views

How to find the time of beginning of the slope of the signal?

I have a time signal in MATLAB format. Sampling rate is 100k, so it is roughly 5 seconds of signal. See the link below https://www.dropbox.com/sh/v7vev2j14i77mlk/AAA-X7JGMAzO6IyElYmFPFwra?dl=0 If ...
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1answer
36 views

Can an audio recording tell whether it is made in a large or small room?

The conversation of one or more people will be analyzed. I think need to look for something similar to reverberation or echo in an audio signal. How can this be implemented? Update: small room is ...
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34 views

Signal Detection in Real Time Sensor Data

Exploring some robust and ingenious methods/algorithms of detecting certain peaks in a signal. For example: The two pictures are the same, the area of interest is just highlighted in the second ...
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24 views

Radar signals features for machine learning

I have project in which I have to classify materials based on the spectra of received radar signal. I want to create feature vectors of the specific materials. Can anyone share his ideas. ?
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33 views

should implementing the MMSE equalizer in time domain and frequency domain give same results?

Assume we have a received signal $r$ explained as below: $r = h * x + n$ where $h, x ,*, n$ denote to the multi-path channel, transmitted signal, convolution operation and AWGN, respectively. ...
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1answer
31 views

Synchronize device to audio stream - Approach

I am working on a device which's actions should be synchronized to the audio played. The audio stream is known in beforehand and can be altered to contain signals for the synchronization. But the ...
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22 views

IID noise assumption at Matched Filter sample time

I read that at the correct sample times of a matched filter output the noise is independent assuming a Nyquist pulse. Can someone provide a proof of this or explain it more? Assuming your matched ...
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14 views

IEC fast RMS measurement

I'm looking how to implement fast RMS measurement according to the IEC 61000-4-30 class A and I would appreciate some advice or guideline, as I'm having some doubts. IEC goes with zero crossing for ...
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19 views

Applying Wavelet on energy disaggregation as denoising technique to remove uncertainties

I would like to apply Wavelet in MATLAB as a denoising technique on Non-Intrusive load Monitoring data. The data was captured by sensors on each appliance and one sensor on the smart meter (Normally ...
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20 views

Understanding shift in Q values?

Can any one help me understand why there is a shift in Q values? It seems there is a DC offset/bias. How do I remove it or set it accordingly to make it equal to the I values/waveform? I am using a ...
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1answer
125 views

Separation of signals without loss of information about the signals themselves

There is a signal that contains: Rectangular pulses on frequency of 1 kHz Rectangular pulses on frequency of 1.4 kHz Other noises. Required: Separate 1kHz pulses from everything else and measure ...
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25 views

How modulate and shift in frequency?

I have a 16-QAM constellation, then I divide it into imaginary part and real part. I convolve both by Srrc pulse and multiply by cos(2*pifct) and -sen(2*pifct). Let's say fc equal to 40 MHz Now, we ...
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I don't know why the packet size is considered in this packet reception probability equation

https://www3.nd.edu/~mhaenggi/pubs/broadnets04.pdf In 3 page of this paper, the packet reception probability without interference is $e^{-\theta N Ad^2/ P}$. $\theta$ is sinr threshold. $N$ is a ...
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13 views

Phase concentration for a broad range of frequency over time

I have local-field potential signals from two animals and I am trying to do phase analysis on these signals. What I am interested in is how phase concentration (or interatrial phase coherence) changes ...
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2answers
57 views

how can we align wto signals with a time lag in between?

I have two signals from two different sensors. I cropped the area i am interested in from both sensor signals. The problem is that the signals start at different time instants. I am searching for a ...
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42 views

pressure decay filtering

So, I've been dealing with a series of pressure decay curves from a pressure transducer. Each one has a waterhammer effect as a consequence of shutting down pumps. Here are examples of 3 curves: I'm ...
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26 views

I want to invert my fourier transform components to waves again

Hi I am using R to analyze some data I basically did fft(data) and got a vector of complex numbers but from that now I want to remove certain harmonics from my actual wave but how do I convert one of ...
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6 views

control points and concentration of sampled points in a parametric curve

Can anybody explain to me what the following sentence means? "In cubic Hermite, as any parametric curve, the control points density reflect in the concentration of sampled points in more dense parts ...
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39 views

Conversion from counts to dB

I have a sound signal, recorded by a hydrophone, which units are counts. I would like to convert the counts into dB re uPa (Decibels relative to microPascals), is that possible?
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52 views

Phase response of an LTI-system

I've got an LTI-system such as follows: $$y'(t)+{2} y(t)={5} x(t-{3}), t>0, \\ \\ y(0)=0 \ \text{ ja } x(t)=0, \ t<0.$$ From this i've already figured out the transfer function: $$H(f)=\frac{5\...