Questions tagged [signal-analysis]

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62 views

Signal Acquisition Game?

I read from Wikipedia that signals obey the uncertainty principle. The product of the measured uncertainty in frequency times the measured uncertainty in time is greater than a constant. The ...
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1answer
1k views

Time duration of a signal to determine the peak frequency

I have two questions regarding signal processing: 1) In my analysis I generate a signal in the time domain with a frequency of 0.1 Hz. I apply the FFT and then determine the peak frequency of the ...
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37 views

Matlab:Sampling Curve into Frames and Plotting

I have a Output Curve of following characteristics http://i.imgur.com/hABfsiC.jpg Following is the data which represents the output curve cited above ...
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3answers
233 views

Separating a signal into its constituent components

First off, I apologize for possibly incorrect use of jargon, as I am new in this area. I have a type of signal that I am assuming can be described by an arbitrary number (let's say $n$) of basis ...
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3answers
2k views

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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3answers
192 views

literature related to Spectral resolution

I am interested in spectral resolution of spectral estimation methods. Can you point me to some good literature, videos or books from which i can read and study? I want to understand how to resolve ...
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1answer
618 views

how to find the “Natural and Total Response” of the system

Hello there I am a Student. I need to know how to find the Natural and Total Response of the given system: where: $x(t)=e^{-t}u(t)$ and $y(0^+)=2, \dfrac{d}{dt}y(0^+)=3$. (If the image above is not ...
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1answer
100 views

Is the quantization noise white here?

If I have the following power spectral density of the quantization error can I tell that quantization noise is approximately white? Can you please provide some justification?
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1answer
141 views

digital IQ modulators

when it comes to digital I/Q signal power measurement we know that this power is viewed as $I^2+Q^2$ (as its polar form). This is the power as referred to final analogue signal. Yet the IQ modulator ...
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549 views

Online FFT of simulated signal

it is a couple of weeks that I am thinking about the following: I have a tool which is able to simulate the dynamic behavior a steel tower exhibites due to the coupled action of wind and waves. ...
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215 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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2answers
921 views

Compare two words from different speakers

I have a set of audio files which contain a word each one, and I'd want to be able to compare a new word (coming from a smartphone mic) to check if it resembles to a specific file and how much it ...
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161 views

TDOA using demodulated signal

Is it possible to find time delay of arrival using demodulated signals (of bandwidth ~200hz)? I have a setup in which I receive (multiple receivers, of course) modulated signal from a source. I want ...
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2answers
105 views

Dealing with echoes / dead-spots in digital transmissions

I'm looking at communicating digital data through the air as soundwaves. To illustrate the problem, I generate a 10-cycle 2kHz wave, play it out through my MacBook's speakers and pick it up on my ...
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4answers
2k views

How do I compare chords played on a guitar with a known sample?

I want to create a project that will recognized the chords that i played in guitar. I recorded a raw sound to be compare to the one that the user will input. Example I have a recorded sound chordA ...
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1answer
137 views

Detecting a curve with certain characteristics in a spectrogram

I have a spectrogram built by breaking a signal into chunks and taking the FFT of these chunks. An example spectrogram is: In this spectrogram I am looking for a curve (aka pitch contour) that: ...
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1answer
698 views

How can I detect when a signal deviates from a flatline?

I apologize if this is not the correct forum, but I thought I'd ask. I have an array of signal samples and I want to detect (retroactively, once I have measured the time/magnitude values) if there ...
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1answer
147 views

Calculate the entropy of Turkish alphabet and compare with the entropy of English alphabet with using Matlab? [closed]

Calculate the entropy of Turkish alphabet and compare with the entropy of English alphabet with using Matlab? How can ı do this question anybody help please?..
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0answers
703 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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2answers
391 views

Need to learn wavelet, suggest steps and resources [closed]

I am looking for a good introduction to wavelets and wavelet transforms. that covers the following: Vector Spaces – Properties– Dot Product – Basis – Dimension, Orthogonality and Orthonormality – ...
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461 views

Analyzing an undersampled recording from an antenna with matlab?

I'm trying to analyze the power spectral density of a signal recorded from a Ham radio antenna. The signal is about 30 seconds long, recorded at a 48 kHz sample rate. The frequency is center frequency ...
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1answer
140 views

FFT of 2 D images

Branching off from this question - https://dsp.stackexchange.com/questions/6020/mapping-the-value-of-a-sample-in-a-2-d-dft-to-cycles-pixel, I have a few more questions related to 2D FFT of images. I ...
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0answers
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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1answer
1k views

Comparasion of two wav files in Matlab [closed]

Hi I am working on one project and I have some trouble with comparison audio files. I have read a lot of articles about this problem but I couldn't find a good one working. In my project I need to ...
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1answer
205 views

Gesture recognition from analog sensor value

Not sure if this is the right place for my question but let me give it a try. I have a very simple analog sensor (piezo transducer) which is attached to a microcontroller. I'm using this sensor to ...
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2answers
2k views

Effect of different downsampling rate on EEG signal

I have a raw EEG signal of length 2,50,000 samples. I band passed it from 0.05-10Hz (sampling frequency=500). Then I down sampled it at 20Hz. Now question is: What will be effect if I vary down ...
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2answers
140 views

Using DFT to determine control system bandwidth from user input

I am currently working on a race car project where steering and braking is to be done by a fully electronic x-by-wire system. To roughly determine the minimum bandwidth of the controllers, I took user ...
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0answers
253 views

Why the number of poles and zeros for a RHS signal in the Z domain is equal?

I can not understand the reason why the following sentence is true: If we have a Right-Hand signal(RHS) x(n), X(z), the Z-transform of x(n), has the same number of poles and zeros except at z = ...
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2answers
107 views

Using under-sampled data, what determinations can be made about the Nyquist rate (correct sampling rate)?

Using under-sampled data, what determinations can be made about the Nyquist rate (correct sampling rate)? If my instrumentation limits me to sampling data at a fixed but insufficient rate what, if ...
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2answers
4k views

Main differences to take into account between continuous and discrete time signals

I started studying DSP and the first things that came out were the differences between continuous and discrete time signals. So, I was wondering if I understood well these concepts before I keep going ...
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1answer
2k views

Exponential decaying Swept / chirp signal [closed]

I'm trying to create a chirp/swept signal that has it's frequency going down exponentially using matlab/octave. I can't use the built in chirp function because I'm trying to create a chirp/swept ...
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3answers
3k views

Checking if u[n] and v[n] are orthogonal

Let $x[n]$ and $y[n]$ be two orthogonal baseband signals, with bandwidth B. Check if the following signals are orthogonal: $u[n] = x[n]*\cos(2*\pi*f_c*n)$ $v[n] = y[n]*\cos(2*\pi*f_c*n)$ I'm not ...
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1answer
41 views

Measuring local “flatness”

I have a function which looks like so: I would like to know if there is a measure for a "weak type run length". How can I know that a function is approximately constant in some specific neighborhood?...
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0answers
307 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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1answer
49 views

Signal spectrum when carrier width changes

If I have spectrum $X_k$ of the signal evaluated at frequencies $k \delta f$ and I want to know what is the value of that same signal at some other frequencies , i.e., $k' \delta f'$.I know that $\...
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1answer
69 views

Determing the frequency of a signal with a sample at a time [closed]

How to determine the frequency of a signal with a value of the sample and value of the time instant the sample was taken ?
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2answers
10k views

What is the difference between a one dimensional and a two dimensional signal?

If a signal depends on only one variable then we call it one dimensional, and if a signal depends on two variable we call it a two dimensional signal. But when we represent an one dimensional signal, ...
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2answers
1k views

Matching two audio inputs (signals) [duplicate]

this is for an application in which passwords are stored in the form of audio inputs . In order to provide user access , the password(in audio form) will be matched with already stored password(audio ...
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1answer
107 views

recognizing words in a sentence

I want to know that what features might be needed for recognizing a word i a sentence exactly? I guess the routine for recognizing the word in a sentence is ganna follow this: 1-calculate voiced and ...
3
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1answer
2k views

Large Laplacian Spatial Filter on EEG?

I want to know that why large laplacian spatial filtering is done on EEG signals? I tried a lot but could not find material on LLSF. And what is meant by spatial filter ( in context of Digital Signal ...
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1answer
681 views

Estimating device height from 3-axis accelerometer data (possibly by supervised learning)

I'm trying to estimate the height of my device using an cheap integrated Freescale accelerometer. First, I estimate the earth direction when measured acceleration is close to 1g, then I project the ...
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2answers
246 views

Examples of mixture of 'almost periodic' signals/data in nature or practice

I am working on algorithms to separate mixtures of 'almost periodic' signals. One such example is composite ECG consisting of maternal and fetal signal. Can anyone help with examples of such signals?...
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1answer
246 views

STFT Time Variance - Threshold

This is a follow up question to: Segment/Idenfication of signal from a spectrogram My main goal is to identify (segment) all of the calls from a given signal. The signal looks like the following (...
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0answers
226 views

Segment/Idenfication of signal from a spectrogram

I have the following Spectrogram of a signal: Essentially, in this signal, I know there is one point of interest (between 60-80) and between the the particular frequencies. I could, potentially ...
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3answers
586 views

strange phenomenon in spectrogram of Windowed Fourier Transform [edited] [closed]

I am trying to understand how the Windowed Fourier transform works, so I used Matlab to create an artificial signal, and plotted the Windowed Fourier transform using a gaussian window. $x(t) = \left\...
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3answers
268 views

How to determine, calculate and plot a probability distribution for a given set of numbers?

A device is rotating with a particular wind speed and producing such pulse frequencies in a minute: ...
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2answers
1k views

How do I perform the sifting process in empirical mode decomposition?

I am programming a voice activity detection algorithm and I found a paper that recommends the use of HHT. I have been trying to program it and understand how to calculate $m1(x)$, but the shifting ...
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1answer
218 views

How to extract the maxima and minima of a noisy period input signal

I have a (rough) known period sine wave coming in, held in an array, with superimposed noise. I need to find and count the maxima and minima (in C). Any suggestions or algorithms? The signal has ...
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0answers
65 views

Common mode noise from two ADC results

I am sampling two sinusoidal analogue signals that are phase separated by $\frac{2\pi}{3}$, and there appears to be a significant amount of common mode noise in my samples. What, if any approach can I ...
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1answer
265 views

Change of bin magnitude when phase of signal changes when doing FFT?

I am working on an implementation in which I need to apply an FFT to determine which of 4 frequencies are present in a signal. I am doing a 64 point FFT on a buffer which only is partly filled (the ...