Questions tagged [signal-analysis]

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4
votes
3answers
1k views

Large sample rate or large number of cycles when estimating frequency?

I wish to determine the frequency, amplitude and phase of a sine wave with some noise and I can only have a fixed number of samples. Should I go for many cycles and a small sample rate or a few cycles ...
1
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1answer
80 views

Clarification regarding signal after pulse shaping

As can be seen from the figure below, I have plotted a signal before it is pulse shaped and after performing half sine pulse shaping using the formula $p(t) = \sin(\pi t/2T_c),\ 0<t<2T_c$ $p(...
2
votes
1answer
139 views

adjust mean of signal using exponential

I have discrete signals whose values are between 0 and 1. I wish to post-process such a signal such that the mean of its values equals 0.5, yet keeping maximum and minimum values 0/1 intact. ...
0
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2answers
6k views

short time energy matlab code for audio feature extraction

Is there code in matlab for short time energy feature extraction in matlab?? I want to extract audio feature (Short time energy) using matlab code
2
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1answer
179 views

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 ...
1
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2answers
319 views

Getting introduced to signal processing for remote sensing

I work mainly in GIS (geographical information systems) but I would like to deepen my knowledge of remote sensing (analyzing imagery acquired remotely from airborne or satellite sensors). I was ...
1
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3answers
3k views

detrending in real time

I have a certain signal that has a linear trend that should be removed: The problem is that the signal needs to be processed in real time(sampling rate is 20Hz). If I only apply the detrending per ...
5
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3answers
3k views

How to remove text region in a document image? or extract image from a document image

Given a document image (i.e. newspaper), how to extract photos in it or remove text region? I think traditional OCR methods may not be suitable here, as I don't need to recognize the text, and OCR is ...
0
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1answer
1k views

Circular Convolution of h(n)*x(n)

So I understand how Convolution works but Circular convolution seems a bit messy to me, all the examples seems to have even series of number like h(n)={1,2,3,4} & x(n)={1,2,3,4} and they are all ...
1
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1answer
1k views

Difference b/w freqz and fft

Since both fft ,freqz are used for finding the frequency response of digital filters. the frequency response using freqz function is given below and frequency response using fft function is it seems ...
0
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2answers
1k views

Calculate Min/Max value of multiple sine waves added together

So I feel like this should be possible, I'm just not sure how to do it. Let's say I'm generating a signal with a sample rate of 10K samples/second. Then let's say my signal is comprised of X number of ...
1
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1answer
1k views

Expected value of signals

If I have two signals $x$ and $y$ and this expression $E\{x[n]y[n-k]\}$, what is the expected value of the product? I have a basic understanding of EV based on probability, such as $$E[X]=\sum_{i=1}^{...
2
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1answer
682 views

Per Window Normalization

I have PPG signal that should be normalized, with offline processing I'd just do $z$-normalization, $$ \displaystyle \frac{x- \mu_x}{\sigma_x} \quad \text{where } x \text{ is the signal.} $$ The ...
2
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1answer
96 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 ...
0
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1answer
82 views

adding phase noise in signal thorugh freuquency

I want to implement a simple signal for phase noise. According to my supervisor, i shoud be adding phase noise in the frquency. This is my signal. A = cos(2*pi*fc*t)...
1
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2answers
858 views

applying single pole filter to simple signal

How to apply single pole filter to simple signal fs = 500; ts = 1/fs; t = 0:ts:1-ts; fc = 50; S = cos(2*pi*fc*t);
0
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3answers
355 views

how can I analyze a basic sine wave for its frequency phase and amplitude at a particular point in time in matlab

How can I analyze a basic sine wave for its frequency phase and amplitude at a particular point in time in MATLAB? Are there any tools to do that? I am trying to do additive synthesis of inharmonic ...
0
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1answer
461 views

DFT: Basis functions and Significance of dividing frequency by Sample length

A time domain signal can be decomposed into sinusoids which are based on basis functions. For a N sampled input, a cosine basis function is defined as: $$C_k[i] = \cos\left[\dfrac{2\pi k i}{N}\right]...
-1
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1answer
85 views

simulating noise with Yuler and burg

I want to simulate short term white noise with Yuler and Burg. It's said that it can give better results than Gauss-Markov. The problem is that each time the series diverge. Do you think that I made ...
0
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0answers
336 views

BFSK modulation what signal the transmitter actually sends?

I am trying to understand how modulation with carriers works(transmission part). I will express my question in terms of BFSK for simplicity. Let us condiser BFSK modulation with symbols {1,2}. Then ...
0
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1answer
1k views

Applying a mathematical function to a 16-bit Python array

I am using scipy.io.wavfile to read a WAV file and playing it with pyaudio. Before the numpy array is written to a string and output through pyaudio, I would like to be able to apply some sort of ...
0
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1answer
555 views

separating stationary and non stationary parts of univariate signal

Does anyone know if there is a procedure as to separate the stationary and non stationary parts of a univariate signal. I have seen signal source separation and blind separation algorithms (all of ...
0
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0answers
53 views

noise in signal

I am trying to add phase noise in signal. However, when i see the graph in frequency domain the spectrum is not broading. Can anyone tell me what mistake i am making? ...
0
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0answers
472 views

Detailed Analysis of Phase Delay of an Audio Signal

I write this question as a new reference point because it is difficult to find something exhaustive regarding this topic. I'm talking about the calculus and interpretation of the phase delay of a ...
0
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1answer
134 views

Bandwidth of a trimmed sinus wave

I generate a sinus which duration is 15ms and frequeuncy of 13KHz. Is its bandwidth is (1/15ms) ? Or in other words, BW = 66.6Hz? I ask that because I have two freqs in my system: 13K & 13.1K. I ...
0
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0answers
256 views

Cross spectrum using `cpsd` (matlab) of 2D matrices

I'm struggling with cpsd for 2D matrices. In my test, I've generated two 100x100 matrices (sine waves) s1 and ...
0
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0answers
411 views

Generating Wavelet family matrixes

We have unnormalized Haar matrix which, is for example, H4=[1 1 1 1;1 1 -1 -1;1 -1 0 0;0 0 1 -1] After normalizing it, we use for haar transform. I know how to ...
1
vote
1answer
86 views

Pixel time series trend: What are the causes?

I have taken an video of the following static scene for 10 mins (3 frames/Sec); totally 1800 frames for 10 mins. I also show here the pixel time series, that is, a set of values of a particular ...
0
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1answer
39 views

Condition for optimal value to be the average

In many single parameter estimation process average is the optimal. Can anyone tell under what condition average is optimal? For example is average optimal if the data is iid, Gaussian or something ...
0
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0answers
563 views

Effect of pathloss on signal power

Consider I have two transmitters $tx_1$ and $tx_2$ at say a distance of $d_1=5\text{ m}$ and $d_2 = 15\text{ m}$ respectively from a receiver. Now, if I consider the effect of path loss in such a ...
1
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2answers
448 views

relation between luminance and eigen values of an image

There are some research papers in the literature which apply Singular Value Decomposition (SVD) on an image to decompose the image matrix into U, ...
1
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1answer
196 views

What is difference between outputs of Fourier transform and Fourier series of a periodic square waveform?

We can use Fourier transform of an aperiodic signal and Fourier series of periodic signal. But we can use Fourier transform formula for periodic function also. Now, let us consider a periodic square ...
3
votes
3answers
7k views

How condition for existence of Fourier transform is valid?

The condition for Discrete time Fourier transform to exist for function $f(n)$ is given as $$\sum_{-\infty}^\infty |f(n)| < \infty.$$ In case of continuous Fourier transform the difference is ...
3
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2answers
3k views

What is phase congruency?

I am beginner in Image processing.I am studying the importance of phase in signal.Can anybody explain what is phase congruency ?
0
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1answer
1k views

Shift a signal by a given number of samples

Is shifting a signal by a given number of samples, say $n$ samples, the same as the following in matlab: signal(n:end) instead of signal(1:end). That is, if the size of $signal$ is 200x1, does it ...
2
votes
2answers
95 views

Any basic paper on biomedical signal processing to practise with?

I am quite interested in biomedical signal processing and I am looking for some biomedical signal processing papers in order to reproduce the results that they obtained. The idea is to redo what they ...
1
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2answers
3k views

Signal magnitude area

I'm confused by the SMA. I'm reading a paper which states that "SMA is the square root of the summation of the filtered acceleration signal". So I understand that it's $sma = \sqrt{\sum{samples}}$ I ...
0
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0answers
133 views

PID Control - process variable / setpoint

I'm trying to design a PID controller but I have a problem in the following case: The process variable can only be between 0 and 1. The setpoint can be close to one, for instance 0.97. Hence the ...
0
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1answer
107 views

Linear Prediction Coefficients

I want to learn how to compute linear coefficient, but to be honest - I can't. I know how to use them if i have it and why I want them. Suppose this toy example: A signal $x=[-1, -2, 0, 1]$ ...
1
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0answers
1k views
0
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0answers
51 views

Goertzel filter Poles on unity circle influence of a behavior of a signal at high frequency

I'm trying to apply a goertzel filter on my sound data of 20500 Hz with sampling rate of 44100[samples/sec]. My bit duration which is passed to the goertzel function is returning a very low magnitude ...
3
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5answers
16k views

Percentage difference between two signals

Apologies in advance for what I imagine is a simple question, however I can't work out how to do this. I have two signals of the same type but with different sensor types, the figure below will give ...
1
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0answers
80 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)|^...
3
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1answer
2k views

What is the reason for filtering out the negative frequencies of a signal?

I am reading this tutorial. Quoting the lines from the topic "Analytic signals and Hilbert transform filters": the corresponding analytic signal $ z(t)=x(t) + j {\cal H}_t\{x\}$ has the property ...
4
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2answers
8k views

What are Autoregressive Coefficients?

Can anyone explain what are Autoregressive Coefficients? What is their meaning that is. Consider a method: ...
0
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2answers
2k views

Log Distance Path Loss Model

While simulating a MISO system, I am trying to consider the effect of varying the distance between the transmitter and receiver on the BER. My search for the effect of varying distance has pointed me ...
1
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2answers
75 views

How can one put information within a signal waveform and make it to traverse through different kind of medium? [closed]

This is a soft question. There are different types of signals like analog ,discrete or digital one. But my question is how can one put information within a signal waveform and make it to traverse ...
0
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0answers
61 views

Changes of phase in high frequency makes the speaker “clicks”

I modulate some data over sound in a 17.7Khz and 17.8Khz. It works like an FSK with a pulse duration of 0.015sec. When playing a string the speaker gives a very strange noise that it seems to be the ...
0
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1answer
74 views

Derivative Notation as a factor

In the figure below, from the book "Principles of Linear Systems and Signals - Lathi", the author uses the notation D to replace the Leibniz's notation $d/dt$, and after that he rewrites the equation, ...
0
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2answers
168 views

Signal decompositon

I am not a good in writing algorithm but please follow below steps 1.There are 4 1D sinusoidal periodic signals.3 of them are given by \begin{cases} x(t)=4\sin(10\pi t) \\ y(t)=8\cos(20\pi t) \\ ...

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