Questions tagged [signal-energy]

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9
votes
4answers
7k views

Is the Dirac delta (impulse) signal a power signal or an energy signal?

I'm a beginner so sorry if this question is very fundamental. Dirac impulse has finite area i.e = 1. But I've heard that $|\delta(t)|^2$ is undefined. So area under $|\delta(t)|^2$ is also undefined ...
8
votes
5answers
700 views

Inconsistency between the units of power spectral density and the definition that people often give

Perhaps someone can help me resolve something - this is my understanding: In deterministic signal analysis, for a signal $x(t)$ the signal energy is defined by $$E_{\textrm{s}} = \int^{+\infty}_{-\...
7
votes
3answers
2k views

Random signals as power signals

Why are random signals considered as power signals (i.e. signals with infinite energy and finite average power)? Does this make any sense? What does it mean for random signals to have infinite energy ...
6
votes
5answers
2k views

Does windowing affect Parseval's theorem?

I have computed Fourier transform from ecg data.It does obey Parseval's theorem, relation $$\sum_{n=0}^{N-1} \Big| x[n] \Big|^2 = \frac{1}{N} \sum_{k=0}^{N-1} \Big| X[k] \Big|^2$$ is fulfiled. ...
6
votes
2answers
637 views

why total energy of a finite duration continuous signal becomes infinite after sampling

If I have a continuous-time energy signal and multiply it with an impulse train, the frequency domain representation has infinite replicas. The total energy if we sum them up becomes infinite. What ...
6
votes
2answers
5k views

Even and odd signal energy property

In Signals and Systems by A. V. Oppenheim, A. S. Willsky, S. Hamid Nawab, 2nd Edition, and Signals and Systems, Simon Haykins, Barry Van Veen, 2nd Edition there is a problem related to energy of real-...
5
votes
3answers
1k views

What is energy in image processing?

There are several web articles on the topic, but, after having read them, I still don't know what "energy" is, in the context of computer vision (CV) and image processing (IP). It is related to ...
4
votes
2answers
188 views

Continuous vs discrete signal energy

I am looking to calculate the signal energy of real, sampled acoustic data. According to this source, the energy of a continuous signal is: $$\tag{1}\hspace{1cm} E_x = \int_{-\infty}^{+\infty}|x(t)|^...
4
votes
1answer
420 views

Is there an equivalent of Parseval's theorem for wavelets?

Parseval's theorem can be interpreted as: ... the total energy of a signal can be calculated by summing power-per-sample across time or spectral power across frequency. For the case of a signal $x(...
3
votes
1answer
217 views

How to compute the energy of two signals?

Say I have two signals, one being $g_1(t)$ and the other one being $g_2(t)$, and say that I am being asked to compute the energy of $g_3(t)$, where $$g_3(t) = g_1(t) + g_2(t)$$ Is it correct to ...
3
votes
1answer
134 views

Fourier transform exercise

I have this signal: $$ X(f)= 2\delta(f)+ \delta\left(f-\frac 1{T_0}\right)+\delta\left(f+\frac 1{T_0}\right)+\textrm{rect}\left(\frac{f-\frac 4{T_0}}{\frac 2{T_0}}\right)+\textrm{rect}\left(\frac{f+\...
3
votes
1answer
82 views

Nyquist Rate (Sampling Frequency) for $ {f}^{2} \left( x, y \right) $

We are given that $f(x,y)$ is highest frequency is $\omega$ what will be the frequency sample rate if we want to restore the function of the form $g(x,y)=f^2(x,y)$ Would it be correct to say that ...
2
votes
2answers
227 views

Is MATLAB documentation wrong on when to use discrete versus continuous wavelet transform?

I was reading some of the MATLAB documentation and I get confused when reading the part about When is Continuous Analysis More Appropriate than Discrete Analysis? My knowledge before reading the ...
2
votes
2answers
98 views

Output of a stable LTI system

Let $\mathcal{L}$ be a stable LTI system. Is it true that if input has finite energy then output also has finite energy? I'm not sure about that. We know that $$\int_{-\infty}^{+\infty}|h(t)|dt\lt\...
2
votes
2answers
549 views

Unit of Energy Spectral Density

The continuous-time Fourier Transform (CTFT) of a signal $x(t)$ (with unit $unit$) is: $$X(\omega)=\int_{-\infty}^{\infty} x(t)e^{-i\omega t}dt$$ which should be in $unit\cdot sec$ or $\frac{unit}{...
2
votes
1answer
381 views

What is signal-energy?

What is energy in terms of signal processing? You can read here, that energy is I just need a simple everyday-example for that energy. And yes, bringing an example like $x(t)$ representing the ...
2
votes
1answer
66 views

Bandwith of a energy signal

I'm studying for my finals , and I'm struggling with finding bandwidths. I have this energy spectral density : Ψ(f)=rect(f) , and I need to find the bandwith, 3 dB band and the band with 90 % power. ...
2
votes
1answer
69 views

Is there a relationship between Average energy of transmission and power saving

As mentioned in many books, the average energy of transmitted symbol is given by: $E_s = (2/3)(M - 1) $ where $M$ indicated the modulation order. Suppose that we are using in the first scenario $...
2
votes
1answer
45 views

How is the energy conservation principle preserved in the case mentioned below?

Suppose there are 2 sinusoidal signals $\cos(\omega t)$ and $\cos(\omega t)$, which implies that their individual power is $1/2$ unit and total power is $1$ unit. When added, the signal $2\cos(\omega ...
1
vote
2answers
9k views

Energy of Sinc function

How to find energy of sinc function $x(t) = \frac{\sin \pi t}{\pi t}$ with out the help of Fourier transform or Parseval's theorem?
1
vote
2answers
67 views

Is this an energy or power signal?

Is the given input signal x[n] an energy or power signal? The image shows what I did so far. Is it correct? Thank you! EDIT: I solved it again, please tell me if I did it correctly this time. $$E= \...
1
vote
2answers
50 views

How are the constellation point coordinates determined in digital modulation

I need to understand where the concept of the distance comes from. What I mean is, how do we know what coordinates are to assign to points in the constellation. For example here for QPSK the points ...
1
vote
2answers
63 views

Showing error energy goes to zero

Let $$\hat{x}[k] = \frac{1}{2\pi}\int_{-W}^{W}X(e^{j\omega})e^{j\omega k}d\omega,\label{ift}\tag1$$ where $$X(e^{j\omega}) = \sum_{n=-\infty}^{+\infty} x[n]e^{-j\omega n}\label{dft}\tag2$$ Also, $$d[k]...
1
vote
1answer
589 views

Definition of minimum-phase system

I saw a couple of definitions for minimum-phase in different textbooks and I'm trying to understand what the implication of each of them. The first definition I saw was: An invertible system which ...
1
vote
2answers
33 views

Partitioning the energy of a signal between its components

In physics, the total energy of a system is the summed energy of its component subsystems, and energy must be conserved, ie, adding the energy of the components gives the total energy. In signal ...
1
vote
1answer
207 views

Total Variation of a Signal - Is It Proportional to Signal Energy?

In an audio application, I found it very useful to measure the total variation of a signal $y[n]$ $$\sum_{n=n_0}^{n_0+N} |y[n]-y[n-1]|$$ over a window of time length $N$ (discrete analogous to total ...
1
vote
1answer
883 views

Error analysis for uniform quantization of uniform input

I was told that error energy $$\delta^2_e=\Delta^2/12,\quad \Delta=(B-A)/2^R$$ signal energy $$\delta^2_x = (B-A)^2/12$$ Here signal bounded:$A\le x[n]\le B.$ $[A,B]$ is split into $2^R$ ...
1
vote
1answer
270 views

Band energy and Parseval theorem

In Python, I consider a dummy signal as follows: fs = 512 sig = np.random.standard_normal((fs,)) sig corresponds to 1s of ...
1
vote
1answer
48 views

Need help deriving the energy of a signal

I am solving old exam problems in preparation of my exam in signals, and I'm having trouble with a question. For a continuous aperiodic signal with the spectrum $X(\omega)=\exp(-\omega^2)$ I am to ...
1
vote
0answers
62 views

Finding the Energy & Power of a Composition of Odd and Even Signal

Given two CT signals $x_1(t)$ (even signal) and $x_2(t)$ (odd signal). If $x_1(t)+x_2(t)$ is an even signal then what is the energy and power of $x_2(t)$. My Attempt $\int \limits _{-\infty}^{+\infty}$...
1
vote
0answers
35 views

What is the “Energy” equivalent of the Magnitude Spectrum

I have a semantic issue regarding the discrete spectrum $X[k]$ of a time domain signal with limited length $x[n]$, so we're talking about the FFT. Now, when I what to compare the bandwidth and ...
1
vote
1answer
67 views

Analytically determine a PSD from a transient function

This question is related to a series of questions I have asked about the units of PSD and ESDs. I include it as a separate question as it may have worth in isolation. As I understand it to compute ...
1
vote
0answers
21 views

Effect of filtering on Energy of a Digital Signal

I am trying to detect (not remove) noise from the digital signal to get meaningful information out of it. The signal I need is in the frequency range of 0.1 Hz to 10 Hz. Anything beyond this is just ...
1
vote
1answer
181 views

Energy definition for Autocorrelation lag 0 and lag 1 for complex signals

I am studying the role of an auto-correlation matrix for random signals and the difference of energy between a lag 0 and lag 1 matrix. Consider a complex input signal $x(k)=[x1,x2]^T$ and $x(k-1)=[x0,...
1
vote
0answers
195 views

Parseval's Theorm and Effective Bandwidth

This question says that RMS bandwidth (effective bandwidth) is defined based on the carrier frequency of a signal. This makes intuitive sense to me that the carrier frequency shouldn't determine the ...
0
votes
3answers
521 views

Is $\arctan(t)$ an energy or power signal?

Is the function $\arctan(t)$ an energy or power signal? I've tried working out the integrals for energy and power but I get stuck on both.
0
votes
2answers
30 views

Energy of a signal with decreasing amplitude

I read that a infinite extension continuous time signal with decreasing amplitude will always be an energy signal. Though if you take the integral of, for example, f(t)=1/(t+1) we can see that is ...
0
votes
1answer
2k views

Average Energy of modified QAM Constellation

How to compute the average energy for the modified 16-QAM constellation below? I know that for regular/rectangular 16-QAM we can utilize the 4-PAM along each axes but I'm not sure how can we find $E_{...
0
votes
1answer
52 views

Spectral Property of Bandlimited Quantized Signal

recently I meet a problem. I generate a random Gaussian signal $x$ with mean $0$ in MATLAB. And use a $4$th lowpass Butterworth filter to acquire $x'$. Then I use the binary rounding quantization ...
0
votes
1answer
94 views

Energy of compressed signals

I have tried a code to compress a signal using Compressed Sensing(CS). The input signal is $x$ and the compressed signal $y$ is given by : $y=Φ*x$ where $Φ$ is the sensing matrix. I have used ...
0
votes
1answer
58 views

SNR contains $\log N$ term where $N$ stands for number of samples

Sampling the signal$ $N times increases the signal energy by a factor of $N^2$ and the noise energy by a factor of $N$. Why? This explanation is written for SNR(dB) = signal peak(dB) – ...
0
votes
1answer
611 views

Absolute and Square Summability & Integration of sinc function

Is the sinc function both absolutely summable (L1 norm for Continuous time signals and l1 norm for Discrete time signals) and square summable (L2 norm for Continuous time signals and l2 norm for ...
0
votes
1answer
2k views

Negative exponential signal's energy and power

Earlier I have dealt with exponential functions multiplied with unit step function. But, energy and power of exponential function alone comes out to be infinite when I put limits of the integrals to ...
0
votes
1answer
644 views

Probability of False Alarm versus SNR

I'm currently testing the performance of an energy detector using two tests. One test involves finding the optimal threshold to achieve a probability of detection(Pd) of 0.9 and a probability of false ...
0
votes
1answer
116 views

Integral of the Fourier spectrum?

The integral $$\int_{-\infty}^{\infty}|X(f)|^2df$$ of the absolute Fourier spectrum squared is the energy in the signal, but what about the integral of the 'simple' absolute Fourier spectrum? $$\...
0
votes
1answer
44 views

Concept of energy threshold

I am analyzing some program responsible for detecting the correct signal in the channel on the receiver side. It seems to me that such an implementation allows for the detection of the correct packets ...
0
votes
1answer
33 views

How do I find the Energy Density Function of $g(t)$ if i am not given an input or impulse response?

$$g(t)=\frac{12a}{t^2+a^2}$$ I need to find the Energy Density Function of the signal, but everywhere I look has an input and an impulse response. Does anyone know how to solve this. Would I just take ...
0
votes
2answers
28 views

Looking for a Mathematical Derivation for the Energy Formula in Continuous-time Domain

I have just started my signal and system course and I would like to know how we derive the corresponding formula for the energy of a continuous-time signal $x(t)$ over an interval $[t_{1},t_{2}]$ : $$...
0
votes
1answer
46 views

How to find the energy of a rect signal?

Given a signal $$ x(t)=-2\operatorname{rect}\left(\frac t4\right) $$ What is the energy of signal $-x(t + 1)$? What are the steps needed to find the energy?
0
votes
2answers
61 views

Energy of audio signal

From audio file [y,FS]=something.wav So the y is typically N cross 2 matrix I want calculate energy so i.e sum(abs(y.^2)) So when I apply these I end with two answer for each column. So I want ...