Questions tagged [continuous-signals]
A continuous signal or a continuous-time signal is a varying quantity (a signal) whose domain, which is often time, is a continuum.
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response of LTI system to a Random Input Signal
what is LTI filter? what is the output when x(t) is input?
let x(t) be the input signal to the system and y(t) denote the output signal. The output of the system may be expressed in terms of ...
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2answers
143 views
A question on Fourier Series and the frequency of the sinusoids
On studying about Fourier series, I encountered 2 doubts:
How is it that a non-periodic function has a Fourier series?
When expressing a periodic function as summation of sinusoids, why is the ...
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3answers
37 views
How does real-time signal processing work when the signal we deal with is assumed to be known for all times?
One thing that never sat right with me after my signal processing course is that in order to do signal processing, we must know the entire signal $x(t)$.
For instance, I cannot take the Fourier or Z ...
2
votes
2answers
74 views
DC value of $x(t)=\frac{1}{t}$
Is it possible to calculate the DC value of signals with undefinable area?
More specificaly, in the case of $x(t)=\frac{1}{t}$. $\int\limits_{-\infty}^\infty\frac1t \, \mathrm dt$ does not converge. ...
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0answers
15 views
How does discrete spectral moment relate to continuous spectral moment?
It is said in discrete/digital signal processing that $r$th spectral moment of signal $x[n]$ is defined as:
$$\sum_{n=-\infty}^{\infty}n^r x[n]$$
But how does this relate to usual continuous $r$th ...
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1answer
41 views
Effective Nyquist frequency / signal resolution for overlapping time averaged signal samples
Say that I have a continuous signal. If I sample the signal at sampling rate f_sample, then the highest signal frequency that I can resolve without worrying about ...
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2answers
30 views
Is there such a thing as a continuous phase BPSK?
My knowledge of signals and signal processing is limited, so I apologize in advance for my naïve and possibly confusing question.
In the case of BFSK, the frequencies are altered to represent the ...
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1answer
64 views
Is there an example of an infinite signal? [closed]
In the real world, Is there an example of an infinite signal?
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1answer
33 views
Fourier Series Representation of Continuous-Time Periodic Signals [closed]
As a novice in signal processing, I have been going through Signals & Systems by Oppenheim to try and understand how continuous time periodic signals are represented by Fourier series coefficients....
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1answer
65 views
How can I get the continuous-time transfer function coefficients (or poles and zeros) from the corresponding discrete-time TF and vice versa?
Let's say I have a continuous time transfer function which I know its numerator coefficients $(B^c = [b^c_m, ..., b^c_1, b^c_0])$ and denominator coefficients $(A^c = [a^c_m, ..., a^c_1, a^c_0])$. ...
1
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1answer
74 views
Can a Fourier Transform exist even if the j$\omega$ axis is not in the Region of Convergence in it's Laplace Transform
A couple of confusions have been occurred. The Signal I'm considering is f(t) = sin(t)*u(t)
Fourier Transform of it can be derived.
$-i \pi (\delta (\omega -1)-\delta (\omega +1))$
According to my ...
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2answers
39 views
Simple problem regarding rectangular pulse shifting
So i have the following rectangular pulse:
$$h(t)=\begin{cases}
1 & 0<t< T \\
0 & \text{otherwise}
\end{cases}$$
Now, i am supposed to create $h(T-t)$, and the ...
0
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1answer
41 views
Bandwidth of the Derivative of a Message [duplicate]
If I have a message signal $m(t)$ and it has a bandwidth $B$. I know that the bandwidth of $m^N(t)$ is $NB$. But what is the bandwidth of $\frac{d m(t)}{dt}$?
Thanks!
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1answer
51 views
Quite confused with Fourier Analysis results
So I'm meant to show how the DFT can find the frequencies, and respective amplitudes, associated to some data. And I have this data set from the curve
$$
f(t) = 1 + 2\cos(2\pi t) + 4\cos(4\pi t)
$$
...
2
votes
1answer
42 views
Given a plot of both the magnitude $|H(\omega)|$ and its angle, How can you find the $H(\omega)$?
I'm specifically trying to use an inverse Fourier Transform to find $h(t)$, but I'm finding it difficult to get $H(\omega)$ in the first place.
I'm under the impression from my textbook that $H(\...
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1answer
46 views
How to find the coefficients of the following differential equation
An arbitrary signal $v(t)$ pass through the following system,
$w'(t) + 5 w(t) = v'''(t) + 320v''(t) + 40 v' (t) + 40v(t)$
How to determine the coefficients of the following differential equation, ...
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1answer
42 views
How to do convolution in Fourier Series?
Two signals are given to me :
$$x(t)=\cos(4\pi t)$$
$$y(t)=\sin(4\pi t)$$
I have founded their coefficients as follows:
$$a_k = a_1=a_{-1}=\frac{1}{2} $$
$$b_k = b_1=b^*_{-1}=\frac{1}{2j}...
6
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7answers
423 views
Intuition behind commutativity of convolution in LTI systems
Why is convolution commutative, as it seems to treat two signals in a different way in an LTI system?
If you imagine $y[n] = x[n] \star h[n]$ with $x[n]$ being an input signal and $h[n]$ being the ...
0
votes
2answers
49 views
How will I draw the following signal?
I want to know that if I have any signal given how will I draw it according to the following equation
$$x(t-1)-1/2$$
what will be the role of $1/2$ when drawing the new signal?
2
votes
1answer
74 views
Does the Fourier series coefficient of AC components remains same if DC component is subtracted form the given signal?
Suppose a signal is defined by
$
x(t)= \begin{cases}
t & 0\leq t \leq 1 \\
2-t & 1\leq t\leq 2 \\
\end{cases}
$
Since $x(t)$ has even symmetry, I can calculate fourier coefficient as
$$
a_n = ...
0
votes
1answer
54 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 ...
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votes
1answer
33 views
Frequency component not filtered properly
Are frequency components other than wanted signal present in the output? If yes then why does it not disturb the original signal? I think all practical filter responses are not ideal, so all frequency ...
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1answer
80 views
Linearity of the given system
I am given the following system and I am checking the additive property:
$$y(t)=x(e^t)$$
where $y(t)$ is the output and $x(t)$ is the input given to the system.
Now this is what I did so far:
\...
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1answer
29 views
Finding Harmonics Analytically
I've always obtained harmonics using simulation and never by hand.
My question is how can someone find the harmonics for a signal (say a square wave) by hand? What equations come in handy for finding ...
0
votes
1answer
50 views
How to calculate the power of a finite length signal?
I am confused with these concepts. If the signal is expressed as r(t), I know the power of the signal is given by:
But if the the length of signal T is finite and cannot approach infinity, how can I ...
1
vote
4answers
185 views
Difference Between Dirac delta and unit impulse function
The definition of Dirac delta function states that it gives a value of $\infty$ at t=0 and 0 elsewhere.
But, the definition of unit impulse function states that it gives a value of 1 at t=0 and 0 ...
0
votes
1answer
23 views
identify equilibrium region after large transient
I am looking at data from a mechanical system under an unsteady load. I'm trying to find the simplest way to identify the portion of the signal once the system reaches its new equilibrium. Here's a ...
0
votes
3answers
132 views
What is the magnitude of the impulse function at t=0?
The unit impulse function, in a few textbooks that I have referred, has a value of 0 at t≠0 , and an area of unity (1). The height of the impulse function also tends to infinity at t=0. But since it's ...
0
votes
1answer
92 views
Show that any continuous-time signal $x(t)$ can be represented as $x(t)= x_e(t) + x_o(t)$
Show that any continuous-time signal $x(t)$ can be represented as $x(t)= x_e(t) + x_o(t)$
where $x_e(t) =\frac{1}{2}[x(t) + x(-t)]$ and $x_o(t) = \frac{1}{2}
[x(t) − x(-t)]$
are even and odd ...
0
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1answer
59 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
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1answer
69 views
Properties of Invertible System [closed]
I have come to the understanding that if these three properties hold true then the system is a memory system:
1) Time Scaling:
$$y(t)=x(2t)\,,$$
2) Time Shifting:
$$y(t)=x(t+2)\,,$$
3) ...
1
vote
2answers
70 views
Adding/subtracting sinusoids
I'm trying to calculate resultant function from adding two sinusoids:
$9\sin(\omega t + \tfrac{\pi}{3})$ and $-7\sin(\omega t - \tfrac{3\pi}{8})$
The correct answer is $14.38\sin(\omega t + 1.444)$, ...
2
votes
1answer
101 views
Bridging CTFT and DTFT for a cosine
I'm trying to understand how I can start from the CTFT of a signal and end up with a DTFT.
For example if I take a basic example:
$$
x(t) = cos(\omega_x \cdot t) = \frac{1}{2} \cdot \left( e^{j\...
0
votes
1answer
21 views
Conversion of airflow signal into 1-D as a input for CNN [closed]
Trying to detect apnea from airflow signal. I have 100 files of the patient each file contains at least 8 hours of data and sampling rate is 32 Hz. How to prepare my dataset which is used as an input ...
1
vote
1answer
52 views
Separating two frequency component
How can we separate two frequency component when they get mixed means when signal get mixed with noise how receiver can judge which part is signal and which is noise ?
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3answers
139 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
1answer
79 views
How can I determine the order of filter?
This is my first study about signal analysing. I'm very confused about filter order. My problem is how can I know whether its 12-th order, or 2nd order like the book says so? I already knew that slope ...
0
votes
2answers
39 views
Reconciling Continuous and Discrete Complex Domains
Having taken some courses in Systems and Stability dealing mostly with continuous time signals, I am accustomed to thinking about the Laplace and Fourier transforms dealing with complex and pure ...
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votes
2answers
53 views
Is there a specific preferred order of operation on signals?
Basic Signal Operations Performed on dependent variables-- The periodicity of the signal is varied by modifying the horizontal axis values, while the amplitude or the strength remains constant. These ...
0
votes
1answer
59 views
PN code generation
Can we generate PN codes (maximal length sequence) using this technique in Matlab where L is the PN length?
pn=2*(rand(1,L)>0.5)-1
If yes, why?
0
votes
2answers
732 views
Understanding the frequency domain [duplicate]
I'm trying to understand what frequency domain is. I found general explanations on the Internet, for example:
frequency-domain graph shows how much of the signal lies within each given frequency band ...
1
vote
1answer
127 views
Determining sampling rate for signal reconstruction
I want to know how to determine the signal sampling rate required to reconstruct electrical signals whose frequency components are unknown, such as, for example, signals of charge/discharge voltage on ...
1
vote
0answers
21 views
Multiplicative Input-Dependent Noise [closed]
This question might not be exactly suitable to the question format of StackExchange but I couldn't find a better way to put it forward.
Lately, I have been dealing with ECG Signal processing and due ...
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votes
2answers
92 views
How to convert a sound signal function to wave file? [closed]
I am new to understanding sound signals. A sound signal, as far as I know, is a real function of time $x:[0,\infty)\to \Bbb R$. For example, $x(t)=\sin(t)$ is a sinusoidal signal.
What is $x(t)$. For ...
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votes
1answer
56 views
methods of crest factor minimization
i am studying the methodes CF minimization. and have a doubt.
in each methods there are steps with DFT and IDFT or like this FFT and IFFT.
Everyone provides the fact, that they use DFT and IDFT for ...
0
votes
1answer
47 views
Homodyne concept of receiver
I would like to understand a concept of homodyne architecture of I-Q demodulator and how the wave looks like at each step.
It is a bandpass Signal:
Step 1: multiplication with cos and sin wave. I ...
0
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0answers
31 views
How to calculate FFT when many samples are observed?
I was given a classwork(which I flunked) where a continuous time wave of the format below was given:
$x(t) = A\sin(\omega_1 t) + A\sin(\omega_2 t)$.
with different frequencies for $\omega_1$ and $\...
1
vote
2answers
48 views
Fourier series of $cos(\omega_0 t)$ in continuous time
Can any one please help me with understanding how we can calculate the Fourier series of Cos(w0t) using the formula:
I saw that they did the following calculus, but I Don't really understand how we ...
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votes
1answer
64 views
Converting Time Shift to Phase Shift
I have just started taking signal & systems lessons and here is my question:
If we say that x0(t) = A.cos(w0t). (a cosine signal with zero phase shift, w0 ...
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0answers
24 views
How does this digital signal controlling a switch in the circuit affect the output voltage?
Suppose you have a circuit which has the input signal $x(t)=2\sin (ω_ot + \pi/6)$. The switch in the circuit is controlled with a digital signal of the form: $s(t)=\sum_{k=-\infty}^{+\infty} (u(t+ε-...
