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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1answer
53 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 ...
-1
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0answers
14 views
how to plot data from Vector Network Analyzer using Matlab? [on hold]
Please help:
I have a VNA HP8735D 30KHz-6GHz. I am working on my project to measure the spectrum of the signal. I succeeded.
I am trying to do a report with a plot which I have seen on the VNA using ...
0
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0answers
14 views
multi-user communications techniques
I am working on multi-user communications. But I saw several differences in communication with one user.
For example, there are several techniques to compensate for Doppler in a communication with ...
0
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2answers
29 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 ...
-3
votes
2answers
43 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
25 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
62 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
44 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
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0answers
17 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 ...
0
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2answers
59 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 ...
0
votes
1answer
36 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
38 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
votes
0answers
26 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
46 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 ...
-1
votes
1answer
22 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 ...
0
votes
0answers
23 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-...
0
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0answers
62 views
How to do cross correlation in real time?
I want to measure the signal similarities between two time domain signals a and b in real time. I do not know where to start. I think cross correlation might help but not sure how. Please guide me :-)
...
0
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1answer
17 views
Investigating correlation for unequal signal lengths
I have measurements from two tablet sensors. The first sensor measures the touch pressure applied to the tablet and the second sensor is the acceleration of the tablet (in z direction). The sensor ...
3
votes
1answer
93 views
What techniques are available for correcting constellation rotation due to phase ambiguity?
In order for a receiver to recover a baseband signal, it needs a carrier signal equivalent to that used by the transmitter for upconverting the original baseband signal. Unless pilot tones are used, a ...
0
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0answers
40 views
Basic question on sampling frequency relationship with sampling rate?
I'm using Matlab and have a signal that I'm simulating and I want to take the fft of the signal eventually. The intermediate steps performed is fixing the number of samples and the samples per meter.
...
1
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0answers
56 views
How to generate the amplitude of a signal with a certain power spectral density?
I am a newbie. If I posted a question someone else already asked, please forgive me. Thank you!
Now, I have a power spectral density named $P(f)$ as a function of $f$. Let's say this function is ...
1
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1answer
31 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 ...
0
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0answers
79 views
Why does bandpass performance break down at low frequencies? [duplicate]
I've got a basic bandpass filter design that works great at higher frequencies, but breaks down at around 150 Hz. Here's the MATLAB code:
...
0
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2answers
134 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?
0
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1answer
20 views
What would be the proper notation for denoting part of signal that satisfies a condition?
I have a signal $E(t)$ which start at $t=0$ and dies out overtime. What would be a proper notation to specify part of which is above a certain threshold (say for e.g. C)?. Is $E_{interested} = E(t)>...
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0answers
15 views
Can the Tonality index in psychoacoustics model be positive?
I have an issue with understanding the attached equation of Calculating the Tonality index.
If you trace the equation, it appears that it is always less than 1 because the spectrum unpredictability (...
0
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2answers
93 views
Problem with convolution
For a flat fading channel (SISO system) we have:
$y=h \star s+n$
But for a mimo system, we have:
$y=Hx+n$ with $H \in \mathbb{C}^{N_r \times N_t}$
Why is there not the product of convolution for a ...
1
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1answer
64 views
Fourier coefficients of sum of two functions with different fundamental periods?
If we assume $\quad x(t)\leftrightarrow a_k\:$ and it is periodic with fundamental period T.
How can we determine the fourier coefficients of the sum
$x(t-7)+x(-2t+3)$
I know that $x(t-7)\...
2
votes
3answers
127 views
What is the filter with the less phase shift?
I have to analyze a dynamic signal but there is too much noise so I applied low pass filter but then there is too much phase shift.So what is the most reactive filter I can apply to my signal ?
Best ...
0
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0answers
34 views
How can we find the signal power of $x_{out}(t)=\frac{1}{2}Am(t)\cos \theta$?
I am trying to solve the following question:
I have partially worked out the problem and we have:
$$x_{out}(t)=\frac{1}{2}Am(t)\cos \theta,$$
which is the output of the LPF.
and
$$x(t)=Am(t)\cos (2\...
1
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1answer
33 views
Eigenfunction property for LTI sinusoidal and the sinusoidal steady-state response
All LTI systems possess the eigenfunction property for complex exponential inputs. That is (restricting our attention to periodic complex exponentials), if $e^{j\omega_k t}$ is an input to the LTI ...
3
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1answer
134 views
Designing high-pass filters using impulse invariance
One of the main disadvantages of realizing digital filters using impulse invariance is aliasing. According to the Nyquist sampling criterion, in order for the frequency response of the digital filter ...
0
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0answers
59 views
EEG Signal Preprocessing BCI Competition
I have downloaded a dataset from BCI Competition III(Dataset 3a).
I wish to classify the data into given 4 classes. The signal array is a time X channel matrix of some 900000 values sampled as 250 ...
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2answers
55 views
Why Derivative/Integration in time domain act as Highpass/Lowpass filter in frequency domain respectivly? [closed]
It is one of Fourier transform properties
1
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1answer
72 views
Is it possible to replace an integrator system with an equivalent differentiator?
I have a system whose input-output relation is as follows
$$y(t)=x(t)+\int_{-\infty }^{t} x(\tau) \,\mathrm d \tau$$
Can I create an equivalent system by using differentiators rather than ...
0
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1answer
76 views
Using the flip-and-drag method to draw a convolution
So, we are asked to graphically convolve (using the flip-and-drag method) the following pair of signals: $$x_1(t) = \delta(t+1)-2\delta(t-1) \ \ \ \ \ \ \ \ \ \ \ \ \ x_2(t) = \begin{cases} -1-2t, &...
0
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1answer
19 views
How do I simulate a purely real signal being received on multiple antennae in an array?
I have a signal created at baseband and then transmitted as $$\Re\{s_{bb}*e^{2\pi f_ct}\}$$ which is then received at a 5 element array for further processing. How do I interpret the real signal at ...
0
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1answer
40 views
impulse response of a system from its step response;confusion
If the step response of a system is given as $$c(t)=(10e^{-5t}-2e^{-10t}+1)u(t)$$
then its impulse response is _______?
My Approach:
we know: $$h(t)= \frac {d}{dt} c(t)$$
Process(1):
$$h(t)= \{ ...
2
votes
1answer
37 views
How is the energy conservation principle preserved in the case mentioned below?
Suppose there are 2 sinusoidal signals $\cos(\omega t)$ and $\cos(\omega t)$, which implies that their individual power is $1/2$ unit and total power is $1$ unit. When added, the signal $2\cos(\omega ...
0
votes
1answer
44 views
Impulse Invariant mapping [closed]
Can someone help me to better understand the Impulse Invariant mapping? :
$$h[n] = T \cdot h(nT)$$
I don't understand why the discrete-time impulse response, $h[n]$, is taken from the sampled ...
1
vote
1answer
238 views
Proof of the convolution property of Fourier Series in continuous time
I am facing problem in understanding the proof of Convolution property of Fourier Series (FS) in continuous time CT;
that is: $$\mathrm{FS} \big\{x_1(t)\star x_2(t)\big\}=T\sum_{n=-\infty}^{\infty}...
1
vote
1answer
504 views
Impulse response of ideal filters
I am aware that an ideal low-pass filter in both continuous time and discrete time has a $\mathrm{sinc}$ impulse response. What would the impulse response of an ideal high-pass or band-pass filter ...
1
vote
2answers
72 views
BIBO Stability and the convergence of the frequency response of a system
It is my understanding that an LTI system is BIBO stable if and only if its impulse response $h(t)$ is absolutely integrable. This also happens to be one of the Dirichlet conditions for the ...
1
vote
2answers
83 views
Fourier transform of even/odd parts of a complex signal
Why does Oppenheim state the following properties:
\begin{align}
\mathcal F\big\{x_e (t) \big\} &= \Re\big\{ X(j\omega) \big\}\\
\mathcal F\big\{x_o (t) \big\} &= j \Im\big\{ X(j\omega) \big\...
0
votes
1answer
53 views
Uniqueness of Fourier Series Representation and the Fourier Transform of Periodic Signals
If we are given a signal of the form $$x(t) = \sum_{k = -\infty}^{+\infty} a_k e^{j k \omega_0 t},$$ can we call it a Fourier Series representation of $x(t)$ right away?
Suppose we are given the ...
2
votes
3answers
144 views
Periodicity of the discrete-time Fourier Transform
The DTFT of a sequence $x[n]$ can be written as $$X(e^{j\omega}) = \sum_{n = -\infty}^{\infty} x[n] e^{-j\omega n}.$$
Is the smallest (fundamental) period in frequency of the DTFT always $2\pi$? Or ...
0
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1answer
31 views
Echo effect on sinusoidal input: Intuition
I am currently reading about adding echo effects on signals. I was wondering if my understanding is correct.
In the attached figure, the blue line represents the original signal and the red line is ...
0
votes
3answers
88 views
Causality as applied to capacitors
This question stems from a point of confusion that I still have about the causality, linearity, and time-invariance in LCCDEs. I wanted to use the capacitor as an example.
Consider a capacitor with ...
0
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2answers
53 views
Duality of the continuous-time Fourier transform - derivation and notation
Suppose we have the Fourier transform pair $x(t)$ and $X(\omega)$ such that
$$X(\omega) = \int_{-\infty}^{\infty} x(t) e^{-j\omega t} \mathrm{d}t$$
The duality property states that $X(t)$ and $2\pi ...
1
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1answer
50 views
How to model a generic low frequency signal?
I'm trying to apply Fourier analysis to a specific problem I have.
I have essentially an integral like the following
$$
\int_{\Omega} f(t) g(t) dt
$$
And I'm trying to assume that $g$ is a narrow ...
