Questions on the mathematical aspects of signal processing. Please consider first if your question might be more suitable for http://dsp.stackexchange.com/
Questions tagged [signal-processing]
2068 questions
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How do I get the phase of a sine wave at a specific time
I have a sine wave $w_0$ with a linearly increasing frequency $f_0$
$f_0(t) = r_0 \cdot (t - c_0)$
$w_0(t) = a \cdot sin(2 \pi \cdot f(t) \cdot t + \phi) $
I want to glue that sine wave to another sine wave at the moment $c_1$:
$f_1(t) = r_1 \cdot…
Typhaon
- 121
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Find the energy spectrum of a function
We have been given x(t) and h(t) with their functions and we are required to compute the energy spectra of y $S_y(f)=S_X(f)|H(f)|^2$
Where $S_y$ is the energy spectrum of $y(t)$ and $S_x$ is the energy spectrum of $x(t)$
I have found $S_x(f)$ and…
Severjan Lici
- 125
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Numerically extracting the phase of a sinusoid without constant phase?
I have experimental data that is proportional to $I(k) = cos(Ak + \phi(k))$, where the phase $\phi(k)$ is not constant for different values of $k$. How would I go about numerically calculating $\phi(k)$? If the phase where constant, a Fourier…
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A request for an example of a band limited signal.
Recall that a signal $x(t)$ is band-limited signal if its Fourier transform
$$
X_{\Phi}(\Omega)=\int_{-\infty}^{\infty}x(t)e^{-j\Omega t}dt
$$
vanishes outside an interval, say $[-\Omega_0,\Omega_0]$. The problem is that I can not find any examples…
boaz
- 4,783
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1 answer
Finding the signal $y[n]$ that results from the linear transformation of $x[n]$
I have this two signals $$x[n]=4\delta[n+1]+\delta[n-2]-2\delta[n-5]$$ $$y[n]=(3n-5)(u[n-1]-u[n-4]$$
I know that $y[n]$ results by the linear transformation of $x[n]$ and I have to find the parameters that make this possible.
Since $x[-1]=y[3]$ and…
Favolas
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Hot to get $e^{iwT} = 1$, $T = \frac{2\pi}{w}$?
Can someone please explain how to get to the above conclusion for T from the equation provided? I understand:
$e^{iwT} = 1$
Can be written as:
$\cos(wT) + i\sin(wT) = 1$
But I’m at a loss as how to proceed further. Though I know:
$T = \frac{2\pi}{w}…
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Signals and systems kroneckers delta
Hi I'm supposed to determine if $y[n]=nx[n]$ is invertible.
I found an answer that says that it's not because $x[n]=δ[n]$ and $x[n]=cδ[n]$ (c is a constant) gives the same output.
Could someone please explain why that is?
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Show that the equation is shift invariant and linear
I came across a question while studying signals and systems, and I am not able to prove it.
The question wants me to show that the following equation is shift invariant and linear. Showing that it is linear is not too difficult, but I am having a…
big tree
- 11
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Frequency Change with Tape Speed
I recorded my own voice in an old tape recorder. When I put the device in fast forward mode my voice turned a little squeaky. I wonder if the fundamental frequency of the voice had changed? Is that possible?
JMFS
- 247
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1 answer
Can u tell me something about these signals?
I have a problem with these signals:
$x[n]$ is given:
$ x[n] = 3 \delta [n] - 2 \delta [n-1] + \delta [n-1] \text{, } n = 0,...,N \text{, N=8 }$
I computed the DFT and afterwards the 5 IDFT's of the resulting signal.
But now i have to explain what…
madmax
- 439
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Reconstructing signal without aliasing
$$x[n]=2\sin\left(0.2\pi n-\frac{\pi}{2}\right)+4\cos(0.5\pi n-\pi)+\cos(0.8\pi n)$$
This signal is the result of sampling $x(t)$ with a frequency of 40Hz.
I have to see if this frequency can reconstruct the signal without aliasing. I understand…
Favolas
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Is this system linear?
$$y(t)=\begin{cases}0 \hspace{4.86cm}x(t)<0\\
x(t)+x(t-2)\hspace{2cm} x(t)\geq0\end{cases}$$
Assuming $C>0$. If $x(t) = C$ is an input, the output will be $2C$, and the output of $-x(t)=-C$ must be $-2C$ to satisfy scaling. But when the input is…
ringo
- 1
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Given one sine wave in time domain, how to find its frequency?
Given one sine wave in time domain, I want to find its frequency. Because I observe only a very small part of the sine wave ~1 cycle, FFT methods have a poor spectral resolution.
Has there been work that bounds the error on the frequency estimate?…
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Find the frequency of a sine wave from its angle
I know I'm doing something stupid but I just can't find out where.
Suppose that I have a sine wave whose angular frequency varies linearly with time. So:
$\omega = ct$
And the sine wave would be:
$S=sin(\omega t) =sin(ct^2)$
Now suppose I have $S$…
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8 point dft with impulse signal
the question is: find the dft of x(n) ={ individual digits of your roll number } - delta (n) using DIT FFT
I do not understand this question. what do I do with the impulse signal here? if it was just x(n) then it can easily be solved but how do I…
Arpit
- 101