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What are the units of the product of two signals?

If the multiplier takes two voltages as input and returns a voltage as output, then there is necessarily a constant involved, with units of [1/V]. Take for example, AD633 (which was the first search ...
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Is the Dirac delta (impulse) signal a power signal or an energy signal?

[Added a reference on Schwartz's impossibility theorem for products of distribution] The continuous Dirac delta $\delta$ is not considered a true function or signal, but a distribution. From its ...

How can I get the power of a specific frequency band after FFT?

To get the total power across bins, sum the power in each bin. Also you need to compensate for your window loss if you want an accurate result. For a rectangular window, the power in each DFT bin is ...
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Why the "20" in calculating db ratio?

According to this source, the sound power received by an aperture is proportional to the pressure squared, i.e.: $$P = \frac{A p^2}{\rho c} \cos \theta,$$ where: $P$ is the received power $A$ is ...
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What are the units of the product of two signals?

In addition to Juancho's answer for the general mixer, I would like to give an example for a more simpler frequency mixer most commonly used in communication systems to shift the frequency spectrum of ...
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Does the RMS value of a signal yields its root-power?

Given that RMS means Root Mean Square the answer is rather obvious: it's a root power quantity. The RMS of a signal has the same units that the signal itself. Saying that "RMS is proportional to ...
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Undestanding antenna gain applicability

The answer has to do with the definitions of antenna gain and space loss. Antenna "gain" is essentially defined relative to space loss, which is due to isotropic (uniform spherical) ...
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Undestanding antenna gain applicability

Of course, the gain of an antenna is not like that of an op-amp. It is just a measure of how sharply it focuses the beam in a specific direction with regards to a reference antenna, e.g., an isotropic ...
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Power of noise signal through a matched filter (Digital Receiver)

Can anyone explain why that is? Which is the starting thought, or formula that yields to different times $t_1$ and $t_2$? The noise power $P_N(t)$ at any given time $t$ at the output of any filter (...
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What's the meaning of negative frequencies after taking the FFT in practice?

negative frequencies don't exist in practice, and this is just a mathematical representation? I'd say it's exactly the the opposite. Signals with only positive frequencies do not exist in nature and ...
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$\delta(x)$ doesn't really exist at all for any particular $x$. Like Laurent Duval said, Dirac is not an $\mathbb{R}\to\mathbb{R}$ function, rather the whole mapping $$\backslash f \mapsto f(a) \equiv ... • 1,269 3 votes Is the Dirac delta (impulse) signal a power signal or an energy signal? You're right that the square of a Dirac delta impulse is undefined, so energy and power cannot be defined in the usual way for signals containing Dirac impulses. However, in analogy with discrete-... • 90.5k 3 votes Random signals as power signals I think simple. We want to model a random physical phenomenon for analysis purpose. One way is to model it by a stochastic process X(t), i.e. a time series of random variables \left\lbrace X(t_k) =... • 6,605 3 votes Accepted Limiting bandwidth by adjusting sample rate Depends on your signal. Typically we try to sample at the Nyquist rate, which is equal to two times the maximum frequency of your signal. If you sample less often than this, you will lose information ... • 460 3 votes Accepted Definition of average power? The first definition works for deterministic as well as for random signals. For random signals we define the autocorrelation by$$R_x(\tau)=E\{x^*(t)x(t+\tau)\}\tag{1}$$where E\{\cdot\} is the ... • 90.5k 3 votes Accepted Calculate the signal's average power A signal either has finite energy, finite power or even infinite power. If it has finite energy, it will have zero average power, according to your definition$$P_x=\lim_{T_0\rightarrow\infty}\frac{1}{...
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First of all, note that your formula for signal power is only valid for real-valued $x(t)$ that satisfy $x(t)=0$ for $t<0$. A more general formula is P_x=\lim_{T\to\infty}\frac{1}{2T}\int_{-T}^{...