Recent content by Jiho

The pulse laser is converted by photo detector(PD) into electrical current. And we can see output voltage of photo detector by using oscilloscope. Now we get voltage function detected by PD. Now I need to calculate energy of pulse. But I don't know how I do it.. Is there any formula I can use??

How cna I choose Fs high enough when no upper frequency limit?? Is there any criterion in signal processing??

I can't understand why max freq is 5Ghz. Do you mean that value corresponding freq lower at about 5Ghz is close to 0?

I run sympy.fourier_transform. from sympy import fourier_transform, exp,symbols from sympy.abc import x, k a=fourier_transform(exp(-x**2), x, k) s=symbols('s') Ori=(s)*exp(-(x**2)/(s**2)) FT=fourier_transform(Ori,x,k) a.subs({k:1}).evalf()...

Hello. I'm studying Fourier analysis. If we look at attached graph where Gaussian functions are transformed by Fourier analysis, we can find Gaussian functions in frequency domain have maximum value at 0 hertz. So I confused what is the Nyquist frequency at Gaussian signal. I need to know...

Sorry to my expression. I didn't know how to write LATEX letter. When x(t) represent voltage, E = ## \int x(t)^2 \, dx ## = ## \int X(f)^2 \, df ## by definition of Parsevals' theorem, But when x(t) represent power, I wonder if E = ## \int x(t) \, dx ## = ## \int X(f) \, df ## or not. X(f)...

## \left( \frac a b \right) ## Thank you. I got it!

Could you kindly give me specific detail?? I can't find proper information about LaTeX in the link you said.

I want to write LaTeX. So I write e.g) '\left( \frac a b \right)' . But it looks just back space bar not mathematical equation. Does there need to install TeX program if I want to type LaTeX in Physics Forums?

Then, in Parseval's theorem, E= integral x(t) square dt = integral X(f) square df. But if x(t) represent 'power integral x(t) dt'= energy as you said. I wonder when x(t) represent power, if 'integral x(t) dt' = 'integral X(f) df' or not.

Homework Statement In Parseval's theorem, energy equals integral x(t) squre when x(t) represents voltage. I wonder if x(t) represernts power, then does integral x(t) dt equal energy?? Because 'power multiplied time' means energy. Homework Equations The Attempt at a Solution

Homework Statement By using Fourier transform, I want to calculate power of signal. I confuse that f(x) in attached equation represents voltage or power. Is that possible when f(x) means power to use Fourier transform. Homework Equations The Attempt at a Solution

you mentioned it doesn't matter that signal x(t) represents voltage or power. But I can't understand if x(t) represent power, this equation doesn't make sense as I think. In my opinion, How can power^2 be just power?? Unit of dimension is not same as I know.

I have a Gaussian like shaped pulse waveform. It has 0.3ns pulse width, and it means 1.45Ghz half-band width in my calculation. If signal has 13dBm then what is output voltage from power detector? Is this enough information to calculate output or not? It's ok if I could get approximate value.

Thank you. I absolutely understand about pulse response time. But I still have two question. 1.What does isolation between output ports 1 and 2 mean? Is ratio of isolation between port 1 and port 2? Would you kindly explain me isolation 1-2?? I know isolation mean -10log(Pout/Pin). But I...