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??
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)
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' theorm,
But when x(t) represent power, I wonder if
E = ## \int x(t) \, dx ## = ## \int X(f) \, df ## or not.
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 theorm, 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.
In Parseval's theorm, 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.
The Attempt at a Solution
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.
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...
Thank you for your answer. But I have three questions.
1.What does isolation 1-2 in the data sheet??? I can't catch meaning of number(1-2).
2.What happen if isolation becomes higher or lower??
3.Does fast response on falling edge mean small number of fall time? If I want to get low power...
I will use 3 way power splitter and power detector.
1. This is power splitter data sheet. In this data sheet, there are different isolation values. What does it mean?? Also in that point, I wonder definition of isolation at power splitter.
2. This is power detector data sheet. In this data...
I'm studying how to catch pulse width without oscilloscope. Unknown pulse is from Q-switched laser which has a symmetric Gaussian-like shape.
If a pulse is sinusoidal wave form, the problem becomes quite simple. I can find exact frequency because Fourier transform of sinusoidal wave form has...