i mean, the delta function has no physical meaning and there is no negative frequency's.
Since you have already made up your mind about these two opinions, which you state as facts, we have no way to help you. When you are willing to open your mind and consider that the Dirac delta has physical meaning (that's why Dirac invented it) and that there is meaning to negative frequency (just as there is meaning to negative distance) please let us know and we may be able to help you.
i found this java applet which is pretty cool https://ptolemy.eecs.berkeley.edu/eecs20/week10/negativefreqs.html
I'm not sure I follow you here. The coefficients are generally used as they are, not with absolute value. Maybe I'm just not understanding what you are saying.about the amplitude and dirak function i simply used the Fourier coefficient aκ and a-κ in absolute value to show that the amplitude is A.
i did get into some trouble explaining triangular periodic wave with the foureir transform.the wave is 4Vp-p 1KHz. first i raised the dc level to get triangular wave that goes from 0 to 4V. which does not change the amplitude in the frequency domain. then i got the foureir transform which is T1*sinc^2(ωT1/2) and from that transform i got the coefficient using that any periodic function is represented as X(ω)=Ʃ2πaκδ(ω-ω0κ) so i got aκ=(T1/2π)*(sin(0.5πκ)/(0.5^2π^2k^2). i know that the sine function is correct because i got that for even K the amplitude is 0. the problem i got is that everything else doesn't much what i got (and others) in the lab. i should get something like 0.89/k^2*sin((0.5πκ)) but i get something a lot smaller like 3.22*10^-5/k^2 which make no sense seen that this number is so small. i guess i got something wrong in the transform but i cant seem to find it. when i tried to directly calculate the transform i didnt get anything like the sinc function. if you can find what i did wrong that will be great
thank you again for all your help
"Does negative frequency have any real physical representation".
Also, i assume that by 'physical' you mean something that can be measured in some way or at least being able to theorize that it could be measured some how.
So even with geometrical interpretation we still havent answered the question: "Does negative frequency have any real physical representation". .
If you had to use the concept of negative frequency to arrive at a solution and you also had to measure this frequency that could mean something.
But we are still looking for a physical explanation of the impulse shown in the attachment that exists in the negative frequency domain.
Yes- we can try to find a physical explanation. But - for me - it would be not a surprise if we fail in some cases. Can we always expect to find a physical explanation for a phenomenon that results from a mathematical manipulation only?
Look to the far right to the image that has the two impulses. One is on the positive frequency side (first quadrant) and the other is on the negative frequency side (second quadrant). We assume we know what the positive frequency impulse is, but maybe we dont even understand that in it's entirety either. Integrating either side (squared) from zero to positive infinity gives us only half the total 1 ohm energy, while integrating both sides gives us the total energy. So actually neither side explains the whole picture
But remember: It is a known fact that the one-sided spectrum (which results from the real form of the FOURIER transform) contains amplitude that are twice as high if compared with the two-sided spectrum. Thus, there is no problem to interpret it correctly.
So we're looking for an explanation. I tend to agree however that it's just a mathematical tool. We also use "imaginary numbers" to arrive at real life conclusions, but we dont expect to find imaginary apples sitting on the shelf at the supermarket
As explained in my example with the complex frequency (s=sigma+jw) I have no problems to accept that we are using from time to time mathematical tools, which lead to results without direct physical "existence".
Nevertheless, we normally don`t create new names but we use words and units that come from the known real physical quantities. This may be one reason for misunderstandings and misinterpretations.
(see also comment at the end of my post)
As a counterexample - I like to mention the group delay. Some people think (and even some textbooks claim) that group delay and group velocity cannot be negative. I agree, that - at first sight - one could have problems to understand the meaning of negative values. However, negative group delay/velocity has been experimentally proven to exist.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?