The fourier tag has no wiki summary.
0
votes
4answers
109 views
Mathematical rigour in Signal and Systems
I'm an electronics engineering student with high inclination to analysis and pure mathematics ( abstract algebra/linear algebra ... ). I was just wondering if there was any book ( or any resource ) ...
-1
votes
0answers
45 views
Zero-Padding seems to CHANGE FFT of signal! [closed]
I am having trouble with zero-padding. As I understand it, in theory, zero-padding in the time-domain should 'sinc-interpolate' the FFT of the signal in the frequency domain.
This would mean, that 1) ...
-2
votes
2answers
90 views
A simpler method or more descriptive answer to the Fourier Transform
I'm trying to do a CT Fourier Transform of these two signals
$$e^{-a(t-1)} \cdot u(t-1)$$
and
$$e^{-a(t-1)} \cdot u(t)$$
Where \$a\$ is any real number, and \$u(t)\$ is the unit step function.
My ...
-3
votes
2answers
70 views
Would we have communication theory and systems without trignometric ratio? [closed]
Trigonometric identities happen to be invented for triangles: sin, cosine and through them tangent.
Later at school I learnt that they are periodic and have wave appearance. Than in University I came ...
2
votes
2answers
164 views
How does Fourier series apply to signals?
I have the complex form of Fourier serie:
It says that an and bn are real numbers, while c is a complex number. I need Fourier serie to represent an electrical signal that should transmit bits. ...
-3
votes
1answer
66 views
Mobile phone or iPod as digital signal generator? [closed]
I have an idea to use the mobile phone audio output to use as a signal generator.
Because we could decode tones from sound, it should be possible to decode pluses from the sound too.
My question ...
0
votes
2answers
458 views
Why output of square wave signal after bypass capacitor is a triangular wave?
I understand square wave contains many sine waves of different frequencies as so does triangular wave.
My impression with bypass capacitor is that the higher the frequencies the better it attenuates ...
2
votes
4answers
502 views
Square wave / Sine wave is more audible
Consider you have 50 Hz both square wave as well as sine wave put on to a same speaker at different time. Which signal is more audible and what is the reason behind that ?
We know that by taking the ...
1
vote
1answer
58 views
Effect of Quantisation of a Signal on the Estimated Spectrum
I have been applying the Welch Estimation technique to a signal in MATLAB to give a Spectral Density plot for frequencies from 0 to 0.5 the sample rate. I have two issues:
I have a peak at 0.25 for ...
3
votes
1answer
139 views
Why does increasing sampling density in the frequency domain separate overlapping artifacts in the spatial domain?
I have employed the fourier(projection) slice theorem in matlab. I have a 3D image, P(x,y,z) defines their pixel intensities at a given location int he image volume, it is discrete and uniform. I take ...
0
votes
0answers
65 views
what should the amplitude be when plotting 1-sided Amplitude Spectrum?
I have a continuous signal x(t) such that
\$ x(t)=12 \cdot cos(6\pi t)+6 \cdot cos(24 \pi t)+3 \cdot cos(30 \pi t) \$
and is asked to sketch a 1-sided Amplitude Spectrum of the signal x(t) if ...
2
votes
5answers
297 views
Time-limited signal Fourier transform
Suppose that there are two periodic signals with particular frequencies. Two signals are then combined into one signal.
Suppose that we take finite samples of these signals. (so, finite time of ...
1
vote
3answers
532 views
Fourier transform of a sum of signals
Let us say that there are some signals, and all of them are Fourier-transformable and are a unique, single-frequency sine wave.
Now, we combine (add) these signals into one signal. Then, we do ...
2
votes
3answers
212 views
DC level in Fourier series
From this answer:
The Fourier series:
\$ V_t = \dfrac{a_0}{2} + \displaystyle \sum_{i=1}^{\infty}[a_i sin(i \omega_0 t) + b_i cos(i \omega_0 t) ] \$
Why is the DC level written as ...
4
votes
2answers
335 views
Nyquist-Shannon sampling theorem and highest frequency
Nyquist-Shannon sampling theorem states that sufficient condition for sampling is sampling rate higher than twice the highest frequency.
By highest frequency, does this refer to the highest ...
2
votes
5answers
489 views
A signal that can be transformed by Fourier transform and its frequency
A signal A, which is in time domain, can be transformed by Fourier transform into its frequency contents.
Then, is the signal A's frequency the highest frequency part of its Fourier transform? (i.e. ...
0
votes
1answer
130 views
Harmonic and Fourier transform
I heard somewhere that Fourier transform only works on a signal that contains parts that are harmonic to each other (i.e. f, 2f, 3f etc.).
Can anyone explain me on proof of this? Or if I am mistaken, ...
14
votes
5answers
3k views
What exactly are harmonics and how do they “appear”?
From reading so many sources online, I still cannot grasp why a different waveforms have harmonics.
For example: when designing a silly amplitude modulation (AM) circuit that puts a square wave from ...
6
votes
2answers
496 views
Scaling FFT output by number of points in FFT
When computing the N-point FFT of some signal, the result is always divided by N. I can understand why this is the case for a summation over the N points, but often the result of the FFT operation is ...
3
votes
2answers
330 views
Meaning of phase in Fourier Transform of audio signal
I'm looking at the Fourier Transform (really, at a sliding DFT) to analyze (visually and intuitively) the frequency components of a sound over time. But the DFT produces complex numbers, and I'm not ...
15
votes
4answers
678 views
