Questions tagged [fourier]
Anything related to Fourier series, Fourier transform and similar mathematical tools used to analyze the frequency content of a signal.
338 questions
4 votes
0 answers
93 views
Uncertainty principles and signal recovery (Donoho and Stark)
I am trying to reconstruct a signal that has missing samples using the methods proved in the title paper. The paper is readily available (https://web.stanford.edu/dept/statistics/cgi-bin/donoho/wp-...
- 141
2 votes
1 answer
111 views
Interpretation of Laplace Variable
Through my study of circuits and signal processing, it is my understanding that the complete response of an LTI system is the sum of a transient response and a steady-state response. When analyzing ...
- 334
0 votes
1 answer
149 views
Rectangular wave to pure sine wave of fundamental frequency
This is a follow up of my previous question... Lets say my input produces a square waveform. By playing with the Fourier series simulator of Falstad, I noticed that you only have odd harmonics, but ...
0 votes
1 answer
142 views
How does half wave symmetry cancel out even harmonics?
Can someone simply prove the above statement. I am at a complete loss. I am told that even harmonics are not found in functions with half-wave symmetry. Yet, why do functions like cosine(2t) and ...
- 471
1 vote
0 answers
66 views
Complex Fourier series coefficients of a perturbed switching waveform
I am trying to recreate the analysis from a paper published in 2008. I will try to provide a detailed understanding of what I was able to comprehend from the paper so that the readers don't need to go ...
- 63
0 votes
1 answer
58 views
Parseval's Relation Fourier Transform Question
This is an example from Oppenheim's Signals and Systems book, the example continues but i couldn't understand how we found 5/8 for E as book suggests. I tried to apply the formula but i obtained a ...
- 1
0 votes
3 answers
182 views
Why do we need phasors for analysing signals and systems?
Phasor includes a real part as well as an imaginary part, in real domain the intuition is more clear, i.e we can use vectors instead to represent things, but to imagine a signal in a complex domain ...
- 109
0 votes
1 answer
116 views
Input of RC low pass filter from the output
In general, for an RC low pass filter, the output signal is related to the input signal by $$ Q_{out}(\omega) = H(\omega) Q_{in} (\omega), $$ where the \$Q\$s are the Fourier transforms of the time ...
- 11
1 vote
1 answer
151 views
How does DC converter switching cause broadband noise in this case?
As per Source1: "a broadband disturbance is defined as an electromagnetic disturbance which has a bandwidth greater than that of a particular measuring apparatus, receiver or susceptible device.” ...
- 3,408
0 votes
2 answers
235 views
MATLAB Fourier: Why do I see less harmonics the more I increase the sampling frequency?
I made MATLAB calculate the Fourier transform of these square wave pulses which have a frequency of 60Hz. I do not understand why, the more I increase the sampling frequency, the less visible the ...
- 4,344
0 votes
2 answers
143 views
Why is \$e^{-j2\pi f ~t_0} \$ instead of \$e^{-j2\pi f ~(t - t_0)} \$ for time shifting in the Fourier transform?
In signal processing and the study of Fourier transforms, the time-shifting property is a fundamental concept. This property describes how a shift in the time domain of a signal affects its Fourier ...
- 1,127
4 votes
2 answers
611 views
How do I calculate THD?
I want to calculate the total harmonic distortion of the signal using this graph and formula. The formula is taken from this page: Calculating harmonic distortion First Question: So my problem is to ...
- 159
0 votes
1 answer
114 views
How to use Fourier analysis for a daily sound? [closed]
Consider I want to set up a device to record any sound near my resident. It will be, of course, record all sounds, including humans sound, birds, cats, dogs, cars, motors, building constructions, wind ...
- 291
0 votes
1 answer
151 views
Fourier series complex to real
I have to find the Fourier series of this function in complex form and transfer it to real: \$f:(-\pi;\pi]\to \mathbb{R},\;\;\;f(x)= \begin{cases} x & -\frac{\pi}{2} \leq x \leq \frac{\pi}{2} \\ 0 ...
- 1
2 votes
3 answers
844 views
Fourier circuit analysis of a RLC circuit
I was trying to calculate output voltage across the inductor in the RLC circuit below. I had used the Fourier transform to convert input signal \$V_{i}(t)\$ which is a single rectangular wave pulse in ...
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