Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [fourier]

Anything related to Fourier series, Fourier transform and similar mathematical tools used to analyze the frequency content of a signal.

Anything related to Fourier series, Fourier transform and similar mathematical tools used to analyze the frequency content of a signal.

Fourier series and transform are named after French mathematician Jean Baptiste J. Fourier (1768-1830), who gave great contributions to trigonometric series theory while he was studying heat transfer in solid bodies.

See also Wikipedia on Fourier series and Fourier transform.

320 questions
71
votes
6 answers

Relation and difference between Fourier, Laplace and Z transforms

I have become a bit confused about these topics. They've all started looking the same to me. They seem to have the same properties such as linearity, shifting and scaling associated with them. I can't seem to put them separately and identify the…
Vineet Kaushik
  • 1,147
  • 2
  • 13
  • 19
32
votes
7 answers

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 a microcontroller in to an antenna, how are…
John Quinn
  • 331
  • 1
  • 3
  • 4
23
votes
7 answers

Would a triangle wave have finite or infinite sinusoidal components?

A discontinuity causes a signal to have infinite sinusoidal components, but a triangle wave is continuous, I was taking a class in which an instructor said that since the triangle wave is continuous it can be represented by a finite number of sine…
Syed Mohammad Asjad
  • 447
  • 4
  • 12
18
votes
4 answers

What is the function of a Fourier Series?

What is a Fourier Series? What it is used for?
coldshine
  • 505
  • 1
  • 5
  • 8
15
votes
4 answers

Can I use the FFT to recognize musical notes on a piano?

I want to create a tool which recognizes a few musical notes (I know this is re-inventing the wheel). So I would play middle C, D, and E on a piano and it should be able to classify those notes. Here's how I think I should approach it: Record a…
michaelsnowden
  • 269
  • 1
  • 2
  • 7
13
votes
6 answers

What kind of hardware implements Fourier transform?

I looked around online but I found nothing relevant. It is very difficult for an electronic device to decompose a signal in different frequencies. How this is done at the bare metal level? Any suggested source or comment will be very helpful
veronika
  • 412
  • 1
  • 7
  • 17
12
votes
3 answers

Do square wave exist?

If we send a square waveform through an antenna, will we get square electromagnetic waves with electric and magnetic fields looking like squares? Also, since there is an abrupt/almost jump in amplitude, will we get very high frequency sine waves…
Vishwa Mithra Tatta
  • 581
  • 1
  • 6
  • 17
12
votes
1 answer

Why isn't the Fourier transform of a single sine wave cycle a single bar?

I have tried different Fourier transform codes out there on single sine waves, and all of them produce a distributed spectrum with a resonance at the signal frequency when they should theoretically display a single bar. The sampling frequency has…
Mister Mystère
  • 9,477
  • 6
  • 51
  • 82
10
votes
3 answers

Why is a signal that is finite in time domain, infinite in its frequency domain?

Why does every single band-limited signal in frequency have an infinite time domain and vice versa (As it's a symmetric relation, inf in one is finite in the other). I understand how a digital signal with an infinite slope needs infinite amount of…
JustLearning321
  • 109
  • 1
  • 5
8
votes
2 answers

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 a vector of length N rather than a summation. Why…
john
  • 83
  • 1
  • 1
  • 3
8
votes
4 answers

Why does my rectangle function on a FPGA look like this?

I programmed my FPGA to create a simple 1 MHz rectangle function. But when I display the resulting function on my oscilloscope it shows some oscillation after the edges. At first I thought this might be the the Fourier components, but this doesn't…
Stein
  • 191
  • 2
7
votes
3 answers

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 Fourier transform into frequency contents. Will Fourier…
user25148
  • 165
  • 1
  • 1
  • 6
6
votes
2 answers

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 sure how or whether to visualize them. Should I…
Grumdrig
  • 505
  • 4
  • 12
5
votes
2 answers

How does one measure the Fourier components of a signal?

I attended a lecture on ground penetrating radar (GPR). I am used to reflection seismic where the incoming pressure amplitude is measured as a function of time. In GPR, instead the Fourier components are measured. That is the amplitude and phase as…
Andy
  • 265
  • 1
  • 9
5
votes
1 answer

Fourier series of output voltage

I've been practicing some Fourier series questions and then verifying my answers by generating an equivalent graph on MATLAB and comparing it with the graph generated by PSpice in simulating the same circuit. This is my working: The Fourier series…
Lachlan
  • 83
  • 1
  • 7
1
2 3
…
21 22