Linked Questions

0 votes
1 answer
82 views

Why dft sine plot is so strange

Why does my dft plot of $\sin(x)$ look so strange? It goes to negative and then inverts closer to the edge. ...
Alexander's user avatar
1 vote
1 answer
168 views

possible spectral leakage

If I perform a FFT of a real signal which is limited on time (for example the atmospheric pressure in time from 0s to 5000s), is it possible that the fact that is limited on time can affect the FFT ...
user49811's user avatar
2 votes
1 answer
514 views

How to interpret a 1D-DFT of an image with a sinus grating/gradient compared to its 2D-DFT outcome?

For getting a better and more intuitive understanding on how the 2D-DFT works I was playing around with sinus gratings in grayscale. I tried to compute the 1D-FFT first and compare it with the 2D-DFT ...
OuttaSpaceTime's user avatar
1 vote
2 answers
2k views

Window functions and the Fourier transform

I want to clarify the 'correct' way to use windowing and Fourier transforms. My question is somewhat related to this one, but I have a few additional queries. I have some real, non periodic signal ...
user1887919's user avatar
0 votes
1 answer
161 views

Why sine wave leakage in FFT spectrum

The input is three sine waves with different amplitudes and frequencies. After FFT the spectrum shows the correct characteristic of each wave without leakage error. Why does the other spectrum leakage ...
Harry Sung's user avatar
0 votes
1 answer
73 views

Difference between two sine generators

I have two sine oscillators and I get these two different spectrum analysis (let's disregard the slight frequency difference). Is there any deductions that can be made about the "quality", or sine ...
John Am's user avatar
  • 103
0 votes
1 answer
290 views

DFT independent variable as fraction of sampling rate

When the frequency domain's independent variable is labeled as a fraction of the sampling rate, the values along the horizontal axis always run between $0$ and $0.5$, since discrete data can only ...
Stephen K. Karanja's user avatar
6 votes
5 answers
10k views

About Discrete Fourier Transform vs. Discrete Fourier Series

I am new to the field of signal processing. I am wondering what is the difference between DFS(Fourier Series) vs. DFT(Fourier Transform). For common applications, usually we get a segment(length <...
aha's user avatar
  • 171
0 votes
1 answer
116 views

Analyzing Spectrum of a signal?

my_signal = 8192*cos(2*pi*6*(0:7)/8) + 1i* 8192*sin(2*pi*6*(0:7)/8); my_signal_fft = fft(my_signal); plot(abs(my_signal_fft)); This is matlab code. What do you ...
Anarkie's user avatar
  • 137
4 votes
2 answers
1k views

Working around FFT windowing?

I have the following problem, that I ran into recently, when calculating the spectra of data that I obtain from a measurement technique, we are using in our group. In short what we do in the technique,...
packoman's user avatar
  • 255
2 votes
3 answers
2k views

Calculating the extent of spectral leakage

As a follow up to this question - Is there a way that I can calculate the amount of spectral leakage in a given bin, i.e., given an input amplitude, what percentage of the amplitude is present in ...
Kitchi's user avatar
  • 721