# Questions tagged [dft]

The Discrete Fourier Transform (DFT) is a mapping between a finite set of discrete points in a (primal) domain (time, space) and the dual frequency domain. DFT requires an input sequence which is discrete, such as a sampling from an analogue audio signal.

769 questions
Filter by
Sorted by
Tagged with
276 views

211 views

198 views

### Whitening signal vs. whitening its DFT

A whitening transformation (PCA) is simply a rotation into a space in which variables become uncorrelated. Because a DFT is a transformation into a coordinate space of orthogonal frequency components,...
1k views

### Understanding LPC for Formant Estimation

I went through the Matlab tutorial on Formant Estimation using LPC Coefficients. Though I vaguely understand the details, it's not entirely clear why we need to do this. From http://person2.sol.lu.se/...
1k views

### Expression for discrete fourier transform of linear ramp

I am trying to compute a single coefficient of the DFT of a linearly ramping sequence, $x[n]=an$ where $a$ is a constant that changes from sequence to seqeunce. I have looked at loads of DFT transform ...
170 views

### non-uniform sampling on the unit circle - applications

If there is an N-point sequence, it has a Fourier Transform. DFT of this sequence is the sampling of the Fourier Transform at N equally spaced points on the unit circle. What happens if we take some ...
2k views

### Difference between 2D DFT's and 1D DFT's of Linearized Matrices

I have recently left the safe and easy MATLAB environment and begun to use CUDA-C/C++ for image processing. Since CUDA doesn't allow 2D arrays to be passed into kernels I am now used to linearizing ...
414 views

### Exercise Related to Frequency Resolution and SNR

I'm studying a book about DSP and trying to make exercises. Here is one I'm interested in: A scientist acquires 65,536 samples from an experiment at a sampling rate of 1 MHz. He knows that the signal ...
620 views

### Sliding DFT: I think my results are accurate, but I can't buy a swap-swap IDFT

I've got a sliding DFT implementation that appears to be working (judging from an output plot). I would like to be able to invert this implementation using the standard tricks of swapping the real and ...
131 views

### Does chirp have constant magnitude frequency response?

Pg. 223 claims so, yet my results via DFT differ: Is the textbook wrong? My attempted explanations: (code) DFT vs DTFT: "frequency response" is computed via latter. Still, DFT should ...
45 views

### Cross Domain Equivalent to Nyquist Sampling Theorem?

In attempting to answer this question by @Oliver here: What characterizies 'causality' for a finite FFT? I have considered the minimum requirement to avoid time domain aliasing in the Discrete ...
447 views

### 2D DFT in image processing in python

I try to compute 2D DFT in a greyscale image with this formula: I write the code bellow with python ...
71 views

### Leakage in power spectral density estimation

What does it mean for a power spectral density exhibiting leakes from one frequency bin to other. I am reading a book which states the following: "Often the time series we use as input for our ...
172 views

### What is the DFT of a pure cosine wave cos(θ)

I want to find a DFT of a pure cosine wave cos(θ) sampled at N equally spaced points on the interval $[0, 2\pi)$ so for our cosine wave, I put my $x$ like this $x=cos(\phi)$ then I just put it in ...
76 views