21 questions linked to/from What happens when N increases in N-point DFT
179k views

### Why should I zero-pad a signal before taking the Fourier transform?

In an answer to a previous question, it was stated that one should zero-pad the input signals (add zeros to the end so that at least half of the wave is "blank") What's the reason for this?
4k views

### What is Frequency Resolution?

Im trying to tackle the following problem while still not having a firm idea on what "frequency resolution" means : Suppose we sample a continuous time signal with sampling period Ts = 1/2000, and ...
3k views

### Link between DFS, DFT, DTFT

My understanding of DFT is as follows For a signal $x[n]$ of finite-length, the DFT is DFS of the periodic extension, $\tilde{x}[n]$, of that signal $x[n]$ and also another way to view DFT is that it’...
3k views

### FFT of any sinusoidal signal -- how many point fft to take?

suppose I have to measure the DFT of an 60 hz sinusoidal signal and calculate upto 20 harmonics of this. Value of the 20th harmonic will be 20*60 = 1200 HZ. Then my sampling frequency should be >= 20*...
914 views

### How to derive the bin width / maximum frequency of DFT/STFT

The bin width is given by the $F_s / N$ and the maximum frequency is given by $F_s / 2$ where $F_s$ is the sample rate and $N$ is the number of samples of the DFT. Going between these is trivial, but ...
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### For 2D signals can it be said that the frequency response is the same as the Fourier transform?

Say I have a signal: [1, 1 , 1; 1 100 1; 1 1 1];, I wanted its frequency response, then can I take its FFT? Why does MATLAB have two functions to do the same ...
5k views

### DTFT of any finite sequence in matlab

I think freqz in a MATLAB toolbox, is the way to obtain DTFT of sequence. freqz can calculate frequency response of: H(z)=(Num)/...
2k views

### Specific Frequency Resolution

I have an audio signal SampleRate Fs: 44100 Hz TotalSamples: 94144 samples Duration t: 2.1348 s The frequency resolution is given by ...
3k views

### Computing the Power Spectrum Density (PSD) on a CSV File in Python

im quit new with signal processing and im trying to calculate the PSD of a signal im sampling. the signal is an output of a DC buck converter this is the code im using and this is the plot im getting ...
848 views

### FFT and number of samples relations

I am new in signal processing. I generated a signal with $f_{in}=10 \mathrm{kHz}$ and also take 64 sample from this signal after doing some process in an ADC block. I want to convert the result to the ...
394 views

### Effect of changing sample rate, window duration and zero padding on DTFT and DFT

Let $T$ be the window duration, $N$ be the DFT size, $F_s$ be the sample rate, and $F_{max}$ be the frequency of the highest bin. In the context of image below: halving the $F_s$ (keeping $T$ ...
496 views

### Smallest FFT buffer size given zero-padding

I am currently working on a project that involves processing an audio signal by dividing it into chunks of size B. The buffer is then zero padded to have a size of 44100 points, after which FFT is ...
772 views

### What proportion of a padded FFT should be actual values

For a given signal, I've been told that you can pad the vector with $0$s at the end to get a larger DFT, and as a result get more precision in frequency bins. What are the limits to this approach? ...