Fft number of samples

The number of samples (N) in the FFT must be an integer power of 2. Therefore, N = 2^p, where p is a positive integer. This rule minimizes the number of multiplications—and therefore the computation time—needed to compute the coefficients of the Fourier series.

1. How do you find the number of samples of a signal?
2. How many samples are needed for DFT?
3. How do I choose my FFT size?
4. How many data points needed for FFT?

How do you find the number of samples of a signal?

The sampling frequency or sampling rate, f_s, is the average number of samples obtained in one second, thus f_s = 1/T. Its unit is sample per second or hertz e.g. 48 kHz is 48,000 samples per second.

How many samples are needed for DFT?

So at least 6 samples should be taken to complete one cycle of min frequency. Now the frequency resolution is 100 Hz. Since the sampling frequency is 10 MHz, Maximum frequency can be detected is 5 MHz. So 5MHz/100Hz = 50000 points will be there in first half of FFT.

How do I choose my FFT size?

The frequency resolution is equal to the sampling frequency divided by FFT size. For example, an FFT of size 256 of a signal sampled at 8000Hz will have a frequency resolution of 31.25Hz. If the signal is a sine wave of 110 Hz, the ideal FFT would show a sharp peak at 110Hz.

How many data points needed for FFT?

Typical benchtop instruments use FFTs of 1,024 and 2,048 points.