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What is FFT sampling?
The sampling rate is the number of samples per second. It is the reciprocal of the sampling time, i.e. 1/T, also called the sampling frequency, and denoted Fs. The frequency axis for the FFT is linked to the number N of points in the DFT and the sampling rate Fs. It is defined as f=k⋅FsN. With k going up to N.
What is sampling frequency in DFT?
call T the sampling period. Thus, the corresponding sampling frequency is given by fs = 1/T. The discrete times at which we sample the signal are given by. tn = nT = n fs where n = 0,1,2,…,N − 1.
Which transform is used in frequency sampling?
Fourier transformation
The sampling frequency required by the sampling theorem is called the Nyquist frequency. The transformation of signals into the frequency domain (Fig. 2.5) is performed by the Fourier transformation, which essentially reformulates the signal into a cosine function space.
How is FFT resolution related to sampling rate?
The frequency resolution is dependent on the relationship between the FFT length and the sampling rate of the input signal. Consider, If the sampling rate of the signal is 10khz and we collect 8192 samples for the FFT then we will have:
What is the relation between FFT length and sample length?
Then, our frequency bin resolution is: This is may be the easier way to explain it conceptually but simplified: your bin resolution is just , where is the input signal’s sampling rate and N is the number of FFT points used (sample length).
Which is the maximum frequency of the FFT?
The maximum frequency of the FFT is half of the signal sampling frequency (in this case the sample rate was 22000 samples/sec), but in the upper region the results are never reliable, so the sampling result should be set to: 1.25 is the absolute minimum factor for getting the right values also in the upper region of the FFT.
What is the relation between FFT length and DSP?
A 8192 point FFT takes some decent processing power. A way to reduce this need is to reduce the sampling rate, which is the second way to increase frequency resolution.