because they have a high speed compared to fft
FFT reduces the computation since no. of complex multiplications required in FFT are N/2(log2N). FFT is used to compute discrete Fourier transform.
To plot the frequency spectrum using the fft function in MATLAB, first compute the one-dimensional discrete Fourier transform using fft, provide the data series as an input. Then use the abs() function to get the magnitude spectrum, and plot the result using the plot() function, with the frequency domain on the x-axis and the magnitude spectrum on the y-axis.
FT is needed for spectrum analysis, FFT is fast FT meaning it is used to obtain spectrum of a signal quickly, the FFT algorithm inherently is fast algorithm than the conventional FT algorithm
Zoom FFT is a diagnostic tool for the detection of blood clots and other diseases. It is less costly than other techniques. Zoom FFT uses a low frequency to measure blood flow in order to find clots. A transmitter passes an ultrasonic wave through the blood vessels. A reflected signal is passed to a DSP processor. (This is similar to the Doppler technique.) The process is achieved with one DSP chip in order to keep the costs lower.
There's no need for it.
The commutator is used to convert the AC to DC
The commutator is used to convert the AC to DC
FFT is faster than DFT because no. of complex multiplication in DFT is N^2 while in FFT no. of complex multiplications are N/2(log2N). for example if N=8 no. of complex multiplications required in DFT are 64. while no. of complex multiplications required in FFT are 12 thus reduces computation time.
Food For Thought
Fast Fourier Transform
hi.... for DIT fft algorithm, refer to this link, it has c-code for that. http://cnx.org/content/m12016/latest/