Window functions and the Fourier transform

1. What is window in Fourier transform?
2. Why is windowing function used in FFT?
3. What does a windowing function do?

What is window in Fourier transform?

A window function provides a weighted selection of a portion of a time waveform for fast Fourier transform (FFT) analysis. It is generated by multiplying the original time waveform by a user-defined window function of some width. In this case, width equals two times the number of analysis lines.

Why is windowing function used in FFT?

You can minimize the effects of performing an FFT over a noninteger number of cycles by using a technique called windowing. Windowing reduces the amplitude of the discontinuities at the boundaries of each finite sequence acquired by the digitizer.

What does a windowing function do?

Window functions perform calculations on a set of rows that are related together. But, unlike the aggregate functions, windowing functions do not collapse the result of the rows into a single value. Instead, all the rows maintain their original identity and the calculated result is returned for every row.